Short message based precise point positioning method, device and medium with fixed ambiguity

Abstract

Provided are a short message-based fixed ambiguity precise point positioning method, device and medium, and a method, device and medium for providing the same. The method comprises: obtaining, by a user terminal, initial coordinates of a station, selecting a system frequency band, and sending to the system via short message communication; converting, by the system terminal, the SSR orbit clock correction number of a satellite into an OSR comprehensive correction number in the line-of-sight direction of the station-satellite; performing polynomial coefficient fitting on the OSR comprehensive correction number in a predetermined time period by the system terminal to obtain polynomial coefficients, estimating phase fraction offset products of the frequency points, encoding them, and sending them to the user terminal via short message communication; broadcasting, by the system terminal, the OSR comprehensive correction number of the latest epoch to the user terminal via short message communication; extrapolating, by the user terminal, the OSR comprehensive correction number via the polynomial coefficients to obtain the extrapolated current epoch OSR comprehensive correction number, and combining the phase fraction offset products to achieve fixed ambiguity precise point positioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of satellite positioning, and more particularly, to a method, an electronic device and a non-transitory storage medium for implementing precise point positioning of a fixed ambiguity of a multi-system based on a satellite short message by a system end and / or a user end. BACKGROUND

[0002] A satellite positioning system is a technology for accurately positioning an object using a satellite, and can implement functions such as navigation, positioning, and time service.

[0003] A global navigation satellite system (GNSS) uses satellite signals to determine the geographical coordinates of a satellite signal receiver. Currently, the global navigation satellite system mainly includes a global positioning system (GPS), a Galileo global positioning system (Galileo), a Glonass global satellite navigation system (Glonass), a Beidou satellite navigation system (BDS), and the like. Because various interference factors, such as the interference of the ionosphere and the troposphere, will cause a delay in the transmission of satellite signals, resulting in a positioning error of the global positioning system in the range of about ten meters.

[0004] In order to further improve the positioning accuracy of the global positioning system, a precise point positioning algorithm (PPP) as an important means of high-precision absolute positioning in the field of positioning and navigation, based on precise orbit and clock error products, can achieve decimeter-centimeter level positioning accuracy. A user end can use the carrier phase and ranging pseudo-code observation values of a GNSS receiver to achieve high-precision positioning. The PPP technology can obtain accurate positioning results through accurate modeling of satellite positioning errors and broadcasting to the user end, and can also obtain accurate positioning results through satellite links without relying on the Internet. In the PPP, the position and clock error of the satellite are extracted and processed separately. Commonly used are precise ephemeris and precise clock error products of the International GNSS Service (IGS), and the corresponding errors are also more refined, for example, the ionosphere is used as a no-ionosphere combination, and the troposphere error is estimated as a parameter.

[0005] The PPP observation equation based on the no-ionosphere combination is as follows:

[0006]

[0007] wherein each parameter is:

[0008] The pseudorange no-ionosphere combination observation value of the receiver (user end) r for the satellite j is subtracted from the geometric distance from the satellite to the receiver.

[0009] Direction vector between satellite j and receiver r;

[0010] Ar: Position correction vector of receiver (to be solved);

[0011] c: Speed of light;

[0012] Receiver clock error;

[0013] Projection coefficient of zenith tropospheric delay;

[0014] d trop,r : Zenith tropospheric delay;

[0015] Pseudo-range observation noise;

[0016] Phase ionosphere-free combination observation of receiver r for satellite j minus geometric distance from satellite to receiver;

[0017] Ambiguity of ionosphere-free combination;

[0018] Carrier observation noise.

[0019] Real-time PPP relies on the real-time orbit clock error products provided by the International GNSS Service (IGS) and its subordinate Multi-GNSS Experiment (MGEX) to restore real-time precise orbit clock error by correcting it to the broadcast ephemeris broadcast by the satellite. At present, the analysis centers that provide real-time orbit clock correction products mainly include: French National Space Research Center (CNES), German Geoscience Center (GFZ), German Aerospace Center (DLR), Chinese Academy of Sciences (CAS), Wuhan University (WHU), Federal Office for Cartography and Geodesy (BKG), Shanghai Astronomical Observatory (SHA) and the like. The products of each analysis center are broadcast according to the International Maritime Radio Technical Commission (RTCM) agreement through network data stream.

[0020] However, how to make the user end real-time fast precise positioning is still a problem to be improved. SUMMARY

[0021] According to an aspect of the present application, a method for implementing multi-system fixed ambiguity precise point positioning based on satellite short message by a system end and a user end is provided, comprising: obtaining initial station coordinates by the user end, selecting a system frequency band, and sending the initial station coordinates of the user end and the system frequency band selection to the system; obtaining the initial station coordinates of the user end and the system frequency band selection by the system end through short message communication; converting state space representation SSR orbit and clock correction numbers of a plurality of satellites observable by the user end into observation space representation OSR comprehensive correction numbers in station-satellite line-of-sight direction according to the initial station coordinates sent by the user end by the system end; performing polynomial coefficient fitting on the observation space representation OSR comprehensive correction numbers within a predetermined time period to obtain polynomial coefficients of the plurality of satellites by the system end for the plurality of satellites, estimating phase decimal bias products of frequency points selected by the system frequency band selection by the system end for the plurality of satellites, encoding and broadcasting the polynomial coefficients of the plurality of satellites and the phase decimal bias products of the frequency points to the user end; broadcasting the OSR comprehensive correction numbers of the nearest epoch of the plurality of satellites to the user end by the system end through short message communication by one or more epochs in turn; receiving and decoding the OSR comprehensive correction numbers of the nearest epoch of the plurality of satellites by the user end through short message communication, extrapolating the OSR comprehensive correction numbers of the nearest epoch of the plurality of satellites by the received polynomial coefficients of the plurality of satellites to obtain the OSR comprehensive correction numbers of the current epoch of the plurality of satellites, correcting errors of satellite coordinates and satellite clock bias in satellite-station direction by the OSR comprehensive correction numbers of the current epoch, and correcting satellite end phase decimal bias by the phase decimal bias products to implement fixed ambiguity precise point positioning.

[0022] According to another aspect of the present application, a method for implementing correction number broadcasting of multi-system fixed ambiguity precise point positioning based on satellite short message by a system end is provided, comprising: obtaining initial station coordinates of the user end and system frequency band selection by the system end through short message communication; converting state space representation SSR orbit and clock correction numbers of a plurality of satellites observable by the user end into observation space representation OSR comprehensive correction numbers according to the initial station coordinates sent by the user end by the system end; performing polynomial coefficient fitting on the observation space representation OSR comprehensive correction numbers within a predetermined time period to obtain polynomial coefficients of the plurality of satellites by the system end for the plurality of satellites, estimating phase decimal bias products of frequency points selected by the system frequency band selection by the system end for the plurality of satellites, encoding and broadcasting the polynomial coefficients of the plurality of satellites and the phase decimal bias products of the frequency points to the user end; broadcasting the OSR comprehensive correction numbers of the nearest epoch of the plurality of satellites to the user end by the system end through short message communication by one or more epochs in turn.

[0023] According to another aspect of the present application, there is provided a method for implementing multi-system precise point positioning with fixed ambiguity based on satellite short message by a user terminal, comprising: obtaining initial station coordinates by the user terminal, selecting a system frequency band, and sending the initial station coordinates of the user terminal and the system frequency band selection to a system terminal through short message communication; receiving and decoding polynomial coefficients of multiple satellites sent by the system terminal through short message communication by the user terminal, wherein the polynomial coefficients of the multiple satellites are obtained by at least the following steps: converting, by the system terminal, state space representation (SSR) orbit clock correction numbers of the multiple satellites observable by the user terminal into observation space representation (OSR) integrated correction numbers in the station-satellite line-of-sight direction according to the initial station coordinates sent by the user terminal; performing polynomial coefficient fitting on the observation space representation (OSR) integrated correction numbers in a predetermined time period to obtain the polynomial coefficients of the multiple satellites by the system terminal for the multiple satellites; receiving, by the user terminal, phase fractional offset products of the frequency points selected by the system frequency band selection estimated and encoded by the system terminal through short message communication; receiving, by the user terminal, OSR integrated correction numbers of the nearest epochs of the multiple satellites broadcast by the system terminal through short message communication through one or more epochs; extrapolating, by the user terminal, the OSR integrated correction numbers of the nearest epochs of the multiple satellites based on the received polynomial coefficients of the multiple satellites to obtain the current OSR integrated correction numbers of the multiple satellites, correcting the errors of satellite coordinates and satellite clock errors in the satellite-station direction through the current OSR integrated correction numbers, and correcting the satellite-end phase fractional offset through the phase fractional offset products, so as to implement precise point positioning with fixed ambiguity.

[0024] According to another aspect of the present application, there is provided an electronic device, comprising: a memory for storing instructions; and a processor for reading the instructions in the memory and performing the method according to various embodiments of the present application.

[0025] According to another aspect of the present application, there is provided a non-transitory storage medium having instructions stored thereon, wherein the instructions, when read by a processor, cause the processor to perform the method according to various embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure or the prior art, hereinafter, a brief introduction will be given to the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0027] Figure 1 A scenario diagram of a satellite positioning system according to embodiments of the present application is shown.

[0028] Figure 2 A flowchart of a method of generating, encoding and broadcasting corrections for real-time multi-system fixed ambiguity precise point positioning applicable to Beidou short message system according to embodiments of the present application is shown.

[0029] Figure 3 An example diagram of corrections for certain epochs is shown.

[0030] Figure 4 A diagram of the number of available satellites for each epoch compared to the number of available satellites for traditional single system solution is shown.

[0031] Figure 5 A comparison of results of user end positioning verification using the broadcasted corrections in embodiments of the present application and traditional broadcasted positioning verification results is shown.

[0032] Figure 6 A flowchart of a method of implementing multi-system fixed ambiguity precise point positioning based on satellite short messages by a system end and a user end according to embodiments of the present application is shown.

[0033] Figure 7 A flowchart of a method of broadcasting corrections for implementing multi-system fixed ambiguity precise point positioning based on satellite short messages by a system end according to embodiments of the present application is shown.

[0034] Figure 8 A flowchart of a method of implementing multi-system fixed ambiguity precise point positioning based on satellite short messages by a user end according to embodiments of the present application is shown.

[0035] Figure 9 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present application is shown.

[0036] Figure 10 A diagram of a non-transitory computer readable storage medium according to embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0037] Reference will now be made in detail embodiments of the present application, examples of which are illustrated in the accompanying drawings. While the present application will be described in conjunction with the embodiments, it will be understood that the present application is not limited to the described embodiments. Rather, the present application is intended to cover alternatives, modifications and equivalents, which can be included within the spirit and scope of the present application as defined by the appended claims. It should be noted that the steps of the methods described herein can all be implemented by any functional block or functional arrangement, and any functional block or functional arrangement can be implemented as a physical entity or a logical entity, or a combination of both.

[0038] Traditional PPP techniques usually require an initial positioning time of ten to several tens of minutes to converge to centimeter-level accuracy. This is because GNSS uses medium earth orbit (MEO) satellite orbits that are high and have slow geometric changes, making the correlation of observations at similar epochs strong, resulting in poor ambiguity precision for a short time. It takes ten to several tens of minutes to fix the ambiguity. Such a long time obviously cannot meet the requirements of high real-time and high-precision applications such as unmanned aerial vehicle flight control, agricultural machinery navigation, and intelligent driving.

[0039] The precise point positioning ambiguity resolution (PPP-AR) is a precise point positioning ambiguity resolution algorithm. Compared with the traditional precise point positioning float solution positioning algorithm, the significant advantage of ambiguity resolution is that it can provide faster convergence speed and higher positioning convergence accuracy, especially in the east (E) direction of the station north east up (NEU) coordinate system. Compared with the traditional real-time PPP float solution, real-time PPP-AR requires not only real-time orbit clock difference products but also system-side real-time calculation of satellite-side phase hardware delay (uncalibrated phase delay, UPD) and broadcast of the UPD together with real-time precise orbit clock difference information to the user side (in the full text, also known as the station or receiver (end)).

[0040] When using the UPD method to estimate the satellite-side wide lane UPD, the observation equation is as follows:

[0041]

[0042] wherein the meanings of the various parameters are as follows:

[0043] L wl : wide lane observation value of carrier phase;

[0044] λ w : wavelength of wide lane observation value;

[0045] N w : wide lane integer ambiguity;

[0046] b r,i : receiver-side phase hardware delay of the i-th frequency point, i being, for example, 1, 2;

[0047] satellite-side phase hardware delay of the i-th frequency point;

[0048] d r,i : receiver-side pseudorange hardware delay of the i-th frequency point;

[0049] Hardware delay of satellite end pseudo-range of the i-th frequency point;

[0050] λ i : wavelength of the original observation value of the i-th frequency point;

[0051] λ n : wavelength of the narrow-lane observation value.

[0052] The system estimates the wide-lane UPD using multiple stations, and the equation is as follows:

[0053]

[0054] Wherein, the meanings of various parameters are as follows:

[0055] UPD wl : phase decimal deviation of the wide-lane ambiguity;

[0056] Wide-lane floating ambiguity;

[0057] N wl : integer ambiguity of the wide-lane;

[0058] Rounding the floating value of the wide-lane ambiguity.

[0059] The real ambiguity of the ionosphere-free combination (IF, Ionosphere-free Combination) can be expressed as follows:

[0060]

[0061] Wherein, the meanings of various parameters are as follows:

[0062] Ambiguity of the ionosphere-free combination;

[0063] f i : frequency of the i-th frequency point, i is for example 1, 2;

[0064] Narrow-lane floating ambiguity;

[0065] Wide-lane floating ambiguity.

[0066] In the above formula, and For the float ambiguity, combined with the wide-lane UPD calculated above, all the wide-lane ambiguities can be obtained by using the Least square AMBiguity Decorrelation Adjustment (LAMBDA) method. If the fixed wide-lane integer ambiguity is substituted, the corresponding wide-lane float part is forced to be assigned to the narrow-lane, and the above equation can be expressed as:

[0067]

[0068] The meanings of various parameters are as follows:

[0069] Ionosphere-free combined ambiguity;

[0070] f i : frequency of the i-th frequency point, i is for example 1, 2;

[0071] Narrow-lane float ambiguity;

[0072] N WL : wide-lane integer ambiguity.

[0073] Similar to the wide-lane UPD product estimation, when estimating the narrow-lane UPD, a set of relatively accurate narrow-lane UPD initial values should be determined first, and then the Kalman filter is used to obtain accurate narrow-lane UPD estimation values. After the wide-lane and narrow-lane UPD are estimated, the system end can convert it into a single frequency point UPD through linear transformation and broadcast it to the user.

