A high-sensitivity satellite signal capture method, device and computer storage medium

Abstract

The present invention provides a high-sensitivity satellite signal capture method and device. The method comprises: multiplying the result of fast Fourier transform after resampling the satellite data with the result of fast Fourier transform after taking the conjugate, and performing inverse fast Fourier transform on the multiplied data; repeating the above operation for every 1ms delay of the satellite data; performing NH code stripping; performing conjugate multiplication of the result of the first 1ms and the result of the last 1ms to obtain a differential result, and accumulating the differential result to obtain the final differential coherent integration result. The present invention is based on making a difference between the first 1ms and the last 1ms, and then performing several accumulations, which can weaken the influence of bit flipping, solve the influence of NH code phase jump on integration, and thus improve the sensitivity of capturing satellite signals.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a high-sensitivity satellite signal capture method, device and computer storage medium. Background Art

[0002] In some environments where the satellite signal strength is weak, the signal cannot be captured using general capture methods, so it is very important to study high-sensitivity capture methods. Usually, the methods to improve capture sensitivity include increasing the coherent integration time and increasing the incoherent integration time. Increasing the incoherent integration time can improve the capture sensitivity to a certain extent, but it will introduce square loss, and the capture effect is not very ideal. At present, increasing the coherent integration time is often used to improve the capture sensitivity. Increasing the coherent integration time maintains the phase information of the signal and does not bring square loss. However, considering the characteristics of satellite signals such as B1I and B2A, it is limited by the signal structure. Taking the B1I signal as an example, there are mainly two aspects: one is that the signal is affected by bit flipping; the other is that the NH code (New Hoffman code) is modulated every millisecond on the B1I signal, and the influence of the NH code phase jump needs to be solved, thereby increasing the coherent integration time. The current Beidou weak signal capture method cannot effectively solve the influence of the NH code phase jump, and the integration time is limited, resulting in low capture sensitivity. Summary of the invention

[0003] In view of this, the present invention provides a high-sensitivity satellite signal capture method and device based on differential coherent integration, which can effectively increase the differential coherence time according to the degree of weak signals and effectively solve the influence of NH code phase jumps, thereby capturing the code phase and Doppler of the signal and determining the sign of the current NH code (subcode).

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] An embodiment of the present invention provides a high-sensitivity satellite signal acquisition method, comprising:

[0006] The satellite data after stripping the carrier for a preset time is resampled and then fast Fourier transformed, and the result after the fast Fourier transform is multiplied by the conjugate result after the fast Fourier transform of the local spread spectrum code;

[0007] Perform inverse fast Fourier transform on the multiplied data to get the result R 1 ;

[0008] Repeat the above operation after delaying the satellite data by 1ms to obtain the result R 2 , delay the satellite data by 2ms and repeat the above operation to get the result R 3 , and so on, delay the satellite data by Nms and repeat the above operation to get the result RN+1 ;

[0009] The result R 1 To R N+1 Strip the NH code to get the result R′ 1 To R' N+1 ;

[0010] The result R′ 1 and the result R′ 2 Perform conjugate multiplication to obtain the difference result DR 1 , the result R′ 2 and the result R′ 3 Perform conjugate multiplication to obtain the difference result DR 2 , and so on, the result is R′ N and the result R′ N+1 Perform conjugate multiplication to obtain the difference result DR N ;

[0011] For the difference result DR 1 To DR N The final differential coherent integration result SR is obtained by accumulation;

[0012] The differential coherent integration results corresponding to all Doppler values ​​within the specified range are obtained and the maximum value is calculated, and the signal-to-noise ratio corresponding to the maximum value is compared with a preset threshold value to determine whether the capture is successful.

[0013] Furthermore, before the step of “re-sampling the satellite data after stripping the carrier wave for a preset time”, the following steps may also be included:

[0014] Initializing capture parameters; the capture parameters include specifying satellite numbers, Doppler search ranges, and search steps;

[0015] Generate a local spreading code of a designated satellite pseudo-random code, and perform fast Fourier transform on the local spreading code and then take the conjugate;

[0016] Acquire satellite intermediate frequency data and intercept satellite intermediate frequency data of preset duration;

[0017] Generate a local carrier according to the intermediate frequency and the specified current Doppler frequency;

[0018] The satellite data after carrier stripping is obtained by multiplying the intercepted satellite intermediate frequency data with the in-phase and quadrature components of the local carrier.

