A Beidou weak signal capture method and system

Abstract

The present invention belongs to the field of satellite navigation technology, and discloses a Beidou weak signal capture method and system. First, the sampled data is stripped of carriers and code chips are merged, and then the overlapping folding method is used to realize the reuse of code-merged data, Doppler stripping and data folding, thereby reducing the consumption of hardware resources; and the data block is code-parallel coherent with the local pseudo code through FFT and IFFT to obtain the coherent values ​​of all code phases. Then, the coherent values ​​of different code phases are differentiated through the inter-code difference algorithm to avoid the influence of NH code jump and navigation data jump; then, the differential data is coherent after Doppler compensation to improve the signal-to-noise ratio of the signal, the data is incoherent, the capture sensitivity is improved, and finally, it is determined whether the satellite signal is captured through threshold judgment. The present invention finally captures Beidou D2 navigation data of ‑146dBm and D1 navigation data of ‑145dBm.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation technology, and in particular relates to a Beidou weak signal capture method and system. Background Art

[0002] At present, with the rapid development of satellite navigation systems, satellite navigation receivers are gradually applied to various fields, and navigation receivers used in the aerospace field are also developing rapidly. In the high-orbit environment, due to the obstruction of the earth, most of the main lobe signals cannot be received by the receiver, and the side lobe signal strength is extremely weak. In order for the receiver to complete the positioning solution requirements normally, it poses a great challenge to the capture sensitivity of the navigation receiver. At the same time, with the vigorous development of my country's aerospace industry, the development and design of a high-sensitivity navigation receiver can reduce the cost of spacecraft and satellite navigation. The development of Beidou navigation receivers suitable for high-orbit environments is also conducive to my country's rapid development in the aerospace field in the future and accelerates the pace of my country's deep space exploration.

[0003] Traditional Beidou navigation receivers use delayed differential and zero-padding block methods to capture Beidou satellite signals, such as the improved differential algorithm mentioned in Han Zhifeng's article "Beidou weak signal capture algorithm based on improved zero-padding / differential". Although this method can avoid the impact of NH code jumps on capture sensitivity, its delayed differential algorithm requires the storage of a large amount of data. At the same time, its zero-padding block algorithm doubles the number of FFT and IFFT points, consumes a lot of hardware resources, and the capture performance of the receiver is affected to a certain extent. For example, the article "Verification and Analysis of Long-term Performance of GEO Satellite GNSS Navigation in Orbit" mentioned that my country's current high-orbit navigation receiver has a capture sensitivity of only -139dBm for Beidou signals, which cannot meet the capture requirements of weak signals in many cases. At the same time, due to the defects of the existing Beidou capture algorithm structure, the capture sensitivity of Beidou D2 navigation messages is not enough. Therefore, it is necessary to design a navigation receiver with low resource consumption, high sensitivity, and compatible with the capture of D1 and D2 navigation messages.

[0004] Through the above analysis, the problems and defects of the prior art are as follows:

[0005] (1) Traditional Beidou navigation receivers use delayed differential and zero-padding methods to capture Beidou satellite signals, which consumes a lot of hardware resources;

[0006] (2) Traditional navigation receivers have insufficient capture sensitivity due to algorithm structure;

[0007] (3) Since the rate of D2 navigation messages is too fast, traditional navigation receivers cannot capture D2 navigation messages with high sensitivity. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a Beidou weak signal capture method and system.

[0009] The present invention is implemented in the following way: a Beidou weak signal capture method, wherein the Beidou weak signal capture method performs carrier stripping on sampled data, performs code chip merging on the sampled data, and then realizes the reuse of code-merged data, Doppler stripping and data folding by overlapping and folding method; performs differentiation on the coherence values ​​of different code phases by using an inter-code difference algorithm; performs coherence on the differential data after Doppler compensation; and finally determines whether to capture the satellite signal by using a threshold judgment, and transmits the captured information to a tracking module.

[0010] Further, the Beidou weak signal acquisition method specifically includes:

[0011] The residual carrier in the baseband data is stripped off to obtain zero intermediate frequency data, and the data is transmitted to the code combining module;

[0012] The digital down-converted data are accumulated and combined to obtain half-code data, and the half-code data are transmitted to the overlapping and folding module;

[0013] The chip data is stored and overlapped into 2 millisecond data blocks, then the Doppler in the data blocks is stripped and the data is folded into 1 millisecond data blocks, and finally the 1 millisecond data blocks are sent to the FFT module;

[0014] The satellite ranging code is generated locally and used for satellite acquisition with data coherence. The local pseudo code will be sent to the FFT module at the beginning of acquisition.

