A b3i signal simulation method and device, terminal equipment and storage medium

Abstract

The application discloses a B3I signal simulation method and device, terminal equipment and storage medium, through obtaining ephemeris data, generating pseudo code and extension code, and modulating the same, a real B3I signal can be quickly and accurately generated. In this way, the original signal simulation can be freed from the dependence on hardware equipment, and only ephemeris data provided by a user and satellite messages of a Beidou satellite are needed to generate a corresponding B3I signal. In addition, a Doppler frequency shift is calculated according to the distance between a satellite and the user, and is applied to carrier modulation, so that the B3I signals of various satellites can be more accurately simulated. By comprehensively considering ephemeris data, distance calculation, pseudo code generation, Doppler frequency shift and navigation messages and the like, a real B3I signal with a Doppler effect can be generated, which provides a beneficial tool and data for testing and verification of a B3I signal receiver, so that the research and development efficiency of a navigation satellite signal receiver is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of signal simulation, and in particular to a B3I signal simulation method and device, a terminal device and a storage medium. BACKGROUND

[0002] The BeiDou satellite navigation system is referred to as the BeiDou system, and the English abbreviation is BDS. The BeiDou system is divided into three development stages of BeiDou-1, BeiDou-2 and BeiDou-3. With the construction of the BeiDou system, the research on the BeiDou navigation and positioning signal receiver is also developing vigorously. In the development process of the traditional navigation receiver, a dedicated professional simulator is generally used. The development process of the satellite navigation receiver usually uses a dedicated professional simulator. These simulators are used to simulate the signal characteristics and environmental conditions of the satellite navigation system to generate B3I signals (BeiDou-3) so as to test and verify the receiver.

[0003] In the prior art, the development of domestic simulators is mainly concentrated in colleges and institutes, among which the Beijing University of Aeronautics and Astronautics first proposed the research on satellite navigation simulators, and the hardware architecture of "DSP (Digital Signal Processing) + FPGA (Field-Programmable Gate Array)" is used to generate B3I signals (BeiDou-3). In the hardware architecture of "DSP + FPGA", the DSP is equivalent to the CPU of the computer, and the FPGA is the hard disk of the computer. Many scientific researches in the academic field also follow this idea.

[0004] However, the existing "DSP + FPGA" navigation satellite signal simulator design is too complex, and professional personnel is required for configuration in the operation of the host computer, which leads to difficult operation for users. SUMMARY

[0005] The present application provides a B3I signal simulation method, device, terminal device and storage medium to solve the problem of complex design of the satellite signal simulator in the prior art, which leads to difficult operation.

[0006] In a first aspect, the present application provides a B3I signal simulation method, comprising:

[0007] Obtaining ephemeris data, and obtaining the distance between each satellite and the user and the pseudo code of the visible satellite according to the ephemeris data;

[0008] Obtaining the spreading code according to the pseudo code and the navigation message of each satellite;

[0009] The spread code and the carrier are modulated to obtain two IQ baseband signals, and a digital intermediate frequency signal of a B3I signal is obtained according to the two IQ baseband signals; wherein the carrier is obtained by a Doppler shift according to distances between each satellite and the user.

[0010] In this way, by acquiring ephemeris data, generating a pseudo code and a spread code, and modulating the same, a simulated real B3I signal can be quickly and accurately generated. Thus, the dependence on hardware devices in the original signal simulation is eliminated, and only ephemeris data provided by a user and satellite navigation messages of a Beidou satellite are needed to generate a corresponding B3I signal. Further, by calculating a Doppler shift according to distances between satellites and the user and applying the same in carrier modulation, B3I signals of various satellites can be more accurately simulated. Considering ephemeris data, distance calculation, pseudo code generation, Doppler shift and navigation messages, a real B3I signal with Doppler effect can be generated, which provides a useful tool and data for testing and verification of a B3I signal receiver and improves the development efficiency of a navigation satellite signal receiver.

[0011] Further, the pseudo code of the visible satellite comprises:

[0012] According to the ephemeris data, positions of Beidou satellites in the ephemeris data are acquired, and user coordinates are acquired.

[0013] According to the user coordinates and the positions of all satellites, an elevation angle of each satellite is obtained, and when the elevation angle of a satellite is greater than zero, the satellite is determined as a visible satellite.

[0014] According to a preset shift register circuit, a pseudo code of all visible satellites is generated.

[0015] In this way, by acquiring ephemeris data, position information of Beidou satellites in the ephemeris data can be obtained. The position information is very important for subsequent calculation and pseudo code generation. By accurately calculating the positions of the satellites, the accuracy of pseudo code generation can be improved. Meanwhile, the elevation angles of the satellites can be determined. When the elevation angle of a satellite is greater than zero, it indicates that the satellite is within the visible range of the user. Thus, a set of visible satellites can be determined, unnecessary pseudo code generation for invisible satellites is avoided, and the calculation amount is reduced and the calculation rate is improved. Further, by using a preset shift register circuit, the accuracy and consistency of pseudo code generation can be ensured, and the periodicity of the pseudo code can be controlled to adapt to different application requirements.

[0016] Further, the distance between the satellite and the user according to the ephemeris data is specifically:

[0017] According to the ephemeris data, position and velocity information of each satellite at a normalized time is obtained, and the position and velocity information is corrected according to correction term satellite parameters in the ephemeris data to obtain position information of all satellites;

[0018] According to the position information of all satellites and the obtained user coordinates, distances between each satellite and the user are obtained.

[0019] The position and velocity information includes average angular velocity, mean anomaly, eccentric anomaly and latitude amplitude.

[0020] Thus, through the calculation and correction of these parameters, accurate satellite position information can be obtained. The correction term satellite parameters in the ephemeris data are used to correct the satellite position and velocity information. These correction terms include satellite clock error, relativistic effect, atmospheric delay, etc., which can eliminate errors and deviations and improve the accuracy of the position information. By applying the correction terms, the satellite position and velocity information can be corrected, further improving the accuracy of satellite position calculation and distance calculation.