[0019] Furthermore, the “obtaining differential coherent integration results corresponding to all Doppler values ​​within a specified range and finding the maximum value, and comparing the signal-to-noise ratio corresponding to the maximum value with a preset threshold value to determine whether the capture is successful” specifically includes:

[0020] Calculate the final differential coherent integration results corresponding to all specified Doppler values ​​respectively;

[0021] The maximum value of the final differential coherent integration results corresponding to all Doppler values ​​is calculated, and the code phase and NH code phase corresponding to the maximum value are obtained;

[0022] The signal-to-noise ratio corresponding to the maximum value is compared with a preset threshold value; when the signal-to-noise ratio is greater than or equal to the preset threshold value, the current satellite is captured successfully; when the signal-to-noise ratio is less than the preset threshold value, the current satellite is captured unsuccessfully.

[0023] Furthermore, the “generating a local carrier according to the intermediate frequency and the specified current Doppler frequency” uses the following formula:

[0024]

[0025] Where C represents the local carrier, f i is the intermediate frequency, f dop is the currently specified Doppler frequency, f s is the sampling frequency.

[0026] Furthermore, the preset duration is 2ms, the local spread code is 1ms, and the 2ms satellite data is slidably correlated with the 1ms local spread code. When the data millisecond boundary is aligned with the spread code boundary, the correlation result reaches a maximum value.

[0027] Furthermore, the “result R 1 To R N+1 Strip the NH code to get the result R′ 1 To R' N+1 Specifically include:

[0028] Perform preset m NH code searches and convert N+1 results R 1 To R N+1 Multiply them by the corresponding NH code respectively to obtain the preset m groups of N+1 data;

[0029] R′ i =R i NH(mod((i+ii),m))

[0030] Wherein, m represents the NH code period, i=1, 2, ..., N+1; NH(ii) represents the phase symbol of the ii-th NH code, ii=0, 1, 2, ..., m-1.

[0031] The embodiment of the present invention further provides a high-sensitivity satellite signal acquisition device, comprising: a resampling module, a first FFT module, a second FFT module, a multiplier, an inverse FFT module, a difference module, and an accumulation module;

[0032] The resampling module is used to resample the satellite data after stripping the carrier;

[0033] The first FFT module is used to perform fast Fourier transform on the resampled data to obtain a baseband spectrum signal;

[0034] The second FFT module is used to perform fast Fourier transform on the local spread spectrum code to obtain a spread spectrum code spectrum signal;

[0035] The multiplier is used to perform complex multiplication of the baseband spectrum signal and the spread spectrum code spectrum signal;

[0036] The inverse FFT module is used to perform an inverse fast Fourier transform on the result output by the multiplier to obtain the despreading and demodulation of all code phases of the satellite signal corresponding to the specified Doppler frequency;

[0037] The difference module is used to perform conjugate multiplication on the capture processing result of the satellite data and the capture processing result of the satellite data after a delay of 1 ms;

[0038] The accumulation module is used to perform coherent accumulation on the differential results according to a preset differential coherence number.

[0039] Further, it also includes: a local carrier generator and a mixer;

[0040] The local carrier generator is used to generate a local carrier according to the intermediate frequency and the specified current Doppler frequency;

[0041] The mixer is used to perform carrier stripping on the satellite intermediate frequency data according to the local carrier generated by the local carrier generator.

[0042] Further, it also includes: a spread spectrum code generator;

[0043] The spreading code generator is used to generate a local spreading code of a designated satellite pseudo-random code.

[0044] Furthermore, it also includes: a capture detection module;

[0045] The capture detection module is used to determine whether the current satellite is captured successfully based on the current final differential coherent accumulation result.

[0046] An embodiment of the present invention further provides a high-sensitivity satellite signal acquisition device, comprising: a memory and a processor;

[0047] The memory is used to store computer programs;

[0048] The processor is used to execute the steps of the above high-sensitivity satellite signal acquisition method when running the computer program.

[0049] An embodiment of the present invention further provides a computer storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above high-sensitivity satellite signal acquisition method are implemented.