[0074] The user end receives the UPD parameters of each frequency point broadcast by the system end, respectively, and changes them into the wide-lane observation equation and the ionosphere-free combined observation equation, fixes the wide-lane integer ambiguity and eliminates the satellite end phase decimal bias in the non-difference ionosphere-free combined observation equation. The non-difference ionosphere-free combined observation equation is shown as follows:

[0075]

[0076] The meanings of the parameters are as follows:

[0077] The ionosphere-free combined observation value of the receiver (user end) r for the satellite j;

[0078] The phase observation value of the receiver (user end) r for the satellite j (the j-th satellite);

[0079] The geometric distance between the satellite j and the receiver r;

[0080] c: light speed;

[0081] dt r : clock bias of receiver r;

[0082] dt j : clock bias of satellite j;

[0083] projection coefficient of zenith tropospheric delay;

[0084] d trop,r : zenith tropospheric delay;

[0085] pseudorange observation noise;

[0086] λ IF : ionosphere-free combined wavelength;

[0087] ionosphere-free combined ambiguity;

[0088] B IF,r : receiver-end pseudorange hardware delay;

[0089] satellite-end pseudorange hardware delay;

[0090] b IF,r : receiver-end phase hardware delay;

[0091] satellite-end phase hardware delay;

[0092] δOSR j : OSR combined correction;

[0093] The formula for calculating the OSR combined correction is:

[0094]

[0095] wherein, is the polynomial coefficient received by the user from the receiver end;

[0096] ionosphere-free combined ambiguity;

[0097] carrier observation noise.

[0098] The ionosphere-free combined observation equation is further eliminated by the inter-satellite difference of the receiver-end phase hardware delay, and the inter-satellite single-difference observation equation is as follows:

[0099]

[0100] represents the inter-satellite single-difference of the value.

[0101] λ IF : ionosphere-free combined wavelength;

[0102] ionosphere-free combined ambiguity of satellite j;

[0103] ionosphere-free combined pseudorange observation of receiver (user end) r for satellite j;

[0104] phase observation of receiver (user end) r for satellite j (jth satellite);

[0105] geometric distance between satellite j and receiver r;

[0106] c: speed of light;

[0107] dt r : clock bias of receiver r;

[0108] dt j : clock bias of satellite j;

[0109] projection coefficient of zenith tropospheric delay between satellite j and receiver r;

[0110] d trop,r : zenith tropospheric delay of receiver r;

[0111] pseudorange observation noise of receiver (user end) r for satellite j;

[0112] phase observation noise of receiver (user end) r for satellite j;

[0113] phase hardware delay of satellite j;

[0114] δOSR j : OSR integrated correction number of satellite j.

[0115] The ionosphere-free combined ambiguity is obtained by fixing narrow-lane ambiguity through LAMBDA method and combining with the fixed wide-lane integer ambiguity, and the fixed solution of user end position is obtained by substituting the ionosphere-free combined ambiguity into the observation equation to re-estimate the receiver coordinates.

[0116] In addition to the UPD method described above, the clock difference can be re-estimated by an integer clock estimation method (Integer Recovery Clocks, IRC), and the clock difference based on the phase is used instead of the clock difference based on the pseudo-range provided by IGS. At this time, the system end only needs to broadcast the wide lane ambiguity to realize the user end ambiguity fixing.

[0117] The Beidou short message communication system (Short Message Communication, SMC) provides three basic services of location reporting, emergency search and rescue, and message communication services, and can interconnect with other information systems. Other business applications are based on these three basic services. Among them, the message communication service provides three message services of end-to-end two-way message communication, multicast and broadcast communication.

[0118] Since the short message system does not depend on the Internet, it can be used under the condition of no Internet and no real-time kinematic (RTK) reference station nearby, so it can realize communication in multiple scenarios without relying on the Internet. However, due to the small amount of communication data under the short message communication mode, for example, the short message of Beidou satellite can broadcast 560 bits or 624 bits at a time, it is not possible to well transmit the satellite orbit clock correction number and phase decimal bias product and clock product required by the satellite positioning system, therefore, the traditional short message communication mode will not be used for satellite-based user positioning.

[0119] The applicant thought of using the characteristics of the Beidou No. 3 medium earth orbit (MEO) satellite orbit coverage, taking advantage of the interconnection and intercommunication of constellation satellites, based on the existing resource margin on the satellite, integrating various user demands, innovating technical systems and working modes, and based on short message precise differential positioning, it can improve user positioning accuracy and integrity in a wider geographical area or even range, has the advantages of high user compatibility, large coverage, good concealment, etc., at the same time, without the need to increase additional differential data link, convenient to use, has important significance for ensuring high safety, high reliability and high precision of positioning in special combat scenarios.

[0120] The obstacle of realizing differential positioning based on short message system is that satellite resource is limited, which results in limited frequency and bandwidth of broadcasting differential correction. Taking the short message broadcasting and receiving terminal equipment produced by Beijing Shenzhou Tianhong Science and Technology Co., Ltd. as an example, the maximum broadcasting quantity of a single time supported by a three-level integrated circuit (IC) card is 560 bits, and the shortest broadcasting interval is 60 seconds. In the most widely used RTCM-SC-104 network differential correction broadcasting protocol, the satellite data length of radial, tangential and normal correction numbers of GPS satellite and clock error correction number is 22 bits, 20 bits, 20 bits and 22 bits respectively, the total length of correction numbers of each satellite is 92 bits, and the broadcasting interval based on network can reach 5 seconds. Obviously, it is difficult to realize real-time precise positioning of multiple systems by using RTCM-SC-104 broadcasting protocol in short message terminal, and it is also impossible to realize ambiguity fixing of user end by broadcasting UPD of satellite end. Therefore, an effective correction number generation, encoding and broadcasting strategy is needed to realize real-time ambiguity fixing algorithm of multiple systems based on short message system (such as Beidou satellite).

[0121] The present application uses real-time orbit and clock correction numbers broadcasted by network data stream and global IGS station observation data, and focuses on the overall structure of precise differential positioning system based on (Beidou) short message system, designs the differential correction information generation, parameter encoding method and broadcasting strategy, and further improves the precision and reliability of real-time precise differential positioning based on short message system.

[0122] Figure 1 A schematic diagram of a scene of a satellite positioning system according to an embodiment of the present application is shown.

[0123] The system end communicates with Beidou satellite BDS through short message communication, for example, sends correction information such as correction numbers, polynomial coefficients, phase fractional offset products to Beidou satellite, and Beidou satellite can forward correction information such as correction numbers, polynomial coefficients, phase fractional offset products to user end through short message communication. The user end (or station or receiver) obtains initial coordinates and other information of the station by observing multiple GNSS satellites to obtain observation data. The user end can also send information to be forwarded to the system end to Beidou satellite through short message communication of Beidou satellite, such as initial coordinates and frequency point selection information of user end. And the user end performs precise point positioning such as ambiguity fixing of each embodiment of the present application by using correction numbers, polynomial coefficients, phase fractional offset products or clock products sent by Beidou satellite through short message communication to obtain precise position information of user end.

[0124] The whole process will be described in detail by subsequent drawings.

[0125] The application provides a correction number generation, coding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning of a Beidou short message system. The main features are that the high-frequency state space representation (SSR) orbit clock correction number is projected in the user-satellite line-of-sight direction to become an observation space representation (OSR) comprehensive correction number, thereby reducing the number of bytes occupied by the broadcast correction number while not losing too much information; the OSR comprehensive correction number in the user-satellite line-of-sight direction is polynomial fitted to generate polynomial coefficient parameters, thereby enabling the current OSR comprehensive correction number to be derived from the polynomial coefficient parameters and the historical time OSR comprehensive correction number (without the need to obtain (usually cannot be obtained in real time) the current OSR comprehensive correction number in real time), thereby improving the available time length of the correction number; the fitting polynomial coefficients of the OSR comprehensive correction number of the user-satellite line-of-sight of each system satellite and the phase fractional offset product are broadcast to the user end in a multi-epoch rotation coding and broadcasting manner through short message communication; the user end receives and decodes the OSR comprehensive correction number through short message communication, stores the fitting polynomial coefficients of the satellite OSR comprehensive correction number received in the previous epochs and the phase fractional offset product, for example, uses the fitting polynomial coefficients to extrapolate the received OSR comprehensive correction number to obtain the predicted OSR comprehensive correction number of the current epoch, and combines the phase fractional offset product decoded in the current epoch, thereby realizing real-time multi-system fixed ambiguity precise point positioning of the user end.

[0126] Figure 2 A flowchart of the correction number generation, coding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning of a (Beidou) short message system according to the embodiment of the application is shown.

[0127] Referring to Figure 2 The implementation process of the correction number generation, coding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning of a (Beidou) short message system is as follows:

[0128] In step 201, the system end receives the state space representation (SSR) orbit clock correction number in real time; receives global IGS station observation data and calculates the multi-system satellite end phase fractional offset (product) in real time. The state space representation SSR means that each positioning error of the GNSS satellite is described independently.

[0129] In step 202, the user terminal obtains the initial coordinates of the station (user) by, for example, pseudo-single point positioning, and the user terminal selects the frequency points of each system.

[0130] In step 203, the user terminal encodes the initial coordinates of the user and the frequency point selection information, and sends them to the system terminal through short message communication (of the Beidou satellite).

[0131] In step 204, the system terminal receives and decodes the initial coordinates of the user and the frequency point selection information of the system frequency band selection.

[0132] The system terminal obtains the initial approximate coordinates of the user and the frequency point selection information of the system frequency band selection through short message communication. The encoding format of the short message communication from the user terminal to the system terminal can be specified as shown in the following table:

[0133]

[0134]

[0135] Wherein, GPSWeek represents the global positioning system GPS week, GPSSec represents the GPS second, X(ECEF) represents the X axis of the Earth-Centered Earth-Fixed coordinate system ECEF, Y(ECEF) represents the Y axis of the Earth-Centered Earth-Fixed coordinate system ECEF, Z(ECEF) represents the Z axis of the Earth-Centered Earth-Fixed coordinate system ECEF, GPS frequency point represents the frequency point combination of the global positioning system GPS used by the user terminal during positioning, BDS frequency point represents the frequency point combination of the Beidou satellite navigation system BDS used by the user terminal during positioning, and Galileo frequency point represents the frequency point combination of the Galileo system used by the user terminal during positioning.

[0136] In step 205, the system terminal projects the SSR orbit clock correction number to the user line-of-sight direction (station-satellite line-of-sight direction or user-satellite line-of-sight direction) according to the initial coordinates of the user and the frequency point selection information, to generate the OSR (integrated) correction number. The observed space means that one correction number is used to integrate all positioning errors.

[0137] Because the data volume of the (integrated) correction number in the user line-of-sight direction is small, and the information contained is more suitable for the user terminal, while ensuring that the data volume is small enough to be sent and received through the Beidou satellite short message communication mode, the relative useful information of the correction number is also ensured to facilitate the subsequent real-time multi-system fixed ambiguity precise point positioning of the user terminal.

[0138] Wherein, the phase decimal bias (UPD) of each satellite of each system at each frequency point is estimated in real time, and the SSR real-time clock correction number of the user terminal visible satellite is converted into the station-satellite line-of-sight direction OSR integrated correction number according to the initial coordinates of the user.

[0139] Step (1): Calculate real-time orbit correction number δO in satellite coordinate system;

[0140] Step (2): Calculate real-time clock difference correction number δC s ;

[0141] Step (3): Convert δO calculated in step (1) from satellite coordinate system to δX in ECEF geocentric coordinate system s ;

[0142] Step (4): Convert δX s , δC s in step (2), step (3) to station-satellite line-of-sight direction comprehensive correction number δOSR s .

[0143] In step (1), real-time orbit correction number δO in satellite coordinate system is calculated, and the formula is as follows:

[0144]

[0145] Wherein, δO r , δO a , δO c are radial, tangential and normal correction numbers of the satellite in satellite coordinate system respectively, are radial, tangential and normal velocities of the satellite in satellite coordinate system respectively. t is the current time, and t0 is the SSR ephemeris reference time.

[0146] In step (2), real-time clock difference correction number δC s is calculated, and the formula is as follows:

[0147] δC s = C0+C1·(t-t0)+C2·(t-t0) 2

[0148] Wherein, C0, C1 and C2 are constant term, first term and second term in clock difference fitting polynomial respectively. t is the current time, and t0 is the SSR ephemeris reference time.

[0149] In step (3), real-time SSR orbit correction number δO is converted from satellite coordinate system to δX in ECEF geocentric coordinate system s , and the formula is as follows:

[0150] δX s =[e r ,e a ,e c ]·δO

[0151]

[0152] where r and v are the position and velocity coordinates of the satellite in ECEF, respectively, which can be obtained from the broadcast ephemeris. r is the radial vector in the satellite coordinate system, e a is the tangential vector in the satellite coordinate system, e c is the vector in the direction determined by the right-hand rule in the satellite coordinate system.

[0153] In step (4), the δX s , δC s are converted into the observation space representation OSR comprehensive correction δOSR s in the direction of the line of sight from the station to the satellite, as follows:

[0154] δOSR s = c · δC s - e · δX s

[0155] where c is the speed of light, e is the unit vector from the station to the satellite, and is obtained from the previously obtained user initial position (i.e., the user approximate position) and the satellite coordinates. That is,

[0156]

[0157] where r' is the geometric distance from the satellite to the user end, x s , y s , z s are the three-dimensional coordinates of the satellite, and x r′ , y r′ , z r′ are the three-dimensional coordinates of the station initial coordinates.

[0158] In step 206, the system end performs polynomial fitting on the OSR comprehensive corrections in a period of time to obtain polynomial coefficients.

[0159] Here, after the system end sends the current OSR comprehensive correction measured by the system end itself to the user end, the user end needs a certain time to receive, and there is a certain delay. Therefore, after the delay, the actual real-time correction will change. Here, the system end performs polynomial fitting on the OSR comprehensive corrections measured by the system end in a period of time to obtain polynomial coefficients, i.e., to obtain the change rule of the OSR comprehensive corrections in a period of time, so that the polynomial coefficients (the change rule in a period of time) can be used to infer what value the OSR comprehensive correction will change to when the user end receives the OSR comprehensive correction sent by the system end according to the change rule, so that the user end can use the OSR comprehensive correction closer to the current time of the user end, thereby improving the positioning accuracy and increasing the available time length of the correction.

[0160] ​Taking the first-order polynomial fitting as an example, the OSR correction numbers in the accumulated time length are fitted by the first-order polynomial to obtain the constant term a0 and the first-order term coefficient a1, including:

[0161] The estimated formula is as follows: s The correction number fitting is a polynomial coefficient of multiple satellites including the constant term a0 and the first-order term coefficient a1:

[0162]

[0163] t1…t n is each time in a predetermined time period in time sequence, is the observation space of each time t1…t n in the station-satellite line-of-sight direction.

[0164] Here, the multiple correction numbers can be fitted into a first-order polynomial, so the polynomial parameters are two parameters of the constant term a0 and the first-order term coefficient a1. That is, it is considered that the relationship between the multiple correction numbers is a linear relationship, and the multiple correction numbers are fitted into a linear straight line. However, the present application is not limited thereto, and the multiple correction numbers can also be fitted into a second-order, third-order, …, or N-order (N is a positive integer) polynomial, and the polynomial parameters can also correspond to these orders of polynomials. That is, it can be considered that the multiple OSR comprehensive correction numbers are a nonlinear relationship, and the multiple OSR comprehensive correction numbers are fitted into a curve and the like, as long as the variation law of the OSR comprehensive correction number in a period of time is obtained.

[0165] In linear fitting, when the broadcast ephemeris switching occurs at the whole hour, it can cause the jump of the SSR correction before and after the switching time. At this time, the ephemeris before and after the jump cannot be directly fitted, and it is necessary to reduce the δOSR s correction to the last broadcast ephemeris to ensure the continuity of the fitting. When the broadcast ephemeris is switched from BRDM1 to BRDM2, the δOSR s′ after the jump is reduced to the formula of δOSR s .

