A capture implementation method and system that take into account both capture speed and capture sensitivity

Abstract

The present invention discloses a capture implementation method and system that take into account both capture speed and capture sensitivity. The method includes: in the integration mode, using a single-channel capture method to capture satellite data of multiple satellites, and processing the satellite data to obtain the operation result of the satellite data in the integration mode; performing a single decision on the operation result of the satellite data in the integration mode, and if the decision is successful, determining that the satellite navigation signal capture in the integration mode is successful; after the satellite navigation signal capture in the integration mode is successful, in the sub-channel capture mode, using multi-channel parallel to capture satellite data of multiple satellites, and processing the data to obtain the operation result of the satellite data in the sub-channel mode; performing multiple decisions on the operation result of the satellite data in the sub-channel mode, and if the multiple decisions are successful, determining that the satellite navigation signal capture in the sub-channel mode is successful. The present invention can take into account the capture speed while ensuring the capture sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite navigation signal processing, and particularly to a capture implementation method and system that take into account both capture speed and capture sensitivity. Background Art

[0002] The Beidou satellite navigation system is a global satellite positioning and communication system independently developed by China, and is the third mature satellite navigation system after GPS (Global Positioning System) and GLONASS (Global Navigation Satellite System). In order to effectively utilize this strategic resource of the satellite navigation system, extensive research has been carried out in the field of satellite receivers and great achievements have been made. Especially in the development of civilian application products, the technologies of medium- and low-dynamic receivers have been quite mature and are widely used in fields such as geodetic surveying, vehicle navigation and positioning, ship navigation, and aircraft approach. However, the research on high-dynamic and high-sensitivity satellite receivers commonly used in the aerospace field is still in its infancy.

[0003] Spacecraft operate at relatively high speeds and accelerations during both the launch and operation phases. After superimposing the speeds and accelerations of the navigation satellites themselves, the high-speed moving receivers face extremely high dynamic conditions. The navigation signals under high dynamic conditions bring some difficulties to signal processing and increase the complexity of baseband signal processing. At this time, it is necessary to quickly achieve the capture of navigation signals to avoid Doppler deviation caused by long-term capture. In addition, in many space applications, the reception quality of navigation signals is relatively poor, such as hostile or non-hostile radio interference signals, weak signals received in high-orbit and GNSS-R applications, etc. If the receiver does not perform weak signal processing, the receiver will face the situation of no available signal reception and then lose its function. Therefore, the signal processing of space GNSS receivers must also consider the problems brought by this application scenario. Summary of the Invention

[0004] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, and providing a capture implementation method and system that take into account both capture speed and capture sensitivity.

[0005] The technical solution of the present invention is:

[0006] In a first aspect, an embodiment of the present invention provides a capture implementation method that takes into account both capture speed and capture sensitivity, including:

[0007] In the integration mode, a single-channel capture method is used to capture satellite data of multiple satellites, and the satellite data is processed to obtain the satellite data operation result in the integration mode;

[0008] Perform a single decision on the satellite data operation result in the integration mode. In the case of a successful decision, it is determined that the satellite navigation signal acquisition in the integration mode is successful;

[0009] After the satellite navigation signal acquisition in the integration mode is successful, in the sub-channel acquisition mode, use multi-channel parallel acquisition to acquire satellite data of multiple satellites, and process the data to obtain the satellite data operation result in the sub-channel mode;

[0010] Perform multiple decisions on the satellite data operation result in the sub-channel mode. In the case of multiple successful decisions, it is determined that the satellite navigation signal acquisition in the sub-channel mode is successful.

[0011] Optionally, the step of using single-channel acquisition to acquire satellite data of multiple satellites and processing the satellite data to obtain the satellite data operation result in the integration mode includes:

[0012] Process the local carrier NCO (Numerically Controlled Oscillator) according to the local intermediate frequency carrier frequency and local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0013] Perform mixing processing on the acquired satellite data to generate two-way mixed-frequency data, where the two-way mixed-frequency data includes: in-phase (I) mixed-frequency data and quadrature (Q) mixed-frequency data;

[0014] Under the action of the half-chip pulse signal, perform half-chip accumulation downsampling extraction processing on the two-way mixed-frequency data, and perform truncation processing on the half-chip accumulation amount to generate downsampling truncated data;

[0015] Perform superposition and caching processing on the downsampling truncated data, and store it in the downsampling data memory bank;

[0016] Read the mixed-frequency downsampling data in the downsampling data memory bank, and perform secondary mixing processing on the read mixed-frequency downsampling data to obtain secondary mixed-frequency data, and use the secondary mixed-frequency data as the satellite data operation result.

[0017] Optionally, the step of using multi-channel parallel acquisition to acquire satellite data of multiple satellites and processing the data to obtain the satellite data operation result in the sub-channel mode includes:

[0018] Process the local carrier NCO according to the local intermediate frequency carrier frequency and local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0019] Mix the collected satellite data to generate two channels of mixed data, where the two channels of mixed data include: in-phase (I) channel mixed data and quadrature (Q) channel mixed data;

[0020] Under the action of the half-chip pulse signal, perform half-chip accumulation downsampling extraction processing on the two channels of mixed data, and truncate the half-chip accumulation amount to generate downsampled and truncated data;

[0021] Perform superposition and caching processing on the downsampled and truncated data, and store it in the downsampled data memory bank;

[0022] Read the mixed and downsampled data in the downsampled data memory bank, and perform 4096-point radix-8 FFT operation and related processing on the read mixed and downsampled data to obtain the IFFT calculation result;

[0023] Perform non-coherent accumulation processing on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

[0024] Optionally, perform multiple judgments on the satellite data operation result in the sub-channel mode. When multiple judgments are successful, it is determined that the satellite navigation signal capture in the sub-channel mode is successful, including:

[0025] Perform statistical averaging operation on the values with different phases in the non-coherent accumulation result to obtain the power average value;

[0026] According to the power average value and a pre-configured threshold, obtain the peak detection threshold value;

[0027] Compare the peak detection threshold value with a pre-set maximum value to obtain a judgment result;

[0028] Perform multiple operations and judgment processing on the multiple satellite data captured in the multi-channel capture to obtain multiple judgment results;

[0029] When at least N judgment results in the multiple judgment results indicate successful judgment, it is determined that the satellite navigation signal capture in the sub-channel mode is successful.