[0050] Based on the above scheme provided by the present invention, based on the parallel search of the code phase of the cyclic correlation and the differential coherence of the 2 millisecond data, the difference is made based on the first 1ms and the last 1ms, and then several accumulations are performed, which can weaken the influence of the bit flip, and cleverly process the NH code (subcode), thereby solving the influence of the NH code (subcode) phase jump on the integration. Thus, the sensitivity of capturing satellite signals is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A schematic diagram of a process flow of a high-sensitivity satellite signal acquisition method provided by an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of performing correlation calculation on 2 ms satellite data and 1 ms local spread spectrum code provided in an embodiment of the present invention;

[0054] Figure 3 A flowchart of a high-sensitivity satellite signal acquisition method provided by an embodiment of the present invention;

[0055] Figure 4 A schematic diagram of the composition of a high-sensitivity satellite signal acquisition device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] Figure 1 The figure is a flow chart of a high-sensitivity satellite signal acquisition method provided by an embodiment of the present invention. The method comprises the following steps:

[0058] S101, resampling the satellite data after stripping the carrier for a preset time and then performing a fast Fourier transform, and multiplying the result of the fast Fourier transform with the conjugate result of the fast Fourier transform of the local spread spectrum code.

[0059] like Figure 2 As shown in the figure, the preset duration is 2ms, the local spread code is 1ms, and the 2ms satellite data is slid and correlated with the 1ms local spread code. When the data millisecond boundary is aligned with the 1ms local spread code boundary, the correlation result reaches the maximum value. The code phase accuracy obtained by single-channel search is 1 code chip, and the combination of odd and even channels achieves 0.5 code chip accuracy. Considering the uncertainty of the code phase, assuming that the NH code symbols of the continuous 2ms data are consistent, at least 1ms of valid data can be guaranteed.

[0060] Figure 3 The figure shows a complete flow chart of a high-sensitivity satellite signal acquisition method provided by an embodiment of the present invention, which further includes the following steps before resampling the satellite data after stripping the carrier for a preset time:

[0061] S001. Initialize capture parameters; the capture parameters include specifying satellite numbers, Doppler search ranges, and search steps.

[0062] S002. Generate a local spread spectrum code of a designated satellite pseudo-random code, and perform fast Fourier transform on the local spread spectrum code and then take the conjugate.

[0063] S003. Acquire satellite intermediate frequency data and capture satellite intermediate frequency data of a preset duration, such as 2 ms.

[0064] Input the satellite intermediate frequency data into the system and process the 2ms data first.

[0065] S004. Generate a local carrier according to the intermediate frequency and the specified current Doppler frequency.

[0066] The following formula is used to generate the local carrier:

[0067]

[0068] Where C represents the local carrier, f i is the intermediate frequency, f dop is the currently specified Doppler frequency, f s is the sampling frequency.

[0069] S005. Multiply the intercepted 2 ms satellite intermediate frequency data with the in-phase and quadrature components of the local carrier to obtain the satellite data after 2 ms carrier stripping.

[0070] Stripping the carrier means multiplying the satellite intermediate frequency data and the in-phase and quadrature components of the local carrier output by the local carrier generator; using the following formula: S = D·C.

[0071] Among them, D represents satellite intermediate frequency data; S represents satellite data after carrier stripping; C represents local carrier.

[0072] S102, perform inverse fast Fourier transform on the multiplied data to obtain the result R 1 .

[0073] Results 1 The expression of R is as follows: 1 =IFFT(FFT(S)·conj(FF(Td B1I )))

[0074] Among them, FFT() and IFFT() are the operation symbols for obtaining FFT and inverse FFT, and conj() is the operation symbol for obtaining conjugate; d B1I is the local spreading code, and S is the satellite data after stripping the carrier.

[0075] S103, delay the satellite data by 1ms and repeat the above operation to obtain the result R 2 , delay the satellite data by 2ms and repeat the above operation to get the result R 3 , and so on, delay the satellite data by Nms and repeat the above operation to get the result R N+1 .

[0076] Delay the satellite intermediate frequency data by 1ms and execute the above steps S003, S004, S005, S101, S102 to obtain the result R 2 Delay the satellite intermediate frequency data by 2ms and execute the above steps S003, S004, S005, S101, S102 to obtain the result R 3 Similarly, delay the satellite intermediate frequency data by Nms and execute the above steps S003, S004, S005, S101, S102 to obtain the result R N+1 That is, between two adjacent results (R 1 With R 2 , R 2 With R 3 ,……,R N With R N+1 )’s satellite intermediate frequency data delay is 1ms.

[0077] S104. Result R 1 To R N+1 Strip the NH code to get the result R′ 1 To R' N+1 .