[0166] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0167] Wherein, Coor BRDM1 is the satellite coordinates calculated using the set of ephemeris before switching; Coor BRDM2 is the satellite coordinates calculated using the set of ephemeris after switching.

[0168] Before enough SSRs under new IODEs are fitted in the sample, the above formula is used to convert δOSR under new IODE s However, when all IODEs are consistent in the fitting sample, the IODE of the broadcast ephemeris can be switched, and no conversion of δOSR is needed s .

[0169] In step 207, the system end encodes the polynomial coefficients, phase fractional offset products and other information of each satellite according to the encoding format.

[0170] Here, the encoding can further reduce the size of the data to be transmitted, thereby satisfying the information transmission and reception by short message communication. Of course, the short message communication is a unique communication mode of the Beidou satellite, but the application is not limited to the short message system of the Beidou satellite, and any satellite short message communication mode with small data transmission and independent of the Internet can be used.

[0171] The overall information encoding requirements for the system end to send information are shown in the following table:

[0172]

[0173] Among them, the information content part is the encoding part of the OSR comprehensive correction number of the nearest epoch of the plurality of satellites, and according to the bandwidth limitation of the Beidou non-classified user 3-level IC card, the information content is not more than 560 bits. Of course, the maximum number of bits is not necessarily limited to 560 bits, but can be other values according to the bandwidth limitation. The encoding requirements in the above table are only an example, and in fact other encoding methods can be used, including the content and bit number limitation can be different according to the actual situation. However, limiting the content and the number of bits can make the encoded information more suitable for short message communication with small bandwidth.

[0174] Encode the correction information of the current epoch: encode the time identifier of the epoch difference correction number in the form of a header file. The encoding method of the header file information is shown in the following table:

[0175] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0176] GPSWeek represents the global positioning system GPS week, and GPSSec represents GPS seconds. Here, the satellite number parameter is added to the header file, because the number of satellites sent by the system end is not necessarily the maximum value, and the user end needs to know how many satellites are included in advance to correctly decode when receiving the correction number information. The previously obtained polynomial coefficients of the fitting of each OSR comprehensive correction number are encoded together with the satellite system information, satellite number, and IODE of the satellite difference information.

[0177] When using the UPD method, the encoding of the correction number of a single satellite is shown in the following table:

[0178]

[0179]

[0180] Where the satellite system information is represented as what system the satellite is, for example, a GPS system, a BDS system, or a Galileo system. The satellite number PRN can be, for example, 01, 02, 03, …. The symbol G01 can be used to identify the 01 satellite of the GPS system.

[0181] Under this scheme, the correction number of a single satellite broadcast occupies a total of 77 bits. According to the bandwidth limit of the Beidou non-classified user 3rd IC card, the correction number of a maximum of 7 satellites can be broadcast each time. Of course, the present application is not limited to this encoding method and this bit number. Such a bit number limit is only to broadcast as many satellite correction numbers as possible each time under the bit number limit of short message communication while ensuring the amount of information.

[0182] When using the IRC method, the encoding method is shown in the following table (taking the first-order polynomial fitting parameter as an example):

[0183]

[0184] Under this scheme, the correction number of a single satellite broadcast occupies a total of 61 bits. According to the bandwidth limit of the Beidou non-classified user 3rd IC card, the correction number of a maximum of 9 satellites can be broadcast each time. Of course, the present application is not limited to this encoding method and this bit number. Such a bit number limit is only to broadcast as many satellite correction numbers as possible each time under the bit number limit of short message communication while ensuring the amount of information.

[0185] In this way, the bit amount of the broadcast information after encoding is relatively small, and can adapt to the data amount requirement of short message communication of satellites such as Beidou satellites.

[0186] Where, since the single broadcast amount of short messages is limited, the correction numbers of more than 20 satellites of multiple systems cannot be broadcast all at once, and need to be broadcast over two to three epochs. The OSR comprehensive correction number of different satellites is broadcast each time. The user end needs to store the fitted polynomial coefficients of each satellite. The fitted polynomial coefficient parameter here refers to the latest received two polynomial coefficients a0, a1.

[0187] Figure 3 An example diagram of the correction information of some epochs encoded as described above is shown.

[0188] In Figure 3In the table, PG: GPS system, PE: GALILEO system, PC: Campass (Beidou) system. The last two numbers are satellite numbers, such as PG01 refers to the 01 satellite of GPS.

[0189] In step 208, the system end broadcasts the OSR comprehensive correction number of each satellite of multiple systems through short message communication in a multiple epoch round-robin manner.

[0190] This is because the time interval of an epoch is limited, and if the number of satellites is large, multiple epochs are required to round-robin broadcast the OSR comprehensive correction number of all satellites of multiple systems.

[0191] For example, all satellites that can be observed by the user end are broadcasted with the latest time OSR comprehensive correction number encoded in step 207 to the user in a multiple epoch round-robin manner. Under the condition that the satellite elevation angle is greater than 10°, the OSR comprehensive correction number can be broadcasted in the order of GPS, BDS, and GALILEO; and after all satellites are broadcasted, a new round of OSR comprehensive correction number is broadcasted.

[0192] As described above, the overall information encoding requirement of the system end sending information can be as shown in the following table:

[0193]

[0194] Among them, the information content includes the encoding part of the OSR comprehensive correction number of the nearest epoch of multiple satellites. Of course, the application is not limited to this encoding method and the number of bits. Such bit number limitation is only to broadcast more information each time under the bit number limitation of short message communication while ensuring the amount of information.

[0195] In step 209, the user end receives and decodes the OSR comprehensive correction number of the nearest epoch of each satellite.

[0196] In step 210, the user end interpolates the OSR comprehensive correction number of the nearest epoch through the fitted polynomial coefficients, that is, obtains the recovered OSR comprehensive correction number of the current time, thereby fixing the wide-lane ambiguity and calculating the ionosphere-free combined float solution.

[0197] In step 211, the user end performs multi-system precise point positioning and attempts to fix the narrow-lane ambiguity.

[0198] If the fixing is successful, the user end substitutes the integer ambiguity, obtains the ambiguity fixed solution coordinate, and takes it as the satellite positioning coordinate of the user end.

[0199] If the fixing fails, the user end outputs the float solution coordinate as the satellite positioning coordinate of the user end.

[0200] The user terminal receives and decodes the OSR combined corrections through short message communication, stores the fitting polynomial parameters of the satellite OSR combined corrections received at previous epochs and the phase fractional offset product, extrapolates the OSR combined corrections at the current epoch using the fitting polynomial parameters to obtain the OSR combined corrections at the current epoch, and combines the OSR combined corrections obtained at the current epoch to realize real-time precise point positioning with fixed ambiguity of multiple systems. Here, the phase fractional offset product is regarded as a constant in a short time and is not used for extrapolation. Specifically, the non-difference positioning model formula (for obtaining the position of the user terminal) is as follows:

[0201]

[0202] wherein T in the superscript is the time identifier of the latest OSR combined corrections, T-n in the superscript is the time identifier of the corrections at n epochs ago. n is a positive integer. The following parameter descriptions do not have superscripts, and the superscripts are added to the above time identifiers to indicate the time when the related parameters are obtained.

[0203] The inter-satellite differences are made for the parameters;

[0204] The ionosphere-free combined observation value of the pseudo-range of the receiver (user terminal) r for the satellite j;

[0205] The phase observation value of the receiver (user terminal) r for the satellite j (the jth satellite);

[0206] The geometric distance between the satellite j and the receiver r;

[0207] c: the speed of light;

[0208] dt r : the clock error of the receiver r;

[0209] dt j : the clock error of the satellite j;

[0210] The projection coefficient of the zenith tropospheric delay between the satellite j and the receiver r;

[0211] d trop,r : the zenith tropospheric delay of the receiver r;

[0212] λ IF : the ionosphere-free combined wavelength;

[0213] The ionosphere-free combined ambiguity of the satellite j;

[0214] Receiver (user end) r's pseudorange observation noise for satellite j;

[0215] Receiver (user end) r's phase observation noise for satellite j;

[0216] Phase hardware delay of satellite j;

[0217] OSR comprehensive correction number of satellite j at time T.

[0218] For the correction information obtained by decoding the previous epoch stored by the user end, whenever a new OSR comprehensive correction number of a satellite is received, the old OSR comprehensive correction number is replaced by the new OSR comprehensive correction number and the time information thereof is recorded; when the polynomial coefficient parameters are used for extrapolation, the extrapolation error increases with the increase of the extrapolation time, which reduces the user accuracy, therefore, a threshold of the extrapolation time is set, for example, 5 minutes, so that the OSR comprehensive correction number exceeding 5 minutes is not used, so as to ensure the reliability of the OSR comprehensive correction number.

[0219] The user end uses the first-order polynomial coefficient and phase decimal deviation product broadcast by the present application to perform positioning calculation, Figure 4 A graph showing the number of satellites available at each epoch according to the embodiment of the present application compared with the number of satellites available for traditional single system calculation is shown, which shows that more available satellites can be calculated by using the embodiment of the present application; Figure 5 The results of user end positioning verification using the correction number broadcast in the embodiment of the present application are compared with the results of traditional broadcast positioning verification, it can be seen that the results of user end positioning according to the embodiment of the present application are more stable and have smaller error.

[0220] Figure 6 A flow chart of a method 600 for implementing precise point positioning of multiple systems with fixed ambiguity based on satellite short message by the system end and the user end according to the embodiment of the present application is shown.

[0221] As Figure 6As shown, a method 600 for implementing multi-system precise point positioning with fixed ambiguity based on satellite short message by a system end and a user end includes: step 610, obtaining initial station coordinates by the user end, selecting a system frequency band, and sending the initial station coordinates of the user end and the system frequency band selection to the system; step 620, obtaining the initial station coordinates of the user end and the system frequency band selection by the system end through short message communication; step 630, converting the state space representation SSR orbit clock correction number of the plurality of satellites observable by the user end into observation space representation OSR comprehensive correction number in the station-satellite line of sight direction according to the initial station coordinates sent by the user end by the system end; step 640, polynomial coefficient fitting of the observation space representation OSR comprehensive correction number in a predetermined time period to obtain the polynomial coefficients of the plurality of satellites by the system end for the plurality of satellites, estimating the phase fraction offset product of the frequency point selected by the system frequency band selection, encoding and broadcasting the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point to the user end by the system end; step 650, broadcasting the OSR comprehensive correction number of the nearest epoch of the plurality of satellites to the user end by the system end through short message communication through one or more epochs in turn; step 660, receiving and decoding the OSR comprehensive correction number of the nearest epoch of the plurality of satellites by the user end through short message communication, extrapolating the OSR comprehensive correction number of the nearest epoch of the plurality of satellites through the received polynomial coefficients of the plurality of satellites to obtain the predicted OSR comprehensive correction number of the current epoch of the plurality of satellites, correcting the errors of satellite coordinates and satellite clock bias in the satellite-station direction through the OSR comprehensive correction number of the current epoch, and correcting the satellite end phase fraction offset through the phase fraction offset product, to realize precise point positioning with fixed ambiguity.

[0222] In one embodiment, wherein the SSR correction number includes orbit and clock correction numbers, wherein in the case of using a non-calibrated phase delay UPD method to perform precise point positioning with fixed ambiguity, the clock correction number is a pseudo-range-based clock correction number product, and the phase fraction offset product is a phase fraction offset product including the frequency point selected by the system frequency band selection, or in the case of using an integer clock estimation IRC method to perform precise point positioning with fixed ambiguity, the clock correction number is a phase-based clock correction number product, and the phase fraction offset product is a phase fraction offset product including only wide-lane ambiguity.

[0223] In one embodiment, the system side performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in a predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites, estimates the phase fraction offset product of the selected frequency point selected by the system frequency band for the plurality of satellites, encodes and broadcasts the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point to the user side, and the system side encodes the epoch difference correction number time identifier, satellite system information, satellite number, satellite differential information ephemeris data period number IODE together with the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point.

[0224] In one embodiment, the system side performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in a predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites, estimates the phase fraction offset product of the selected frequency point selected by the system frequency band for the plurality of satellites, encodes and broadcasts the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point to the user side, and the system side encodes the epoch difference correction number time identifier, satellite system information, satellite number, satellite differential information ephemeris data period number IODE together with the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point.

[0225] In one embodiment, the encoding format of the short message communication from the user side to the system side is as shown in the following table

[0226]

[0227] In one embodiment, the encoding format of the short message communication from the user side to the system side is as shown in the following table

[0228] In one embodiment, the phase fractional bias products of the frequency points are used by the system end for the plurality of satellites, wherein the system end broadcasts wide-lane ambiguities, and the user end performs precise point positioning with fixed ambiguities based on the phase fractional bias products of the frequency points.

[0229] In one embodiment, the epoch-difference correction time identifier, satellite system information, satellite number, IODE of the satellite differential information ephemeris data period, and the polynomial coefficients of the plurality of satellites and the phase fractional bias products of the frequency points are encoded by the system end at least by the following steps:

[0230] The epoch-difference correction time identifier is encoded in the following header file:

[0231] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0232] GPSWeek represents Global Positioning System (GPS) week, and GPSSec represents GPS seconds. Here, the parameter of the number of satellites is added in the header file because the number of satellites sent by the system end is not necessarily the maximum value, and the user end needs to know in advance how many satellites are included to correctly decode when receiving the correction information for decoding.

[0233] In one embodiment, the epoch-difference correction time identifier, satellite system information, satellite number, IODE of the satellite differential information ephemeris data period, and the polynomial coefficients of the plurality of satellites and the phase fractional bias products of the frequency points are encoded by the system end at least by the following steps:

[0234] When the UPD method is used, the above encoding method is shown in the following table:

[0235]

[0236]

[0237] When the IRC method is used, the above encoding method is shown in the following table:

[0238]

[0239] In one embodiment, the state space representation (SSR) orbit clock correction of the plurality of satellites is converted into an observation space representation (OSR) integrated correction in the station-satellite line-of-sight direction by the system end for the plurality of satellites observable by the user end according to the initial coordinates of the station sent by the user end at least by the following steps:

[0240] The real-time SSR orbit correction δO of the nearest epoch in the satellite coordinate system is calculated by the following formula:

[0241] where δO r , δO a , δO c are the radial, tangential and normal corrections of the satellite in the satellite coordinate system respectively, are the radial, tangential and normal velocities of the satellite in the satellite coordinate system respectively, t is the current time, t0 is the SSR epoch reference time.

[0242] The real-time clock difference correction δC s in the satellite coordinate system at the nearest epoch is calculated by the following equation: s δC 2 = C0+ C1·(t-t0)+ C2·(t-t0)

[0243] where C0, C1 and C2 are the constant term, the first order term and the second order term in the clock difference fitting polynomial respectively, t is the current time, t0 is the SSR epoch reference time.

[0244] The real-time SSR orbit correction δO s is converted from the satellite coordinate system to the ECEF geocentric coordinate system δX

[0245] δX s = [e r , e a , e c ]·δO

[0246]

[0247] where r and are the position and velocity coordinates of the satellite in the ECEF respectively, e r is the radial vector in the satellite coordinate system, e a is the tangential vector in the satellite coordinate system, e c is the vector in the satellite coordinate system determined by the right-hand rule.

