A method for acquiring high-sensitivity satellite navigation signals

Abstract

This invention provides a high-sensitivity satellite navigation signal acquisition method. It utilizes an improved acquisition algorithm based on FFT coefficient compensation and block code Doppler compensation to acquire satellite navigation signals, obtaining the acquisition result. This invention effectively reduces the impact of Doppler frequency offset during long coherent acquisition times through coefficient-compensated FFT operations and the block code Doppler compensation algorithm. When calculating the FFT spectrum, only the spectral lines at specified positions need to be calculated, effectively shortening the calculation time, improving acquisition efficiency, and achieving high-sensitivity acquisition of weak signals.

Description

Technical Field

[0001] This invention belongs to the field of satellite navigation signal acquisition technology, and particularly relates to a high-sensitivity satellite navigation signal acquisition method. Background Technology

[0002] Currently, Global Navigation Satellite System (GNSS) has been widely used in terrestrial scenarios and low Earth orbit (LEO). With the development of aerospace technology and further exploration of outer space, research institutions and scientists worldwide are striving to expand GNSS applications to medium and high Earth orbits, and even higher and farther lunar orbits. Compared to terrestrial or LEO applications, GNSS applications in medium and high Earth orbits and lunar orbits face more technical challenges. First, the signal energy at the receiver is weak, making it impossible for ordinary receivers to acquire and track the signal; improving acquisition performance requires longer acquisition data. Second, due to the high speed of the spacecraft and the high dynamic characteristics of the satellite, relative motion will produce a significant Doppler frequency shift, making the Doppler effect of the signal more pronounced.

[0003] Therefore, in order to improve the acquisition speed and acquisition sensitivity, existing technologies need to further optimize the acquisition scheme. The methods generally adopted include: (1) increasing the parallelism of the time domain and frequency domain to improve the acquisition speed; (2) extending the coherent integration time to improve the signal processing gain; (3) adding Doppler compensation method to the two-dimensional signal search to reduce the influence of residual Doppler frequency offset on the acquisition result; and (4) performing multi-channel joint acquisition for multi-channel composite signals to improve the acquisition sensitivity. However, the effectiveness of the above four methods still needs to be improved.

[0004] Therefore, those skilled in the art urgently need to propose a method to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a high-sensitivity satellite navigation acquisition method that combines FFT coefficient compensation and block code Doppler compensation, which can be used for high-sensitivity acquisition of signal modulation methods such as ACEBOC / AltBOC / SCBOC, such as B2a+B2b joint acquisition of BDS and E5a+E5b joint acquisition of Galileo system.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for acquiring high-sensitivity satellite navigation signals includes the following steps:

[0008] An improved acquisition algorithm is built based on FFT coefficient compensation and block code Doppler compensation;

[0009] The satellite navigation signal is captured using a capture engine based on the aforementioned capture algorithm, and the capture result is obtained.

[0010] Preferably, the acquisition engine based on the acquisition algorithm is used to acquire satellite navigation signals to obtain acquisition results, specifically including the following steps:

[0011] S1: Pre-configure local reproduction signal, use the local reproduction signal to perform short-time correlation on multiple down-converted navigation signals to obtain coherent integration results, and store them in multiple coherent integration arrays;

[0012] S2: Perform block code Doppler compensation on the coherent integration result based on the Doppler offset;

[0013] S3: Perform FFT operation on the result of step S2 to complete the FFT coefficient compensation and obtain the FFT operation result;

[0014] S4: The FFT operation result is moduloed and the maximum value is selected to determine the carrier Doppler and code phase corresponding to the peak value and the information is output.

[0015] Preferably, the pre-configured local reproduction signal includes:

[0016] Configure the carrier NCO and code NCO of the local reproducible signal according to the carrier frequency and code frequency captured and searched by the satellite navigation signal receiver, and complete the pre-configuration of the local reproducible signal.