[0078] Perform preset m NH code searches and convert N+1 results R 1 To R N+1 Multiply them by the corresponding NH code respectively to obtain the preset m groups of N+1 data;

[0079] R′ i =R i NH(mod((i+ii),m))

[0080] Where m represents the NH code period, i = 1, 2, ..., N + 1; NH (ii) represents the phase symbol of the ii-th NH code, ii = 0, 1, 2, ..., m-1. The mod (x, y) function is a remainder function.

[0081] The B3I signal structure has the same characteristics as the B1I signal. The main code period is 1ms. The NH code is modulated on the basis of the spread spectrum code. The NH code period is 20. For the Beidou B1I signal and Beidou B3I signal, the result R 1 To R N+1 Perform NH code stripping, that is, perform 20 NH code phase searches, multiply the N+1 results by the corresponding NH code, and obtain 20 groups of N+1 data;

[0082] R′ i =R i NH(mod((i+ii),20)), where R′ i The result R i The data after stripping the NH code, i=1,2,…,N+1; NH(ii) represents the phase symbol of the ii-th NH code, ii=0,1,2,…,19.

[0083] The data channel structure of the B2A signal has the same characteristics as the B1I signal. The main code period is 1ms, and the subcode is modulated on the basis of the main code. The B2A subcode period is 5. For the Beidou B2A signal, the result R 1 To R N+1 NH code stripping is performed, that is, five sub-code phase searches are performed, and the N+1 results are multiplied by the corresponding NH code to obtain five groups of N+1 data;

[0084] R′ i =R i NH(mod((i+ii),5)), where R′ i The result R i The data after stripping the NH code, i = 1, 2, ..., N + 1; NH (ii) represents the phase symbol of the ii-th NH code, ii = 0, 1, 2, 3, 4.

[0085] The data channel and pilot channel structure of GPS L5 signal have the same characteristics as B1I signal, and the main code period of both channels is 1ms, and NH code is modulated on the basis of the main code. For GPS L5 signal, since the Q channel of L5 modulates the NH code with a length of 20, and the I channel modulates the NH code with a length of 10, only 10 NH code phase searches are required for the NH code phase of the I channel. 20 NH code phase searches are required for the NH code phase of the Q channel.

[0086] S105, the result R' 1 and the result R′ 2 Perform conjugate multiplication to obtain the difference result DR 1 , the result R′ 2 and the result R′ 3 Perform conjugate multiplication to obtain the difference result DR 2 , and so on, the result is R′ N and the result R′ N+1 Perform conjugate multiplication to obtain the difference result DR N .

[0087] S106: Differential result DR 1 To DR N The final differential coherent integration result SR is obtained by accumulation.

[0088] The final differential coherent integration result SR can be expressed as follows:

[0089]

[0090] Among them, SR is the final differential coherent integration result.

[0091] S107, obtaining the differential coherent integration results corresponding to all Doppler values ​​within the specified range and finding the maximum value, and comparing the signal-to-noise ratio corresponding to the maximum value with a preset threshold value to determine whether the capture is successful.

[0092] When searching at each Doppler frequency, the corresponding local carrier is first generated according to the Doppler frequency, and the local carrier is used to strip the carrier to obtain the corresponding satellite data. This is done until all frequencies within the Doppler frequency search range are searched, and multiple sets of final differential coherent integration results (SR 1 , SR 2 , SR 3 ……). Whether the capture of the current satellite is successful is determined based on the multiple groups of final differential coherent integration results.

[0093] “Obtain the differential coherent integration results corresponding to all Doppler values ​​within the specified range and calculate the maximum value, and compare the signal-to-noise ratio corresponding to the maximum value with the preset threshold value to determine whether the capture is successful” specifically includes: respectively calculating the final differential coherent integration results corresponding to all specified Doppler values. Calculate the maximum value of the final differential coherent integration results corresponding to all Doppler values, and obtain the code phase and NH code phase corresponding to the maximum value. Compare the signal-to-noise ratio corresponding to the maximum value with the preset threshold value; when the signal-to-noise ratio is greater than or equal to the preset threshold value, the current satellite is captured successfully; when the signal-to-noise ratio is less than the preset threshold value, the current satellite fails to be captured.

[0094] The present invention can effectively increase the differential coherence time according to the degree of weak signal, effectively capture the code phase and Doppler of the signal and determine the symbol of the current NH code (subcode). Aiming at the disadvantage that the satellite signal is affected by bit flipping and NH code (subcode) phase jump under weak signal condition, the code phase parallel search based on cyclic correlation and 2 milliseconds data differential coherence are adopted, and several accumulations are performed, so that the influence of bit flipping can be weakened, and the NH code (subcode) is cleverly processed, thereby solving the influence of NH code (subcode) phase jump on integration.