[0021] Further, the carrier is obtained according to the distance between each satellite and the user by Doppler shift, specifically:

[0022] According to the distance between each satellite and the user, pseudo-range rates and pseudo-ranges of the satellite and the user in several movements are obtained.

[0023] According to the pseudo-range rate and the preset Doppler shift, the carrier wavelength is obtained, and the carrier phase cycle value is obtained by dividing the pseudo-range by the carrier wavelength. The carrier is obtained according to the carrier phase cycle value and the carrier wavelength.

[0024] Thus, by obtaining the carrier according to the distance between the satellite and the user, the carrier phase information can be obtained. The Doppler shift is applied to calculate the carrier wavelength, the carrier phase cycle value is calculated, and the carrier is applied to perform accurate positioning and navigation calculation.

[0025] Further, the extended code is obtained according to the pseudo-code and the navigation message of each satellite, including:

[0026] Time information is obtained and added to each subframe set in advance, and a check code corresponding to each subframe is obtained according to BCH encoding;

[0027] All subframes and corresponding check codes are interleaved, and the navigation message of each satellite is obtained according to the interface control file of each satellite.

[0028] The pseudo-code is spread spectrum modulated according to the navigation message of each satellite to obtain the extended code.

[0029] Thus, by acquiring time information and adding it to the subframe, it can be ensured that the time information in the navigation message is consistent with the actual time, ensuring the accuracy of the time information and improving the accuracy and reliability of positioning and navigation. Further, interleaving all subframes and corresponding check codes can optimize the transmission of navigation messages. Interleaving can disrupt the order of data and reduce continuous errors in data transmission. Through interleaving, the reliability and anti-interference ability of the navigation message can be improved. And according to the navigation message of each satellite, the pseudo code is spread spectrum modulated to obtain the spread code. Spread spectrum modulation is a method of expanding low-speed data into high-speed signals, which can improve the anti-interference and transmission efficiency of the signal. By applying spread spectrum modulation, the information capacity of the spread code can be increased, and the reliability of the navigation signal and the sensitivity of the receiver can be improved.

[0030] Further, the modulation of the spread code and the carrier wave to obtain two IQ baseband signals includes:

[0031] The spread code and the carrier wave are modulated by a binary phase shift keying modulation method to obtain two IQ baseband signals.

[0032] Thus, the two IQ baseband signals generated by the binary phase shift keying modulation method can realize multiplexing. The spread codes and carrier waves of multiple satellites can be modulated at the same time, transmitted through mutually orthogonal I and Q signals, and realize simultaneous transmission and reception of multiple signals.

[0033] Further, the digital intermediate frequency signal obtained from the two IQ baseband signals includes:

[0034] A noise signal and / or an interference signal is added to the two IQ baseband signals by a preset noise interference algorithm to obtain a digital intermediate frequency signal.

[0035] Thus, by adding a noise signal and / or an interference signal to the two IQ baseband signals by a preset noise interference algorithm, the signal transmission situation in a real environment can be simulated, so that a more realistic signal is used to verify and debug the performance of the navigation satellite signal receiver.

[0036] In a second aspect, the present application provides a B3I signal simulation device, comprising: an ephemeris module, a spread code module and a signal module;

[0037] The ephemeris module is used to acquire ephemeris data, and to acquire the distance between each satellite and the user and the pseudo code of the visible satellite according to the ephemeris data;

[0038] The spread code module is used to acquire a spread code according to the pseudo code and the navigation message of each satellite;

[0039] The signal module is configured to obtain an extension code according to the pseudo code, modulate the extension code and a carrier to obtain two IQ baseband signals, and obtain a digital intermediate frequency signal of a B3I signal according to the two IQ baseband signals; wherein the carrier is obtained by a Doppler frequency shift according to distances between each satellite and the user.

[0040] Further, the ephemeris module comprises a coordinate unit, a visible satellite unit and a pseudo code unit.

[0041] The coordinate unit is configured to obtain all satellite positions of the Beidou satellite in the ephemeris data according to the ephemeris data, and obtain a user coordinate.

[0042] The visible satellite unit is configured to obtain an elevation angle of each satellite according to the user coordinate and all satellite positions, and determine the satellite as a visible satellite when the elevation angle of the satellite is greater than zero.

[0043] The pseudo code unit is configured to generate pseudo codes of all visible satellites according to a preset shift register circuit.

[0044] Further, the ephemeris module comprises a position information unit and a distance unit.

[0045] The position information unit is configured to obtain position and velocity information of each satellite in a normalized time according to the ephemeris data, correct the position and velocity information according to correction term satellite parameters in the ephemeris data, and obtain position information of all satellites.

[0046] The distance unit is configured to obtain distances between each satellite and the user according to the position information of all satellites and the obtained user coordinate.

[0047] The position and velocity information comprises an average angular velocity, a mean anomaly angle, an eccentric anomaly angle and a latitude amplitude angle.

[0048] Further, the signal module comprises a pseudo range unit and a carrier unit.

[0049] The pseudo range unit is configured to obtain a pseudo range rate and a pseudo range of the satellite and the user in several movements according to the distances between each satellite and the user.

[0050] The carrier unit is configured to obtain a carrier wavelength according to the pseudo range rate and a preset Doppler frequency shift, obtain a carrier phase period value by dividing the pseudo range by the carrier wavelength, and obtain a carrier according to the carrier phase period value and the carrier wavelength.

[0051] Further, the extension code module comprises a subframe unit, a message unit and a spread spectrum unit.

[0052] The time information is obtained in the subframe units and added in each subframe, and the check code corresponding to each subframe is obtained according to BCH encoding;

[0053] The text unit is used for interleaving all the subframes and the corresponding check codes, and obtaining the navigation text of each satellite according to the interface control file of each satellite;

[0054] The spread unit is used for spread spectrum modulation of the pseudo code according to the navigation text of each satellite, to obtain the spreading code.