[0017] Preferably, the local reproduced signal is used to perform short-time correlation on the navigation signals after multiple down-conversion processing to obtain coherent integration results, which are then stored in multiple coherent integration arrays, specifically including:

[0018] Short-time correlation accumulation is performed on the N correlator branches in the local reconstructed signal to achieve parallel search of N code phases. The coherent integration time is varied by configuring different numbers of short-time correlation segments, and the integration results are stored in an array to complete M segments of short-time correlation accumulation, forming an M*N coherent integration array.

[0019] The principle behind steps S2-S3 is as follows:

[0020] ;

[0021] in, This represents the M*N array storing the coherent integration results. The first element of the coherent integral array represents the first element of the coherent integral array. Lines, ranging from 0 to M-1, The first element of the coherent integral array represents the first element of the coherent integral array. The column ranges from 0 to N-1, where M is the number of segments in the short-time correlation. This represents the Doppler frequency difference between the satellite navigation signal and the locally generated signal. Let t = M * T represent the coherent integration time for each segment, and let t = M * T be the total integration time. Indicates the center frequency of the satellite navigation signal. With spreading code frequency The ratio, that is , represents the discrete Fourier transform after coefficient compensation of the coherent integral result; where This indicates that the code Doppler grouping compensation is performed, then rounded down to the nearest integer.

[0022] The FFT operation compensation coefficient is:

[0023]

[0024] in This represents the FFT compensation coefficient. This indicates the subcarrier frequency of the signal.

[0025] For multi-channel satellite navigation signals, in the scheme combining the FFT coefficient compensation and the block code Doppler compensation, the FFT calculation method for the upper sideband of the signal is as follows:

[0026]

[0027] The FFT calculation method for the lower sideband of the signal is as follows:

[0028] .

[0029] Preferably, when performing the FFT calculation, it is not necessary to calculate all spectral lines, but only a portion of the spectral lines, and the calculation range of the spectral lines is determined by the code Doppler compensation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The acquisition method provided by this invention, which combines FFT coefficient compensation and block code Doppler compensation, can eliminate the influence of spectral line shift in the signal acquisition result caused by the Doppler effect in the short-time correlation combined with coefficient compensation FFT acquisition algorithm, thereby realizing the joint acquisition of multiple composite modulation signals.

[0032] 2. The acquisition method provided by this invention, which combines FFT coefficient compensation and block code Doppler compensation, overcomes the influence of Doppler frequency offset during long coherent integration time through its code Doppler compensation algorithm, effectively achieving high-sensitivity acquisition.

[0033] 3. The acquisition method provided by this invention, which combines FFT coefficient compensation and group code Doppler compensation, can effectively shorten the calculation time, reduce the amount of calculation, and improve the acquisition efficiency by calculating FFT spectral lines based on code Doppler.

[0034] In summary, this invention can effectively reduce the impact of the Doppler effect on weak signal acquisition, and achieve high-sensitivity acquisition of weak signals. Attached Figure Description

[0035] Figure 1 This is a flowchart of a high-sensitivity capture scheme based on the capture algorithm developed in this invention.

[0036] Figure 2 A schematic diagram of the capture algorithm structure provided for an embodiment of the present invention.

[0037] Figure 3 is a schematic diagram of the peak code phase shift and frequency shift of the search results caused by Doppler frequency shift, according to an embodiment of the present invention.

[0038] Figures 4(a)-(c) are schematic diagrams of the results of directly performing two-dimensional search and capture of satellite navigation signals without using this scheme.

[0039] Figure 5 This is a schematic diagram showing the result of capturing satellite navigation signals using the high-sensitivity acquisition scheme based on Doppler compensation. Detailed Implementation

[0040] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] This invention proposes a high-sensitivity satellite navigation signal acquisition scheme that combines FFT coefficient compensation and block code Doppler compensation. This scheme effectively improves acquisition sensitivity by extending the coherent integration time, eliminates the Doppler frequency offset effect of the upper and lower sidebands of the BOC signal through FFT operation with coefficient compensation, and realizes joint acquisition of multiple signals. At the same time, code Doppler compensation is performed to effectively reduce the impact of peak offset and improve the signal detection probability. Furthermore, the FFT spectral line calculation range is selected according to the code Doppler to improve acquisition efficiency and achieve high-sensitivity acquisition of weak signals.