[0015] The local pseudo code and the overlapped 1 millisecond data block are Fourier transformed, the local pseudo code is Fourier transformed and the conjugate is stored, and the overlapped data block is Fourier transformed and sent to the complex multiplication module;

[0016] The FFT conjugate value of the local pseudo code is multiplied by the FFT value of the data to obtain a frequency domain coherent result, and the complex multiplication result is transmitted to the IFFT module;

[0017] The complex multiplication result is subjected to IFFT transformation. This module can convert the frequency domain coherence value into the time domain, obtain the time domain coherence value of different code phases, and transmit the coherence value to the inter-code difference module.

[0018] The coherence values ​​of different code phases are inter-code differentiated. The inter-code differential method can avoid the influence of NH code jump in D1 navigation message, too fast rate of D2 navigation message and navigation data jump on capture sensitivity, and the differential result is transmitted to Doppler compensation module.

[0019] Compensate for the code phase offset caused by the Doppler effect, and then transmit the data to the coherent module and the incoherent module;

[0020] The result obtained by the Doppler compensation module is processed N times coherently and then M times incoherently to obtain the final capture result, and the result is transmitted to the peak decision module;

[0021] The capture results are compared to obtain the maximum and average values, determine whether the peak-to-average ratio exceeds the capture threshold, and transmit the capture results to the tracking module.

[0022] Furthermore, the overlapping and folding module first overlaps two adjacent 1 millisecond data blocks into 2 millisecond data blocks in units of 1 millisecond data; in the process of forming the data blocks, except for the 1st millisecond data and the last 1 millisecond data, which are used once, each of the remaining 1 millisecond data blocks will be used twice; after the data blocks are formed, the Doppler frequency in the data blocks will be stripped off and folded in half to form 1 millisecond data blocks; after the module processes the data, it transmits the data to the FFT module.

[0023] Furthermore, the FFT module performs Fourier transform on the 1 millisecond data block and the local pseudo code respectively.

[0024] Furthermore, the inter-code difference module is to differentiate the data of two adjacent ones among the 4096 different coherent values, and to differentiate the first and last data to obtain 4096 difference results.

[0025] Another object of the present invention is to provide a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the Beidou weak signal acquisition method.

[0026] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the Beidou weak signal acquisition method.

[0027] Another object of the present invention is to provide an information data processing terminal, which is used to implement the Beidou weak signal capture method.

[0028] Another object of the present invention is to provide a Beidou weak signal capture system for implementing the Beidou weak signal capture method, the Beidou weak signal capture system comprising:

[0029] A digital down-conversion module is used to remove the residual carrier in the baseband data, obtain zero intermediate frequency data, and transmit the data to the code combining module;

[0030] A code combining module is used to accumulate and combine the data after digital down-conversion to obtain half-code data, and transmit the half-code data to the overlapping and folding module;

[0031] The overlap and fold module stores the chip data and overlaps them into 2 millisecond data blocks, then removes the Doppler in the data blocks and folds the data into 1 millisecond data blocks, and finally transmits the 1 millisecond data blocks to the FFT module;

[0032] The local pseudo code module generates satellite ranging codes locally for satellite acquisition in conjunction with data coherence. The local pseudo code is fed into the FFT module at the start of acquisition.

[0033] The FFT module is used to perform Fourier transform on the local pseudo code and the 1 millisecond data block after the overlap is folded. After the local pseudo code is Fourier transformed, the conjugate is taken for storage, and the overlapped data block is Fourier transformed and then sent to the complex multiplication module;

[0034] A complex multiplication module is used to complex-multiply the FFT conjugate value of the local pseudo code with the FFT value of the data to obtain a frequency domain coherent result, and transmit the complex multiplication result to the IFFT module;

[0035] The IFFT module is used to perform IFFT transformation on the complex multiplication result. The module can convert the frequency domain coherence value into the time domain, obtain the time domain coherence value of different code phases, and transmit the coherence value to the inter-code difference module;

[0036] The code difference module performs code difference on the coherent values ​​of different code phases. The code difference method can avoid the influence of NH code jump in D1 navigation message, too fast rate of D2 navigation message and navigation data jump on capture sensitivity, and transmit the difference result to Doppler compensation module;

[0037] Doppler compensation module, which compensates for the code phase offset caused by the Doppler effect, and then transmits the data to the coherent module and the incoherent module;

[0038] The coherent module and the incoherent module perform N coherent operations on the result obtained by the Doppler compensation module and then perform M incoherent operations to obtain the final capture result, and transmit the result to the peak decision module;

[0039] The peak decision module compares the capture results, obtains the maximum value and the average value, determines whether the peak-to-average ratio exceeds the capture threshold, and transmits the capture results to the tracking module.