[0030] In a second aspect, an embodiment of the present invention provides a capture implementation system that takes into account capture speed and capture sensitivity, including:

[0031] An integrated mode operation result acquisition module, configured to capture satellite data of multiple satellites in a single-channel capture mode in the integrated mode, and process the satellite data to obtain the satellite data operation result in the integrated mode;

[0032] An integration mode capture success determination module is used to perform a single decision on the satellite data operation result in the integration mode. When the decision is successful, it is determined that the satellite navigation signal capture in the integration mode is successful;

[0033] A sub-channel mode operation result acquisition module is used to, after the satellite navigation signal capture in the integration mode is successful, in the sub-channel capture mode, capture satellite data of multiple satellites in parallel through multiple channels and process the data to obtain the satellite data operation result in the sub-channel mode;

[0034] A sub-channel mode capture success determination module is used to perform multiple decisions on the satellite data operation result in the sub-channel mode. When the multiple decisions are successful, it is determined that the satellite navigation signal capture in the sub-channel mode is successful.

[0035] Optionally, the integration mode operation result acquisition module includes:

[0036] A carrier quantization result generation unit is used to process a local carrier NCO (Numerically Controlled Oscillator) according to a local intermediate frequency carrier frequency and a local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0037] A two-channel mixing data generation unit is used to perform mixing processing on the collected satellite data to generate two-channel mixing data, where the two-channel mixing data includes: I-channel mixing data and Q-channel mixing data;

[0038] A downsampling truncated data generation unit is used to perform half-chip accumulation downsampling extraction processing on the two-channel mixing data under the action of the half-chip pulse signal and perform truncation processing on the half-chip accumulation amount to generate downsampling truncated data;

[0039] A downsampling truncated data storage unit is used to perform superposition and caching processing on the downsampling truncated data and store it in a downsampling number memory bank;

[0040] An integration mode operation result acquisition unit is used to read the mixed frequency downsampling data in the downsampling number memory bank, perform secondary mixing processing on the read mixed frequency downsampling data to obtain secondary mixing data, and use the secondary mixing data as the satellite data operation result.

[0041] Optionally, the sub-channel mode operation result acquisition module includes:

[0042] A half-chip pulse signal generation unit is used to process a local carrier NCO according to a local intermediate frequency carrier frequency and a local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0043] A mixing data generation unit is configured to perform mixing processing on the collected satellite data to generate two paths of mixed data, where the two paths of mixed data include: in-phase (I) mixed data and quadrature (Q) mixed data;

[0044] A decimation data generation unit is configured to perform half-chip accumulation decimation extraction processing on the two paths of mixed data under the action of the half-chip pulse signal, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data;

[0045] A decimation data storage unit is configured to perform superposition and caching processing on the decimated and truncated data, and store it in a decimation data memory bank;

[0046] An IFFT calculation result acquisition unit is configured to read the mixed and decimated data in the decimation data memory bank, and perform 4096-point radix-8 FFT operation and related processing on the read mixed and decimated data to obtain an IFFT calculation result;

[0047] A sub-channel mode operation result acquisition unit is configured to perform non-coherent accumulation processing on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

[0048] Optionally, the sub-channel mode acquisition success determination module includes:

[0049] A power average value acquisition unit is configured to perform statistical average operation on the values of different phases in the non-coherent accumulation result to obtain a power average value;

[0050] A detection threshold value acquisition unit is configured to obtain a peak detection threshold value according to the power average value and a pre-configured threshold;

[0051] A decision result acquisition unit is configured to compare the peak detection threshold value with a pre-set maximum value to obtain a decision result;

[0052] Multiple decision result acquisition units are configured to perform multiple operations and decision processing on the multiple satellite data captured in the multi-channel to obtain multiple decision results;

[0053] A sub-channel mode acquisition success determination unit is configured to determine that the satellite navigation signal acquisition in the sub-channel mode is successful when at least N decision results in the multiple decision results indicate acquisition success.

[0054] The advantages of the present invention compared with the prior art are as follows:

[0055] The embodiments of the present invention provide two capture modes, namely the Merge mode applicable to the super-fast capture of satellites with normal sensitivity and the Split mode applicable to weak signal scenarios. The two modes share hardware resources, taking into account both the capture speed and capture sensitivity benefits, and can achieve low-power and high-performance capture processing of satellite navigation signals under limited resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flowchart of steps of a capture implementation method that takes into account both capture speed and capture sensitivity provided by the embodiments of the present invention;

[0057] Figure 2 It is a schematic diagram of a capture process provided by the embodiments of the present invention;

[0058] Figure 3 It is a schematic diagram of the secondary mixing Doppler coverage in the Merge mode provided by the embodiments of the present invention;

[0059] Figure 4 It is a schematic diagram of the logic structure of the secondary mixing module in the Merge mode provided by the embodiments of the present invention;

[0060] Figure 5 It is a schematic diagram of the structure of a capture implementation system that takes into account both capture speed and capture sensitivity provided by the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] In the embodiments of the present invention, two capture modes are adopted, namely the integration mode (Merge mode) and the split-channel mode (Split mode). In the Merge mode, the entire capture module is regarded as a capture channel, which is mainly used for cold start to provide super-fast capture of satellites with normal sensitivity, aiming to improve the capture speed as much as possible. In the Split mode, the hardware can be split into up to 16 parallel capture channels, which is applicable to both cold start and hot start. The Split mode captures and processes data in real time and can perform multiple non-coherent accumulations, aiming to improve the capture sensitivity as much as possible. The Merge mode is applicable to fast capture with normal sensitivity, and the Split mode is applicable to capture of weak navigation signals. The two capture modes share capture resources, taking into account both the benefits of fast capture and high capture sensitivity.