[0042] Example 1

[0043] This embodiment discloses a high-sensitivity satellite navigation signal acquisition method, including the following steps:

[0044] An improved acquisition algorithm is built based on FFT coefficient compensation and block code Doppler compensation;

[0045] A capture engine based on a capture algorithm is used to capture satellite navigation signals and obtain the capture results.

[0046] Specifically:

[0047] The acquisition engine, based on an acquisition algorithm, is used to acquire satellite navigation signals and obtain the acquisition results. The specific steps include:

[0048] S1: Pre-configure local reproduction signal, use the local reproduction signal to perform short-time correlation on multiple down-converted navigation signals to obtain coherent integration results, and store them in multiple coherent integration arrays;

[0049] S2: Perform block code Doppler compensation on the coherent integral results based on the Doppler offset;

[0050] S3: Perform FFT operation on the result of step S2 to complete FFT coefficient compensation and obtain the FFT operation result;

[0051] S4: The FFT operation results are moduloed and the maximum value is selected to determine the carrier Doppler and code phase corresponding to the peak value and output the information.

[0052] The pre-configured local reproduction signals specifically include:

[0053] Configure the carrier NCO and code NCO of the local reproducible signal based on the carrier frequency and code frequency captured and searched by the satellite navigation signal receiver, and complete the pre-configuration of the local reproducible signal.

[0054] Specifically, the coherent integration results are obtained by performing short-time correlation on multiple down-converted navigation signals using locally reproduced signals and storing them in multiple coherent integration arrays, including:

[0055] Short-time correlation accumulation is performed on the N correlator branches in the local reconstructed signal to achieve parallel search of N code phases. The coherent integration time is varied by configuring different numbers of short-time correlation segments, and the integration results are stored in an array to complete M segments of short-time correlation accumulation, forming an M*N coherent integration array.

[0056] Taking the Galileo E5 signal as an example, the signal adopts a four-channel constant envelope AltBOC modulation method. The center frequencies of the E5a and E5b signals are 1176.45 MHz and 1207.14 MHz, respectively, and they contain four signal components: E5a-I, E5a-Q, E5b-I, and E5b-Q. The received E5 signal can be represented as:

[0057]

[0058] For an E5 signal received by the receiver that contains Doppler frequencies, the Doppler frequencies include the code Doppler frequency, the subcarrier Doppler frequency, and the carrier Doppler frequency. When the relative velocity is v, the code Doppler frequency... Subcarrier Doppler carrier Doppler .

[0059] Substituting this into the expression for the E5 signal above, we get:

[0060]

[0061] If the carrier Doppler frequency of the locally configured signal is The corresponding subcarrier Doppler frequency is The Doppler frequency is downconverted to The signal is subjected to short-time correlation.

[0062] Using the E5b-Q signal above for short-time correlation, we can obtain:

[0063]

[0064] Using the lower-band E5a-Q signal for short-time correlation, we can obtain:

[0065]

[0066] Additionally, it should be noted that in short-time correlation acquisition algorithms, for signals with large frequency offsets, the acquisition peak will shift accordingly with the increase of time. Therefore, when using longer acquisition data, the influence of Doppler frequency offset needs to be considered, and a code Doppler compensation scheme needs to be added to eliminate the influence.

[0067] If the transmitted code is as fast as the local code (i.e., the received signal and the local signal are at the same frequency), the peak value of the acquisition result will appear in the 0th half-chip phase. When the transmitted code is faster than the local code (i.e., the received signal frequency is higher than the local signal frequency), after coherent integration, the peak value will not appear in the 0th half-chip phase, but will shift to the right. For example, after a certain time, the peak value may appear in the 1st half-chip, and then again in the 2nd half-chip. Therefore, in the code Doppler compensation algorithm, the shift position of the peak value is calculated based on code Doppler, the coherent integration matrix is ​​grouped, and the shifted sum is performed according to the group.