[0248] δX s , δC s are converted to the observed space representation OSR comprehensive correction δOSR in the station-satellite line-of-sight direction by the following equation: s

[0249] δOSR s = c·δC s -e·δX s

[0250] where c is the speed of light, e is the unit vector from the station to the satellite, and

[0251]

[0252] wherein r' is the geometric distance from the satellite to the user terminal, xs, ys, zs are the three-dimensional coordinates of the satellite, x r′ , y r′ , z r′ are the three-dimensional coordinates of the initial coordinates of the station.

[0253] In one embodiment, the system end performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in the predetermined time period for the plurality of satellites to obtain the polynomial coefficients of the plurality of satellites including the constant term a0and the first-order term coefficient a1by the following formula:

[0254]

[0255] t1...t n are the time sequence of each time in the predetermined time period, is the observation space representation OSR comprehensive correction number in the station-satellite line-of-sight direction of each time t1...t n .

[0256] In one embodiment, when the broadcast ephemeris is switched from the broadcast ephemeris BRDM1 to the broadcast ephemeris BRDM2, the jump δOSR s′ is calculated as δOSR s :

[0257] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0258] wherein Coor BRDM1 is the coordinates of the satellite calculated using the set of ephemeris before switching; Coor BRDM2 is the coordinates of the satellite calculated using the set of ephemeris after switching.

[0259] The observation space representation OSR comprehensive correction number in the station-satellite line-of-sight direction of the plurality of satellites currently observable by the user terminal is broadcast in a plurality of ephemeris rotation manner, under the condition that the satellite elevation angle is greater than 10°, and the correction number is sequentially broadcast to the user terminal in the order of GPS satellite, BDS satellite, and GALILEO satellite; after all the satellites are broadcasted, a new round of correction number is broadcasted in a cycle.

[0260] In one embodiment, the overall information coding requirement of the system end sending information is shown in the following table:

[0261]

[0262] The information content includes encoded parts of OSR comprehensive corrections of the plurality of satellites at the latest epoch.

[0263] In one embodiment, for the decoded OSR comprehensive corrections of previous epochs stored at the user end, whenever a new OSR comprehensive correction of one satellite is received, the old OSR comprehensive correction is replaced by the new one and the time information is recorded; when the polynomial coefficients of the plurality of satellites are used for extrapolation, a threshold of the extrapolation length is set, wherein the threshold includes 5 minutes, so that the OSR comprehensive corrections exceeding 5 minutes are not used.

[0264] Therefore, the present application provides a correction number generation, encoding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning suitable for (Beidou) short message system. The main features are as follows: the high-frequency orbit clock correction number is projected on the user-satellite line-of-sight direction to reduce the number of bytes occupied by the correction number; the line-of-sight direction correction number is fitted by a first-order polynomial to generate polynomial coefficients, thereby improving the available length of the correction number; the fitting coefficients of the line-of-sight correction number and the phase fractional offset product of each satellite of each system are broadcast to the user by the multi-epoch rotation encoding and broadcasting mode; the user end receives and decodes the correction number through short message communication, stores the satellite OSR (observed space representation) fitting coefficients and UPD (phase fractional offset) correction numbers received in the previous epochs, uses the fitting coefficients to extrapolate the OSR correction number to obtain the OSR correction of the current epoch, and combines the decoded correction number of the current epoch to realize real-time multi-system fixed ambiguity precise point positioning at the user end. Compared with the conventional precise point positioning algorithm suitable for (Beidou) short message system single-system ambiguity floating point solution, the correction number generation, encoding and broadcasting strategy proposed in the present application can further shorten the user end convergence time while improving the positioning accuracy under the same bandwidth and frequency limitation.

[0265] Figure 7 A flowchart of a method 700 of correction number broadcasting for multi-system fixed ambiguity precise point positioning based on satellite short message by the system end according to the embodiments of the present application is shown.

[0266] As Figure 7As shown, a method 700 for broadcasting correction numbers of precise point positioning with fixed ambiguities of multiple systems by a system end based on satellite short message includes: step 710, obtaining initial coordinates of a station and system frequency band selection of a user end by the system end through short message communication; step 720, converting state space representation SSR orbit clock correction numbers of multiple satellites observable by the user end into observation space representation OSR integrated correction numbers in station-satellite line-of-sight direction according to the initial coordinates of the station sent by the user end; step 730, performing polynomial coefficient fitting on the observation space representation OSR integrated correction numbers in a predetermined time period to obtain polynomial coefficients of the multiple satellites by the system end for the multiple satellites, estimating phase fractional offset products of frequency points selected by the system frequency band selection by the system end for the multiple satellites, encoding and broadcasting the polynomial coefficients of the multiple satellites and the phase fractional offset products of the frequency points to the user end; step 740, broadcasting the OSR integrated correction numbers of the multiple satellites in the nearest epoch to the user end by the system end through short message communication.

[0267] In one embodiment, wherein the SSR orbit clock correction numbers include orbit and clock correction numbers, wherein in the case of performing precise point positioning with fixed ambiguities by using a non-calibrated phase delay UPD method, the clock correction numbers are clock correction number products based on pseudoranges, and the phase fractional offset products include phase fractional offset products of frequency points selected by the system frequency band selection, or in the case of performing precise point positioning with fixed ambiguities by using an integer clock estimation IRC method, the clock correction numbers are clock correction number products based on phases, and the phase fractional offset products include phase fractional offset products of only wide-lane ambiguities.

[0268] In one embodiment, the encoding and broadcasting the polynomial coefficients of the multiple satellites and the phase fractional offset products of the frequency points to the user end by the system end for the multiple satellites includes: encoding epoch difference correction number time identifiers, satellite system information, satellite numbers, IODEs of ephemeris data periods of satellite differential information together with the polynomial coefficients of the multiple satellites and the phase fractional offset products of the frequency points by the system end.

[0269] In one embodiment, the method 700 further includes: using the phase fractional offset products of the frequency points by the system end for the multiple satellites, wherein the system end broadcasts wide-lane ambiguities, and the user end performs precise point positioning with fixed ambiguities based on the phase fractional offset products of the frequency points.

[0270] In one embodiment, the epoch differential correction time identifier, satellite system information, satellite number, satellite differential information IODE of ephemeris data period, and the polynomial coefficients and phase fractional offset of the frequency point of the plurality of satellites are encoded by the system end at least by the following steps:

[0271] The epoch differential correction time identifier is encoded in the following header file:

[0272] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0273] GPSWeek represents Global Positioning System (GPS) week, and GPSSec represents GPS seconds. Here, the parameter of the number of satellites is added in the header file because the number of satellites sent by the system end is not necessarily the maximum value, and the user end needs to know in advance how many satellites are included to correctly decode when receiving the correction number information for decoding.

[0274] In one embodiment, the epoch differential correction time identifier, satellite system information, satellite number, satellite differential information IODE of ephemeris data period, and the polynomial coefficients and phase fractional offset of the frequency point of the plurality of satellites are encoded by the system end at least by the following steps:

[0275] When the UPD method is used, the above encoding method is shown in the following table:

[0276]

[0277]

[0278] When the IRC method is used, the above encoding method is shown in the following table:

[0279]

[0280]

[0281] In one embodiment, the state space representation (SSR) orbit clock correction number of the plurality of satellites is converted into an observation space representation (OSR) comprehensive correction number in the station-satellite line-of-sight direction by the system end according to the initial coordinates of the station sent by the user end for the plurality of satellites observable by the user end at least by the following steps:

[0282] The real-time SSR orbit correction number δO of the nearest epoch in the satellite coordinate system is calculated by the following formula:

[0283] where δO r , δO a , δOc These are the radial, tangential, and normal corrections for the satellite in the satellite coordinate system, respectively. These represent the radial, tangential, and normal velocities of the satellite in the satellite coordinate system, respectively, where t is the current time and t0 is the SSR epoch reference time.

[0284] The real-time clock error correction δC for the most recent epoch in the satellite coordinate system is calculated using the following formula. s δC s =C0 + C1·(t-t0) + C2·(t-t0) 2

[0285] Where C0, C1, and C2 are the constant, linear, and quadratic terms in the clock error fitting polynomial, respectively, t is the current time, and t0 is the SSR epoch reference time.

[0286] The real-time SSR orbital correction δO is transformed from the satellite coordinate system to the ECEF geocentric coordinate system using the following formula. s :

[0287] δX s =[e r e a e c ]·δO

[0288]

[0289] Where r and These are the position and velocity coordinates of the satellite under ECEF, e r It is a radial vector in the satellite coordinate system, e a It is the tangential vector in the satellite coordinate system, e c It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule;

[0290] δX is expressed by the following formula s δC s Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction δOSR s The formula is as follows:

[0291] δOSR s =c·δC s -e·δX s

[0292] Where c is the speed of light, and e is the unit vector from the station to the satellite.

[0293]

[0294] Where r' is the geometric distance from the satellite to the user terminal, xs , y s , z s are three-dimensional coordinates of the satellite, x r′ , y r′ , z r′ are three-dimensional coordinates of the initial coordinates of the station.

[0295] In one embodiment, the system end performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in the predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites including a constant term a0and a first-order term coefficient a1by the following formula:

[0296]

[0297] t1...t n are each time point in the predetermined time period in time sequence, is the observation space representation OSR comprehensive correction number in the station-satellite line-of-sight direction of each time point t1...t n .

[0298] In one embodiment, when the broadcast ephemeris is switched from the broadcast ephemeris BRDM1 to the broadcast ephemeris BRDM2, the δOSR s′ after the jump is reduced to δOSR s by the following formula:

[0299] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0300] Wherein, Coor BRDM1 is the coordinates of the satellite calculated using a set of ephemeris before the switch; Coor BRDM2 is the coordinates of the satellite calculated using a set of ephemeris after the switch.

[0301] The observation space representation OSR comprehensive correction number in the station-satellite line-of-sight direction of the plurality of satellites observable by the current user end is broadcast in a plurality of ephemeris rotation manner, under the condition that the satellite elevation angle is greater than 10°, the correction number is sequentially broadcast to the user end in the order of GPS satellite, BDS satellite, GALILEO satellite; when all satellites are broadcasted, a new round of correction number is broadcasted.

[0302] In one embodiment, the overall information coding requirement of the system end sending information is shown in the following table:

[0303]

[0304]

[0305] wherein the information content comprises encoded parts of OSR combined corrections of the plurality of satellites for the most recent epoch. Such encoding requirements can apply to scenarios when using the latest Beidou-3 global short message function.

[0306] Therefore, the present application provides a correction number generation, encoding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning applicable to (Beidou) short message system. The main features are to reduce the number of bytes occupied by the correction number by projecting the high-frequency orbit clock correction number in the user-satellite line-of-sight direction; to improve the available time length of the correction number by fitting the line-of-sight direction correction number with a first-order polynomial to generate polynomial coefficients; to broadcast the fitting coefficients of the line-of-sight correction number of each system satellite and the phase fractional bias product to the user by the multi-epoch rotation encoding and broadcasting mode; the user end receives and decodes the correction number through short message communication, stores the satellite OSR (observation space representation) fitting coefficients and UPD (phase fractional bias) correction numbers received in the previous epochs, uses the fitting coefficients to extrapolate the OSR correction number to obtain the OSR correction of the current epoch, and combines the correction number decoded in the current epoch to achieve real-time multi-system fixed ambiguity precise point positioning at the user end. Compared with the conventional precise point positioning algorithm applicable to (Beidou) short message system single-system ambiguity floating point solution, the correction number generation, encoding and broadcasting strategy proposed in the present application can further shorten the convergence time of the user end while improving the positioning accuracy under the same bandwidth and frequency limitation.

[0307] Figure 8 A flow chart of a method 800 for implementing multi-system fixed ambiguity precise point positioning by a user end based on satellite short message according to an embodiment of the present application is shown.

[0308] As Figure 8As shown, a method 800 for implementing multi-system fixed ambiguity precise point positioning based on satellite short message by user terminal includes: step 810, obtaining initial station coordinates by the user terminal, selecting system frequency band, and sending initial station coordinates of the user terminal and system frequency band selection to the system terminal through short message communication; step 820, receiving and decoding the polynomial coefficients of multiple satellites sent by the system terminal through short message communication by the user terminal, wherein the polynomial coefficients of multiple satellites are obtained by at least the following steps: converting the state space representation SSR orbit clock correction number of the multiple satellites into observation space representation OSR comprehensive correction number in the station-satellite line of sight direction according to the initial station coordinates sent by the user terminal by the system terminal for the multiple satellites observable by the user terminal; fitting the observation space representation OSR comprehensive correction number in a predetermined time period to obtain the polynomial coefficients of multiple satellites by the system terminal for the multiple satellites; step 830, receiving the phase fractional offset product of the frequency point selected by the system frequency band selection estimated and encoded by the system terminal for the multiple satellites by the user terminal through short message communication; step 840, receiving the OSR comprehensive correction number of the latest epoch of the multiple satellites broadcast by the system terminal through short message communication through one or more epochs by the user terminal through short message communication; step 850, extrapolating the OSR comprehensive correction number of the latest epoch of the multiple satellites based on the received polynomial coefficients of the multiple satellites to obtain the predicted current OSR comprehensive correction number of the multiple satellites, correcting the errors of satellite coordinates and satellite clock error in the satellite-station direction through the current OSR comprehensive correction number, and correcting the satellite end phase fractional offset through the phase fractional offset product, to realize fixed ambiguity precise point positioning.

[0309] In one embodiment, wherein the SSR orbit clock correction number includes orbit and clock correction number, wherein in the case of using non-calibration phase delay UPD method to perform fixed ambiguity precise point positioning, the clock correction number is a pseudo-range based clock correction number product, and the phase fractional offset product is a phase fractional offset product including the frequency point selected by the system frequency band selection, or in the case of using integer clock estimation IRC method to perform fixed ambiguity precise point positioning, the clock correction number is a phase-based clock correction number product, and the phase fractional offset product is a phase fractional offset product including only wide lane ambiguity.

[0310] In one embodiment, the user terminal receives the epoch difference correction number time identifier, satellite system information, satellite number, satellite differential information ephemeris data period number IODE encoded together with the phase fractional offset product of the frequency point by the system terminal through short message communication.

[0311] The OSR comprehensive correction number of the most recent epoch of the plurality of satellites is extrapolated by the user terminal based on the received polynomial coefficients of the plurality of satellites, to obtain the current OSR comprehensive correction number of the plurality of satellites, the errors of satellite coordinates and satellite clock bias in the satellite-station direction are corrected by the current OSR comprehensive correction number, and the satellite end phase fraction offset is corrected by the phase fraction offset product, so as to realize precise point positioning with fixed ambiguity.

[0312] In one embodiment, the encoding format of the short message communication from the user terminal to the system terminal is as shown in the following table

[0313]

[0314] Wherein, GPSWeek represents global positioning system GPS week, GPSSec represents GPS seconds, X(ECEF) represents the X axis of the Earth-Centered Earth-Fixed coordinate system ECEF, Y(ECEF) represents the Y axis of the Earth-Centered Earth-Fixed coordinate system ECEF, Z(ECEF) represents the Z axis of the Earth-Centered Earth-Fixed coordinate system ECEF, GPS frequency point represents the frequency point combination of the global positioning system GPS used by the user terminal for positioning, BDS frequency point represents the frequency point combination of the Beidou satellite navigation system BDS used by the user terminal for positioning, and Galileo frequency point represents the frequency point combination of the Galileo system used by the user terminal for positioning.

