Method and apparatus for pps signal correction of a satellite receiver and satellite receiver

Abstract

The application provides a PPS signal correction method and device of a satellite receiver, the satellite receiver, a computer readable medium and a computer program product, wherein the method comprises: receiving a navigation constellation signal; judging whether positioning of the satellite receiver is valid, determining valid time and invalid time of the satellite receiver; obtaining an effective point receiver clock error corresponding to the valid time of the satellite receiver, correcting and outputting the PPS signal of the satellite receiver based on the effective point receiver clock error; obtaining a real-time counting mean value corresponding to the effective point receiver clock error, determining an effective compensation counting value of the satellite receiver based on the real-time counting mean value; in response to the invalid time of the satellite receiver, determining a counting correction value at the invalid time based on the effective compensation counting value; and correcting and outputting the PPS signal of the satellite receiver based on the counting correction value. The application solves the problems of high cost and low efficiency of the PPS signal correction method of the satellite receiver in the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PPS signal correction, and particularly relates to a PPS signal correction method and device of a satellite receiver, an electronic device, a computer readable medium, and a computer program product. BACKGROUND

[0002] GNSS (Global Navigation Satellite System) is an air-based radio navigation positioning system that can provide users with three-dimensional coordinates, speed and time information at any location on the earth's surface or near space. GNSS mainly includes a navigation constellation, a ground control station and a working satellite, etc. The navigation constellation generates navigation constellation signals and broadcasts them to the working satellite, and receives signals from the ground control station to control itself.

[0003] Satellite local time synchronization counting refers to that a receiver installed on a working satellite realizes time synchronization counting between systems of each subsystem of the satellite through received navigation constellation signals, and acquires nanosecond (ns) level unified time by relying on a PPS (Pulse Per Second) signal output by the receiver and a corresponding timestamp.

[0004] Generally, the navigation constellation of GNSS has a time system based on observation quantities of atomic clocks on the ground control station and atomic clocks (or crystal oscillators) installed on the navigation constellation, and a clock is also installed on the receiver of the working satellite, that is, a working satellite receiver clock. When the navigation constellation signal transmitted by the navigation constellation is captured by the receiver of the working satellite, the time read by the time system of the navigation constellation is GNSS local time, and the time read by the working satellite receiver clock is receiver time, and the receiver time is usually not synchronized with the GNSS local time. The difference between the two is defined as the receiver clock error, which directly affects the accuracy of the PPS signal output by the working satellite receiver.

[0005] For the working satellite receiver, the received navigation constellation signal is easily affected by the external environment. In the scene where the signal is limited due to obstruction, electromagnetic interference, etc., the decline or interruption of the signal quality will cause the data of each device in the working satellite subsystem to have discontinuous time stamps, time rollback, etc. Especially when there is L-band suppression interference or deception interference in the external environment, the working satellite receiver cannot receive the navigation constellation signal, and thus cannot be positioned. At this time, the receiver clock error will gradually increase under the influence of the interference, and the error of the output PPS signal will also gradually increase accordingly.

[0006] In order to make the normal progress of the satellite subsystem load task, the accuracy and continuity of the PPS signal output in any environment must be ensured. The current mainstream PPS signal correction method generally includes three methods: increasing the clock training function in the working satellite receiver, using a high-precision atomic clock in the working satellite receiver, and uploading the clock difference information in real time through the ground control station. Among them, the scheme of increasing the clock training function in the working satellite receiver or using a high-precision atomic clock often leads to the increase of the design size and cost of the working satellite receiver, and the method of uploading the clock difference information in real time through the ground control station itself has a certain delay and cannot guarantee the real-time of PPS correction. Therefore, a new PPS signal correction method is urgently needed. SUMMARY

[0007] The main purpose of the present application is to provide a satellite receiver PPS signal correction method, device, equipment, computer readable medium and computer program product, aiming at solving the problems of high cost and low efficiency of the PPS signal correction method of the working satellite in the prior art.

[0008] In order to solve the above technical problems, in a first aspect, the present application provides a satellite receiver PPS signal correction method, comprising: receiving a navigation constellation signal; judging whether the satellite receiver positioning is valid, determining the valid time and invalid time of the satellite receiver; obtaining the valid point receiver clock difference corresponding to the valid time of the satellite receiver, correcting and outputting the PPS signal of the satellite receiver based on the valid point receiver clock difference; obtaining the real-time counting mean value corresponding to the valid point receiver clock difference, determining the valid compensation counting value of the satellite receiver based on the real-time counting mean value; in response to the invalid time of the satellite receiver, determining the counting correction value at the invalid time based on the valid compensation counting value; correcting and outputting the PPS signal of the satellite receiver based on the counting correction value.

[0009] Further, obtaining the real-time counting mean value corresponding to the valid point receiver clock difference, and determining the valid compensation counting value of the satellite receiver based on the real-time counting mean value, comprises: obtaining a plurality of real-time counting values corresponding to a plurality of valid point receiver clock differences at a plurality of consecutive valid times, wherein the last time in the plurality of consecutive valid times is located before the first invalid time; determining the real-time counting mean value of the i th real-time counting value to the i+k th real-time counting value, wherein 1≤i≤i+k; determining the valid compensation counting value based on the real-time counting mean value.

[0010] Further, the real-time clock difference mean value is obtained by a weighted moving average method.