[0055] Further, the signal module comprises a modulation unit;

[0056] The modulation unit is used for modulating the spreading code and the carrier to obtain two-way IQ baseband signals by binary phase shift keying modulation method.

[0057] Further, the signal module comprises a noise interference unit;

[0058] The noise interference unit is used for adding noise signals and / or interference signals to the two-way IQ baseband signals by a preset noise interference algorithm, to obtain digital intermediate frequency signals.

[0059] Correspondingly, the present application also provides a terminal device, comprising a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to realize the B3I signal simulation method according to any one of the above.

[0060] Correspondingly, the present application also provides a computer readable storage medium, comprising a stored computer program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to execute the B3I signal simulation method according to any one of the above when the computer program runs.

[0061] Thus, by obtaining ephemeris data, generating pseudo code and spreading code, and modulating them, the B3I signal simulation method can quickly and accurately generate simulated real B3I signals. Thus, the dependence of the original signal simulation on hardware devices can be eliminated, and only ephemeris data provided by users and satellite text of Beidou satellites are needed to generate corresponding B3I signals. In addition, the Doppler shift is calculated according to the distance between the satellite and the user, and is applied to the carrier modulation, so that the B3I signals of various satellites can be more accurately simulated. Considering the ephemeris data, distance calculation, pseudo code generation, Doppler shift and navigation text, etc., the B3I signal simulation method can generate real B3I signals with Doppler effect, which provides a useful tool and data for testing and verifying the B3I signal receiver, thereby improving the development efficiency of the navigation satellite signal receiver. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 Figure 1 is a flow chart of an embodiment of a B3I signal simulation method provided by the present application;

[0063] Figure 2 Figure 2 is a pseudo code generator diagram of an embodiment of a B3I signal simulation method provided by the present application;

[0064] Figure 3 Figure 3 is a frame structure of a D1 navigation message of an embodiment of a B3I signal simulation method provided by the present application;

[0065] Figure 4 Figure 4 is a frame structure of a D2 navigation message of an embodiment of a B3I signal simulation method provided by the present application;

[0066] Figure 5 Figure 5 is a module structure diagram of an embodiment of a B3I signal simulation device provided by the present application. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0068] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0069] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one feature. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0070] Any processes or methods described in the flowcharts or otherwise described herein can be understood as representing a module, segment, or portion of code that includes one or more executable instructions for implementing specific logical functions or steps, and the preferred embodiments of the application include additional or fewer steps, in various sequences, as appropriate, or in parallel, depending upon the function to be implemented. It is therefore intended that additional steps be implemented for the purpose of improving the efficiency, performance, and / or accuracy of the processes.

[0071] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a list of executable instructions for implementing the logic function, and can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor- containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions, or a combination thereof. For the purposes of this specification, a "computer-readable medium" can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

[0072] It should be noted that the pseudo code is a kind of ranging code, the Beidou satellite navigation system is adopted CDMA (Code Division Multiple Access) mode communication, the purpose is to distinguish each satellite, so as to effectively prevent the interference between signals. CDMA (Code Division Multiple Access) needs to select the code with good autocorrelation and poor cross-correlation as the ranging code, and the pseudo-random code (pseudo code) meets these characteristics. The receiver detects the peak value of the autocorrelation function by correlating the received satellite signal with the pseudo code copied in the receiver, so as to determine the phase of the pseudo code in the received signal and measure the spatial distance from the satellite to the receiver, so the pseudo code is also called ranging code in the Beidou technology.

[0073] The navigation message is carried by the data code in the satellite signal structure hierarchy, which contains the satellite ephemeris and almanac information that can be used for calculation, including time, satellite orbit, ionospheric delay, etc. That is, the message is the current state data of the satellite. Different categories of satellites have their corresponding interface control files (ICD files), which define the interface specifications between the space constellation part and the user equipment part, including the format and content of the ranging code and the navigation message, and the ICD file is also the main reference for signal simulation.

[0074] Spread spectrum: that is, using high-rate spread spectrum sequence to expand the spectrum of the signal at the transmitting end. Direct sequence spread spectrum technology can expand the bandwidth range of signal transmission and hide the real information in the frequency band of noise. Therefore, direct sequence spread spectrum technology has the advantages of strong anti-interference, large transmission bandwidth range, long transmission distance, and easy modulation and demodulation, and is widely used in satellite communication, satellite navigation, radar and other communication systems.

[0075] Further, the B3I signal is modulated on the carrier by "pseudo code + navigation message", and the signal expression is:

[0076]

[0077] In the formula, the subscript j represents the satellite number; represents the amplitude of the B3I signal; represents the B3I signal ranging code; represents the data code modulated on the B3I signal ranging code; B3I represents the B3I signal carrier frequency; represents the initial phase of the B3I signal carrier.

[0078] Embodiment one

[0079] Please refer to Figure 1 A B3I signal simulation method provided by the embodiment of the application, comprising steps S1 to S3, and each step is specifically as follows:

[0080] Step S1: obtaining ephemeris data, and obtaining the distance between each satellite and the user and the pseudo code of the visible satellite according to the ephemeris data;

[0081] Further, the pseudo code of the visible satellite comprises:

[0082] According to the ephemeris data, the positions of all the satellites in the ephemeris data are obtained, and the user coordinates are obtained;

[0083] According to the user coordinates and the positions of all the satellites, the elevation angles of each satellite are obtained, and when the elevation angle of a satellite is greater than zero, the satellite is determined as a visible satellite;

[0084] According to the preset shift register circuit, the pseudo code of all the visible satellites is generated.

[0085] In a specific embodiment, the pseudo code of the B3I signal is spread at the transmitting end of the satellite navigation signal, and the satellite signal is despread and captured at the receiving end. The related parameters of the B3I signal pseudo code are: code rate 10.23Mcps, code length 10230.