[0315] In one embodiment, the epoch differential correction number time identifier, the satellite system information, the satellite number, and the IODE of the satellite differential information ephemeris data period are encoded by the system terminal together with the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point by at least the following steps:

[0316] The epoch differential correction number time identifier is encoded in the following header file form:

[0317] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0318] GPSWeek represents global positioning system GPS week, GPSSec represents GPS seconds.

[0319] In one embodiment, the system end encodes the epoch differential correction time mark, satellite system information, satellite number, satellite differential information IODE of ephemeris data period, polynomial coefficients and phase fractional offset of the frequency point of the plurality of satellites together by at least the following steps:

[0320] When the UPD method is used, the above encoding mode is shown in the following table:

[0321]

[0322] When the IRC method is used, the above encoding mode is shown in the following table:

[0323]

[0324] In one embodiment, the system end uses the phase fractional offset of the frequency point for the plurality of satellites, wherein the system end broadcasts wide-lane ambiguity, and the user end performs precise point positioning of fixed ambiguity based on the phase fractional offset of the frequency point.

[0325] In one embodiment, the system end converts the state space representation (SSR) orbit clock correction number of the plurality of satellites into an observation space representation (OSR) integrated correction number in the station-satellite line-of-sight direction according to the station initial coordinates sent by the user end for the plurality of satellites observable by the user end by at least the following steps:

[0326] The real-time SSR orbit correction number δO of the nearest epoch in the satellite coordinate system is calculated by the following formula:

[0327] Wherein δO r , δO a , and δO c are the radial, tangential, and normal correction numbers of the satellite in the satellite coordinate system, are the radial, tangential, and normal velocities of the satellite in the satellite coordinate system, t is the current time, and t0 is the SSR epoch reference time,

[0328] The real-time clock correction number δC of the nearest epoch in the satellite coordinate system is calculated by the following formula: s : δC s = C0+ C1·(t-t0)+ C2·(t-t0) 2

[0329] Wherein C0, C1, and C2 are the constant term, the first-order term, and the second-order term in the clock difference fitting polynomial, t is the current time, and t0 is the SSR epoch reference time,

[0330] The real-time SSR orbital correction δO is transformed from the satellite coordinate system to the ECEF geocentric coordinate system using the following formula. s δX s =[e r e a e c ]·δO

[0331]

[0332] Where r and These are the position and velocity coordinates of the satellite under ECEF, e r It is a radial vector in the satellite coordinate system, e a It is the tangential vector in the satellite coordinate system, e c It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule;

[0333] δX is expressed by the following formula s δC s Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction δOSR s The formula is as follows:

[0334] δOSR s =c·δC s -e·δX s

[0335] Where c is the speed of light, and e is the unit vector from the station to the satellite.

[0336]

[0337] Where r' is the geometric distance from the satellite to the user terminal, x s y s , z s Let x be the three-dimensional coordinates of the satellite. r′ y r′ , z r′ These are the three-dimensional coordinates of the initial coordinates of the station.

[0338] In one embodiment, the system performs polynomial coefficient fitting on the OSR comprehensive correction for the observation spatial representation within a predetermined time period for the multiple satellites using the following formula to obtain the polynomial coefficients for the multiple satellites, including the constant term a0 and the first-order coefficient a1:

[0339]

[0340] t1...t n It refers to the various moments in chronological order within a predetermined time period. It is each time point t1...tn OSR is the observation space representation in the direction of the station-satellite line-of-sight.

[0341] In one embodiment, when the broadcast ephemeris is switched from broadcast ephemeris BRDM1 to broadcast ephemeris BRDM2, the jump of δOSR s′ is calculated by the following formula: s

[0342] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0343] wherein Coor BRDM1 is the coordinate of the satellite calculated using the set of ephemeris before the switch; Coor BRDM2 is the coordinate of the satellite calculated using the set of ephemeris after the switch.

[0344] The observation space representation OSR comprehensive correction number in the direction of the station-satellite line-of-sight of the multiple satellites observable by the current user terminal is broadcast in a manner of multiple ephemeris rotation, under the condition that the satellite elevation angle is greater than 10°, and the correction number is sequentially broadcast to the user terminal in the order of GPS satellite, BDS satellite, and GALILEO satellite; after all the satellites are broadcast, a new round of correction number is broadcast.

[0345] In one embodiment, the overall information coding requirement of the system terminal sending information is shown in the following table:

[0346]

[0347] wherein the information content includes the coding part of the OSR comprehensive correction number of the nearest ephemeris of the multiple satellites.

[0348] In one embodiment, for the OSR comprehensive correction number decoded from the previous ephemeris stored by the user terminal, whenever a new OSR comprehensive correction number of a satellite is received, the old OSR comprehensive correction number is replaced by the new OSR comprehensive correction number and the time information thereof is recorded; when the polynomial coefficients of the multiple satellites are used for extrapolation, a threshold of the extrapolation length is set, wherein the threshold includes 5 minutes, so that the OSR comprehensive correction number exceeding 5 minutes is not used.

[0349] ​Therefore, the application provides a correction number generation, coding and broadcasting method for real-time multi-system fixed ambiguity precise point positioning of a (Beidou) short message system. The main features are that the high-frequency orbit clock correction number is projected on the user-satellite line-of-sight direction to reduce the number of bytes occupied by the correction number; the line-of-sight direction correction number is fitted by a first-order polynomial to generate polynomial coefficients, thereby improving the available time length of the correction number; the fitting coefficients of the line-of-sight correction number and the phase fraction bias product of each system satellite are broadcast to the user in a multi-epoch rotation coding and broadcasting mode; the user end receives and decodes the correction number through short message communication, stores the satellite OSR (observation space representation) fitting coefficients and UPD (phase fraction bias) correction numbers received in the previous epochs, extrapolates the OSR correction number using the fitting coefficients to obtain the OSR correction of the current epoch, and combines the correction number decoded in the current epoch to realize real-time multi-system fixed ambiguity precise point positioning at the user end. Compared with the conventional precise point positioning algorithm for (Beidou) short message system single-system ambiguity floating point solution, the correction number generation, coding and broadcasting strategy proposed in the application can further shorten the convergence time of the user end while improving the positioning accuracy under the same bandwidth and frequency limitation.

[0350] Figure 9 A block diagram of an exemplary electronic device suitable for implementing embodiments of the application is shown.

[0351] The electronic device can include a processor (H1), a storage medium (H2) coupled to the processor (H1) and storing computer executable instructions therein for performing steps of various methods of embodiments of the application when executed by the processor.

[0352] The processor (H1) can include, but is not limited to, for example, one or more processors or microprocessors, etc.

[0353] The storage medium (H2) can include, but is not limited to, for example, random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (such as hard disks, floppy disks, solid state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0354] In addition, the electronic device can also include a data bus (H3), an input / output (I / O) bus (H4), a display (H5) and an input / output device (H6) (such as a keyboard, a mouse, a speaker, etc.), etc.

[0355] The processor (H1) can communicate with external devices (H5, H6, etc.) via a wired or wireless network (not shown) through the I / O bus (H4).

[0356] The storage medium (H2) can also store at least one computer-executable instruction for performing steps of various functions and / or methods in the embodiments described by the present technology when executed by the processor (H1).

[0357] In one embodiment, the at least one computer-executable instruction can also be compiled into or constitute a software product, wherein one or more computer-executable instructions are executed by the processor to perform steps of various functions and / or methods in the embodiments described by the present technology.

[0358] Figure 10 A schematic diagram of a non-transitory computer-readable storage medium according to an embodiment of the present disclosure is shown.

[0359] As Figure 10 shown, the computer-readable storage medium 1020 stores instructions, for example, computer-readable instructions 1010. When the computer-readable instructions 1010 are executed by a processor, various methods described above can be performed. The computer-readable storage medium includes, but is not limited to, for example, volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory, etc. The non-volatile memory may, for example, include read-only memory (ROM), a hard disk, a flash memory, etc. For example, the computer-readable storage medium 1020 can be connected to a computing device such as a computer, and then when the computing device executes the computer-readable instructions 1010 stored on the computer-readable storage medium 1020, various methods described above can be performed.

[0360] The present application provides the following items:

[0361] 1. A method for implementing precise point positioning with fixed ambiguity of multiple systems based on satellite short message by a system end and a user end, comprising:

[0362] acquiring initial coordinates of a station by the user end, selecting a system frequency band, and sending the initial coordinates of the station of the user end and the selection of the system frequency band to the system;

[0363] acquiring the initial coordinates of the station of the user end and the selection of the system frequency band by the system end through short message communication;

[0364] converting, by the system end, state space representation (SSR) orbit clock correction numbers of multiple satellites observable by the user end into observation space representation (OSR) comprehensive correction numbers in a station-satellite line-of-sight direction according to the initial coordinates of the station sent by the user end;

[0365] The system side performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in a predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites, estimates phase fraction offset products of selected frequency points selected by the system frequency band for the plurality of satellites, and encodes and broadcasts the polynomial coefficients of the plurality of satellites and the phase fraction offset products of the frequency points to the user side;

[0366] The system side broadcasts the OSR comprehensive correction number of the latest epoch of the plurality of satellites to the user side through one or more epochs in turn through short message communication;

[0367] The user side receives and decodes the OSR comprehensive correction number of the latest epoch of the plurality of satellites through short message communication, extrapolates the OSR comprehensive correction number of the latest epoch of the plurality of satellites based on the received polynomial coefficients of the plurality of satellites to obtain the predicted current epoch OSR comprehensive correction number of the plurality of satellites, corrects the errors of satellite coordinates and satellite clock bias in the satellite-station direction based on the current epoch OSR comprehensive correction number, and corrects the satellite end phase fraction offset based on the phase fraction offset product to realize precise point positioning with fixed ambiguity.

[0368] 2. The method of item 1, wherein the system side performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in a predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites, estimates phase fraction offset products of selected frequency points selected by the system frequency band for the plurality of satellites, and encodes and broadcasts the polynomial coefficients of the plurality of satellites and the phase fraction offset products of the frequency points to the user side, comprising:

[0369] The system side encodes the epoch difference correction number time identifier, satellite system information, satellite number, satellite difference information ephemeris data period number IODE together with the polynomial coefficients of the plurality of satellites and the phase fraction offset products of the frequency points,

[0370] The user side performs polynomial coefficient fitting on the observation space representation OSR comprehensive correction number in a predetermined time period for the plurality of satellites to obtain polynomial coefficients of the plurality of satellites, estimates phase fraction offset products of selected frequency points selected by the system frequency band for the plurality of satellites, and encodes and broadcasts the polynomial coefficients of the plurality of satellites and the phase fraction offset products of the frequency points to the user side, comprising:

[0371] The user terminal extrapolates the precise point positioning of the fixed ambiguity of the current OSR comprehensive correction number of the satellite based on the polynomial coefficients of the received multiple satellites, the phase fraction offset product or the clock difference, the epoch difference correction time identifier, the satellite system information, the satellite number, the satellite differential information IODE of the ephemeris data period, obtains the predicted current OSR comprehensive correction number of the multiple satellites, and corrects the satellite coordinate and satellite clock difference in the satellite-station direction through the current OSR comprehensive correction number, and corrects the satellite end phase fraction offset through the phase fraction offset product, to realize the precise point positioning of the fixed ambiguity.

[0372] The observation space of the current user terminal observable multiple satellites in the station-satellite line-of-sight direction is represented by the OSR comprehensive correction number, which is broadcast in multiple epochs in turn, under the condition that the satellite elevation angle is greater than 10°, and the correction number is sequentially broadcast to the user terminal in the order of GPS satellite, BDS satellite and GALILEO satellite; after all the satellites are broadcast, a new round of correction number is broadcast.

[0373] 3. The method according to item 1, wherein the encoding format of the short message communication from the user terminal to the system terminal is as shown in the following table

[0374]

[0375]

[0376] Wherein, GPSWeek represents Global Positioning System GPS week, GPSSec represents GPS second, X(ECEF) represents X axis of Earth-Centered Earth-Fixed coordinate system ECEF, Y(ECEF) represents Y axis of Earth-Centered Earth-Fixed coordinate system ECEF, Z(ECEF) represents Z axis of Earth-Centered Earth-Fixed coordinate system ECEF, GPS frequency point represents the frequency point combination of Global Positioning System GPS system used by the user terminal for positioning, BDS frequency point represents the frequency point combination of Beidou Satellite Navigation System BDS system used by the user terminal for positioning, Galileo frequency point represents the frequency point combination of Galileo system used by the user terminal for positioning.

[0377] 4. The method according to item 4, wherein the epoch difference correction time identifier, the satellite system information, the satellite number, the satellite differential information IODE of the ephemeris data period are encoded by the system terminal together with the polynomial coefficients of the multiple satellites and the phase fraction offset product of the frequency point through at least the following steps:

[0378] The epoch difference correction time identifier is encoded in the following header file form:

[0379] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0380] GPSWeek denotes Global Positioning System (GPS) week, and GPSSec denotes GPS seconds.

[0381] 5. The method according to item 1, wherein the state space representation (SSR) orbit clock correction numbers of the plurality of satellites are converted into observation space representation (OSR) integrated correction numbers in the station-satellite line-of-sight direction by the system end for the user end observable plurality of satellites according to the station initial coordinates sent by the user end at least by the following steps:

[0382] The real-time SSR orbit correction number δ0 at the nearest epoch in the satellite coordinate system is calculated by the following formula:

[0383] wherein δ0 r , δ0 a , δ0 c are the radial, tangential and normal correction numbers of the satellite in the satellite coordinate system, respectively, are the radial, tangential and normal velocities of the satellite in the satellite coordinate system, respectively, t is the current time, and t0 is the SSR epoch reference time,

[0384] The real-time clock correction number δC at the nearest epoch in the satellite coordinate system is calculated by the following formula: s : δC s = C0+ C1·(t-t0)+ C2·(t-t0) 2

[0385] wherein C0, C1 and C2 are the constant term, the first order term and the second order term in the clock fitting polynomial, respectively, t is the current time, and t0 is the SSR epoch reference time,

[0386] The real-time SSR orbit correction number δ0 is converted from the satellite coordinate system to the ECEF geocentric coordinate system δX by the following formula: s : δX s = [e r , e a , e c ]·δ0

[0387]

[0388] wherein r and are the position and velocity coordinates of the satellite in the ECEF, respectively, e r is the radial vector in the satellite coordinate system, e a is the tangential vector in the satellite coordinate system, and e c is the vector in the direction determined by the right-hand rule in the satellite coordinate system;

[0389] The δX s , δC s is converted into the observation space representation OSR comprehensive correction δOSR s in the direction of the line of sight of the station-satellite by the following formula:

[0390] δOSR s = c·δC s - e·δX s

[0391] where c is the speed of light, e is the unit vector pointing from the station to the satellite, and

[0392]

[0393] where r' is the geometric distance from the satellite to the user terminal, x s , y s , z s are the three-dimensional coordinates of the satellite, x r′ , y r′ , z r′ are the three-dimensional coordinates of the initial coordinates of the station.

[0394] 6. The method according to item 1, wherein

[0395] The observation space representation OSR comprehensive correction in a predetermined time period is polynomial coefficient fitted by the system terminal for the plurality of satellites to obtain the polynomial coefficients of the plurality of satellites including the constant term a0and the first-order term coefficient a1by the following formula:

[0396]

[0397] t1...t n are each time point in time order in the predetermined time period, is the observation space representation OSR comprehensive correction in the direction of the line of sight of the station-satellite at each time point t1...t n .