[0011] Further, in response to the invalid time of the satellite receiver, the count correction value at the invalid time is determined based on the valid compensation count value, including: in response to the first invalid time, obtaining the down rounding value of the valid compensation count value, and setting the down rounding value of the valid compensation count value as the count correction value of the first invalid time; in response to the second invalid time, obtaining the up rounding value of the valid compensation count value, and setting the up rounding value of the valid compensation count value as the count correction value of the second invalid time; obtaining the average value of the up rounding value of the valid compensation count value and the down rounding value of the valid compensation count value, and obtaining the difference value between the average value and the valid compensation count value; if the difference value is greater than 0, obtaining the down rounding value of the average value, and setting the down rounding value of the average value as the count correction value of the third invalid time; if the difference value is less than or equal to 0, obtaining the up rounding value of the average value, and setting the up rounding value of the average value as the count correction value of the third invalid time.

[0012] Further, after the step of setting the down rounding value of the average value as the count correction value of the third invalid time, or after the step of setting the up rounding value of the average value as the count correction value of the third invalid time, further comprising: in response to any jth invalid time, obtaining the average value of all count correction values corresponding to the 1st invalid time to the (j-1)th invalid time, wherein j≥4; obtaining the count verification difference value between the average value of the count correction values and the valid compensation count value; if the count verification difference value is greater than 0, obtaining the down rounding value of the average value of the count correction values, and setting the down rounding value as the count correction value of the jth invalid time; if the count verification difference value is less than or equal to 0, obtaining the up rounding value of the average value of the count correction values, and setting the up rounding value as the count correction value of the jth invalid time.

[0013] Further, determining whether the positioning of the satellite receiver is valid, and determining the valid time and the invalid time of the satellite receiver, including: in response to the navigation constellation signal, performing PVT positioning calculation to obtain the result of the PVT positioning calculation; determining the real-time receiver clock difference according to the time information of the PVT positioning calculation result; obtaining the clock difference verification difference value between the real-time receiver clock difference and the preset clock difference threshold of the satellite receiver; determining whether the clock difference verification difference value is greater than 0, and determining whether the positioning of the satellite receiver is valid according to the determination result; if the clock difference verification difference value is less than or equal to 0, determining that the positioning of the satellite receiver is valid, and determining the receiving time of the navigation constellation signal as the valid time; if the clock difference verification difference value is greater than 0, determining that the positioning of the satellite receiver is invalid, and determining the receiving time of the navigation constellation signal as the invalid time.

[0014] In a second aspect, the application further provides a PPS signal correction device of a satellite receiver, comprising: a receiving module configured to receive a navigation constellation signal; a judging module configured to judge whether positioning of the satellite receiver is valid, and determine valid time and invalid time of the satellite receiver; a first correction module configured to obtain an effective point receiver clock error corresponding to the valid time of the satellite receiver, and correct and output the PPS signal of the satellite receiver based on the effective point receiver clock error; a first determination module configured to obtain a real-time count average corresponding to the effective point receiver clock error, and determine an effective compensation count value of the satellite receiver based on the real-time count average; a second determination module configured to, in response to the invalid time of the satellite receiver, determine a count correction value at the invalid time based on the effective compensation count value; and a second correction module configured to correct and output the PPS signal of the satellite receiver based on the count correction value.

[0015] In a third aspect, the application provides a satellite receiver, comprising a radio frequency front-end processing unit and a baseband digital signal processing unit, the baseband digital signal processing unit being configured to implement the steps of the PPS signal correction method of the satellite receiver according to the first aspect.

[0016] Further, the radio frequency front-end processing unit comprises a satellite antenna, a low-noise power amplifier and a radio frequency circuit connected in sequence, and the navigation constellation signal is transmitted to the baseband digital signal processing unit after being processed by the radio frequency front-end processing unit in sequence; the baseband digital signal processing unit comprises a satellite baseband and a satellite processor connected in communication, and the satellite processor is configured to generate a receiver clock error, and the satellite baseband is configured to correct and output the PPS signal of the satellite receiver based on the receiver clock error.

[0017] In a fourth aspect, the application provides a computer readable medium, the computer readable medium storing a program or instructions, the program or instructions being executed by a processor to implement the steps of the PPS signal correction method of the satellite receiver according to the first aspect.

[0018] In a fifth aspect, the application provides a computer program product, the computer program product comprising a computer program, the computer program being executed by a processor to implement the steps of the PPS signal correction method of the satellite receiver according to the first aspect.

[0019] Compared with the prior art, the application has the following advantages:

[0020] The effective compensation count value of the working satellite receiver at the effective time is acquired, the effective compensation count value is used as reference information at the invalid time, the count correction value at the invalid time is determined through the reference information, the PPS signal output by the working satellite receiver at the invalid time is corrected based on the count correction value, the precision of the PPS signal output at the invalid time is ensured to be within 9ns, the correction cost of the PPS signal is greatly reduced and the precision of the PPS signal is improved, so that the normal operation of the subsystem load task in the on-orbit satellite in the GNSS is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The working principle of the satellite receiver in the existing GNSS is shown in the figure;

[0022] Figure 2 The flowchart of the PPS signal correction method of the satellite receiver in the embodiment of the application is shown in the figure;

[0023] Figure 3 The flowchart of step S120 in the embodiment of the application is shown in the figure;