[0068] Frequency offset Chip offset from peak value The correspondence between them is as follows:

[0069]

[0070] The principle behind steps S2-S3, which perform block code Doppler compensation and FFT calculation in step S1, is as follows:

[0071] ;

[0072] in, This represents the M*N array storing the coherent integration results. The first element of the coherent integral array represents the first element of the coherent integral array. Lines, ranging from 0 to M-1, The first element of the coherent integral array represents the first element of the coherent integral array. The column ranges from 0 to N-1, where M is the number of segments in the short-time correlation. This represents the Doppler frequency difference between the satellite navigation signal and the locally generated signal. Let t = M * T represent the coherent integration time for each segment, and let t = M * T be the total integration time. Indicates the center frequency of the satellite navigation signal. With spreading code frequency The ratio, that is The above equation represents the discrete Fourier transform after coefficient compensation of the coherent integral result; where... This indicates that the code Doppler grouping compensation is performed and then rounded to the nearest integer.

[0073] The FFT operation compensation coefficient is:

[0074] ;

[0075] in Represents the FFT compensation coefficient. This indicates the subcarrier frequency of the signal.

[0076] For multi-channel satellite navigation signals, in the scheme of joint FFT coefficient compensation and block code Doppler compensation, the FFT calculation method for the upper sideband of the signal is as follows:

[0077] ;

[0078] The FFT calculation method for the lower sideband of the signal is as follows:

[0079] .

[0080] When performing FFT calculations, it is not necessary to calculate all spectral lines; only a portion of the spectral lines need to be calculated. The calculation range of the spectral lines is determined by code-Doppler compensation.

[0081] Spectral lines calculated by FFT With frequency The correspondence between them is as follows:

[0082] ;

[0083] Code Doppler frequency deviation chip offset The correspondence between them is as follows:

[0084] ;

[0085] Because the half-chip search precision is The correspondence between the frequency range and the half-chip offset range is shown in Table 1:

[0086] Table 1. Correspondence between frequency range and half-chip offset range

[0087] Frequency step range Half chip offset （- ， ） 0 （ ， ） 1 （ ， ） 2 ... ...

[0088] Taking the AltBOC signal as an example, the center frequency of the signal With spreading code frequency The ratio is Therefore, the half-chip search precision is Therefore, when the frequency offset is 1100Hz, assuming the coherent integration time is 1s, the peak offset is at most about 19 half-chips within the time interval t=MT=1s. Assuming the short-time correlation matrix has M=3000 rows and the short-time correlation time is (1 / 3)ms, the FFT calculation takes 4096 points, and the spectral frequency step is 3000 / 4096Hz.

[0089] The above configuration can cover a frequency range of ±1500Hz. During the search, frequency segment search is performed based on Table 1. When the half-chip offset is 0, the spectrum is calculated in the range of ±29Hz (58.25 / 2). When the half-chip offset is 1, the spectrum is calculated in the range of 29Hz to 87Hz, and so on. This way, it is not necessary to calculate all the spectrum lines, so as to reduce the amount of calculation.

[0090] The FFT result is moduloed and the maximum value is found to determine the carrier Doppler and code phase corresponding to the peak value and the information is output.

[0091] When performing FFT calculations, it is not necessary to calculate all spectral lines; only a portion of the spectral lines need to be calculated. The calculation range of the spectral lines is determined by code-Doppler compensation.

[0092] Example 2

[0093] Based on Example 1, Example 2 further discloses a capture engine constructed based on the capture algorithm built in Example 1;

[0094] Specifically:

[0095] In this embodiment, the acquisition scheme involves obtaining the acquisition integration result of the navigation signal receiver, compensating the coherent integration matrix based on the Doppler offset, and finally performing incoherent integration to obtain the two-dimensional acquisition result of the signal.