[0086] The code is a kind of pseudo code, which is generated by the exclusive-OR addition of two 13-stage shift register linear sequences (hereinafter referred to as G1 sequence and G2 sequence). The generating polynomials of the G1 sequence and the G2 sequence are:

[0087]

[0088] The period of the G1 sequence and the G2 sequence is 8191 chips. The last chip of the G1 sequence is truncated to change the period into 8190 chips of the CA sequence. The CA sequence is exclusive-OR added with the G2 sequence according to different phase combinations, and thus the code with different PRN numbers is obtained. The period of the code is 10230. As shown in Figure 2 A schematic diagram of the pseudo code generator.

[0089] In the embodiment, the pseudo codes of the B3I signals have 63 different phase combinations, and at most 63 satellites in orbit can be supported to broadcast signals.

[0090] In this way, the position information of the Beidou satellite in the ephemeris data can be obtained by acquiring the ephemeris data. The position information is very important for subsequent calculation and pseudo code generation. By accurately calculating the satellite position, the accuracy of the pseudo code generation can be improved. At the same time, the elevation angles of the satellites can be determined. When the elevation angle of a satellite is greater than zero, it means that the satellite is in the user's visible range. In this way, the set of visible satellites can be determined, unnecessary pseudo code generation for invisible satellites can be avoided, and the calculation amount can be reduced to improve the calculation rate. And by using the preset shift register circuit, the accuracy and consistency of the pseudo code generation can be ensured, and the periodicity of the pseudo code can be controlled to adapt to different application requirements.

[0091] Further, the distance between the satellite and the user is obtained according to the ephemeris data, specifically:

[0092] According to the ephemeris data, the position and velocity information of the current satellites in the normalized time is obtained, and the position and velocity information is corrected according to the correction term satellite parameters in the ephemeris data to obtain the position information of all satellites.

[0093] According to the position information of all satellites and the obtained user coordinates, the distance between each satellite and the user is obtained.

[0094] The position and velocity information includes: average angular velocity, mean anomaly, eccentric anomaly and latitude amplitude.

[0095] In a specific embodiment, according to the ephemeris data, the position and velocity information of the current satellites in the normalized time is obtained, and the position and velocity information is corrected according to the correction term satellite parameters in the ephemeris data to obtain the position information of all satellites, specifically:

[0096] In the user needs to provide a series of parameters in the ephemeris file, using ephemeris data calculated at a time of the space position of the satellite. The ephemeris data used at least includes:

[0097] Square root of the major axis The difference between the average motion rate of the satellite and the calculated value Δn, the ephemeris reference time t oe The mean anomaly M0 of the reference time, the eccentricity e, the argument of perigee ω, the amplitude C of the cosine harmonic correction term of the latitude amplitude uc The amplitude C of the sine harmonic correction term of the latitude amplitude us The amplitude C of the cosine harmonic correction term of the orbital radius rc The amplitude C of the sine harmonic correction term of the orbital radius rs The amplitude C of the cosine harmonic correction term of the orbital inclination ic The amplitude C of the sine harmonic correction term of the orbital inclination is The orbital inclination i0 of the reference time, the orbital inclination rate i dot The calculated right ascension Ω0 of the reference time, the right ascension rate Ω dot .

[0098] In a specific embodiment, the average angular velocity of the satellite is calculated as follows:

[0099] From Kepler's third law:

[0100] The average angular velocity of the hypothetical satellite running on a circular orbit is calculated as follows:

[0101] Where T is the satellite running period, a is the major radius of its elliptical orbit, GM is a constant, which is the geocentric gravitational constant under the Beidou coordinate system

[0102] According to the parameters given by the ephemeris data, the average angular velocity of the corrected satellite is calculated as follows: n = n0 + Δn.

[0103] In a specific embodiment, the position and velocity information includes the normalized time t k , and the normalized time t k is calculated as follows:

[0104] The effective ephemeris of the Beidou satellite is updated every hour, that is, the ephemeris reference time t oe ; the initial launch time of the system is set to the time t oe1 indicated by the first effective ephemeris; and the subsequent launch time t of the system is obtained;

[0105] In an embodiment, the subsequent launch time t of the system is constantly updated, such as 4ms launch (at this time t = toe1 +4ms).

[0106] The normalization time t k For t k =tt oe .

[0107] It should be noted that for a valid ephemeris, t should be within t. oe Between the first and last hour, i.e.: |t k |<7200s.

[0108] In one specific embodiment, the mean anomaly angle of the satellite is calculated as follows:

[0109] Using the normalized time and the corrected average angular velocity of the satellite, plus the mean anomaly angle m0 at the signal reference time in the ephemeris data, the mean anomaly angle at time t is calculated: M k =M0+n*t k ;

[0110] Where M0 is the mean anomaly angle at the reference time; n is the corrected average angular velocity of the satellite; t k For time planning; M k Let be the mean anomaly angle of the satellite at time t.

[0111] In one specific embodiment, the calculation method for the satellite's anomalous angle is as follows:

[0112] The aperitone angle E can be calculated using the Kepler equation M = Ee*sinE and an iterative method. k The initial value of the iteration is set to M. k The iterative equation is: E i =M k +e*sinE i-1 ; i represents the iteration number, and in one embodiment, i can be selected as 3.

[0113] Where M is the level anterior angle; E is the deviated anterior angle; M k Let be the mean anomaly angle of the satellite at time t;

[0114] In one specific embodiment, the latitude argument of the satellite is calculated as follows:

[0115]

[0116] Where, φ k E represents the latitude argument of the satellite. k ω is the perigee angle of the satellite; ω is the perigee deflection angle.