[0095] like Figure 4 As shown, an embodiment of the present invention further provides a high-sensitivity satellite signal acquisition device, including: a resampling module 103, a first FFT module 104, a second FFT module 106, a multiplier 107, an inverse FFT module 108, a difference module 109, an accumulation module 110, a local carrier generator 101, a mixer 102, a spread spectrum code generator 105 and a capture detection module 111.

[0096] The resampling module 103 is used to resample the satellite data after stripping the carrier.

[0097] The first FFT module 104 is used to perform fast Fourier transform on the resampled data to obtain a baseband spectrum signal.

[0098] The second FFT module 106 is used to perform fast Fourier transform on the local spread spectrum code to obtain a spread spectrum code spectrum signal.

[0099] The multiplier 107 is used to perform complex multiplication on the baseband spectrum signal and the spread spectrum code spectrum signal.

[0100] The inverse FFT module 108 is used to perform an inverse fast Fourier transform on the result output by the multiplier 107 to obtain the despreading and demodulation of all code phases of the satellite signal corresponding to the specified Doppler frequency.

[0101] The difference module 109 is used to perform conjugate multiplication on the acquisition processing result of the satellite data and the acquisition processing result of the satellite data after a delay of 1 ms.

[0102] The accumulation module 110 is used to perform coherent accumulation on the differential results according to a preset differential coherence number.

[0103] The local carrier generator 101 is used to generate a local carrier according to the intermediate frequency and the specified current Doppler frequency; the mixer 102 is used to strip the satellite intermediate frequency data according to the local carrier generated by the local carrier generator 101 and output it to the resampling module 103. The resampling frequency is determined by the code phase search accuracy.

[0104] The spreading code generator 105 is used to generate a local spreading code of a designated satellite pseudo-random code.

[0105] The capture detection module 111 is used to determine whether the current satellite is captured successfully based on the current final differential coherent accumulation result.

[0106] It should be noted that: the high-sensitivity satellite signal acquisition device provided in the above embodiment only uses the division of the above program modules as an example when performing acquisition. In actual applications, the above processing can be assigned to different program modules as needed, that is, the internal structure of the device is divided into different program modules to complete all or part of the processing described above. In addition, the high-sensitivity satellite signal acquisition device provided in the above embodiment belongs to the same concept as the acquisition method embodiment. The specific implementation process is detailed in the method embodiment. The beneficial effects are the same as the method embodiment, and will not be repeated here.

[0107] The embodiment of the present invention further provides a high-sensitivity satellite signal acquisition device, comprising: a memory and a processor. The memory is used to store a computer program. When the processor is used to run the computer program, the steps of the high-sensitivity satellite signal acquisition method of the present invention are executed.

[0108] The embodiment of the present invention further provides a computer storage medium, which is a computer-readable storage medium, on which a computer program is stored. The computer program can be executed by a processor of a high-sensitivity satellite signal acquisition device to complete the steps of the above-mentioned high-sensitivity satellite signal acquisition method. The computer-readable storage medium can be a magnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disk, or a compact disc read-only memory (CD-ROM).

[0109] In the several embodiments provided by the present invention, it should be understood that the disclosed methods and intelligent devices can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0110] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0111] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high-sensitivity satellite signal acquisition method, It is characterized in that include: S1: resample the satellite data after stripping the carrier for a preset time and then perform a fast Fourier transform, and multiply the result of the fast Fourier transform with the conjugate result of the local spread spectrum code after the fast Fourier transform; S2: Perform inverse fast Fourier transform on the multiplied data to obtain the result R 1 ; S3: delay the satellite data by 1ms and repeat the S1-S2 operation to obtain the result R 2 , delay the satellite data by 2ms and repeat the S1-S2 operation to get the result R 3 , and so on, delay the satellite data by Nms and repeat the S1-S2 operation to get the result R N+1 ; S4: Results R 1 To R N+1 Strip the NH code to get the result R 1 ' to R' N+1 ; Specifically include: performing a preset m NH code search, and converting N+1 results R 1 To R N+1 Multiply them by the corresponding NH code respectively to obtain the preset m groups of N+1 data; R i ′=R i ·NH(mod((i+ii),m)) Wherein, m represents the NH code period, i=1,2,…,N+1; NH() represents the phase symbol of the NH code, ii=0,1,2,…,m-1; S5: The result R 1 ′ and the result R 2 'Conjugate multiplication is performed to obtain the difference result DR 1 , the result R 2 ′ and the result R 3 'Conjugate multiplication is performed to obtain the difference result DR 2 , and so on, the result is R′ N and the result R′ N+1 Perform conjugate multiplication to obtain the difference result DR N ; S6: Differential result DR 1 To DR N The final differential coherent integration result SR is obtained by accumulation; S7: Obtain the differential coherent integration results corresponding to all Doppler values ​​within the specified range and calculate the maximum value, and compare the signal-to-noise ratio corresponding to the maximum value with a preset threshold value to determine whether the capture is successful.