[0096] The capture engine includes: digital intermediate frequency signal down-conversion processing, local signal generation, coherent integration module, block code Doppler compensation module, coefficient-compensated FFT, incoherent accumulation module, and peak finding module. Specifically, the working process of the capture algorithm structure includes:

[0097] Step 1: First, configure the local signal's carrier NCO and code NCO according to the carrier frequency and code frequency acquired and searched by the satellite navigation signal receiver. Then, configure the satellite secondary code of the code generator according to the satellite number acquired and searched by the satellite navigation signal receiver. Start the process. Figure 2 The capture engine is shown.

[0098] Step 2: Obtain the coherent integral matrix using a short-time correlation algorithm. The coherent integration time and the number of segments are determined by the acquired signal information, and a two-dimensional search is performed multiple times segment by segment. In this example, the main code length of the signal is 10230 chips, the coherent integration time can be selected as 1 second, and the number of segments is 3000. Using a longer coherent integration time can effectively improve the acquisition sensitivity, but it also means a longer acquisition time.

[0099] Step 3: Use the block code Doppler compensation module to process the I-channel and Q-channel data after coherent integration to obtain the array after code Doppler compensation.

[0100] Figure 3(a) illustrates the principle of peak code phase shift in search results due to Doppler frequency shift provided in this embodiment. Specifically, in this experiment, the local code search chip interval is 0.5 code phases. For the short-time correlation algorithm, if the short-time correlation time is set to (1 / 3) ms, the theoretical frequency search range covers ±1500Hz.

[0101] Due to frequency offset Chip offset from peak value The correspondence between them is as follows:

[0102]

[0103] Therefore, when capturing 1 second of Galileo E5 signal data with a Doppler frequency offset of 1100Hz, the chip offset is:

[0104] 1100 / 116.5*1=9.44

[0105] That is, for a frequency offset of 1100Hz, a 1-second time deviation would result in a deviation of approximately 9.44 * 2 ≈ 19.5 chips. Therefore, code Doppler compensation needs to be considered when using longer acquisition data.

[0106] If the transmitted code and the local code have the same code frequency, and the receiver captures them at the beginning, they should always be captured on the 0th half-chip phase. Assuming the transmitted code is faster and the local code is slower, that is, when the received frequency is higher than the local frequency, the peak will shift after a certain period of time and appear on the 1st half-chip, and then appear on the 2nd half-chip.

[0107] Based on the above correspondence, the compensation groups are calculated, the 3000-row coherent integral matrix is ​​segmented, and then shifted by column, performing left shift and right shift of groups respectively to complete code Doppler compensation.

[0108] Step 4: Perform frequency-compensated FFT calculation using the capture engine. Figure 3(b) shows the schematic diagram of the peak frequency shift of the search results due to Doppler frequency shift provided in this embodiment.

[0109] Specifically, the Galileo signal employs a four-channel constant envelope AltBOC modulation scheme. The center frequencies of the E5a and E5b signals are 1176.45 MHz and 1207.14 MHz, respectively. When a Doppler offset exists, the modulation power spectrum includes subcarrier Dopplers, causing a shift in the main lobe and preventing joint acquisition. For the E5 signal received by the receiver containing Doppler frequencies, the Doppler frequencies include the code Doppler frequency, the subcarrier Doppler frequency, and the carrier Doppler frequency. When the relative velocity is v, the code Doppler frequency... Subcarrier Doppler carrier Doppler .

[0110] If the carrier Doppler frequency of the locally configured signal is The corresponding subcarrier Doppler frequency is The Doppler frequency is downconverted to The signal is subjected to short-time correlation.

[0111] Taking the E5a-Q signal as an example, when the Doppler offsets of the received signal and the locally configured signal are respectively and At that time, the carrier frequency of the signal is The code frequency is .