[0398] 7. The method according to item 6, wherein

[0399] When the broadcast ephemeris is switched from the broadcast ephemeris BRDM1 to the broadcast ephemeris BRDM2, the δOSR s′ after the jump is reduced to δOSR s by the following formula:

[0400] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0401] Coor BRDM1 is the coordinate of the satellite calculated using the set of ephemeris before the switch; Coor BRDM2 is the coordinate of the satellite calculated using the set of ephemeris after the switch.

[0402] 8. The method according to item 1, wherein,

[0403] The system end encodes the epoch differential correction time mark, satellite system information, satellite number, satellite differential information ephemeris data period number IODE, and the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point together by at least the following steps:

[0404] When the UPD method is used, the above encoding method is shown in the following table:

[0405]

[0406]

[0407] When the IRC method is used, the above encoding method is shown in the following table:

[0408]

[0409] 9. The method according to item 1, wherein,

[0410] The total information encoding requirements of the information sent by the system end are shown in the following table:

[0411]

[0412] Among them, the information content includes the encoding part of the OSR comprehensive correction number of the nearest epoch of the plurality of satellites.

[0413] 10. The method according to item 1, wherein, for the OSR comprehensive correction number decoded by the user end stored in the previous epoch, whenever a new OSR comprehensive correction number of a satellite is received, the old OSR comprehensive correction number is replaced with the new OSR comprehensive correction number and the time information is recorded; when the polynomial coefficients of the plurality of satellites are used for extrapolation, a threshold of the extrapolation length is set, wherein the threshold includes 5 minutes, so that the OSR comprehensive correction number exceeding 5 minutes is not used.

[0414] 11. A method for system end to broadcast correction number of precise point positioning with fixed ambiguity of multiple systems based on satellite short message, comprising:

[0415] The system end obtains the initial station coordinates of the user end and the system frequency band selection through short message communication;

[0416] converting, by the system side, state space representation SSR orbit and clock correction numbers of the plurality of satellites into observation space representation OSR combined correction numbers in station-satellite line-of-sight direction according to the station initial coordinates sent by the user side;

[0417] polynomial coefficient fitting, by the system side, observation space representation OSR combined correction numbers in a predetermined time period to obtain polynomial coefficients of the plurality of satellites, estimating, by the system side, phase fractional bias products of the frequency points selected by the system frequency band selection, encoding and broadcasting, by the system side, the polynomial coefficients of the plurality of satellites and the phase fractional bias products of the frequency points to the user side;

[0418] broadcasting, by the system side, OSR combined correction numbers of the plurality of satellites in the latest epoch through one or more epochs to the user side through short message communication.

[0419] 12. The method according to item 11, wherein the SSR orbit and clock correction numbers comprise orbit and clock correction numbers, wherein in the case of precise point positioning with fixed ambiguities using a non-calibrated phase delay UPD method, the clock correction numbers are clock correction number products based on pseudoranges, and the phase fractional bias products are phase fractional bias products comprising phase fractional biases of the frequency points selected by the system frequency band selection, or in the case of precise point positioning with fixed ambiguities using an integer clock estimation IRC method, the clock correction numbers are clock correction number products based on phases, and the phase fractional bias products are phase fractional bias products comprising only wide-lane ambiguities.

[0420] 13. The method according to item 11, wherein, by at least the following steps, converting, by the system side, state space representation SSR orbit and clock correction numbers of the plurality of satellites into observation space representation OSR combined correction numbers in station-satellite line-of-sight direction according to the station initial coordinates sent by the user side:

[0421] calculating real-time SSR orbit correction numbers δO in the satellite coordinate system at the latest epoch by the following formula:

[0422] wherein δO r , δO a , δO c are radial, tangential and normal correction numbers of the satellite in the satellite coordinate system respectively, are radial, tangential and normal velocities of the satellite in the satellite coordinate system respectively, t is the current time, and t0 is the SSR epoch reference time,

[0423] The real-time clock error correction δC for the most recent epoch in the satellite coordinate system is calculated using the following formula. s δC s =C0 + C1·(t-t0) + C2·(t-t0) 2

[0424] Where C0, C1, and C2 are the constant, linear, and quadratic terms in the clock error fitting polynomial, respectively, t is the current time, and t0 is the SSR epoch reference time.

[0425] The real-time SSR orbital correction δO is transformed from the satellite coordinate system to the ECEF geocentric coordinate system using the following formula. s δX s =[e r e a e c ]·δO

[0426]

[0427] Where r and These are the position and velocity coordinates of the satellite under ECEF, e r It is a radial vector in the satellite coordinate system, e a It is the tangential vector in the satellite coordinate system, e c It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule;

[0428] δX is expressed by the following formula s δC s Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction δOSR s The formula is as follows:

[0429] δOSR s =c·δC s -e·δX s

[0430] Where c is the speed of light, and e is the unit vector from the station to the satellite.

[0431]

[0432] Where r' is the geometric distance from the satellite to the user terminal, x s y s , z s Let x be the three-dimensional coordinates of the satellite. r′ y r′ , z r′ These are the three-dimensional coordinates of the initial coordinates of the station.

[0433] 14. According to the method described in Project 13, wherein

[0434] The polynomial coefficients of the plurality of satellites are fitted by the system end for the plurality of satellites by a polynomial coefficient fitting of the observation space representation OSR comprehensive correction number in a predetermined time period to obtain a polynomial coefficient including a constant term a0 and a first order term coefficient a1:

[0435]

[0436] t1...t n is each time in chronological order in a predetermined time period, is the observation space representation OSR comprehensive correction number in the direction of the line of sight of the station-satellite at each time.

[0437] 15. The method according to item 14, wherein,

[0438] When the broadcast ephemeris is switched from the broadcast ephemeris BRDM1 to the broadcast ephemeris BRDM2, the δOSR s′ jumped is calculated as δOSR s :

[0439] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0440] Wherein, Coor BRDM1 is the coordinates of the satellite calculated using a set of ephemeris before switching; Coor BRDM2 is the coordinates of the satellite calculated using a set of ephemeris after switching.

[0441] 16. The method according to item 11, wherein the polynomial coefficients of the plurality of satellites are fitted by the system end for the plurality of satellites by a polynomial coefficient fitting of the observation space representation OSR comprehensive correction number in a predetermined time period, the phase fraction offset product of the frequency point selected by the system frequency band selection is estimated by the system end for the plurality of satellites, the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point are encoded and broadcast to the user end, comprising:

[0442] The system end encodes the ephemeris data epoch number IODE of the satellite system information, the satellite number, the satellite differential information, the time tag of the epoch difference correction number, the polynomial coefficients of the plurality of satellites and the phase fraction offset product of the frequency point,

[0443] Among them, the observation space represented OSR comprehensive correction number of the current user terminal observable multiple satellites in the station-satellite line-of-sight direction is broadcast in multiple ephemeris round-robin mode, under the condition that the satellite elevation angle is greater than 10°, the correction number is sequentially broadcast to the user terminal according to the order of GPS satellite, BDS satellite and GALILEO satellite; When all satellites are broadcasted, a new round of correction number is broadcasted.

[0444] 17. The method according to item 16, wherein the ephemeris differential correction number time identification, satellite system information, satellite number, satellite differential information ephemeris data period number IODE are encoded by the system end together with the polynomial coefficients and phase fraction offset products of the multiple satellites at least by the following steps:

[0445] The ephemeris differential correction number time identification is encoded in the following header file form:

[0446] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0447] GPSWeek represents Global Positioning System GPS week, and GPSSec represents GPS seconds.

[0448] 18. The method according to item 16, wherein the ephemeris differential correction number time identification, satellite system information, satellite number, satellite differential information ephemeris data period number IODE are encoded by the system end together with the polynomial coefficients and phase fraction offset products of the multiple satellites at least by the following steps:

[0449] When the UPD method is used, the above encoding method is shown in the following table:

[0450]

[0451]

[0452] When the IRC method is used, the above encoding method is shown in the following table:

[0453]

[0454] 19. The method according to item 11, wherein,

[0455] The total information encoding requirements of the system end sending information are shown in the following table:

[0456]

[0457] Among them, the information content includes the encoding part of the OSR comprehensive correction number of the nearest ephemeris of the multiple satellites.

[0458] 20. The method of item 11, wherein for the decoded OSR combined corrections of previous epochs stored by the user end, each time a new OSR combined correction of one satellite is received, the old OSR combined correction is replaced by the new OSR combined correction and its time information is recorded; when using the polynomial coefficients of the plurality of satellites for extrapolation, a threshold of extrapolation time length is set, wherein the threshold includes 5 minutes, such that the OSR combined corrections beyond 5 minutes are not used

[0459] 21. A method for implementing multi-system fixed ambiguity precise point positioning by a user end based on satellite short message, comprising:

[0460] acquiring initial coordinates of a station by the user end, selecting a system frequency band, and sending the initial coordinates of the station and the selection of the system frequency band to a system end through short message communication;

[0461] receiving and decoding the polynomial coefficients of a plurality of satellites sent by the system end through short message communication by the user end, wherein the polynomial coefficients of the plurality of satellites are obtained by at least the following steps: converting, by the system end, the state space representation (SSR) orbit clock correction of the plurality of satellites into the observation space representation (OSR) combined correction in the station-satellite line of sight direction according to the initial coordinates of the station sent by the user end for the plurality of satellites observable by the user end; fitting the observation space representation (OSR) combined correction in a predetermined time period to obtain the polynomial coefficients of the plurality of satellites for the plurality of satellites by the system end;

[0462] receiving, by the user end, the phase fractional offset product of the frequency point selected by the system frequency band estimated and encoded by the system end through short message communication for the plurality of satellites through short message communication;

[0463] receiving, by the user end, the OSR combined correction of the most recent epoch of the plurality of satellites broadcasted by the system end through one or more epochs through short message communication through short message communication;

[0464] extrapolating, by the user end, the OSR combined correction of the most recent epoch of the plurality of satellites based on the received polynomial coefficients of the plurality of satellites to obtain the extrapolated current OSR combined correction of the plurality of satellites, correcting the errors of the satellite coordinates and the satellite clock error in the satellite-station direction by the current OSR combined correction, and correcting the satellite end phase fractional offset by the phase fractional offset product to implement the fixed ambiguity precise point positioning.

[0465] 22. The method of item 21, wherein the SSR orbit clock correction number comprises orbit and clock correction numbers, wherein in the case of precise point positioning with fixed ambiguities using a non-calibrated phase delay (UPD) method, the clock correction number is a pseudo-range based clock correction number product and the phase fractional bias product is a phase fractional bias product comprising the selected frequency of the system band selected, or in the case of precise point positioning with fixed ambiguities using an integer clock estimation (IRC) method, the clock correction number is a phase based clock correction number product and the phase fractional bias product is a phase fractional bias product comprising only wide-lane ambiguities.

[0466] 23. The method of item 21, wherein

[0467] The epoch difference correction number time mark encoded with the phase fractional bias product of the frequency by the system end is received by the user end through short message communication, satellite system information, satellite number, satellite differential information ephemeris data period number IODE are sent by the system end through short message communication;

[0468] Wherein, the observation space representation (OSR) comprehensive correction number of the current user end observable multiple satellites in the station-satellite line of sight direction is broadcasted in multiple epochs, under the condition that the satellite elevation angle is greater than 10°, the correction number is sequentially broadcasted to the user end in the order of GPS satellite, BDS satellite, GALILEO satellite; After all the satellites are broadcasted, a new round of correction number is broadcasted.

[0469] 24. The method of item 21, wherein the encoding format of the short message communication from the user end to the system end is as shown in the following table

[0470]

[0471]

[0472] Wherein, GPSWeek represents Global Positioning System (GPS) week, GPSSec represents GPS seconds, X(ECEF) represents the X-axis of the Earth-Centered Earth-Fixed coordinate system (ECEF), Y(ECEF) represents the Y-axis of the Earth-Centered Earth-Fixed coordinate system (ECEF), Z(ECEF) represents the Z-axis of the Earth-Centered Earth-Fixed coordinate system (ECEF), GPS frequency point represents the frequency combination of the Global Positioning System (GPS) system used by the user end for positioning, BDS frequency point represents the frequency combination of the Beidou Satellite Navigation System (BDS) system used by the user end for positioning, Galileo frequency point represents the frequency combination of the Galileo system used by the user end for positioning.

[0473] 25. According to the method described in Project 21, wherein, at least the following steps are performed: the system, for multiple satellites observable by the user, converts the state space representation (SSR) orbital clock error corrections of the multiple satellites into the observation space representation (OSR) integrated corrections in the station-satellite line-of-sight direction based on the initial coordinates of the station sent by the user:

[0474] The real-time SSR orbit correction δO in the most recent epoch of the satellite coordinate system is calculated using the following formula:

[0475] Where δO r δO a δO c These are the radial, tangential, and normal corrections for the satellite in the satellite coordinate system, respectively. These represent the radial, tangential, and normal velocities of the satellite in the satellite coordinate system, respectively, where t is the current time and t0 is the SSR epoch reference time.

[0476] The real-time clock error correction δC for the most recent epoch in the satellite coordinate system is calculated using the following formula. s δC s =C0 + C1·(t-t0) + C2·(t-t0) 2

[0477] Where C0, C1, and C2 are the constant, linear, and quadratic terms in the clock error fitting polynomial, respectively, t is the current time, and t0 is the SSR epoch reference time.

[0478] The real-time SSR orbital correction δO is transformed from the satellite coordinate system to the ECEF geocentric coordinate system using the following formula. s δX s =[e r e a e c ]·δO

[0479]

[0480] Where r and These are the position and velocity coordinates of the satellite under ECEF, e r It is a radial vector in the satellite coordinate system, e a It is the tangential vector in the satellite coordinate system, e c It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule;

[0481] δX is expressed by the following formula s δC s Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction δOSR s, the formula is as follows:

[0482] δOSR s = c · δC s - e · δX s

[0483] where c is the speed of light, e is the unit vector from the station to the satellite, and

[0484]

[0485] where r' is the geometric distance from the satellite to the user terminal, x s , y s , and z s are the three-dimensional coordinates of the satellite, and x r′ , y r′ , and z r′ are the three-dimensional coordinates of the initial coordinates of the station.

[0486] 26. The method of item 21, wherein

[0487] The polynomial coefficients of the plurality of satellites are fitted by the system end for the plurality of satellites by polynomial coefficient fitting the observation space representation OSR comprehensive correction number in a predetermined time period to obtain a polynomial including a constant term a0and a first-order term coefficient a1:

[0488]

[0489] t1…tn are each time in a predetermined time period in time order, is the observation space representation OSR comprehensive correction number in the station-satellite line-of-sight direction at each time.

[0490] 27. The method of item 21, wherein

[0491] When the broadcast ephemeris is switched from broadcast ephemeris BRDM1 to broadcast ephemeris BRDM2, the δOSR s′ after the jump is reduced to δOSR s :

[0492] δOSR s = Coor BRDM1 - (Coor BRDM2 - δOSR s′ )

[0493] where Coor BRDM1 is the coordinates of the satellite calculated using a set of ephemeris before the switch; and Coor BRDM2 is the coordinates of the satellite calculated using a set of ephemeris after the switch.