[0024] Figure 4 The flowchart of step S140 in the embodiment of the application is shown in the figure;

[0025] Figure 5 The timing diagram of the PPS signal correction method of the satellite receiver in the embodiment of the application is shown in the figure;

[0026] Figure 6 The flowchart of step S150 in the embodiment of the application is shown in the figure;

[0027] Figure 7 The flowchart of another aspect of step S150 in the embodiment of the application is shown in the figure;

[0028] Figure 8 The structural diagram of the PPS signal correction device of the satellite receiver in the embodiment of the application is shown in the figure;

[0029] Figure 9 The structural diagram of the satellite receiver in the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the application will be described clearly and completely in the embodiments of the application in combination with the drawings, but the embodiments described below are only some of the embodiments of the application, not all the embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application. Unless it is obvious from the language environment or otherwise stated, the same reference signs in the figures represent the same structure or operation.

[0031] As shown herein and in the claims, the indefinite articles "a," "an," "at least one," and / or "the" are not intended to mean one and only one unless explicitly indicated by the context. In general, the term "comprising" is used herein to mean including, but not limited to.

[0032] Flow diagrams are used herein to illustrate the operations performed by systems in accordance with embodiments of the present application. It is understood that the operations shown and described above or below are not necessarily performed in the order shown. Rather, various steps can be performed in different orders or simultaneously. Also, other operations can be added to, or removed from, these processes, or one or more steps can be added to, or removed from, these processes.

[0033] See Figure 1 In a Global Navigation Satellite System (GNSS), a navigation constellation transmits a navigation constellation signal at a time ts(t), which is referred to as the transmission time of the navigation constellation signal, and the signal is received by a working satellite receiver at a time tr(t), which is referred to as the receiver time. For ease of description, the working satellite in this application refers to any on-orbit satellite in the GNSS other than the navigation constellation.

[0034] It can be understood that the transmission time ts(t) of the navigation constellation signal is observed on a time axis T1 based on a clock on the navigation constellation, the receiver time tr(t) is observed on a time axis T2 based on a clock installed on the working satellite receiver, and the navigation constellation also has a time system based on an atomic clock of a ground control station and an observation quantity of the clock on the navigation constellation, and a time observed on a time axis T3 based on the time system is referred to as GNSS local time tlocal. The transmission time ts(t) of the navigation constellation signal and the receiver time tr(t) are both functions of the GNSS local time tlocal.

[0035] It should be noted that, in general, the time axis T1 and the time axis T2 both have a lead or lag relative to the time axis T3. Taking the lead as an example, the lead of the time axis T1 relative to the time axis T3 is denoted as δts(t), and the lead of the time axis T2 relative to the time axis T3 is denoted as δtr(t). The above leads are both functions of the GNSS local time tlocal. If the receiver time tr(t) corresponds to a time t0 on the time axis T3, since the actual propagation time required for the navigation constellation signal from transmission to reception by the working satellite receiver is τ, the transmission time ts(t) of the navigation constellation signal corresponds to a time (t0-τ) on the time axis T3. Accordingly, the following relationship can be obtained:

[0036] tr(t0) = t0 + δtr(t0) (1)

[0037] ts(t0-τ) = t0-τ + δts(t0-τ) (2)

[0038] In the above equations, equation (1) represents the conversion relationship between time axis T2 and T3, and equation (2) represents the conversion relationship between time axis T1 and T3. δts(t0-τ) in equation (2) is called a navigation constellation clock difference, which can be corrected by a correction parameter in the navigation constellation signal, and thus its value can generally be considered as known. δtr(t0) in equation (1) is called a receiver clock difference, which is positive when time axis T1 leads time axis T3 by a certain amount, and negative otherwise. The value of the receiver clock difference is generally unknown, and the receiver clock difference affects the accuracy of the PPS signal output by the working satellite receiver.

[0039] Referring to Figure 2 The present application provides a method for correcting a PPS signal of a satellite receiver, comprising:

[0040] Step S110, receiving a navigation constellation signal;

[0041] Step S120, judging whether positioning of the satellite receiver is valid, and determining valid time and invalid time of the satellite receiver;

[0042] Step S130, obtaining an effective point receiver clock difference corresponding to the valid time of the satellite receiver, and correcting and outputting a PPS signal of the satellite receiver based on the effective point receiver clock difference;

[0043] Step S140, obtaining a real-time counting mean value corresponding to the effective point receiver clock difference, and determining an effective compensation counting value of the satellite receiver based on the real-time counting mean value;

[0044] Step S150, in response to the invalid time of the satellite receiver, determining a counting correction value at the invalid time based on the effective compensation counting value;

[0045] Step S160, correcting and outputting the PPS signal of the satellite receiver based on the counting correction value.

[0046] The application provides a PPS signal correction method of a satellite receiver.

[0047] Next, the steps S110-S160 will be described in detail in combination with specific embodiments.

[0048] In some embodiments, the navigation constellation signal mainly includes a carrier wave, a ranging code and navigation messages in step S110.

[0049] Please refer to Figure 3 In some embodiments, step S120 further includes the following steps:

[0050] In step S121, PVT positioning calculation is performed in response to the navigation constellation signal, and a PVT positioning calculation result is obtained.

[0051] In step S122, a real-time receiver clock difference is determined according to time information of the PVT positioning calculation result.