[0062] Next, the technical solutions of the embodiments of the present invention will be described in detail in combination with specific embodiments.

[0063] Embodiment 1

[0064] Referring to Figure 1 , it shows a flowchart of steps of a capture implementation method that takes into account both capture speed and capture sensitivity provided by the embodiments of the present invention, as shown in Figure 1As shown, the method may include the following steps:

[0065] Step 101: In the integration mode, capture satellite data of multiple satellites using a single-channel capture method, and process the satellite data to obtain the operation result of the satellite data in the integration mode.

[0066] In an embodiment of the present invention, first, the satellite navigation signal may be captured once in the Merge mode. In the Merge mode, the satellite data of multiple satellites may be captured using a single-channel capture method, and the satellite data may be processed to obtain the data operation result of the satellite navigation signal in the Merge mode. Specifically, it may be described in detail in combination with the following specific implementation manners.

[0067] In a specific implementation manner of the present invention, the above step 101 may include:

[0068] Sub-step A1: Process the local carrier NCO (Numerically Controlled Oscillator) according to the local intermediate-frequency carrier frequency and the local code frequency respectively to generate the local carrier quantization result and the half-chip pulse signal.

[0069] In this embodiment, it may be combined with Figure 2 The technical solution of this embodiment will be described in detail as follows.

[0070] Referring to Figure 2 , a schematic diagram of a capture process provided by an embodiment of the present invention is shown. As Figure 2 shown, the capture system provided in this example may include a local carrier and half-chip pulse generation module, and this module may be used to perform the following operations:

[0071] The local carrier NCO may be processed according to the local intermediate-frequency carrier frequency and the local code frequency respectively to generate the local carrier quantization result and the half-chip pulse signal.

[0072] Specifically, according to the local intermediate-frequency carrier frequency local_if, the local carrier NCO may be accumulated to obtain the carrier NCO accumulated value sum_carr. The sin and cos quantization results of the local carrier may be obtained by looking up the table for the carrier NCO accumulated value sum_carr.

[0073] The local code NCO may be accumulated according to the local code frequency local_codefreq, and the half-chip pulse signal may be obtained according to the "positive" and "negative" of the local code NCO. Among them, the local code frequency local_codefreq is obtained by carrier-assisted code frequency compensation based on the reference code frequency.

[0074] In Merge mode, since only one intermediate frequency mixing is performed, the intermediate frequency carrier frequency local_if here is actually the reference carrier intermediate frequency, and the local code frequency local_codefreq corresponds to the reference code frequency. That is to say, during the entire frequency search process of acquisition, the code Doppler compensation actually does not play a role.

[0075] Sub-step A2: Mix the collected satellite data to generate two mixed data, where the two mixed data include: I-channel mixed data and Q-channel mixed data.

[0076] As Figure 2 shown, the acquisition system may further include: a mixing module, which can mix the collected satellite data to obtain two mixed data, and the two mixed data are the I-channel mixed data and the Q-channel mixed data.

[0077] Sub-step A3: Under the action of the half-chip pulse signal, perform half-chip accumulation decimation extraction processing on the two mixed data, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data.

[0078] As Figure 2 shown, the acquisition system may further include: a decimation and truncation module, which can perform half-chip accumulation decimation extraction processing on the two mixed data after mixing under the action of the half-chip pulse signal, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data.

[0079] Sub-step A4: Perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank.

[0080] As Figure 2 shown, the acquisition system may further include: a data superposition and caching module, which can perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank.

[0081] Among them, the decimated data memory bank consists of two storage blocks, mem0 and mem1. Among them, mem0 consists of 16 storage units with a depth of 2048 and a width of 16 bits, and the total storage capacity is 16×2048×16 = 512Kb. The Mem1 storage block consists of 16 storage units with a depth of 2048 and a width of 20 bits, and the total storage capacity is 20×2048×16 = 640Kb.

[0082] The stored content in the decimated data memory bank is not exactly the same in Merge mode and Split mode.

[0083] In the Merge integration mode, the entire capture module is regarded as a capture channel. The 16 storage units of the mem0 storage block and the 16 storage units of the mem1 storage block are both used to store the decimated data. Among the 16 storage units of the mem1 storage block, only the lower 16 bits are used in the 20-bit width of each storage address. Each sampled data is 4 bits, and each storage address is 16 bits. Therefore, 4 sampled data can be stored in each storage address, and a total of 32 * 2048 * 4 sampled data can be stored in the two storage blocks of mem0 and mem1. In the GPS mode, the sampled data is half-chip sampling, and there are 2046 sampling points in 1 ms of sampled data. Therefore, in the GPS mode, the two storage blocks of mem0 and mem1 can store at most 32 * 4 = 128 ms of satellite data.

[0084] Sub-step A5: Read the mixed-frequency decimated data in the decimated data memory bank, perform secondary mixing processing on the read mixed-frequency decimated data to obtain secondary mixed-frequency data, and use the secondary mixed-frequency data as the operation result of the satellite data.