[0494] 28. The method of item 23, wherein the system end encodes the epoch-difference correction number time identification, satellite system information, satellite number, IODE of satellite differential information ephemeris data period, polynomial coefficients of the plurality of satellites and phase fraction offset products of frequency points together by at least the following steps:

[0495] The epoch-difference correction number time identification is encoded in the following header file form:

[0496] Parameter Accuracy (unit) Valid range Number of bits GPS Week 1 (week) 0-4095 12 GPS Sec 1 (second) 0-604800 20 Number of satellites 1 (satellite) 0-15 4

[0497] GPSWeek represents Global Positioning System (GPS) week, and GPSSec represents GPS seconds.

[0498] 29. The method of item 23, wherein,

[0499] The system end encodes the epoch-difference correction number time identification, satellite system information, satellite number, IODE of satellite differential information ephemeris data period, polynomial coefficients of the plurality of satellites and phase fraction offset products of frequency points together by at least the following steps:

[0500] When the UPD method is used, the above encoding method is shown in the following table:

[0501]

[0502]

[0503] When the IRC method is used, the above encoding method is shown in the following table:

[0504]

[0505] 30. The method of item 21, wherein,

[0506] The total information encoding requirement of the system end sending information is shown in the following table:

[0507]

[0508] Among them, the information content includes the encoding part of the OSR comprehensive correction number of the nearest epoch of the plurality of satellites.

[0509] 31. The method of item 21, wherein for the decoded OSR combined corrections of previous epochs stored for the user terminal, each time a new OSR combined correction for one satellite is received, the old OSR combined correction is replaced with the new OSR combined correction and its time information is recorded; when using the polynomial coefficients of the plurality of satellites for extrapolation, a threshold of extrapolation time length is set, wherein the threshold includes 5 minutes, such that the OSR combined corrections beyond 5 minutes are not used.

[0510] 32. An electronic device, comprising:

[0511] a memory for storing instructions;

[0512] a processor for reading the instructions in the memory and performing the method of any of items 1-31.

[0513] 33. A non-transitory storage medium having stored thereon instructions,

[0514] wherein the instructions, when read by a processor, cause the processor to perform the method of any of items 1-31.

[0515] Of course, the above-mentioned specific embodiments are only examples and are not limiting, and a person skilled in the art can combine and combine some steps and devices from the above separately described various embodiments according to the concept of the present application to achieve the effect of the present application, and such combined and combined embodiments are also included in the present application, and such combined and combined embodiments are not described here.

[0516] Note that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and are not limiting, and these advantages, advantages, effects, etc. cannot be considered as the various embodiments of the present application must have. In addition, the specific details of the above disclosure are only for the purpose of example and for the purpose of understanding, and not for the purpose of limitation, and the above details do not limit the present application to the above specific details.

[0517] The block diagrams of the devices, apparatuses, equipment, systems involved in the present disclosure are only illustrative examples and are not intended to require or imply that the connection, arrangement, configuration must be as shown in the block diagram. As a person skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any way. Words such as "include", "contain", "have" and the like are open-ended words, which mean "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.

[0518] The flowchart illustrations and above method descriptions in the present disclosure are only examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be appreciated by one of ordinary skill in the art, the order of steps in the foregoing embodiments can be performed in any order. Words such as "thereafter," "then," "next," etc. are not intended to limit the order of the steps; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles "one," "a" or "an," is not used to limit the element to the singular.

[0519] In addition, the steps and apparatuses in various embodiments herein are not limited to be performed only in certain embodiments, in fact, new embodiments can be conceived by combining relevant partial steps and partial apparatuses in various embodiments herein according to the concepts of the present application, and these new embodiments are also included in the scope of the present application.

[0520] The various operations of methods described above can be performed by any suitable means caused by any suitable apparatuses. The means can include any suitable combination of hardware and / or software, including, without limitation, circuitry, dedicated hardware, an application specific integrated circuit (ASIC) or processor that is programmed with software to perform the functions.

[0521] The various illustrative logical blocks, modules, and circuits described in connection with the present disclosure can be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an ASIC, a Field Programmable Gate Array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any commercially available processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0522] The steps of a method or algorithm described in connection with the present disclosure can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in any form of storage medium that is tangible. Some examples of storage media that can be used include random access memory (RAM), read only memory (ROM), a flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM and so forth. A storage medium can be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The software module can comprise single instruction or many instructions, and can be distributed over several different code segments, among different programs, and across multiple storage media.

[0523] The methods disclosed herein include actions for implementing the described methods. The methods and / or actions can be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and / or use of specific actions can be modified without departing from the scope of the claims.

[0524] The functions described above can be implemented in hardware, software, firmware or any combination thereof. If implemented in software, the functions can be stored as instructions on a tangible computer-readable medium, when executed, to cause a processor to carry out actions. Storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other tangible medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.

[0525] Computer program products can therefore be provided to perform the operations presented herein. For example, such computer program products can be tangibly embodied in a computer-readable tangible medium having instructions that can be executed by a processor to perform the operations described herein. The computer program products can also be provided as a package having the package and materials.

[0526] Software or instructions can also be transmitted over a transmission medium. For example, software can be transmitted from a website, server, or other remote source using a transmission medium such as coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave. Thus, a medium that is tangible, such as a physical storage medium, can also be referred to as a computer-readable medium.

[0527] Also, the modules and / or other appropriate means for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by a user terminal and / or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via a storage means (e.g., RAM, ROM, a physical storage medium such as a CD or floppy disk, etc.), such that a user terminal and / or base station can obtain the various methods upon coupling or providing the storage means to the device.

[0528] Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, "or" as used in a list of items prefaced by "at least one of indicates a disjunctive list such that, for example, a list of "at least one of A, B, or C" means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase "exemplary" does not mean that example embodiments described are preferred or better than other embodiments.

[0529] Various changes, modifications, and alterations in the techniques described herein can be made without departing from the teachings of the attached claims. Moreover, the scope of the claims of the present disclosure is not limited to the specific aspects described above. Rather, the scope of the claims of the present disclosure includes all alternatives, modifications, and alterations that can be made to the above-described aspects that would be apparent to one of ordinary skill in the art having the benefit of this disclosure. Accordingly, the appended claims include within their scope all such alternatives, modifications, and alterations.

[0530] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0531] The above description has been presented for the purpose of illustration and description. Furthermore, the description is not intended to limit the embodiments of the application to the forms disclosed herein. Although several example aspects and embodiments have been discussed, those skilled in the art will recognize that certain modifications, substitutions, changes, additions and sub-combinations are possible.

Claims

1. A method for precise single-point positioning with fixed ambiguity across multiple systems based on satellite short messages, comprising: The user terminal obtains the initial coordinates of the station, selects the system frequency band, and sends the initial coordinates of the station and the selected system frequency band to the system. The system obtains the initial coordinates of the station and the system frequency band selection from the user terminal via short message communication; For multiple satellites observable by the user terminal, the system converts the SSR orbital clock error corrections of the multiple satellites into the OSR integrated corrections of the observation space representation along the station-satellite line-of-sight direction based on the initial coordinates of the station sent by the user terminal. This conversion is performed by the system at least through the following steps: The real-time SSR orbital correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , , These are the radial, tangential, and normal corrections for the satellite in the satellite coordinate system, respectively. , , These represent the radial, tangential, and normal velocities of the satellite in the satellite coordinate system. For the current moment, For SSR epoch reference time, The real-time clock error correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , and These are the constant term, the first-order term, and the second-order term in the clock error fitting polynomial, respectively. For the current moment, For SSR epoch reference time, The real-time SSR orbit correction number is calculated using the following formula. Transformation from satellite coordinate system to ECEF geocentric coordinate system : in, and These are the position and velocity coordinates of the satellite under ECEF. It is a radial vector in the satellite coordinate system. It is the tangential vector in the satellite coordinate system. It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule; The following formula will be used to... , Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction. The formula is as follows: Where c is the speed of light. It is the unit vector pointing from the station to the satellite, where, e=[ 　, 　, 　], Where r' is the geometric distance from the satellite to the user terminal. For the satellite's three-dimensional coordinates, , The system performs polynomial coefficient fitting on the OSR (Optical Sequence of Research and Development) composite corrections for the observation spatial representation of the multiple satellites within a predetermined time period to obtain polynomial coefficients for the multiple satellites. The system also estimates the phase fractional deviation product for the selected frequency point based on the system frequency band selection for the multiple satellites. The polynomial coefficients of the multiple satellites and the phase fractional deviation product for the selected frequency point are then encoded and broadcast to the user terminal. The polynomial coefficient fitting on the OSR composite corrections for the observation spatial representation of the multiple satellites within the predetermined time period, using the following formula, yields a polynomial coefficients including a constant term. and the coefficients of the first-order terms Polynomial coefficients of multiple satellites: t1…t n It refers to the various moments in chronological order within a predetermined time period. ... It is the spatial representation of the observations along the station-satellite line-of-sight direction at each moment, representing the OSR composite correction. The system transmits the OSR composite correction values ​​of the most recent epoch of the multiple satellites to the user terminal in turn through one or more epochs via short message communication. The user terminal receives and decodes the OSR composite corrections from the most recent epoch of the multiple satellites via short message communication. Polynomial coefficient fitting is then performed on the received OSR composite corrections from the spatial representation of the multiple satellites within the predetermined time period to obtain a result including a constant term. and the coefficients of the first-order terms The polynomial coefficients are extrapolated to the OSR composite correction of the most recent epoch of the multiple satellites to obtain the inferred OSR composite correction of the multiple satellites at the current epoch. The OSR composite correction of the current epoch is used to correct the errors of satellite coordinates and satellite clock bias in the satellite-station direction. The phase fractional deviation of the satellite end is corrected by the phase fractional deviation product to achieve precise single-point positioning with fixed ambiguity.

2. A method for broadcasting correction data for precise single-point positioning with fixed ambiguity across multiple systems based on satellite short messages from the system end, comprising: The system obtains the initial coordinates of the station and the system frequency band selection from the user terminal via short message communication; For multiple satellites observable by the user terminal, the system converts the SSR orbital clock error corrections of the multiple satellites into the OSR integrated corrections of the observation space representation along the station-satellite line-of-sight direction based on the initial coordinates of the station sent by the user terminal. This conversion is performed by the system at least through the following steps: The real-time SSR orbital correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , , These are the radial, tangential, and normal corrections for the satellite in the satellite coordinate system, respectively. , , These represent the radial, tangential, and normal velocities of the satellite in the satellite coordinate system. For the current moment, For SSR epoch reference time, The real-time clock error correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , and These are the constant term, the first-order term, and the second-order term in the clock error fitting polynomial, respectively. For the current moment, For SSR epoch reference time, The real-time SSR orbit correction number is calculated using the following formula. Transformation from satellite coordinate system to ECEF geocentric coordinate system : in, and These are the position and velocity coordinates of the satellite under ECEF. It is a radial vector in the satellite coordinate system. It is the tangential vector in the satellite coordinate system. It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule; The following formula will be used to... , Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction. The formula is as follows: Where c is the speed of light. It is the unit vector pointing from the station to the satellite, where, e=[ 　, 　, 　], Where r' is the geometric distance from the satellite to the user terminal. For the satellite's three-dimensional coordinates, ; The system performs polynomial coefficient fitting on the OSR (Optical Sequence of Research and Development) composite corrections for the observation spatial representation of the multiple satellites within a predetermined time period to obtain polynomial coefficients for the multiple satellites. The system also estimates the phase fractional deviation product for the selected frequency point based on the system frequency band selection for the multiple satellites. The polynomial coefficients of the multiple satellites and the phase fractional deviation product for the selected frequency point are then encoded and broadcast to the user terminal. The system performs polynomial coefficient fitting on the OSR composite corrections for the observation spatial representation of the multiple satellites within a predetermined time period using the following formula to obtain a polynomial coefficients including a constant term. and the coefficients of the first-order terms Polynomial coefficients of multiple satellites: t1…t n It refers to the various moments in chronological order within a predetermined time period. ... It is the spatial representation of the observations along the station-satellite line-of-sight direction at each moment, representing the OSR composite correction. The system transmits the OSR composite correction values ​​of the most recent epoch of the multiple satellites to the user terminal in turn through one or more epochs via short message communication.

3. The method according to claim 2, wherein the SSR orbit clock correction includes orbit and clock correction, wherein when using the uncalibrated phase delay (UPD) method for precise single-point positioning with fixed ambiguity, the clock correction is a clock correction product based on pseudorange, and the phase fractional deviation product is a phase fractional deviation product including the frequency point selected by the system frequency band selection; or when using the integer clock estimation (IRC) method for precise single-point positioning with fixed ambiguity, the clock correction is a clock correction product based on phase, and the phase fractional deviation product is a phase fractional deviation product including only wide-lane ambiguity.

4. The method according to claim 2, wherein, When broadcast ephemeris from Switch to broadcast ephemeris At that time, the jump result is obtained by using the following formula. Reducing to : in, It uses the satellite coordinates calculated using a set of ephemeris data from before the switch; These are the satellite coordinates calculated using the switched set of ephemeris data.

5. The method according to claim 2, wherein, The steps include: fitting polynomial coefficients of the OSR (Optical Sequence Ratio) comprehensive correction for the observation spatial representation of the multiple satellites to obtain polynomial coefficients for the multiple satellites; estimating the phase fractional deviation product of the selected frequency point by the system frequency band selection for the multiple satellites; and encoding and broadcasting the polynomial coefficients of the multiple satellites and the phase fractional deviation product of the frequency point to the user terminal. The system encodes the epoch difference correction time identifier, satellite system information, satellite number, ephemeris data period number (IODE) of the satellite difference information together with the polynomial coefficients and the phase fractional deviation products of the frequency points of the multiple satellites. Specifically, the OSR integrated corrections, representing the observation space along the station-satellite line-of-sight direction of multiple observable satellites at the current user terminal, are broadcast in turn over multiple epochs. Under the condition that the satellite elevation angle is greater than 10°, the corrections are broadcast to the user terminal in the order of GPS satellites, BDS satellites, and GALILEO satellites. After all satellites have been broadcast, a new round of corrections is broadcast in a loop.

6. The method according to claim 2, wherein at least the following steps are performed by the system to encode the epoch difference correction time identifier, satellite system information, satellite number, ephemeris data period number IODE of satellite difference information together with the polynomial coefficients and phase fractional deviation products of the frequency points of the plurality of satellites: The epoch difference correction time identifier is encoded in the following header format: The parameters encoded in the header file include GPSWeek, GPSSec, and the number of satellites. GPSWeek has a precision of 1 week, GPSSec has a precision of 1 second, and the number of satellites has a precision of 1 satellite. The valid range for GPSWeek is 0-4095, the valid range for GPSSec is 0-604800, and the valid range for the number of satellites is 0-15. GPSWeek has 12 bits, GPSSec has 20 bits, and the number of satellites has 4 bits. GPSWeek represents the GPS week, and GPSSec represents the GPS second.