[0052] In step S123, a clock difference verification difference between the real-time receiver clock difference and a preset clock difference threshold of the satellite receiver is obtained.

[0053] In step S124, it is determined whether the clock difference verification difference is greater than 0, and whether the positioning of the satellite receiver is valid is determined according to the determination result.

[0054] In step S125, if the clock difference verification difference is less than or equal to 0, it is determined that the positioning of the satellite receiver is valid, and it is determined that the receiving time of the navigation constellation signal is the valid time.

[0055] Step S126, if the clock difference verification difference value is greater than 0, it is determined that the positioning of the satellite receiver is invalid, and it is determined that the receiving time of the navigation constellation signal is an invalid time.

[0056] Specifically, in step S120, after receiving the navigation constellation signal, the satellite receiver performs real-time PVT (Position, Velocity, Time) calculation according to the navigation constellation signal. The PVT calculation mainly measures and corrects the atmospheric delay according to the ranging code and the position of the navigation constellation, so as to calculate the velocity and finally determine the position, velocity and time information of the working satellite in the three-dimensional space according to the Doppler shift.

[0057] In some embodiments, in step S122, the time information in the PVT positioning calculation result includes the transmission time ts(t) of the navigation constellation signal, the receiving time tr(t) of the navigation constellation signal, and the propagation time τ between the navigation constellation and the working satellite receiver. Therefore, the working satellite receiver can further calculate the real-time receiver clock difference δre(t) according to the above-mentioned formula (1) and formula (2). The real-time receiver clock difference δre(t) is defined as the absolute value of the receiver clock difference, which satisfies the condition of being always greater than or equal to 0.

[0058] In some embodiments, the working satellite receiver is provided with a preset clock difference threshold δth, which is set to δth=1×10 -6 s (i.e. 1us) in this application. The clock difference verification difference value between the real-time receiver clock difference δre(t) and the preset clock difference threshold δth, i.e. δre(t) - δth, is obtained, and it is judged whether δre(t) - δth is greater than 0, so as to determine whether the positioning of the working satellite receiver is valid according to the judgment result.

[0059] Specifically, if δre(t) - δth≤0, i.e. δre(t)≤1×10 -6 s, the receiver positioning is valid at this time, so it is determined that the receiving time tr(t) of the navigation constellation signal is a valid time; if δre(t) - δth>0, i.e. δre(t)>1×10 -6 s, the receiver positioning is invalid at this time, so it is determined that the receiving time tr(t) of the navigation constellation signal is an invalid time.

[0060] It can be understood that when the working satellite receiver can normally receive the navigation constellation signal and perform PVT positioning solution, the PPS signal is corrected according to the solved real-time receiver clock error δre(t), so as to ensure the output accuracy of the PPS signal; when the navigation constellation signal is disturbed by external interference and other abnormal factors, the working satellite receiver cannot be positioned, and the position, velocity and time information solved at this time will be largely incorrect, so that the accuracy of the corresponding real-time receiver clock error δre(t) and the PPS signal cannot be ensured.

[0061] Please refer to Figure 4 In some embodiments, step S140 further comprises the following steps:

[0062] Step S141, acquiring real-time count values corresponding to the effective point receiver clock errors at a plurality of continuous effective time points, wherein the last time point of the plurality of continuous effective time points is located before the first invalid time point;

[0063] Step S142, determining the real-time count mean value of the i th real-time count value to the i+k th real-time count value, wherein 1≤i≤i+k;

[0064] Step S143, determining the effective compensation count value based on the real-time count mean value.

[0065] The specific content of steps S110 to S140 will be described in detail below with reference to the accompanying drawings. Figure 5 The specific content of steps S110 to S140 will be described in detail below with reference to the accompanying drawings.

[0066] It can be understood that the PPS signal represents the number of periodic pulse signals (i.e. the output frequency of the pulse signal) output by the working satellite receiver in one second, and the pulse signal output frequency in the present application is set to 62MHz, so the corresponding pulse width is 1s / 62MHz≈16.13ns. For the effective point receiver clock error δva, since its value satisfies δva≤δth=1×10 -6 s, the PPS signal is corrected by the principle of "more reduction and less compensation", specifically: if the effective point receiver clock error δva=1×10 -7s=100ns, indicating that the working satellite receiver time tr(t) is ahead of the GNSS local time tlocal by 100ns, that is, for one second of the GNSS local time tlocal, the working satellite receiver time tr(t) is ahead by 100ns, at this time, the count correction value of the PPS signal is obtained by dividing the excess 100ns by the pulse width 16.13ns, that is, the count correction value is 100ns / 16.13ns≈6, so that the original count of the PPS signal is reduced by 6 count values in total; similarly, if the effective point receiver clock difference δva=-6×10-7s=600ns, indicating that the working satellite receiver time tr(t) is behind the GNSS local time tlocal by 600ns, at this time, the count correction value of the PPS signal is obtained by dividing the excess 600ns by the pulse width 16.13ns, that is, the count correction value is 600ns / 16.13ns≈37, so that the original count of the PPS signal is increased by 37 count values in total. By such setting, the output accuracy of the PPS signal during the positioning effective time of the working satellite receiver is ensured.