2. The method according to claim 1, It is characterized in that The “re-sampling the satellite data after stripping the carrier for a preset time” also includes: Initializing capture parameters; the capture parameters include specifying satellite numbers, Doppler search ranges, and search steps; Generate a local spreading code of a designated satellite pseudo-random code, and perform fast Fourier transform on the local spreading code and then take the conjugate; Acquire satellite intermediate frequency data and intercept satellite intermediate frequency data of preset duration; Generate a local carrier according to the intermediate frequency and the specified current Doppler frequency; The satellite data after carrier stripping is obtained by multiplying the intercepted satellite intermediate frequency data with the in-phase and quadrature components of the local carrier.

3. The method according to claim 1, It is characterized in that The "obtaining the differential coherent integration results corresponding to all Doppler values ​​within the specified range and finding the maximum value, and comparing the signal-to-noise ratio corresponding to the maximum value with a preset threshold value to determine whether the capture is successful" specifically includes: Calculate the final differential coherent integration results corresponding to all specified Doppler values ​​respectively; The maximum value of the final differential coherent integration results corresponding to all Doppler values ​​is calculated, and the code phase and NH code phase corresponding to the maximum value are obtained; The signal-to-noise ratio corresponding to the maximum value is compared with a preset threshold value; when the signal-to-noise ratio is greater than or equal to the preset threshold value, the current satellite is captured successfully; when the signal-to-noise ratio is less than the preset threshold value, the current satellite is captured unsuccessfully.

4. The method according to claim 2, It is characterized in that The "generating a local carrier according to the intermediate frequency and the specified current Doppler frequency" uses the following formula: Where C represents the local carrier, f i is the intermediate frequency, f dop is the currently specified Doppler frequency, f s is the sampling frequency.

5. The method according to claim 1, It is characterized in that The preset duration is 2ms, the local spread spectrum code is 1ms, and the 2ms satellite data is slid and correlated with the 1ms local spread spectrum code. When the data millisecond boundary is aligned with the spread spectrum code boundary, the correlation result reaches a maximum value.

6. A highly sensitive satellite signal acquisition device, It is characterized in that include: Resampling module, first FFT module, second FFT module, multiplier, inverse FFT module, difference module, accumulation module; The resampling module is used to resample the satellite data after stripping the carrier; The first FFT module is used to perform fast Fourier transform on the resampled data to obtain a baseband spectrum signal; The second FFT module is used to perform fast Fourier transform on the local spread spectrum code to obtain a spread spectrum code spectrum signal; The multiplier is used to perform complex multiplication of the baseband spectrum signal and the spread spectrum code spectrum signal; The inverse FFT module is used to perform an inverse fast Fourier transform on the result output by the multiplier to obtain the despreading and demodulation of all code phases of the satellite signal corresponding to the specified Doppler frequency; The difference module is used to perform conjugate multiplication on the capture processing result of the satellite data and the capture processing result of the satellite data after a delay of 1 ms; The accumulation module is used to perform coherent accumulation on the differential results according to a preset differential coherence number.

7. The device according to claim 6, It is characterized in that Also includes: Local carrier generator and mixer; The local carrier generator is used to generate a local carrier according to the intermediate frequency and the specified current Doppler frequency; The mixer is used to perform carrier stripping on the satellite intermediate frequency data according to the local carrier generated by the local carrier generator.

8. A highly sensitive satellite signal acquisition device, It is characterized in that include: Memory and processor; The memory is used to store computer programs; The processor is used to execute the steps of the method according to any one of claims 1 to 5 when running the computer program.

9. A computer storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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