[0085] As Figure 2 shown, the capture system may further include: a secondary mixing module, which is only used in the Merge mode and is used to read the mixed-frequency decimated data in the memory banks mem0 and mem1 and perform secondary Doppler compensation within 1 KHz. The secondary mixing is performed through two channels, P and N. When capturing the GPS signal, the Doppler compensation range of the P channel corresponds to 0 - 500 Hz, and the Doppler compensation range of the N channel corresponds to -500 - 0 Hz.

[0086] After secondary mixing, the mixed data of the P and N channels are respectively superimposed to 1 ms and stored in the storage blocks mem_p and mem_n in the coherent accumulation memory bank. Both the storage blocks mem_p and mem_n are composed of 4 storage units with a depth of 512 and a width of 24 bits. The total storage capacity of mem_p and mem_n is 4 * 512 * 24 = 48 Kb. In the GPS mode, after being superimposed to 1 ms, there are 2046 sampling points (half-chip sampling) in the P and N channels respectively, so they exactly occupy 4 storage units each.

[0087] In this embodiment, in the Merge mode, a two-stage mixing mode is adopted. Through the circular shift algorithm in the frequency domain, the frequency of the local carrier local_if of the first-stage mixing can be changed. By controlling the number of circular shifts, a search in units of 1 KHz within the Doppler range is achieved. The second-stage mixing local_freq_bin is a fine Doppler compensation within 1 KHz, reducing the loss caused by residual Doppler. Combining the second-stage mixing thus realizes the scanning of all frequency bins within the search range. Compared with the traditional code parallel scheme, the two-stage mixing structure scheme only performs one round of intermediate frequency mixing, downsampling, data caching, and superposition, which can improve the acquisition speed.

[0088] As Figure 3 shown, it is a schematic diagram of the Doppler coverage of the second-stage mixing in the Merge mode. f0, f1,..., fk are compensation frequencies within 1 KHz, which are -500 Hz to 500 Hz in the GPS mode. If the frequency is circularly shifted n times in both positive and negative directions, the Doppler search range is (f0 - n * 1000) Hz to (fk + n * 1000) Hz.

[0089] Assume that the Doppler search step is 100 Hz. Then, the local frequencies of the second-stage mixing need to be set as f0 = -500 Hz, f1 = -400 Hz, ……, f10 = 400 Hz, f11 = 500 Hz, and the number of circular shift times is n = 5 times for both left and right. When the local Doppler frequency of the second-stage mixing is f0 = -500 Hz, through 5 circular shifts for both left and right, frequency searches for 11 frequency bins of frequencies -500 Hz, -500 Hz + 1 kHz, -500 Hz + 2 kHz, -500 Hz + 3 kHz, -500 Hz + 4 kHz, -500 Hz + 5 kHz, -500 Hz - 1 kHz, -500 Hz - 2 kHz, -500 Hz - 3 kHz, -500 Hz - 4 kHz, -500 Hz - 5 kHz are realized. When the local Doppler frequency of the second-stage mixing is f1 = -400 Hz, through 5 circular shifts for both left and right, frequency searches for 11 frequency bins of frequencies -400 Hz, -400 Hz + 1 kHz, -400 Hz + 2 kHz, -400 Hz + 3 kHz, -400 Hz + 4 kHz, -400 Hz + 5 kHz, -400 Hz - 1 kHz, -400 Hz - 2 kHz, -400 Hz - 3 kHz, -400 Hz - 4 kHz, -400 Hz - 5 kHz are realized. And so on. When the local Doppler frequency of the second-stage mixing is f11 = 500 Hz, through 5 circular shifts for both left and right, frequency searches for 11 frequency bins of frequencies 500 Hz, 500 Hz + 1 kHz, 500 Hz + 2 kHz, 500 Hz + 3 kHz, 500 Hz + 4 kHz, 500 Hz + 5 kHz, 500 Hz - 1 kHz, 500 Hz - 2 kHz, 500 Hz - 3 kHz, 500 Hz - 4 kHz, 500 Hz - 5 kHz are realized. In this way, through the second-stage mixing and circular shift, rapid searches for all frequency bins within the Doppler search range of (f0 - n * 1000) Hz to (fk + n * 1000) Hz = (-500 - 5 * 1000) Hz to (500 + 5 * 1000) Hz are realized.

[0090] As Figure 4 shown, the specific execution process of the second-stage mixing module can be as follows:

[0091] (1) Read the mixed-frequency decimated data from mem0 and mem1 and convert it into serial data for output.

[0092] (2) Perform second-stage mixing processing. When performing second-stage mixing, it is divided into two channels, P and N. The Doppler compensation range of the P channel corresponds to 0 to 500 Hz, and the Doppler compensation range of the N channel corresponds to -500 to 0 Hz. The results after the second-stage mixing are truncated to obtain the I-channel and Q-channel signals after the second-stage mixing.

[0093] (3) The I-channel and Q-channel after the second-stage mixing are combined to obtain the mixing result data_p of the P-channel and the mixing result data_n of the N-channel respectively.

[0094] (4) The data of the P-channel and N-channel after mixing are each superimposed to 1 ms and stored in the storage blocks mem_p and mem_n in the coherent accumulation memory bank respectively.

[0095] Step 102: Perform a single decision on the satellite data operation result in the integration mode. If the decision is successful, it is determined that the satellite navigation signal capture in the integration mode is successful.