[0040] Another object of the present invention is to provide a satellite navigation terminal, which is equipped with the weak signal capture system.

[0041] In combination with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solutions to be protected by the present invention from the following aspects:

[0042] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, closely combining the technical solutions to be protected by the present invention and the results and data in the research and development process, the technical problems solved by the technical solutions of the present invention are analyzed in detail and in depth, and some creative technical effects brought about after the problems are solved. The specific description is as follows: The overlapping folding module of the present invention can reduce the number of Fourier change points and save hardware resources. At the same time, the overlapping use of data can improve data utilization. After processing the data, the module transmits the data to the FFT module. The FFT module of the present invention coheres the data with the local code, and the number of FFT points and IFFT points can be reduced to 4096 points, saving a lot of resources; the inter-code difference module of the present invention can avoid the influence of NH code jumps and navigation data jumps on long-term coherent integration, thereby extending the coherent integration time and improving the capture sensitivity.

[0043] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows: The present invention adopts an inter-code differential algorithm to avoid the influence of NH code jumps and navigation data jumps on the coherent integration time, and improves the capture sensitivity of Beidou signals by increasing the coherent integration time. The overlapping and folding method is used to overlap and distribute data and fold coherence, which improves data utilization while reducing the FFT and IFFT lengths required for subsequent processing, saving a lot of resources for the navigation receiver and reducing the design cost of navigation reception. The inter-code differential algorithm adopted by the present invention avoids the problem of needing to store a large amount of data in traditional algorithms, and solves the problem that traditional high-sensitivity receivers cannot capture weak signals of D2 navigation data.

[0044] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0045] The technical solution of the present invention fills the technical gap in the industry at home and abroad: the present invention adopts an overlapping folding algorithm, which improves the utilization rate of data by overlapping and distributing data and coherently folding it, while reducing the length of data for subsequent processing, and reducing the number of FFT and IFFT points in the traditional algorithm to half of the original, saving a lot of resources. At the same time, the algorithm uses an inter-code difference algorithm to avoid the influence of NH code jumps and navigation data jumps on the coherent value symbol, and improves the capture sensitivity of the navigation receiver by extending the coherent integration time. In addition, since the inter-code difference algorithm is not affected by the jump of navigation data, for D2 navigation messages with too fast code rates, the algorithm can avoid the frequent jumps of navigation data, achieve high-sensitivity capture, and solve the capture defect of D2 navigation messages by traditional navigation receivers. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1It is a flow chart of a Beidou weak signal acquisition method provided by an embodiment of the present invention;

[0047] Figure 2 It is a structural diagram of a Beidou weak signal acquisition system provided by an embodiment of the present invention;

[0048] Figure 3 It is a block diagram of an overlapping and folding structure provided by an embodiment of the present invention;

[0049] Figure 4 is a schematic diagram of overlapping and folding data affected by NH code provided by an embodiment of the present invention;

[0050] Figure 5 This is a capture result diagram of the D2 navigation message broadcast by satellite No. 3 at a signal strength of -145dBm provided by an embodiment of the present invention;

[0051] Figure 6 This is a diagram of the capture result of the D1 navigation message broadcast by satellite No. 24 at a signal strength of -146dBm provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] 1. Explanatory Examples In order to enable those skilled in the art to fully understand how to implement the present invention, this section provides an illustrative example that expands and describes the technical solution of the claims.

[0054] like Figure 1 As shown, the weak signal capture method provided by the embodiment of the present invention includes the following steps:

[0055] S101: Carrier stripping is performed on the sampled data, and chip merging is performed on the sampled data, and then the code-merged data is reused, Doppler stripping is performed, and data folding is performed by an overlapping folding method;

[0056] S102: Differentiating the coherence values ​​of different code phases by using an inter-code differential algorithm;

[0057] S103: performing coherence on the differential data after Doppler compensation;

[0058] S104: Finally, a threshold decision is made to determine whether the satellite signal is captured, and the captured information is transmitted to the tracking module.