[0117] In one embodiment, calculating perturbation correction terms in some ephemeris data specifically includes:

[0118] Latitude amplitude correction term: δu k = C us *sin(2φ k )+C uc *cos(2φ k );

[0119] Radial correction term: δr k = C rs *sin(2φ k )+C rc *cos(2φ k );

[0120] Inclination correction term: δi k = C is *sin(2φ k )+C ic *cos(2φ k );

[0121] And correct part of the parameters in the ephemeris data, specifically:

[0122] Corrected latitude amplitude: u k = δu k +φ k ;

[0123] Corrected radial: r k = δr k +a*(1-ecosE k );

[0124] Corrected inclination: i k = δi k +i0+i dot *t k ;

[0125] Calculate the coordinates of the satellite in the orbital plane:

[0126] Convert polar coordinates (r k , u k ) into Cartesian coordinates in the orbital plane (x pk , y pk ):

[0127]

[0128] The Beidou satellite is divided into GEO satellites and MEO / IGSO satellites. For GEO satellites 1-5: (Ω e is a constant, which is the earth rotation angle speed under the Beidou coordinate system).

[0129] Calculate the epoch ascending node longitude Ω k = Ω0+Ωdot t k -Ω e t oe ;

[0130] Calculate the coordinates (x, y, z) of GEO satellites in Beidou coordinate system:

[0131]

[0132]

[0133] For MEO / IGSO satellites No. 6-37:

[0134] Calculate the ascending node longitude Ω at the epoch k = Ω0+ (Ω dot - Ω e )*t k - Ω e *t oe ;

[0135] Calculate the coordinates (x k , y k , z k ) of MEO / IGSO satellites in Beidou coordinate system:

[0136]

[0137] Calculate the running speed of the satellite: (Ω kdot = Ω dot - Ω e )(i kdot = di k / dt);

[0138]

[0139] Where vel x , vel y , vel z are the satellite speed coordinates.

[0140] In this way, by calculating and correcting these parameters, accurate satellite position information can be obtained. The correction terms in the ephemeris data are used to correct the satellite position and speed information. These correction terms include satellite clock error, relativistic effect, atmospheric delay, etc., which can eliminate errors and deviations and improve the accuracy of position information. By applying the correction terms, the satellite position and speed information can be corrected, further improving the accuracy of satellite position calculation and distance calculation.

[0141] Further, the carrier is obtained by Doppler shift according to the distance between each satellite and the user, specifically:

[0142] According to the distance between each satellite and user, the pseudorange rate and pseudorange of the satellite and user in several movements are obtained;

[0143] In a specific embodiment, the pseudorange rate and pseudorange of the satellite and user in several movements are obtained according to the distance between each satellite and user, specifically:

[0144] The observation vector of the user to the satellite is calculated:

[0145] [x k ,y k ,z k ]-[x,y,z];

[0146] In the previous position calculation, the position of the satellite signal transmission time t is calculated, while the receiver calculates the pseudorange of the signal receiving time t+t0. Wherein, t0 is the transmission time of the signal:

[0147]

[0148] Wherein, c is the speed of light in vacuum, [x k ,y k ,z k ] is the coordinate of the kth satellite, [x,y,z] is the coordinate of the user in the earth-centered earth-fixed coordinate system, and [Δx,Δy,Δz] is the observation vector of the user to the satellite.

[0149] Further, the satellite position at the signal receiving time of the receiver is corrected by using the satellite speed and the formula of the earth rotation correction:

[0150]

[0151]

[0152] Wherein, Ω e is a constant, which is the earth rotation angular velocity in the Beidou coordinate system; t0 is the transmission time of the signal; vel x , vel y , vel z are the satellite speed coordinates.

[0153] The observation vector of the user to the satellite is updated by using the corrected position:

[0154] [x k ,y k ,z k ]-[x,y,z];

[0155] At this time, the geometric distance d of the user to the satellite is:

[0156]

[0157] Correcting the pseudorange using the clock error parameter in the ephemeris:

[0158] delay=a0+a1*t k +a1*t k *t k +relativistic (relativistic correction term);

[0159] range = dc * delay;

[0160] Where a0 and a1 are clock error parameters; c is the proportionality coefficient; t k d represents the time of normalization; d represents the geometric distance from the user to the satellite.

[0161] In a preferred embodiment, the ephemeris data provided by the user includes ionospheric delay parameters. These parameters are used to calculate the ionospheric delay and update the pseudorange: range = range + ionoutc.

[0162] Wherein, ionoutc is the ionospheric delay parameter.

[0163] Ionospheric delay is typically a few meters to a dozen meters, much smaller than pseudorange, so it is an optional addition for high-precision applications to increase the realism of signal simulation.

[0164] In a preferred embodiment, when the ephemeris data provided by the user contains a tropospheric delay parameter, the tropospheric delay in this state can be corrected in the pseudorange, and the pseudorange can be updated as follows: range = range - tropoutc;

[0165] Where tropoutc is the tropospheric delay parameter.

[0166] The carrier wavelength is obtained based on the pseudorange rate and the preset Doppler frequency shift, and the carrier phase cycle value is obtained by dividing the pseudorange by the carrier wavelength. The carrier is then obtained based on the carrier phase cycle value and the carrier wavelength.

[0167] It should be noted that the carrier wave is a sine wave and a cosine wave controlled by the intermediate frequency and the Doppler frequency shift.

[0168] In one specific embodiment, the step of obtaining the carrier wavelength based on the pseudorange rate and a preset Doppler frequency shift, and obtaining the carrier phase cycle value by dividing the pseudorange by the carrier wavelength, specifically involves:

[0169] Doppler shift reveals the relative motion between the satellite and the user receiver, and is key data for the receiver to calculate the user's operating speed. Therefore, Doppler shift needs to be considered in signal simulation.

[0170]

[0171] In the two movements of the satellite and the user receiver, range0 is the pseudo-range in the first movement, range1 is the pseudo-range in the second movement; t is the time interval of the two movements; (range1-range0) / dt is the pseudo-range rate, λ B3I is the carrier wavelength of the B3I signal;

[0172] It can be seen that when the satellite and the receiver are relatively far away, the Doppler frequency shift is a negative number.

[0173] Further, the pseudo-range is divided by the carrier wavelength of the B3I signal to obtain the carrier phase cycle value:

[0174]

[0175] Wherein, range start is the initial value of the pseudo-range; λ B3I is the carrier wavelength of the B3I signal; φ is the carrier phase cycle value; and the initial phase φ0 of the carrier is the decimal part of the carrier phase cycle value φ.