[0112] According to the principle of signal transformation, the complex domain representation of the carrier wave of a signal is: The complex domain representation of the generated signal is as follows: The complex field representation of the subcarrier is as follows The signal is then represented as Similarly, the E5b-Q signal can be represented in the complex field as follows: .

[0113] The table below shows the complex domain representation and frequency difference of the E5a-Q and E5b-Q signals and the local reproducible signal.

[0114] E5a-Q E5b-Q Received satellite navigation signals Local reproduction signal Frequency difference

[0115] In Figure 3(b), the frequency difference between the peaks is the capture peak frequency shift caused by the Doppler offset. Chip offset from peak value The correspondence between them is as follows:

[0116]

[0117] The principle of performing block code Doppler compensation and FFT calculation on a signal is as follows:

[0118]

[0119] The compensation coefficient for FFT operation is:

[0120]

[0121] In an embodiment of the present invention, for the Galileo E5 signal, ,

[0122] When frequency compensation is added to the FFT operation, the principle of the FFT operation scheme after combining block code Doppler compensation and coefficient compensation is as follows:

[0123]

[0124] The FFT calculation method for the upper sideband signal E5b-Q is as follows:

[0125]

[0126] The FFT calculation method for the sideband signal E5a-Q is as follows:

[0127]

[0128] Step 5: After transforming the coherent integral matrix to the frequency domain using FFT operation, the modulus is calculated to obtain the acquisition result after compensation processing;

[0129] Step 6: Compare and output the capture results. Here, the maximum value is selected as the capture result output. Make a judgment on the capture result and compare the peak value of the capture result with the threshold value. If it exceeds the threshold, the corresponding frequency and code phase are the final capture result and the capture is completed. If it does not exceed the threshold value, return to step 1 to continue the search.

[0130] In one specific embodiment of this application, navigation signal data was generated through simulation, and the acquisition scheme was experimentally verified. In this experiment, the data sampling rate was 151MHz, the spreading code rate was 10.23MHz, and for the short-time correlation algorithm, if the short-time correlation time was set to (1 / 3) ms (i.e., 1ms divided into 3 segments), the coherent integration time was 1s, the search interval was 0.5 chips, and finally, 4096-point FFT operation and 1 incoherent integration were performed to compare and analyze the acquisition results. The true Doppler frequency of the satellite navigation signal was 1100Hz, and the carrier-to-noise ratio of the entire E5 signal was 22dBHz. The test results are shown in Figure 4 and... Figure 5 As shown in Figure 4. Figure 4 is a schematic diagram illustrating the results of directly performing a two-dimensional search and capture of satellite navigation signals without using this method. Figure 5 Figure 4 shows the results of acquiring satellite navigation signals using a high-sensitivity acquisition scheme based on Doppler compensation. As can be seen in Figure 4, when the signal is weak, after 1 second of coherent integration and 1 second of incoherent integration, almost no obvious peak information can be seen without Doppler compensation. Due to the Doppler frequency offset, the peak is dispersed to different code phases, and it is not possible to capture the peak on a single code phase. Figure 5 After compensation, the signal peak can be clearly seen. The carrier Doppler corresponds to the 3551st spectral line. According to the calculation formula, the frequency offset is... The result matches the preset Doppler bias. Compared with the results shown in Figure 4, the peak values ​​are effectively accumulated.

[0131] In the embodiments of this application, since the half-chip search precision is When the frequency offset At 1100Hz, the chip offset is 1100 / 116.5*1=9.44, meaning that the deviation in 1 second is approximately 9.44*2≈19 half-chips. Since the correspondence between the frequency range and the half-chip offset range is shown in Table X, the search is performed by frequency segmentation based on Table X. When the half-chip offset is 0, the spectrum is calculated in the range of ±29Hz (58.25 / 2). When the half-chip offset is 1, the spectrum is calculated in the range of 29Hz to 87Hz, and so on.