[0059] like Figure 2As shown, the Beidou signal acquisition system provided by the embodiment of the present invention includes a digital down-conversion module, a code merging module, an overlapping folding module, a local pseudo code module, an FFT (Fourier transform) module, a complex multiplication module, an IFFT (inverse Fourier transform) module, an inter-code difference module, a Doppler compensation module, a coherent module and an incoherent module, and a peak decision module. The digital down-conversion module is used to mix the baseband data and the local carrier signal to obtain zero intermediate frequency data. The code merging module merges the zero intermediate frequency signal into half-code data with a code rate of 4.096MHz. The overlapping folding module combines the code chip data into a 2 millisecond overlapping data block, and folds it after the Doppler in the data block is stripped. The 2 millisecond overlapping data block is formed by overlapping and splicing 1 millisecond data. During the capture process, only the 1st millisecond data and the last 1 millisecond data block are used once, and the remaining 1 millisecond data blocks will be used twice during the splicing process of the data blocks. This ensures that the data has a high utilization rate and also shortens the capture time. The Doppler stripping in the overlapped folding module is to mix the 2 millisecond overlapped data block with the local Doppler frequency to obtain zero Doppler data. The 2 millisecond zero Doppler data block is folded in half to obtain a 1 millisecond data block, which reduces the number of FFT points and IFFT points to 4096 in subsequent processing, greatly reducing the usage of hardware resources. The local pseudo code module obtains the pseudo code data of the currently captured satellite by storing and reading the satellite ranging code, and the local pseudo code will be sent to the FFT module. The FFT module mainly processes the local pseudo code and the 1 millisecond data block after the overlap and folding. The local pseudo code will be conjugated and stored after FFT. The 1 millisecond data block is directly sent to the complex multiplication module after FFT. The complex multiplication module multiplies the stored local pseudo code FFT conjugate value and the FFT value of the data to obtain the parallel coherence value of the frequency domain code. The IFFT module converts the data obtained by the complex multiplication module to the time domain and transmits the data to the inter-code difference module. The inter-code difference module performs inter-code difference on the code parallel coherence value to avoid the influence of NH (Neumann-Hoffman) code and navigation data jump. At the same time, since the data source of the inter-code difference comes from the real-time output data of the IFFT module, there is no need to store the data, which saves a lot of storage space compared with the traditional delay difference algorithm. The Doppler compensation module performs code phase offset compensation on the data obtained by the inter-code difference module according to the Doppler frequency, so that the code phase of each data block in the capture process is completely aligned. The coherent module and the incoherent module perform N times of coherence on the Doppler compensated data to improve the signal-to-noise ratio of the signal, and then perform M times of incoherence on it to improve the capture sensitivity. The peak decision module determines the optimal code phase based on the coherence value of each phase, and determines the optimal Doppler frequency based on the maximum value of each group of Dopplers. Then, it determines whether the satellite signal is captured based on the peak-to-average ratio, and finally transmits the captured result to the tracking module.

[0060] like Figure 3As shown, the present invention adopts an overlapping and folding method to obtain a 1 millisecond data block. This method greatly reduces the number of FFT and IFFT points required for subsequent processing while improving data utilization, saving more hardware resources. This method first overlaps two adjacent 1 millisecond data blocks to form a 2 millisecond data block, then performs Doppler stripping on it, and folds the processing result in half to form a 1 millisecond data block.

[0061] like Figure 4 As shown, when 21 milliseconds of data are used to form 20 overlapping data blocks, the worst case of signal-to-noise ratio improvement is the middle position of the 1 millisecond data block where the jump position appears.

[0062] 2. Application Examples: In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the technical solution of the claims on specific products or related technologies.

[0063] The present invention realizes Beidou weak signal capture by using a programmable logic gate array (FPGA) with a DSP. First, the navigation receiver receives the Beidou B1 frequency signal through an antenna, amplifies the signal through a preamplifier, and transmits the signal to a radio frequency board. In the radio frequency board, the signal is first amplified in one stage, and clutter is filtered out by a filter. At this time, the signal is down-converted in two stages by a mixer to obtain an intermediate frequency signal.