[0096] After obtaining the satellite data operation result in the Merge mode, a single decision can be made on the satellite data operation result in the Merge mode. If the decision is successful, it can be determined that the satellite navigation signal capture in the Merge mode is successful. Specifically, in the Merge mode, only a single decision is made. If the single decision is successful, the capture is completed; otherwise, the capture fails and the search for the next frequency bin is entered. The reason for only making a single decision is that the Merge mode is used at a relatively high signal power, and the probability of false capture is relatively low at this time.

[0097] Step 103: After the satellite navigation signal capture in the integration mode is successful, in the sub-channel capture mode, the satellite data of multiple satellites are captured in parallel through multiple channels, and the data are processed to obtain the satellite data operation result in the sub-channel mode.

[0098] After the satellite navigation signal capture in the Merge mode is successful, the satellite navigation signal can be captured in the sub-channel capture mode (i.e., the Split mode). At this time, the satellite data of multiple satellites can be captured in parallel through multiple channels, and the data are processed to obtain the satellite data operation result in the sub-channel mode. This process can be described in detail in combination with the following specific implementation.

[0099] In another specific implementation of the present invention, the above step 103 may include:

[0100] Sub-step B1: Process the local carrier NCO according to the local intermediate-frequency carrier frequency and the local code frequency respectively to generate the local carrier quantization result and the half-chip pulse signal.

[0101] In the embodiment of the present invention, the capture system provided in this example may include a local carrier and half-chip pulse generation module, and this module can be used to perform the following operations:

[0102] The local carrier NCO can be processed according to the local intermediate-frequency carrier frequency and the local code frequency respectively to generate the local carrier quantization result and the half-chip pulse signal.

[0103] Specifically, the local carrier NCO can be incremented according to the local intermediate frequency carrier frequency local_if to obtain the carrier NCO accumulation value sum_carr. By looking up a table for the carrier NCO accumulation value sum_carr, the sin and cos quantization results of the local carrier can be obtained.

[0104] The local code NCO can be incremented according to the local code frequency local_codefreq, and a half-chip pulse signal can be obtained based on the "positive" and "negative" of the local code NCO. Among them, the local code frequency local_codefreq is obtained by carrier-assisted code frequency compensation based on the reference code frequency.

[0105] In the Merge mode, since only one intermediate frequency mixing is performed, in fact, the intermediate frequency carrier frequency local_if here is the reference carrier intermediate frequency, and the local code frequency local_codefreq corresponds to the reference code frequency. That is to say, during the entire frequency search process of acquisition, in fact, code Doppler compensation does not play a role.

[0106] Sub-step B2: Mix the collected satellite data to generate two paths of mixed data, where the two paths of mixed data include: in-phase (I) mixed data and quadrature (Q) mixed data.

[0107] The acquisition system may further include: a mixing module, which can mix the collected satellite data to obtain two paths of mixed data, and the two paths of mixed data are the in-phase (I) mixed data and the quadrature (Q) mixed data.

[0108] Sub-step B3: Under the action of the half-chip pulse signal, perform half-chip accumulation decimation extraction processing on the two paths of mixed data, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data.

[0109] The acquisition system may further include: a decimation and truncation module, which can perform half-chip accumulation decimation extraction processing on the two paths of mixed data after mixing under the action of the half-chip pulse signal, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data.

[0110] Sub-step B4: Perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank.

[0111] The acquisition system may further include: a data superposition and caching module, which can perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank.

[0112] Among them, the downsampling number memory bank consists of two memory blocks, mem0 and mem1. Mem0 consists of 16 memory cells with a depth of 2048 and a width of 16 bits, and the total storage capacity is 16 × 2048 × 16 = 512Kb. The Mem1 memory block consists of 16 memory cells with a depth of 2048 and a width of 20 bits, and the total storage capacity is 20 × 2048 × 16 = 640Kb.

[0113] The stored contents of the downsampling data memory bank are not exactly the same in the Merge mode and the Split mode.

[0114] In the Split channel mode, it is divided into 16 parallel capture channels. The mem0 memory block is used to store the downsampling data, and the mem1 memory block is used to store the non-coherent integration data. Among them, the 16 memory cells of the mem0 memory block correspond one-to-one with the 16 parallel capture channels, and each memory cell stores the downsampling data of the corresponding capture channel. For the GPS mode, when the coherent integration time is greater than 1ms, the ms data within the coherent integration time is superimposed at the corresponding points, and finally 1ms data is formed for storage. When the coherent integration time is 1ms, no superimposition or other processing is performed, and the 1ms data is directly stored. The 1ms data is half-chip sampled, with a total of 2046 sampling points, and is stored in a memory cell of the mem0 memory block.

[0115] Sub-step B5: Read the mixed-frequency downsampling data in the downsampling number memory bank, and perform 4096-point radix-8 FFT operation and related processing on the read mixed-frequency downsampling data to obtain the IFFT calculation result.

[0116] As Figure 2 shown, the capture system may further include: an FFT calculation control module, whose main function is to complete 4096-point radix-8 FFT operation and related processing, including reading and temporarily storing the data to be subjected to the FFT operation, starting the formal FFT operation, complex multiplication before IFFT, and outputting the IFFT result, etc. The IFFT calculation result is transmitted to the non-coherent accumulation module.

[0117] The FFT calculation memory bank includes a total of 3 memory blocks: prn_mem, data0_mem, and data1_mem. The memory block prn_mem consists of 8 memory cells with a depth of 512 and a width of 28 bits; the memory blocks data0_mem and data1_mem respectively consist of 8 memory cells with a depth of 512 and a width of 32 bits.

[0118] In this example, the FFT calculation module adopts a 4096-point radix-8 FFT method to achieve the purpose of fast calculation. For the 4096-point FFT operation, the speed of radix-8 is 12 times that of radix-2.