[0067] In some embodiments, the prior information of the working satellite receiver at the invalid time is obtained by pre-processing the real-time count values corresponding to the above-mentioned several effective point receiver clock differences δva. Specifically, the navigation constellation continuously broadcasts navigation constellation signals to the working satellite, and the working satellite receiver from the 1st second to the 62nd second (in the observation view of the receiver time tr(t)) is the positioning effective time, and from the 63rd second, it is the positioning invalid time of the working satellite receiver. The working satellite receiver continuously obtains the effective point receiver clock difference δva corresponding to the 1st~62nd second, and at the same time, the working satellite receiver also calculates the real-time count average Clkave of the real-time count value corresponding to the i-th effective point receiver clock difference δva to the real-time count value corresponding to the i+k-th effective point receiver clock difference δva by the weighted moving average method, where 1≤i≤i+k.

[0068] Please refer to Figure 5 In some embodiments, the process of calculating the real-time count average Clkave by the weighted moving average method is as follows: let k=59, then the working satellite receiver determines the real-time count average Clkave with 60 seconds as a time window, and the effective point receiver clock differences δva from the 1st second to the 60th second are δt_1, δt_2, δt_3... δt_60 respectively, and the corresponding real-time count values are clk_1, clk_2, clk_3... clk_60 respectively, the working satellite receiver assigns each real-time count value a corresponding weight w1, w2, w3... w60, and the weight w of the real-time count value is higher as the time sequence is later, so that the real-time count average Clkave of the real-time count values from the 1st~60th second is obtained according to the weighted average algorithm, that is:

[0069] (3)

[0070] As the working satellite receiver continuously receives the navigation constellation signals, the range of the selected real-time count values also correspondingly shifts backward over time, thus, for any continuous 60-second time window within the 1st~62ndsecond, the real-time count average Clkave can be calculated, i.e.:

[0071] (4)

[0072] Further, the working satellite receiver determines the above real-time count average Clkave as the effective compensation count value Clkcom based on the last effective time and the real-time count average Clkave within the previous 59 seconds, and corrects the pulse count of the PPS signal. In some embodiments, the real-time clock difference average Clkave=5.3 within the 3rd~62ndsecond is calculated by the weighted average method, thus the corresponding effective compensation count value Clkcom=5.3, and the effective compensation count value Clkcom is taken as the prior information of the working satellite receiver at the subsequent invalid time.

[0073] Please refer to Figure 6 In some embodiments, the step S150 further comprises the following steps:

[0074] Step S151, in response to the first invalid time, obtaining the floor value of the effective compensation count value, and setting the floor value of the effective compensation count value as the count correction value of the first invalid time;

[0075] Step S152, in response to the second invalid time, obtaining the ceiling value of the effective compensation count value, and setting the ceiling value of the effective compensation count value as the count correction value of the second invalid time;

[0076] Step S153, obtaining the average value of the ceiling value of the effective compensation count value and the floor value of the effective compensation count value, and obtaining the difference between the average value and the effective compensation count value;

[0077] Step S154, if the difference is greater than 0, obtaining the floor value of the average value, and setting the floor value of the average value as the count correction value of the third invalid time;

[0078] Step S155, if the difference is less than or equal to 0, obtaining the ceiling value of the average value, and setting the ceiling value of the average value as the count correction value of the third invalid time.

[0079] In some embodiments, the time point of 63 seconds is set as the invalid time point of positioning of the working satellite receiver, and then the first invalid time point is set as 63 seconds, the second invalid time point is set as 64 seconds, and so on.

[0080] Please refer to Figure 5 In some embodiments, the counting correction value at the first invalid time point is defined as B, and then B=floor(Clkcom)=floor(5.3)=5. The counting correction value at the second invalid time point is defined as C, and then C=ceil(Clkcom)=ceil(5.3)=6. It can be understood that the floor() function means that the maximum integer less than or equal to the arbitrary real number is returned, and the ceil() function means that the minimum integer greater than or equal to the arbitrary real number is returned.

[0081] In some embodiments, the average value D of the counting correction value B at the first invalid time point and the counting correction value C at the second invalid time point is further obtained, and then D=(B+C) / 2=(5+6) / 2=5.5. The difference Δ between the average value D and the effective compensation count value Clkcom is obtained, and then Δ=5.5-5.3=0.2. The counting correction value at the third invalid time point is defined as E, and then E=floor(5.5)=5 because the difference Δ=0.2>0.

[0082] In this application, the effective compensation count value Clkcom is taken as prior information, and the corresponding ceiling value and floor value thereof are taken as the counting correction values at the first invalid time point and the second invalid time point, respectively. The average value of the ceiling value and the floor value corresponding to the effective compensation count value is obtained, and the size relationship between the average value and the effective compensation count value Clkcom is judged. According to the size relationship, the ceiling value or the floor value of the average value is further set as the counting correction value at the third invalid time point.

[0083] Please refer to Figure 7 In some embodiments, after the step S154 or the step S155, the following steps are further included:

[0084] In step S156, in response to any jth invalid time point, the average value of all counting correction values corresponding to the 1st invalid time point to the (j-1)th invalid time point is obtained, where j≥4.

[0085] In step S157, the counting verification difference between the average value of the counting correction values and the effective compensation count value is obtained.

[0086] In step S158, if the counting verification difference is greater than 0, the floor value of the average value of the counting correction values is obtained, and the floor value is set as the counting correction value at the jth invalid time point.

[0087] In step S159, if the count verification difference is less than or equal to 0, an upward rounding value of the average of the count correction values is obtained, and the upward rounding value is set as the count correction value of the jth invalid time.