[0064] Then, the intermediate frequency analog signal is converted into a digital signal through the analog-to-digital conversion chip, and the digital signal is transmitted to the intermediate frequency board. The core processors on the intermediate frequency board are FPGA and DSP. At this time, the FPGA waits for the DSP to trigger the capture start signal and receive the satellite number to be captured. When the capture starts, the digital intermediate frequency signal is first down-converted to zero frequency through the local carrier. The signal is code-merged to obtain half-code data. At this time, the overlapping folding module stores the data and allocates it as a 2-millisecond data block in units of 1 millisecond data. After removing the Doppler of the 2-millisecond data block, the data is folded to obtain a 1-millisecond data block. This operation method can not only ensure that the data block can coherently produce a peak, but also reduce the amount of data. When a 1-millisecond data block is obtained, it is conjugated with the FFT value of the local pseudo code after FFT transformation and then multiplied to achieve frequency domain multiplication. The multiplication result is converted to the time domain through IFFT to obtain the code parallel coherence value. The data points of frequency domain multiplication are reduced to 4096 points based on the traditional navigation receiver, which greatly saves hardware resources. After the code parallel coherent value is obtained, the code difference algorithm is used to avoid the influence of NH code jump and navigation data jump on the coherent value symbol, and the data is Doppler compensated to correct the code phase offset caused by Doppler. Subsequently, the data is coherent and incoherent to improve the capture sensitivity of the satellite signal. Since the code difference algorithm avoids the influence of navigation data jump, the present invention can simultaneously capture D1 and D2 navigation messages with high sensitivity.

[0065] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0066] 3. Evidence of the effects of the embodiments. The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with the data, charts, etc. of the test process.

[0067] The satellite data acquisition card is used to collect satellite signals and conduct simulation verification. The No. 3 satellite (broadcasting D2 navigation message) is captured at a signal strength of -145dBm. The capture results are as follows: Figure 5 As shown;

[0068] according to Figure 5 It can be seen that under the weak signal condition of -145dBm, the present invention can accurately capture the satellite signal.

[0069] At the same time, the No. 24 satellite (broadcasting D1 navigation message) was captured at a signal strength of -146dBm. The capture results are as follows: Figure 6 As shown;

[0070] according to Figure 6 It can be seen that even if the signal strength is reduced to -146dbm, the present invention can still capture the satellite signal, and the Doppler frequency and code phase in the captured signal can be clearly distinguished.

[0071] Comprehensive simulation results show that the present invention has a high capture sensitivity for the D1 and D2 navigation messages of the Beidou signal, and solves the problems existing in traditional navigation receivers with extremely low resource consumption.

[0072] like Figure 4As shown, the 1st, 2nd, 3rd and 17th data blocks can achieve an improvement in signal-to-noise ratio after being folded in half, and half of the data can still achieve an improvement in signal-to-noise ratio after being folded in half for the 4th, 6th, 7th, 8th, 9th, 14th, 15th, 16th and 18th data blocks. This allocation method ensures that the data block can obtain a coherent value by being coherent with the local pseudo code.

[0073] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A Beidou weak signal acquisition method, characterized in that: The Beidou weak signal acquisition method performs carrier stripping on the sampled data and performs chip merging on the sampled data, and then implements code merging data reuse, Doppler stripping and data folding by overlapping and folding method; The coherence values ​​of different code phases are differentiated through the inter-code difference algorithm; the differential data is coherent after Doppler compensation; finally, the threshold judgment is used to determine whether the satellite signal is captured, and the captured information is transmitted to the tracking module; The Beidou weak signal acquisition method specifically includes: The residual carrier in the baseband data is stripped off to obtain zero intermediate frequency data, and the data is transmitted to the code combining module; The digital down-converted data are accumulated and combined to obtain half-code data, and the half-code data are transmitted to the overlapping and folding module; The chip data is stored and overlapped into 2 millisecond data blocks, then the Doppler in the data blocks is stripped and the data is folded into 1 millisecond data blocks, and finally the 1 millisecond data blocks are sent to the FFT module; Generate satellite ranging codes locally to achieve satellite acquisition with data coherence. Local pseudo codes will be sent to the FFT module at the beginning of acquisition. The local pseudo code and the overlapped 1 millisecond data block are Fourier transformed, the local pseudo code is Fourier transformed and the conjugate is stored, and the overlapped data block is Fourier transformed and sent to the complex multiplication module; The FFT conjugate value of the local pseudo code is multiplied by the FFT value of the data to obtain a frequency domain coherent result, and the complex multiplication result is transmitted to the IFFT module; The complex multiplication result is subjected to IFFT transformation. This module can convert the frequency domain coherence value into the time domain, obtain the time domain coherence value of different code phases, and transmit the coherence value to the inter-code difference module; The coherence values ​​of different code phases are inter-code differentiated to avoid the influence of NH code jump in D1 navigation message, too fast rate of D2 navigation message and navigation data jump on capture sensitivity, and the differential result is transmitted to Doppler compensation module; Compensate for the code phase offset caused by the Doppler effect, and then transmit the data to the coherent module and the incoherent module; The result obtained by the Doppler compensation module is processed N times coherently and then M times incoherently to obtain the final capture result, and the result is transmitted to the peak decision module; Compare the capture results to obtain the maximum value and the average value, determine whether the peak-to-average ratio exceeds the capture threshold, and transmit the capture results to the tracking module; The inter-code difference module is used to differentiate the adjacent data in pairs among the 4096 different coherent values, and to differentiate the first and last data to obtain 4096 differential results.