[0176] In an optional embodiment, after adding the initial phase of the carrier and the Doppler frequency shift to the signal, the receiver can solve the carrier phase information by integration through the information, and can calculate the coordinates of the user receiver by combining the ephemeris of the navigation message, thereby realizing the positioning of the user receiver.

[0177] In this way, the carrier phase information can be obtained by obtaining the carrier according to the distance between the satellite and the user, the carrier wavelength can be calculated by applying the Doppler frequency shift, the carrier phase cycle value can be calculated, and the precise positioning and navigation calculation can be performed by applying the carrier.

[0178] Step S2: obtaining the spreading code according to the pseudo-code and the navigation message of each satellite;

[0179] Further, the obtaining of the spreading code according to the pseudo-code and the navigation message of each satellite comprises:

[0180] The time information is obtained and added to each subframe set in advance, and the check code corresponding to each subframe is obtained according to the BCH encoding;

[0181] In a specific embodiment, the time information comprises SOW (seconds within a week) and WN (week number), which are calculated relative to the initial epoch of the Beidou system time, i.e. January 1, 2006, 00:00:00.

[0182] All the subframes and the corresponding check codes are interleaved, and the navigation message of each satellite is obtained according to the interface control file of each satellite.

[0183] In a specific embodiment, the length of the interleaved code obtained after interleaving all the subframes and the corresponding check code is 30 bits.

[0184] The pseudo code is spread spectrum modulated according to the navigation message of each satellite to obtain an extended code.

[0185] Further, the effective time of a set of Beidou ephemeris is 1 hour, and the ephemeris data used in the current subframe arrangement needs to be updated once every half hour (1 hour in total).

[0186] It should be noted that the generation of the navigation message first needs to be subframe encoded, because the satellite is always periodically broadcasting the same frame structure message, the difference is that the internal values (ephemeris or time) are different at different times.

[0187] The pre-set subframes are subframe arrangements made in advance, and the internal values can be updated according to the current time t when simulating the signal.

[0188] The arrangement mode of the subframe arrangement can be simplified as three arranged points:

[0189] 1. Frame header. This is the starting point of the capture and tracking of the receiving end, and must be added.

[0190] 2. Ephemereis for calculating satellite visibility. This is the basis for positioning of the receiving end.

[0191] 3. Time information. Inform the current time state.

[0192] The satellites of B3I are divided into GEO satellites and MEO / IGSO satellites, and the corresponding frame structures are D1 navigation message and D2 navigation message, and the corresponding distinction also needs to be made when arranging the subframes.

[0193] The specific arrangement mode can refer to the ICD file of the B3I signal.

[0194] In a specific embodiment, the navigation message is specifically carried by the data code in the satellite signal structure hierarchy; the navigation message contains ephemeris data and almanac information that can be used for positioning calculation. The ephemeris data can be used for the calculation of the satellite position and the error part, and is broadcast by the satellite. In this embodiment, the user needs to import the ephemeris data for simulating the signal, and the distance between the satellite and the receiver is also calculated from the position, and the user needs to import the coordinate file of the receiver.

[0195] The specific composition of the navigation message can refer to the ICD file. In this embodiment, the content of the navigation message is established through the description of the ICD file.

[0196] In an alternative embodiment, the navigation message of the B3I signal is divided into D1 navigation message and D2 navigation message. The D1 navigation message is broadcasted by the MEO / IGSO satellite with a code rate of 50bps; the D2 navigation message is broadcasted by the GEO satellite with a code rate of 500bps. Both of them need to be BCH (15, 1, 1) and interleaving coded. The difference is that the D1 navigation message is additionally coded by NH (Neumann-Hoffman) code.

[0197] As Figure 3 The frame structure of the D1 navigation message is as follows: Figure 4 The frame structure of the D2 navigation message is as follows.

[0198] The structure hierarchy of the D2 navigation message is basically the same as that of the D1 navigation message, with the difference in code rate and number of main frames. Each word of the D1 navigation message and the D2 navigation message is error-corrected coded. The 16-26 bits of the first word of each subframe are coded by BCH (15, 1, 1) error-correcting code, and the first-11 bits and the 16-26 bits of the other nine words are respectively coded by BCH (15, 1, 1) error-correcting code, and the coding results are interleaved. The first 22 bits after interleaving are valid navigation information, and the last 8 bits are check code.

[0199] In this way, by acquiring time information and adding it to the subframe, it can be ensured that the time information in the navigation message is consistent with the actual time, ensuring the accuracy of the time information, and improving the accuracy and reliability of positioning and navigation. Further, interleaving processing all subframes and corresponding check codes can optimize the transmission of the navigation message. Interleaving processing can disrupt the order of data and reduce continuous errors in data transmission. Through interleaving processing, the reliability and anti-interference ability of the navigation message can be improved. And according to the navigation message of each satellite, the pseudo code is spread modulated to obtain the spread code. Spread modulation is a method of expanding low-speed data to high-speed signals, which can improve the anti-interference and transmission efficiency of the signal. By applying spread modulation, the information capacity of the spread code can be increased, and the reliability of the navigation signal and the sensitivity of the receiver can be improved.

[0200] Step S3: modulating the spread code and the carrier to obtain two IQ baseband signals, and obtaining a digital intermediate frequency signal of the B3I signal according to the two IQ baseband signals; wherein the carrier is obtained by Doppler shift according to the distance between each satellite and the user.

[0201] Further, the modulating the spread code and the carrier to obtain two IQ baseband signals comprises:

[0202] The spread code and the carrier are modulated by binary phase shift keying modulation method to obtain two IQ baseband signals.

[0203] In a specific embodiment, the modulation of the B3I signal is to modulate the spread code after the carrier and the ranging code spread with BPSK (Binary Phase Shift Keying) to the carrier. The finally generated baseband signal is divided into I and Q channels, the I channel is modulated by cosine carrier, and the Q channel is modulated by sine carrier.