[0119] The 4096-point FFT radix-8 operation is divided into four stages, and its address access mode is as follows:

[0120] In the first round, there is 1 large loop of addresses. One block of FFT is performed. The internal ladder within each round is 512. For example, the first group is 0, 512, 1024, …, 3584, and the last group is 511, 1023, 1535, …, 4095.

[0121] In the second round, there are 8 large loops of addresses. The FFT is performed on 8 large blocks respectively. The internal ladder within each block is 64 (512 / 8). The first group of the first block is 0, 64, …, 448, and the last group of the first block is 63, 127, …, 511. The first group of the second block is 512, 512 + 64, ….

[0122] In the third round, there are 64 large loops of addresses. The FFT is performed on 64 large blocks respectively. The internal ladder within each block is 8 (64 / 8). The first group of the first block is 0, 8, …, 56, and the last group of the first block is 7, 15, …, 63. The first group of the second block is 64, 64 + 8, ….

[0123] In the fourth round, there are 512 large loops of addresses. The FFT is performed on 512 large blocks respectively. The internal ladder within each block is 1 (8 / 8). The first group of the first block is 0, 1, …, 7, and the last group of the first block is the same as the first group. The first group of the second block is 8, 8 + 1, ….

[0124] The processing procedure of the FFT calculation control module includes the following steps:

[0125] (1) Read and store the pseudo-code and satellite sampling data to be used for FFT.

[0126] 1) Reading and storing the pseudo-code

[0127] After starting the acquisition module, the pseudo-code generation module starts to generate the pseudo-code, and the generated pseudo-code is stored in the storage block prn_mem. In the GPS acquisition mode, the local pseudo-code takes 2 ms and samples at half a chip. Therefore, there are a total of 2 * 1023 * 2 = 4092 points, and finally 4 zeros are added, forming 4096 sampling points. Therefore, 8 pseudo-code RAM storage units are occupied (512 * 8 = 4096).

[0128] 2) Reading and storing the satellite sampling data

[0129] In the Split mode, the down-sampled satellite sampling data is stored in the storage block mem0. Each storage unit of mem0 stores the GPS satellite data corresponding to a channel. Therefore, in this step of processing, the satellite data is read from the storage unit of mem0 corresponding to the currently enabled channel, with a total of 2046 sampling points. After adding 2 zeros, 2048 sampling points are formed and stored in the first 4 storage units of data_mem0.

[0130] In Merge mode, the satellite data has been superimposed for 1 ms in the second mixer module in Merge mode and stored in the memory blocks mem_p and mem_n. Therefore, different from the split mode, the satellite data before FFT can be stored in mem_p and mem_n, and there is no need to read it out and store it in data_mem0 again.

[0131] (2) Pseudo-code FFT calculation and data storage after FFT.

[0132] After the pseudo-code is stored in the memory block prn_mem, the FFT calculation of the pseudo-code is started. The FFT calculation module reads the pseudo-code data from the memory block prn_mem and performs a radix-8 FFT calculation of 4096 points. After the FFT calculation is completed, the FFT calculation result of the pseudo-code is written back to the memory block prn_mem.

[0133] (3) FFT calculation of satellite sampling data and data storage after FFT.

[0134] After the pseudo-code FFT processing is completed, the FFT calculation and processing of satellite sampling data are started.

[0135] In Split mode, since the satellite data only occupies the first 4 storage units of data_mem0 in GPS mode, only the data in data_mem0 is subjected to FFT calculation, and the data in the last 4 storage units after the FFT operation is forced to be configured as 0, so as to form 4096 sampling points for a radix-8 FFT of 4096 points. The FFT calculation result of the satellite sampling data is written back to the storage unit mem0 again.

[0136] In Merge mode, first start the FFT of P-channel data, and after completion, start the FFT of N-channel data. First, read the satellite data from the storage unit mem_p, perform FFT calculation, and store the calculation result in data_mem0. Then, read the satellite data from the storage unit mem_n, perform FFT calculation, and store the calculation result in data_mem1.

[0137] (4) IFFT calculation

[0138] In Split mode, after receiving the IFFT calculation request, the conjugate complex multiplication of the pseudo-code FFT data read from prn_mem and the satellite signal FFT data read from data_mem0 is performed, and the IFFT calculation is carried out. After the IFFT calculation is completed, the calculation result is transmitted to the non-coherent accumulation module.

[0139] In the Merge mode, circular shift and IFFT calculations are performed. Performing an FFT transformation on the time-domain data can obtain the corresponding spectrum sequence. The circular shift of the spectrum sequence is equivalent to carrier stripping and Doppler search of the time-domain signal. Therefore, the spectrum sequence of the input signal can be shifted to replace carrier stripping. This can reduce a large number of FFT operations in the carrier stripping stage, thereby achieving the purpose of improving the capture speed. The formula is expressed as:

[0140] X(k) = FFT[x(n)] (1)

[0141] Y(k) = X N (k + l)R N (k) (2)

[0142]

[0143] In the above formula, X(k) and Y(k) are the discrete Fourier transforms of x(n) and y(n) respectively; R N [[ID={18}](k) is a rectangular window sequence of length N; Y(k) is a new sequence obtained by circularly shifting X(k) by l points. According to this principle, it can be concluded that when the time series is multiplied by the local replica carrier signal, the discrete spectrum sequence will be circularly shifted by the corresponding number of units. Therefore, circular shift can be used to replace the carrier stripping calculation process.

[0144] Utilizing this feature, only one FFT operation of the input signal is required, and the Doppler search can be completed by circularly shifting its frequency components. Multiply the circularly shifted frequency components and the FFT conjugate of the local pseudo-code respectively, and then perform an IFFT operation to obtain the correlation function of all pseudo-code phases of a certain satellite under this Doppler search unit.