[0088] Please refer to Figure 5 In some embodiments, in response to the fourth invalid time, an average of the count correction value B of the first invalid time, the count correction value C of the second invalid time, and the count correction value E of the third invalid time is obtained, and the average is set as F, so F = (B + C + E) / 3 = (5 + 6 + 5) / 3 ≈ 5.333; further, a count verification difference Clkdiffer between the average F and the valid compensation count value Clkcom is obtained, i.e. Clkdiffer = F - Clkcom = 5.333 - 5.3 = 0.033. Since the count verification difference Clkdiffer = 0.033 > 0, a downward rounding value of the average F is obtained, the downward rounding value is set as G, so G = floor(5.333) = 5, and the downward rounding value G is set as the count correction value of the fourth invalid time.

[0089] Similarly, in response to the fifth invalid time, an average of all count correction values corresponding to the first invalid time to the fourth invalid time is obtained, and the average is set as H, so H = (B + C + E + G) / 4 = (5 + 6 + 5 + 5) / 4 ≈ 5.25; further, a count verification difference Clkdiffer between the average H and the valid compensation count value Clkcom is obtained, i.e. Clkdiffer = H - Clkcom = 5.25 - 5.3 = -0.05. Since the count verification difference Clkdiffer = -0.05 < 0, an upward rounding value of the average H is obtained, the upward rounding value is set as I, so I = ceil(5.25) = 6, and the upward rounding value I is set as the count correction value of the fourth invalid time.

[0090] In the present application, for any invalid time from the fourth invalid time, the count correction value at the invalid time can be determined according to the above method.

[0091] It can be understood that the above-mentioned A, B, C, D, etc. letters used in the embodiments of the present application do not represent the limitation of the foregoing count correction values and average values, and if necessary, other symbols or marks can also be used for representation. In order to facilitate understanding, the correspondence relationship of the count correction values and the determination values from the first invalid time in the present application is arranged as shown in Table 1.

[0092] Table 1 Correspondence relationship of count correction values and determination values from the first invalid time

[0093] Invalidation time One Two Three Four Five j (j > 4) Letter corresponding to the count correction value B=5 C=6 E=5 G=5 I=6 5 or 6 Average of the count correction values at all invalidation times before / / D=5.5 F=5.333 H=5.25 Fluctuate around 5.3

[0094] In summary, the PPS signal correction method of the satellite receiver provided in the application has the following beneficial technical effects: at invalid time, the satellite receiver can only rely on the valid compensation count value Clkcom obtained at valid time as reference information of the count correction value, however, since the valid compensation count value Clkcom obtained by the weighted moving average method is a floating-point value (for example, 5.3), limited by the data processing capability of the working satellite receiver, the floating-point value cannot be directly used for correction of the PPS signal, and only integer values can be used for correction, therefore, the application performs the above method pre-set in the working satellite receiver to obtain an integer count correction value at any invalid time, and can ensure that the average of the count correction values at all invalid times correspondingly floats in a small numerical range near the valid compensation count value Clkcom, that is, the effectiveness of the count correction value at invalid time is ensured as a whole, thereby improving the precision of the PPS signal output by the working satellite receiver, and greatly reducing the correction cost of the PPS signal.

[0095] The PPS signal correction method of the working satellite receiver of the application is verified by the ground control station, and when the positioning invalid time lasts for 30 min, the output precision of the PPS can still be maintained within 2 ns, and the receiver clock difference remains stable, so the method can ensure the normal performance of the task of each subsystem load of the working satellite, and can be considered to be applicable to all GNSS on-orbit working satellites.

[0096] Please refer to Figure 8 Another embodiment of the application provides a PPS signal correction device 200 of a satellite receiver, the device 200 mainly comprises: a receiving module 210 configured to receive a navigation constellation signal; a judging module 220 configured to judge whether the satellite receiver is valid in positioning, and determine valid time and invalid time of the satellite receiver; a first correction module 230 configured to obtain an effective point receiver clock difference corresponding to the valid time of the satellite receiver, correct and output the PPS signal of the satellite receiver based on the effective point receiver clock difference; a first determination module 240 configured to obtain a real-time count average value corresponding to the effective point receiver clock difference, and determine a valid compensation count value of the satellite receiver based on the real-time count average value; a second determination module 250 configured to determine a count correction value at invalid time based on the valid compensation count value in response to the invalid time of the satellite receiver; and a second correction module 260 configured to correct and output the PPS signal of the satellite receiver based on the count correction value.

[0097] The details of other operations performed by the modules in the embodiment can be referred to the foregoing embodiments, and will not be described here.

[0098] The application provides a PPS signal correction device of a satellite receiver, which obtains an effective compensation count value at a valid positioning moment of the receiver, takes the effective compensation count value as reference information at an invalid positioning moment of the receiver, determines a count correction value at an arbitrary invalid moment, corrects the PPS signal based on the count correction value, avoids dependence on hardware and a ground control station, and only needs to complete the PPS signal correction on the working satellite receiver, thereby greatly reducing the PPS signal correction cost and improving the PPS signal precision.

[0099] The PPS signal correction device of the satellite receiver can be a device, a component in a terminal, an integrated circuit or a chip. The PPS signal correction device of the satellite receiver can be a chip, such as an FPGA (Field Programmable Gate Array) or an MCU (Microcontroller Unit), and the application is not limited in this embodiment.