[0132] In summary, this application provides a high-sensitivity satellite navigation signal acquisition scheme that combines FFT coefficient compensation and block code Doppler compensation. The scheme includes the following steps: generating a local intermediate frequency carrier, configuring a local reproducible signal, performing short-time correlation on the down-converted navigation signal using the local reproducible signal to obtain a coherent integration result and storing it in an array, then performing block code Doppler compensation and coefficient compensation FFT operations on the coherent integration result, calculating the modulus of the FFT result and selecting the maximum value, determining the carrier Doppler and code phase corresponding to the peak value, and outputting the information. The coefficient-compensated FFT operation and the code Doppler compensation algorithm effectively reduce the impact of Doppler frequency offset during long acquisition times, and the calculation of the FFT spectrum based on the code Doppler effectively shortens the calculation time, improves acquisition efficiency, and achieves high-sensitivity acquisition of weak signals.

[0133] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-sensitivity satellite navigation signal acquisition method, characterized in that, Includes the following steps: An improved acquisition algorithm is built based on FFT coefficient compensation and block code Doppler compensation; The satellite navigation signal is captured using a capture engine based on the aforementioned capture algorithm to obtain the capture result; The acquisition engine based on the acquisition algorithm is used to acquire satellite navigation signals and obtain the acquisition result. Specifically, the steps include: S1: Pre-configure local reproduction signal, use the local reproduction signal to perform short-time correlation on multiple down-converted navigation signals to obtain coherent integration results, and store them in multiple coherent integration arrays; S2: Perform block code Doppler compensation on the coherent integration result based on the Doppler offset; S3: Perform FFT operation on the result of step S2 to complete the FFT coefficient compensation and obtain the FFT operation result; S4: The FFT operation result is moduloed and the maximum value is selected to determine the carrier Doppler and code phase corresponding to the peak value and the information is output. The principle behind steps S2-S3 is as follows: in, This represents the M*N array storing the coherent integration results. The first element of the coherent integral array represents the first element of the coherent integral array. Lines, ranging from 0 to M-1, The first element of the coherent integral array represents the first element of the coherent integral array. The column ranges from 0 to N-1, where M is the number of segments in the short-time correlation. This represents the Doppler frequency difference between the satellite navigation signal and the locally generated signal. Let t = M * T represent the coherent integration time for each segment, and let t = M * T be the total integration time. Indicates the center frequency of the satellite navigation signal. With spreading code frequency The ratio, that is , represents the discrete Fourier transform after coefficient compensation of the coherent integral result; where This indicates that the block code is rounded to the nearest integer after Doppler compensation. The FFT operation compensation coefficient is: in This represents the compensation coefficient of the FFT operation. This indicates the subcarrier frequency of the signal; For multi-channel satellite navigation signals, in the scheme combining the FFT coefficient compensation and the block code Doppler compensation, the FFT calculation method for the upper sideband of the signal is as follows: The FFT calculation method for the lower sideband of the signal is as follows: ； When performing the FFT calculation, it is not necessary to calculate all spectral lines; only a portion of the spectral lines need to be calculated. The calculation range of the spectral lines is determined by the block code Doppler compensation.

2. The high-sensitivity satellite navigation signal acquisition method according to claim 1, characterized in that, Pre-configured local reproduction signals include: Configure the carrier NCO and code NCO of the local reproducible signal according to the carrier frequency and code frequency captured and searched by the satellite signal receiver, and complete the pre-configuration of the local reproducible signal.

3. The high-sensitivity satellite navigation signal acquisition method according to claim 2, characterized in that, The coherent integral result is obtained by performing short-time correlation on multiple down-converted navigation signals using the locally reproduced signal, and then stored in multiple coherent integral arrays, specifically including: Short-time correlation accumulation is performed on the N correlator branches in the locally reproduced signal to achieve parallel search of N code phases. The coherent integration time is varied by configuring different numbers of short-time correlation segments, and the integration results are stored in an array. This completes the accumulation of M short-time correlations, forming an M*N coherent integral array.

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