[0145] The number of FFT points is selected as 4096, the input data is downsampled to 2.046 MHz, and the Doppler carrier compensated by circular shift is The frequency is The precision is Since in the Merge mode, after superimposing multi-millisecond data into 1 ms data and then performing FFT, if each circular shift is one point, that is, the equivalent Doppler resolution is 500 Hz, then the number of carrier cycles within each millisecond may not be an integer, resulting in discontinuous starting phases per millisecond. Therefore, when performing circular shift here, two points are selected for each shift, and the Doppler resolution is 1 KHz.

[0146] ​The circular shift and IFFT calculation process in Merge mode are as follows: Since the FFT calculation result of the P-channel data stored in the memory block data0_mem corresponds to the secondary Doppler compensation range of 0 to 500 Hz; the FFT calculation result of the N-channel data stored in the memory block data1_mem corresponds to the secondary Doppler compensation range of -500 to 0 Hz. Therefore, it is necessary to process the P-channel and N-channel alternately. After the IFFT calculation is started, first read the pseudo-code FFT data in prn_mem and the P-channel satellite signal FFT data in data0_mem, perform conjugate complex multiplication and then perform IFFT calculation. After the P-channel data processing is completed, read the N-channel data in data1_mem and perform the same processing. After that, each time, alternately perform a circular shift of 2 points on the FFT results of the P-channel and N-channel, and conjugate complex multiply the circular shift result with the pseudo-code FFT result and then perform IFFT calculation until all the circular shift times within the capture search range are completed. As in the Split mode, the IFFT calculation result is transmitted to the non-coherent accumulation module.

[0147] Sub-step B6: Perform non-coherent accumulation processing on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

[0148] As Figure 2 shown, the acquisition system may further include: a non-coherent accumulation module, and the operations performed by this module may include the following two parts:

[0149] (1) Coherent integration data storage

[0150] In GPS mode, 1 ms of satellite data is taken, padded with 1 ms of zeros, 2 ms of local pseudo-code is taken, the satellite data and the local pseudo-code are respectively subjected to 4096-point FFT, and after conjugate multiplication, IFFT calculation is performed. The result of the 4096-point IFFT calculation retains the result of the first 1 ms, a total of 2048 sampling points, and the IFFT calculation result is stored in the memory block coh_mem of the coherent accumulation memory bank. The memory block coh_mem consists of 4 memory cells with a depth of 512 and a width of 40 bits.

[0151] (2) Non-coherent integration accumulation

[0152] In Merge mode, in order to improve the acquisition speed, non-coherent integration processing is not performed. Instead, directly read the IFFT calculation result in the memory block coh_mem, perform a modulo operation, and then send it to the peak detection module.

[0153] In Split mode, to improve the capture sensitivity, multiple non-coherent accumulations are performed. The mem1 storage block is used to store non-coherent integration data in Split mode. The mem1 storage block consists of 16 storage units with a depth of 2048 and a width of 20 bits. The 16 storage units of the mem1 storage block correspond one-to-one with 16 parallel capture channels, and each storage unit stores the non-coherent integration data of the corresponding capture channel. During the first non-coherent accumulation, the IFFT calculation result in the coh_mem storage block is directly read, and after performing a modulo operation, it is stored in the corresponding storage unit in the mem1 storage block. Starting from the second non-coherent accumulation, each time the IFFT calculation result needs to be read from the coh_mem storage block, modulo operation is performed, and then it is added to the result of the previous non-coherent accumulation read from the corresponding storage unit in the mem1 storage block. The addition result is rewritten into the corresponding storage unit in mem1. This is repeated until the last non-coherent accumulation. The result of the last non-coherent accumulation is simultaneously sent to the peak detection module.

[0154] The peak detection module can complete the functions of maximum amplitude and phase search. The values of different phases of the input non-coherent integration result are statistically averaged to obtain the average power, which is multiplied by the threshold configured by the software for comparison with the maximum value.

[0155] Step 104: Perform multiple judgments on the operation results of satellite data in the sub-channel mode. If the multiple judgments are successful, it is determined that the satellite navigation signal capture in the sub-channel mode is successful.

[0156] In Split mode, if the maximum value is greater than the threshold, the current single search is valid and sent for M / N multiple judgments. If it is lower than the threshold, the current search fails and enters the next search unit. In the N judgments, if at least M judgments are successful (the maximum value exceeds the threshold, and the phase corresponding to the maximum value remains the same during the M judgments), it is determined that the capture is successful; otherwise, it is considered that the capture fails. The reason for performing M / N multiple judgments is to prevent false capture under weak signal power. Here, N is the number of executions of the judgment, and M is the number of successful judgments.

[0157] In the embodiments of the present invention, the differences between the two capture modes are as follows:

[0158] 1. In Merge mode, the entire capture module is regarded as a capture channel. First, sampling data for a period of time is stored in mem0 and mem1 as the data source for subsequent multi-star capture. Merge mode uses a two-stage mixing structure to achieve frequency point scanning within 1KHz through secondary mixing processing, and to achieve fast large-step search for frequency points outside 1KHz through FFT / IFFT and circular shift in the frequency domain, greatly improving the capture speed. At the same time, since only one round of intermediate frequency mixing and downsampling is performed, the code Doppler shift cannot be compensated, which limits the non-coherent integration time. Therefore, multiple non-coherent accumulations are not performed in this mode. Merge mode is suitable for fast capture of ordinary sensitivity stars.