2. The Beidou weak signal acquisition method according to claim 1, characterized in that: The overlapping and folding module first overlaps two adjacent 1 millisecond data blocks into 2 millisecond data blocks in units of 1 millisecond data; in the process of forming the data blocks, except that the 1st millisecond data and the last 1 millisecond data are used once, each of the remaining 1 millisecond data blocks will be used twice; after the data blocks are formed, the Doppler frequency in the data blocks will be stripped and folded in half to form 1 millisecond data blocks; after the module processes the data, it transmits the data to the FFT module.

3. The Beidou weak signal acquisition method as claimed in claim 1, characterized in that: The FFT module performs Fourier transform on the 1 millisecond data block and the local pseudo code respectively.

4. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the Beidou weak signal acquisition method according to any one of claims 1 to 3.

5. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the Beidou weak signal acquisition method according to any one of claims 1 to 3.

6. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the Beidou weak signal capture method described in any one of claims 1 to 3.

7. A Beidou weak signal acquisition system implementing the Beidou weak signal acquisition method according to any one of claims 1 to 3, characterized in that: The Beidou weak signal acquisition system comprises: A digital down-conversion module is used to remove the residual carrier in the baseband data, obtain zero intermediate frequency data, and transmit the data to the code combining module; A code combining module is used to accumulate and combine the data after digital down-conversion to obtain half-code data, and transmit the half-code data to the overlapping and folding module; The overlap and fold module stores the chip data and overlaps them into 2 millisecond data blocks, then removes the Doppler in the data blocks and folds the data into 1 millisecond data blocks, and finally transmits the 1 millisecond data blocks to the FFT module; The local pseudo code module generates satellite ranging codes locally for satellite acquisition in conjunction with data. The local pseudo code is fed into the FFT module at the start of acquisition. The FFT module is used to perform Fourier transform on the local pseudo code and the 1 millisecond data block after the overlap is folded. After the local pseudo code is Fourier transformed, the conjugate is taken for storage, and the overlapped data block is Fourier transformed and then sent to the complex multiplication module; A complex multiplication module is used to complex-multiply the FFT conjugate value of the local pseudo code with the FFT value of the data to obtain a frequency domain coherent result, and transmit the complex multiplication result to the IFFT module; The IFFT module is used to perform IFFT transformation on the complex multiplication result. The module can convert the frequency domain coherence value into the time domain, obtain the time domain coherence value of different code phases, and transmit the coherence value to the inter-code difference module; The code difference module performs code difference on the coherence values ​​of different code phases. The code difference method avoids the influence of NH code jump in D1 navigation message, too fast rate of D2 navigation message and navigation data jump on capture sensitivity, and transmits the difference result to Doppler compensation module; Doppler compensation module, which compensates for the code phase offset caused by the Doppler effect, and then transmits the data to the coherent module and the incoherent module; The coherent module and the incoherent module perform N coherent operations on the result obtained by the Doppler compensation module and then perform M incoherent operations to obtain the final capture result, and transmit the result to the peak decision module; The peak decision module compares the capture results, obtains the maximum value and the average value, determines whether the peak-to-average ratio exceeds the capture threshold, and transmits the capture results to the tracking module.

8. A satellite navigation terminal, characterized in that: The satellite navigation terminal is equipped with the Beidou weak signal acquisition system described in claim 7.

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