[0204] In this way, the two-channel IQ baseband signals generated by the binary phase shift keying modulation method can realize multiplexing. The spreading codes and carriers of multiple satellites can be modulated at the same time, transmitted through mutually orthogonal I and Q signals, and multiple signals can be transmitted and received at the same time.

[0205] In an optional embodiment, the digital intermediate frequency signal of the B3I signal obtained according to the two-channel IQ baseband signals comprises:

[0206] The two-channel IQ baseband signals are added with noise signals and / or interference signals through a preset noise interference algorithm to obtain a digital intermediate frequency signal.

[0207] In this way, the two-channel IQ baseband signals are added with noise signals and / or interference signals through a preset noise interference algorithm, which can simulate the signal transmission in a real environment, so that a more real signal is used to verify and debug the performance of the navigation satellite signal receiver.

[0208] Embodiment two

[0209] Please refer to Figure 5 A B3I signal simulation device provided by the embodiment of the application comprises an ephemeris module 210, a spreading code module 220, and a signal module 230.

[0210] The ephemeris module 210 is configured to obtain ephemeris data, obtain the distance between each satellite and a user and the pseudo code of visible satellites according to the ephemeris data.

[0211] The spreading code module 220 is configured to obtain a spreading code according to the pseudo code and the navigation message of each satellite.

[0212] The signal module 230 is configured to obtain a spreading code according to the pseudo code, modulate the spreading code and a carrier to obtain two-channel IQ baseband signals, and obtain a digital intermediate frequency signal of a B3I signal according to the two-channel IQ baseband signals; wherein the carrier is obtained by a Doppler shift according to the distance between each satellite and the user.

[0213] Further, the ephemeris module comprises a coordinate unit, a visible satellite unit, and a pseudo code unit.

[0214] The coordinate unit is configured to obtain the positions of all satellites in the ephemeris data of the Beidou satellite according to the ephemeris data, and obtain the coordinates of a user.

[0215] The visible satellite unit is configured to obtain the elevation angle of each satellite according to the user coordinates and the positions of all the satellites, and determine that the satellite is a visible satellite when the elevation angle of the satellite is greater than zero;

[0216] The pseudo code unit is configured to generate the pseudo code of all the visible satellites according to a preset shift register circuit.

[0217] Further, the ephemeris module comprises a position information unit and a distance unit.

[0218] The position information unit is configured to obtain the position and velocity information of each satellite at a normalized time according to the ephemeris data, and correct the position and velocity information according to the correction term satellite parameters in the ephemeris data to obtain the position information of all the satellites.

[0219] The distance unit is configured to obtain the distance between each satellite and the user according to the position information of all the satellites and the obtained user coordinates.

[0220] The position and velocity information comprises an average angular velocity, a mean anomaly, an eccentric anomaly and a latitude amplitude.

[0221] Further, the signal module comprises a pseudo distance unit and a carrier unit.

[0222] The pseudo distance unit is configured to obtain the pseudo range rate and the pseudo range of the satellite and the user in several movements according to the distance between each satellite and the user.

[0223] The carrier unit is configured to obtain the carrier wavelength according to the pseudo range rate and a preset Doppler frequency shift, obtain the carrier phase cycle value by dividing the pseudo range by the carrier wavelength, and obtain the carrier according to the carrier phase cycle value and the carrier wavelength.

[0224] Further, the spreading code module comprises a subframe unit, a text unit and a spread spectrum unit.

[0225] The subframe unit is configured to obtain time information and add the time information to each subframe set in advance, and obtain the check code corresponding to each subframe according to BCH encoding.

[0226] The text unit is configured to perform interleaving processing on all the subframes and the corresponding check codes, and obtain the navigation text of each satellite according to the interface control file of each satellite.

[0227] The spread spectrum unit is configured to spread spectrum modulate the pseudo code according to the navigation text of each satellite to obtain the spreading code.

[0228] Further, the signal module comprises a modulation unit.

[0229] The modulation unit is used for modulating the spreading code and the carrier by a binary phase shift keying modulation method to obtain two IQ baseband signals.

[0230] Further, the signal module comprises a noise interference unit.

[0231] The noise interference unit is used for adding noise signals and / or interference signals to the two IQ baseband signals by a preset noise interference algorithm to obtain digital intermediate frequency signals.

[0232] Correspondingly, the application further provides a terminal device, comprising a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, and the processor realizes the B3I signal simulation method according to any one of the above embodiments when executing the computer program.

[0233] Correspondingly, the application further provides a computer readable storage medium, comprising a stored computer program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the B3I signal simulation method according to any one of the above embodiments when the computer program runs.

[0234] Thus, the B3I signal simulation method can quickly and accurately generate a simulated real B3I signal by acquiring ephemeris data, generating a pseudo code and a spreading code, and modulating the ephemeris data, the pseudo code and the spreading code. Thus, the B3I signal simulation method can get rid of the dependence on hardware devices in the original signal simulation, and only needs to acquire ephemeris data provided by a user and satellite navigation data of a Beidou satellite to generate a corresponding B3I signal. In addition, the B3I signal simulation method can more accurately simulate B3I signals of various satellites by calculating a Doppler frequency shift according to the distance between the satellites and the user and applying the Doppler frequency shift to carrier modulation. In combination with the ephemeris data, distance calculation, pseudo code generation, Doppler frequency shift and navigation data, the B3I signal simulation method can generate a real B3I signal with a Doppler effect, and provides a beneficial tool and data for testing and verifying a B3I signal receiver, thereby improving the research and development efficiency of the navigation satellite signal receiver.

[0235] The detailed working principle and step flow of the device can be but are not limited to referring to Embodiment One.

[0236] Embodiment Three

[0237] Correspondingly, the application further provides a terminal device, comprising a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, and the processor realizes the B3I signal simulation method according to any one of the above embodiments when executing the computer program.