[0100] Please refer to Figure 9 The application further provides a satellite receiver 300, which comprises a radio frequency front-end processing unit 310 and a baseband digital signal processing unit 320. The baseband digital signal processing unit 320 is configured to implement each process of the above-mentioned PPS signal correction method of the satellite receiver and achieve the same technical effects. To avoid repetition, no further description is given here.

[0101] In some embodiments, the radio frequency front-end processing unit 310 comprises a satellite antenna 311, a low-noise power amplifier 312 and a radio frequency circuit 313 connected in sequence. The navigation constellation signal is transmitted to the baseband digital signal processing unit 320 after being processed by the radio frequency front-end processing unit 310. Specifically, the navigation constellation signal is received by the satellite antenna 311 and reaches the low-noise power amplifier 312. After being processed by the low-noise power amplifier 312, such as filtering and amplification, the signal is output to the radio frequency circuit 313. The radio frequency circuit 313 converts the high-frequency radio frequency signal to a fixed lower-frequency intermediate frequency signal through frequency conversion and mixing operation, and transmits the intermediate frequency signal to the satellite baseband 321. The specific structure and function of the satellite antenna 311, the low-noise power amplifier 312 and the radio frequency circuit 312 are known in the art, and no further description is given here.

[0102] In some embodiments, the baseband digital signal processing unit 320 comprises a satellite baseband 321 and a satellite processor 322 communicatively connected, the satellite processor 322 is configured to generate a receiver clock difference, and the satellite baseband 321 is configured to correct and output a PPS signal of the satellite receiver 300 based on the receiver clock difference.

[0103] Specifically, the data transmission between the satellite baseband 321 and the satellite processor 322 is completed through an EMIF (External Memory Interface) bus: the satellite processor 322 first issues a satellite signal capture requirement to the satellite baseband 321, the satellite baseband 321 captures and tracks the navigation constellation according to the assigned channel and satellite number, after successful tracking, the satellite baseband 321 transmits the ranging code information and navigation message information in the navigation constellation signal to the satellite processor 322, the satellite processor 322 performs PVT calculation according to the above information to obtain the position, velocity and time information of the working satellite, and returns the receiver clock difference to the satellite baseband 321, and the satellite baseband 321 further corrects the PPS signal according to the receiver clock difference, and transmits the corrected PPS signal to each subsystem of the satellite through a hardware pin.

[0104] The embodiment of the application further provides a computer readable medium, and the computer readable medium stores a program or instructions, the program or instructions are executed by a processor to realize each process of the PPS signal correction method of the satellite receiver, and the same technical effects can be achieved. To avoid repetition, no more description is made here.

[0105] The embodiment of the application further provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium, and the computer program product comprises a computer program, the computer program is executed by a processor to realize each process of the PPS signal correction method of the satellite receiver, and the same technical effects can be achieved. To avoid repetition, no more description is made here.

[0106] Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a tangible non-transitory program carrier to be executed by, or to control the operation of, data processing apparatus. Alternatively or additionally, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus.

[0107] The PPS signal correction method of the satellite receiver of the present application, when implemented as a computer program, can also be stored in a computer-readable storage medium as an article of manufacture. For example, the computer-readable storage medium can include, but is not limited to, magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips), optical disks (e.g., compact disk (CD), digital versatile disk (DVD)), smart cards, and flash memory devices (e.g., electrically erasable programmable read only memory (EEPROM), card, stick, key drive). Additionally, the various storage mediums described herein can represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media (and / or storage media) that are capable of storing, containing, and / or carrying code and / or instructions and / or data.

[0108] The above-described application discloses only examples, and is not intended to limit the present application. Although the present application has been described with reference to the specific examples, it is apparent to those skilled in the art that various modifications, improvements and corrections can be made to the present application. Such modifications, improvements and corrections are suggested in the present application, and still fall within the spirit and scope of the exemplary embodiments of the present application.

[0109] Some embodiments use numerical values to describe components, quantities of attributes, it should be understood that such numerical values used in the description of the embodiments are, in some examples, modified by the words "about", "approximately", or "generally". Unless otherwise stated, "about", "approximately", or "generally" indicates that the described value allows for a ±20% variation. Accordingly, numerical values used in the specification and claims are approximations that can vary depending on the desired characteristics of the individual embodiments. In some embodiments, numerical values should be considered in the context of the number of significant digits and errors inherent to some measuring techniques. Although the numerical ranges and parameters setting forth the broadest scope of the application in some embodiments are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values set forth in the specific examples are provided to be as precise as reasonably possible. However, some variations may

[0110] Although the present application has been described with reference to the current specific embodiments, those skilled in the art will recognize that the above-described embodiments are merely illustrative of the present application, and that various changes in form and details can be made to the above-described embodiments without departing from the spirit and scope of the present application.