7. The method according to claim 2, wherein, At least the following steps are required for the system to encode the epoch difference correction time identifier, satellite system information, satellite number, ephemeris data period number (IODE) of the satellite difference information together with the polynomial coefficients and frequency point phase fractional deviation products of the multiple satellites: When using the UPD method, the encoding method described above is as follows: The encoded parameters include satellite system information, satellite number PRN, ephemeris data period number IODE, and polynomial coefficients. polynomial coefficients Phase fractional deviation product at the first frequency point Phase fractional deviation product at the second frequency point The satellite system information has a precision of 1 and a valid range of 0-2, where 0 represents GPS, 1 represents BDS, and 2 represents Galileo. The satellite system information has 2 bits. The satellite PRN has a precision of 1 and a valid range of 0-63. The satellite PRN has 6 bits. The ephemeris date number (IODE) has a precision of 1 and a valid range of 0-255. The ephemeris date number (IODE) has 8 bits. The polynomial coefficients... The accuracy is 0.001 m, and the polynomial coefficients... The effective range is -3 to 3, and the polynomial coefficients are... The number of bits is 10, and the polynomial coefficients are... The accuracy is 1 mm / s, and the polynomial coefficients are... The effective range is -1 to 1, and the polynomial coefficients are... The number of bits is 4, and the phase fractional deviation of the product at the first frequency point The accuracy is 8 mm, and the phase fractional deviation at the first frequency point is [not specified]. The effective range is -2 to 2, and the product has a phase fractional deviation at the first frequency point. The number of bits is 9, and the phase fractional deviation of the product at the second frequency point. The accuracy is 8 mm, and the phase fractional deviation at the second frequency point is [not specified]. The effective range is -2 to 2, and the phase fractional deviation of the product at the second frequency point is... The number of bits is 9. Alternatively, when using the IRC method, the above encoding method is as follows: The encoded parameters include satellite system information, satellite number PRN, ephemeris data period number IODE, and polynomial coefficients. polynomial coefficients Phase decimal deviation products that only include wide-lane ambiguity The satellite system information has a precision of 1 and a valid range of 0-2, where 0 represents GPS, 1 represents BDS, and 2 represents Galileo. The satellite system information has 2 bits. The satellite PRN has a precision of 1 and a valid range of 0-63. The satellite PRN has 6 bits. The ephemeris date number (IODE) has a precision of 1 and a valid range of 0-255. The ephemeris date number (IODE) has 8 bits. The polynomial coefficients... The accuracy is 0.001 m, and the polynomial coefficients... The effective range is -3 to 3, and the polynomial coefficients are... The number of bits is 10, and the polynomial coefficients are... The accuracy is 1 mm / s, and the polynomial coefficients are... The effective range is -1 to 1, and the polynomial coefficients are... The number of bits is 4, and it only includes phase fractional deviation products with wide-lane ambiguity. The accuracy is 8 mm, and the product only includes phase fractional deviations for wide-lane ambiguity. The effective range is -2 to 2, and it only includes phase fractional deviation products with wide-lane ambiguity. The number of bits is 9.

8. The method according to claim 2, wherein, The overall information encoding requirements for information sent by the system are as follows: The encoded parameters include the instruction, length, local user address, message content, and checksum. The instruction includes the communication request ($TXSQ), which is 40 bits in size and 16 bits in length. The local user address is 24 bits in size. The message content includes an 8-bit message category, a 24-bit destination user address, a 16-bit message length, 8 bits of fixed zeros, and a message content less than or equal to 560 bits. The checksum is 8 bits in size. The information content includes the encoded portion of the OSR synthesis correction number of the most recent epoch of the multiple satellites.

9. The method according to claim 2, wherein, For the OSR synthesis corrections obtained from decoding previous epochs stored on the user end, whenever a new OSR synthesis correction from a satellite is received, the old OSR synthesis correction is replaced with the new OSR synthesis correction and its timing information is recorded; when extrapolating using the polynomial coefficients of the multiple satellites, a threshold for the extrapolation duration is set, wherein the threshold includes 5 minutes, so that OSR synthesis corrections exceeding 5 minutes are not used.

10. A method for precise single-point positioning with fixed ambiguity across multiple systems, achieved by a user terminal based on satellite short messages, comprising: The user terminal obtains the initial coordinates of the station, selects the system frequency band, and sends the initial coordinates of the station and the selected system frequency band to the system terminal via short message communication. The user terminal receives and decodes polynomial coefficients of multiple satellites sent by the system terminal via short message communication. These polynomial coefficients are obtained through at least the following steps: The system terminal, for multiple satellites observable by the user terminal, converts the SSR orbital clock error corrections of the multiple satellites into OSR (Optical State Representation) composite corrections in the station-satellite line-of-sight direction based on the initial station coordinates sent by the user terminal. This conversion is achieved through at least the following steps: The real-time SSR orbital correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , , These are the radial, tangential, and normal corrections for the satellite in the satellite coordinate system, respectively. , , These represent the radial, tangential, and normal velocities of the satellite in the satellite coordinate system. For the current moment, For SSR epoch reference time, The real-time clock error correction for the most recent epoch in the satellite coordinate system is calculated using the following formula. : in , and These are the constant term, the first-order term, and the second-order term in the clock error fitting polynomial, respectively. For the current moment, For SSR epoch reference time, The real-time SSR orbit correction number is calculated using the following formula. Transformation from satellite coordinate system to ECEF geocentric coordinate system : in, and These are the position and velocity coordinates of the satellite under ECEF. It is a radial vector in the satellite coordinate system. It is the tangential vector in the satellite coordinate system. It is a vector in the satellite coordinate system whose direction is determined by the right-hand rule; The following formula will be used to... , Converted to the spatial representation of observations along the station-satellite line-of-sight direction, OSR composite correction. The formula is as follows: Where c is the speed of light. It is the unit vector pointing from the station to the satellite, where, e=[ 　, 　, 　], Where r' is the geometric distance from the satellite to the user terminal. For the satellite's three-dimensional coordinates, ; The system performs polynomial coefficient fitting on the OSR comprehensive corrections for the observed spatial representation of the multiple satellites within a predetermined time period to obtain the polynomial coefficients for the multiple satellites. The polynomial coefficients for the OSR comprehensive corrections for the observed spatial representation of the multiple satellites within a predetermined time period are obtained using the following formula, which includes a constant term. and the coefficients of the first-order terms Polynomial coefficients of multiple satellites: t1…t n It refers to the various moments in chronological order within a predetermined time period. ... It is the spatial representation of the observations along the station-satellite line-of-sight direction at each moment, representing the OSR composite correction. The user terminal receives, via short message communication, a phase fractional deviation product estimated and encoded by the system for the multiple satellites and selected by the system frequency band selection. The user terminal receives the OSR composite correction of the most recent epoch from the multiple satellites via short message communication, which is broadcast by the system terminal via short message communication through one or more epochs in turn. The user terminal extrapolates the OSR integrated correction of the most recent epoch of the multiple satellites based on the polynomial coefficients received from the multiple satellites to obtain the inferred current OSR integrated correction of the multiple satellites. The error of satellite coordinates and satellite clock bias in the satellite-station direction is corrected by the current OSR integrated correction. The phase fractional deviation of the satellite end is corrected by the phase fractional deviation product to achieve precise single-point positioning with fixed ambiguity.

11. The method of claim 10, wherein the SSR orbit clock correction includes orbit and clock correction, wherein in the case of using the uncalibrated phase delay (UPD) method for precise single-point positioning with fixed ambiguity, the clock correction is a clock correction product based on pseudorange, and the phase fractional deviation product is a phase fractional deviation product that includes the frequency point selected by the system frequency band selection; or in the case of using the integer clock estimation (IRC) method for precise single-point positioning with fixed ambiguity, the clock correction is a clock correction product based on phase, and the phase fractional deviation product is a phase fractional deviation product that only includes wide-lane ambiguity.

12. The method of claim 10, wherein The user terminal receives, via short message communication, the epoch differential correction time identifier, satellite system information, satellite number, and satellite differential information ephemeris data period number IODE, which is encoded together with the phase fractional deviation product of the frequency point and sent by the system terminal via short message communication. in, The OSR (Optical Sequence of Reference) corrections, representing the observation space along the line-of-sight direction of multiple observable satellites at the current user terminal, are broadcast to the user terminal in turn over multiple epochs, provided that the satellite elevation angle is greater than 10°. The corrections are broadcast to the user terminal in the order of GPS satellites, BDS satellites, and GALILEO satellites. After all satellites have been broadcast, a new round of corrections is broadcast in a loop.

13. The method according to claim 10, wherein, The encoding format for short message communication between the user terminal and the system terminal is specified as follows. The encoded parameters include GPSWeek, GPSSec, X in the ECEF coordinate system, Y in the ECEF coordinate system, Z in the ECEF coordinate system, GPS frequency, BDS frequency, and Galileo frequency. Specifically, GPSWeek has a precision of 1 cycle, an effective range of 0-4095, and 12 bits; GPSSec has a precision of 1 second, an effective range of 0-604800, and 20 bits; X in the ECEF coordinate system has a precision of 1 meter, an effective range of ±9999999, and 25 bits; Y in the ECEF coordinate system has a precision of 1 meter, an effective range of ±9999999, and 25 bits; Z in the ECEF coordinate system has a precision of 1 meter, an effective range of ±9999999, and 25 bits; and the GPS frequency has a precision of 1. The effective range of the frequency points is 0-2, where 0 represents L1 / L2, 1 represents 1:L1 / L5, and 2 represents L2 / L5. The GPS frequency point has 2 bits. The BDS frequency point has a precision of 1, and its effective range is 0-2, where 0 represents B1I / B2a, 1 represents 1:B1I / B3I, and 2 represents B2a / B3I. The Galileo frequency point has 1 bit, and its effective range is 0-2, where 0 represents E1 / E5a, 1 represents 1:E1 / E6, and 2 represents E5a / E6. The Galileo frequency point has 2 bits. In this context, GPSWeek represents the GPS week, GPSSec represents the GPS second, X(ECEF) represents the X-axis of the geocentric-fixed coordinate system ECEF, Y(ECEF) represents the Y-axis of the geocentric-fixed coordinate system ECEF, Z(ECEF) represents the Z-axis of the geocentric-fixed coordinate system ECEF, GPS frequency points represent the frequency combination of the GPS system used for user positioning, BDS frequency points represent the frequency combination of the BeiDou Navigation Satellite System (BDS) used for user positioning, and Galileo frequency points represent the frequency combination of the Galileo system used for user positioning.

14. The method of claim 10, wherein, When broadcast ephemeris from Switch to broadcast ephemeris At that time, the jump result is obtained by using the following formula. Reducing to : in, It uses the satellite coordinates calculated using a set of ephemeris data from before the switch; These are the satellite coordinates calculated using the switched set of ephemeris data.

15. The method according to claim 10, wherein at least the following steps are performed by the system end to encode the epoch difference correction time identifier, satellite system information, satellite number, ephemeris data period number IODE of satellite difference information together with the polynomial coefficients and phase fractional deviation products of the frequency points of the plurality of satellites: The epoch difference correction time identifier is encoded in the following header format: The parameters encoded in the header file include GPSWeek, GPSSec, and the number of satellites. GPSWeek has a precision of 1 week, GPSSec has a precision of 1 second, and the number of satellites has a precision of 1 satellite. The valid range for GPSWeek is 0-4095, the valid range for GPSSec is 0-604800, and the valid range for the number of satellites is 0-15. GPSWeek has 12 bits, GPSSec has 20 bits, and the number of satellites has 4 bits. GPSWeek represents the GPS week, and GPSSec represents the GPS second.

16. The method of claim 10, wherein, At least the following steps are required for the system to encode the epoch difference correction time identifier, satellite system information, satellite number, ephemeris data period number (IODE) of the satellite difference information together with the polynomial coefficients and the phase fractional deviation product of the frequency points of the multiple satellites: When using the UPD method, the encoding method described above is as follows: The encoded parameters include satellite system information, satellite number PRN, ephemeris data period number IODE, and polynomial coefficients. polynomial coefficients Phase fractional deviation product at the first frequency point Phase fractional deviation product at the second frequency point The satellite system information has a precision of 1 and a valid range of 0-2, where 0 represents GPS, 1 represents BDS, and 2 represents Galileo. The satellite system information has 2 bits. The satellite PRN has a precision of 1 and a valid range of 0-63. The satellite PRN has 6 bits. The ephemeris date number (IODE) has a precision of 1 and a valid range of 0-255. The ephemeris date number (IODE) has 8 bits. The polynomial coefficients... The accuracy is 0.001 m, and the polynomial coefficients... The effective range is -3 to 3, and the polynomial coefficients are... The number of bits is 10, and the polynomial coefficients are... The accuracy is 1 mm / s, and the polynomial coefficients are... The effective range is -1 to 1, and the polynomial coefficients are... The number of bits is 4, and the phase fractional deviation of the product at the first frequency point The accuracy is 8 mm, and the phase fractional deviation at the first frequency point is [not specified]. The effective range is -2 to 2, and the product has a phase fractional deviation at the first frequency point. The number of bits is 9, and the phase fractional deviation of the product at the second frequency point. The accuracy is 8 mm, and the phase fractional deviation at the second frequency point is [not specified]. The effective range is -2 to 2, and the phase fractional deviation of the product at the second frequency point is... The number of bits is 9. Alternatively, when using the IRC method, the above encoding method is as follows: The encoded parameters include satellite system information, satellite number PRN, ephemeris data period number IODE, and polynomial coefficients. polynomial coefficients Phase decimal deviation products that only include wide-lane ambiguity The satellite system information has a precision of 1 and a valid range of 0-2, where 0 represents GPS, 1 represents BDS, and 2 represents Galileo. The satellite system information has 2 bits. The satellite PRN has a precision of 1 and a valid range of 0-63. The satellite PRN has 6 bits. The ephemeris date number (IODE) has a precision of 1 and a valid range of 0-255. The ephemeris date number (IODE) has 8 bits. The polynomial coefficients... The accuracy is 0.001 m, and the polynomial coefficients... The effective range is -3 to 3, and the polynomial coefficients are... The number of bits is 10, and the polynomial coefficients are... The accuracy is 1 mm / s, and the polynomial coefficients are... The effective range is -1 to 1, and the polynomial coefficients are... The number of bits is 4, and it only includes phase fractional deviation products with wide-lane ambiguity. The accuracy is 8 mm, and the product only includes phase fractional deviations for wide-lane ambiguity. The effective range is -2 to 2, and it only includes phase fractional deviation products with wide-lane ambiguity. The number of bits is 9.

17. The method according to claim 10, wherein, The overall information encoding requirements for information sent by the system are as follows: The encoded parameters include the instruction, length, local user address, message content, and checksum. The instruction includes the communication request ($TXSQ), which is 40 bits in size and 16 bits in length. The local user address is 24 bits in size. The message content includes an 8-bit message category, a 24-bit destination user address, a 16-bit message length, 8 bits of fixed zeros, and a message content less than or equal to 560 bits. The checksum is 8 bits in size. The information content includes the encoded portion of the OSR synthesis correction number of the most recent epoch of the multiple satellites.

18. The method according to claim 10, wherein, For the OSR synthesis corrections obtained from decoding previous epochs stored on the user end, whenever a new OSR synthesis correction from a satellite is received, the old OSR synthesis correction is replaced with the new OSR synthesis correction and its timing information is recorded; when extrapolating using the polynomial coefficients of the multiple satellites, a threshold for the extrapolation duration is set, wherein the threshold includes 5 minutes, so that OSR synthesis corrections exceeding 5 minutes are not used.

19. An electronic device comprising: Memory, used to store instructions; A processor for reading instructions from the memory and executing the method as described in any one of claims 1-18.

20. A non-temporary storage medium having instructions stored thereon, in, When the instruction is read by the processor, it causes the processor to perform the method as described in any one of claims 1-18.

Images