[0238] The terminal device of this embodiment comprises a processor, a memory, and a computer program stored in the memory and executable on the processor. The processor implements the steps in the above-mentioned embodiment I when executing the computer program, for example Figure 1 The processor implements the functions of the modules / units in the above-mentioned device embodiment when executing the computer program, for example the ephemeris module 210.

[0239] For example, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program in the terminal device. For example, the ephemeris module 210 is used to acquire ephemeris data, and acquire the distances between each satellite and the user and the pseudoranges of the visible satellites according to the ephemeris data.

[0240] The terminal device can be a desktop computer, a notebook computer, a palm computer, a cloud server, and other computing devices. The terminal device can include, but is not limited to, a processor and a memory. Those skilled in the art can understand that the schematic diagram is only an example of the terminal device and does not limit the terminal device, which can include more or fewer components than the schematic diagram, or combine certain components, or different components, for example, the terminal device can also include an input / output device, a network access device, a bus, etc.

[0241] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor and the like. The processor is the control center of the terminal device, which connects all parts of the terminal device through various interfaces and lines.

[0242] The memory can be used to store the computer program and / or modules, and the processor realizes various functions of the terminal device by running or executing the computer program and / or modules stored in the memory, and calling data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required by a function, etc.; and the data storage area can store data created according to the use of the mobile terminal, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state memory devices.

[0243] The modules / units integrated in the terminal device can be stored in a computer readable storage medium if they are realized in the form of software function units and sold or used as independent products. Based on this understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. The computer program can implement the steps of each method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the contents included in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0244] Embodiment four

[0245] Correspondingly, the application further provides a computer readable storage medium, including a stored computer program, wherein when the computer program runs, the device where the computer readable storage medium is located performs the B3I signal simulation method as any one of the above embodiments.

[0246] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of B3I signal simulation, characterized by, The method comprises the following steps: acquiring ephemeris data, and acquiring distances between each satellite and a user and pseudo-codes of visible satellites according to the ephemeris data; acquiring a spreading code according to the pseudo-codes and navigation messages of each satellite; modulating the spreading code and a carrier by a binary phase shift keying modulation method, acquiring two IQ baseband signals, and acquiring a digital intermediate frequency signal of a B3I signal according to the two IQ baseband signals; wherein the carrier is obtained by Doppler frequency shift according to the distances between each satellite and the user; the carrier is obtained by Doppler frequency shift according to the distances between each satellite and the user, and specifically: acquiring a pseudo-range rate and a pseudo-range of the satellite and the user in several movements according to the distances between each satellite and the user; acquiring a carrier wavelength according to the pseudo-range rate and a preset Doppler frequency shift, and acquiring the carrier according to a pseudo-range divided by the carrier wavelength and a carrier phase cycle value according to the carrier phase cycle value and the carrier wavelength.

2. The B3I signal simulation method of claim 1, wherein, The pseudo-codes of the visible satellites comprise: acquiring all satellite positions of the Beidou satellite in the ephemeris data according to the ephemeris data, and acquiring a user coordinate; acquiring an elevation angle of each satellite according to the user coordinate and all the satellite positions, and determining that the satellite is a visible satellite when the elevation angle of the satellite is greater than zero; generating the pseudo-codes of all the visible satellites according to a preset shift register circuit.

3. The method of claim 1, wherein the B3I signal simulation is performed by a computer system. The distances between each satellite and the user according to the ephemeris data comprise: acquiring position and velocity information of each satellite in a normalized time according to the ephemeris data, and correcting the position and velocity information according to correction term satellite parameters in the ephemeris data to acquire position information of all the satellites; acquiring distances between each satellite and the user according to the position information of all the satellites and the acquired user coordinate. The position and velocity information comprises: average angular velocity, mean anomaly, eccentric anomaly and amplitude of latitude.

4. The method of claim 1, wherein the B3I signal simulation is performed by a computer system. The acquiring of the spreading code according to the pseudo-codes and the navigation messages of each satellite comprises: acquiring time information and adding the time information to each preset subframe, and acquiring a check code corresponding to each subframe according to BCH encoding; interleaving all the subframes and the corresponding check codes, and obtaining the navigation messages of each satellite according to an interface control file of each satellite; spreading modulating the pseudo-codes according to the navigation messages of each satellite to acquire the spreading code.

5. The method of claim 1, wherein the B3I signal simulation is performed by a computer system. The acquiring of the digital intermediate frequency signal of the B3I signal according to the two IQ baseband signals comprises: adding a noise signal and / or an interference signal to the two IQ baseband signals by a preset noise interference algorithm to acquire the digital intermediate frequency signal.

6. A B3I signal simulation apparatus characterized by comprising: The method comprises: an ephemeris module, a spreading code module and a signal module; the ephemeris module is used for acquiring ephemeris data, and acquiring distances between each satellite and a user and pseudo-codes of visible satellites according to the ephemeris data; the spreading code module is used for acquiring a spreading code according to the pseudo-codes and navigation messages of each satellite; The signal module is configured to modulate the spreading code and a carrier by a binary phase shift keying modulation method to obtain two IQ baseband signals, and obtain a digital intermediate frequency signal of a B3I signal according to the two IQ baseband signals; wherein the carrier is obtained by a Doppler frequency shift according to distances between each satellite and a user. The signal module comprises a pseudo-range unit and a carrier unit. The pseudo-range unit is configured to obtain pseudo-range rates and pseudo-ranges of satellites and a user in several movements according to distances between each satellite and the user. The carrier unit is configured to obtain a carrier wavelength according to the pseudo-range rate and a preset Doppler frequency shift, obtain a carrier phase period value by dividing the pseudo-range by the carrier wavelength, and obtain a carrier according to the carrier phase period value and the carrier wavelength.

7. A terminal device, characterized by comprising: A computer readable storage medium comprises a computer program stored therein, wherein the computer program, when executed, controls a device in which the computer readable storage medium is located to perform the B3I signal simulation method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a computer program stored therein, wherein the computer program, when executed, controls a device in which the computer readable storage medium is located to perform the B3I signal simulation method according to any one of claims 1 to 5.

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