Claims

1. A method for PPS signal correction in a satellite receiver, characterized in that, include: Receive navigation constellation signals; Determine whether the satellite receiver's positioning is valid, and determine the valid and invalid times of the satellite receiver. When the satellite receiver's positioning is valid, the receiving time is determined to be the valid time of the satellite receiver; when the satellite receiver's positioning is invalid, the receiving time is determined to be the invalid time of the satellite receiver. Obtain the valid point receiver clock error corresponding to the valid time of the satellite receiver, and based on the valid point receiver clock error, correct and output the PPS signal of the satellite receiver; Obtain the real-time average count value corresponding to the clock bias of the effective point receiver, and determine the effective compensation count value of the satellite receiver based on the real-time average count value. This step specifically includes: Obtain real-time count values ​​corresponding to receiver clock errors at several consecutive valid time points, wherein the last time point in the several consecutive valid time points is located before the first invalid time point, and... Determine the average real-time count from the i-th real-time count value to the (i+k)-th real-time count value, where 1 ≤ i ≤ i+k, and, Based on the real-time average count, the effective compensation count value is determined; and In response to the invalid time of the satellite receiver, based on the valid compensation count value, a count correction value for the invalid time is determined, wherein this step specifically includes: In response to the first invalid time, the rounded-down value of the valid compensation count is obtained, and the rounded-down value of the valid compensation count is set to the count correction value at the first invalid time. In response to the second invalid time, the rounded-up value of the valid compensation count is obtained, and the rounded-up value of the valid compensation count is set to the count correction value for the second invalid time. Obtain the average of the rounded-up value and the rounded-down value of the effective compensation count, and obtain the difference between the average value and the effective compensation count. If the difference is greater than 0, obtain the floor value of the average value, and set the floor value of the average value as the count correction value for the third invalid time. If the difference is less than or equal to 0, obtain the floor value of the average value, and set the floor value of the average value as the count correction value for the third invalid time; and, Based on the count correction value, the PPS signal of the satellite receiver is corrected and output.

2. The PPS signal correction method for a satellite receiver according to claim 1, characterized in that, The real-time count mean is obtained using a weighted moving average method.

3. The PPS signal correction method for a satellite receiver according to claim 1, characterized in that, After the step of setting the floor value of the average value to the count correction value of the third invalid time, or after the step of setting the floor value of the average value to the count correction value of the third invalid time, the method further includes: In response to any j-th invalid time, the average value of all count correction values ​​corresponding to the 1st invalid time to the (j-1)th invalid time is obtained, where j≥4; Obtain the count verification difference between the average value of the count correction value and the effective compensated count value; If the count verification difference is greater than 0, obtain the floor value of the average value of the count correction value, and set the floor value as the count correction value at the j-th invalid time. If the count verification difference is less than or equal to 0, obtain the floor value of the average of the count correction values, and set the floor value as the count correction value at the j-th invalid time.

4. The PPS signal correction method for a satellite receiver according to any one of claims 1-3, characterized in that, The step of determining whether the satellite receiver's positioning is valid, and determining the valid and invalid times of the satellite receiver, includes: In response to the navigation constellation signal, PVT positioning calculation is performed to obtain the result of the PVT positioning calculation; Based on the time information of the PVT positioning solution, the real-time receiver clock error is determined; Obtain the clock error verification difference between the real-time receiver clock error and the preset clock error threshold of the satellite receiver; Determine whether the clock error verification difference is greater than 0, and determine whether the positioning of the satellite receiver is valid based on the determination result; If the clock error verification difference is less than or equal to 0, the positioning of the satellite receiver is determined to be valid, and the reception time of the navigation constellation signal is determined to be the valid time. If the clock error verification difference is greater than 0, the positioning of the satellite receiver is determined to be invalid, and the reception time of the navigation constellation signal is determined to be the invalid time.

5. A PPS signal correction device for a satellite receiver, characterized in that, include: The receiving module is configured to receive navigation constellation signals; The judgment module is configured to determine whether the satellite receiver positioning is valid, and to determine the valid time and invalid time of the satellite receiver. When the satellite receiver positioning is valid, the receiving time is determined to be the valid time of the satellite receiver. When the satellite receiver positioning is invalid, the receiving time is determined to be the invalid time of the satellite receiver. The first correction module is configured to obtain the valid point receiver clock error corresponding to the valid time of the satellite receiver, and correct and output the PPS signal of the satellite receiver based on the valid point receiver clock error; The first determining module is configured to obtain the real-time average count value corresponding to the clock difference of the effective point receiver, and determine the effective compensation count value of the satellite receiver based on the real-time average count value. The second determining module is configured to, in response to the invalid time of the satellite receiver, determine the count correction value at the invalid time based on the valid compensation count value; The second correction module is configured to correct and output the PPS signal of the satellite receiver based on the count correction value.

6. A satellite receiver, comprising a radio frequency front-end processing unit and a baseband digital signal processing unit, characterized in that, The baseband digital signal processing unit is configured to implement the method as described in any one of claims 1-4.

7. The satellite receiver according to claim 6, characterized in that, The radio frequency front-end processing unit includes a satellite antenna, a low-noise power amplifier, and a radio frequency circuit that are connected in sequence. The navigation constellation signal is transmitted to the baseband digital signal processing unit after being processed by the radio frequency front-end processing unit. The baseband digital signal processing unit includes a satellite baseband and a satellite processor connected in communication. The satellite processor is configured to generate the receiver clock bias, and the satellite baseband is configured to correct and output the PPS signal of the satellite receiver based on the receiver clock bias.

8. A computer-readable medium, characterized in that, A program or instructions are stored on the computer-readable medium, which, when executed by a processor, implement the method as described in any one of claims 1-4.

9. A computer program product, the computer program product comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-4.

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