[0159] 2. In Split mode, it belongs to the sub-channel mode and supports parallel capture of up to 16 channels at most. In Split mode, at a certain search frequency point, each channel first samples data for a period of time and stores it in mem0. Then the system responds to the calculation requests of each channel within the given 2ms time. After each channel's calculation is completed, the result is modulo stored in mem1, and each channel completes one non-coherent operation. At the same time, the front-end module can sample a section of data for processing and accumulation, so multiple non-coherent operations can be realized. Split mode uses a one-stage mixing structure, and the search for Doppler is achieved by changing the local carrier frequency during intermediate frequency mixing. The advantage of Split mode is that the code Doppler shift is compensated, thereby extending the non-coherent integration time and improving the capture sensitivity, enabling the capture of weak signals.

[0160] In this embodiment, in Split mode, the code Doppler compensation is achieved by changing the half-chip clock during downsampling. The process is as follows:

[0161] (1) Calculate the current local carrier frequency local_if

[0162] The local carrier frequency local_if = intermediate frequency local_if_base + the current searched Doppler local_dop, and local_dop is updated when searching for the next frequency point.

[0163] (2) Deduce the current code frequency based on the currently searched Doppler local_dop

[0164] The local code frequency local_codefreq = code reference frequency local_codefreq_base + local_dop / A.

[0165] Among them, in GPS mode, the code reference frequency local_codefreq_base = 1.023MHz, and the coefficient A is the ratio of the GPS carrier frequency to the code frequency, A = 1575.42MHz / 1.023MHz = 1540.

[0166] (3) Generate a half-chip clock according to the local code frequency local_codefreq.

[0167] (4) Downsample the input data according to the half-chip clock.

[0168] Embodiment 2

[0169] Refer to Figure 5 , which shows a schematic structural diagram of a capture implementation system for a Beidou positioning system provided by an embodiment of the present invention that takes into account both capture speed and capture sensitivity. As Figure 5 shown, the system may include the following modules:

[0170] An integrated mode operation result acquisition module 510, configured to capture satellite data of multiple satellites in a single-channel capture manner in the integrated mode, and process the satellite data to obtain an operation result of the satellite data in the integrated mode;

[0171] An integrated mode capture success determination module 520, configured to perform a single determination on the operation result of the satellite data in the integrated mode, and determine that the satellite navigation signal capture in the integrated mode is successful in the case of a successful determination;

[0172] A sub-channel mode operation result acquisition module 530, configured to, after the satellite navigation signal capture in the integrated mode is successful, capture satellite data of multiple satellites in a multi-channel parallel manner in the sub-channel capture mode, and process the data to obtain an operation result of the satellite data in the sub-channel mode;

[0173] A sub-channel mode capture success determination module 540, configured to perform multiple determinations on the operation result of the satellite data in the sub-channel mode, and determine that the satellite navigation signal capture in the sub-channel mode is successful in the case of multiple successful determinations.

[0174] Optionally, the integrated mode operation result acquisition module includes:

[0175] A carrier quantization result generation unit, configured to process a local carrier NCO (Numerically Controlled Oscillator) according to a local intermediate frequency carrier frequency and a local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0176] A two-channel mixing data generation unit, configured to perform a mixing process on the collected satellite data to generate two-channel mixing data, where the two-channel mixing data includes: I-channel mixing data and Q-channel mixing data;

[0177] A decimation truncated data generation unit, configured to perform half-chip accumulation decimation extraction processing on the two-channel mixing data under the action of the half-chip pulse signal, and perform truncation processing on the half-chip accumulation amount to generate decimation truncated data;

[0178] A decimation truncated data storage unit, configured to perform superposition and caching processing on the decimation truncated data, and store it in the decimation number memory bank;

[0179] An integrated mode operation result acquisition unit, configured to read the mixing decimation data in the decimation number memory bank, perform secondary mixing processing on the read mixing decimation data to obtain secondary mixing data, and use the secondary mixing data as the satellite data operation result.

[0180] Optionally, the sub-channel mode operation result acquisition module includes:

[0181] A half-chip pulse signal generation unit, configured to process the local carrier NCO according to the local intermediate frequency carrier frequency and the local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal;

[0182] A mixing data generation unit, configured to perform mixing processing on the collected satellite data to generate two-channel mixing data, where the two-channel mixing data includes: I-channel mixing data and Q-channel mixing data;

[0183] A decimation data generation unit, configured to perform half-chip accumulation decimation extraction processing on the two-channel mixing data under the action of the half-chip pulse signal, and perform truncation processing on the half-chip accumulation amount to generate decimation truncated data;

[0184] A decimation data storage unit, configured to perform superposition and caching processing on the decimation truncated data, and store it in the decimation number memory bank;

[0185] An IFFT calculation result acquisition unit, configured to read the mixing decimation data in the decimation number memory bank, and perform 4096-point radix-8 FFT operation and related processing on the read mixing decimation data to obtain an IFFT calculation result;

[0186] A sub-channel mode operation result acquisition unit, configured to perform non-coherent accumulation processing on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

[0187] Optionally, the sub-channel mode capture success determination module includes:

[0188] A power average value acquisition unit, configured to perform statistical average operation on the values of different phases in the non-coherent accumulation result to obtain a power average value;

[0189] A detection threshold value acquisition unit, configured to obtain a peak detection threshold value according to the power average value and a pre-configured threshold value.

[0190] A decision result acquisition unit, configured to compare the peak detection threshold value with a pre-set maximum value to obtain a decision result.

[0191] Multiple decision result acquisition units, configured to perform multiple operations and decision-making processes according to the multiple satellite data captured by the multi-channel, and obtain multiple decision results.

[0192] A sub-channel mode capture success determination unit, configured to determine that the satellite navigation signal capture in the sub-channel mode is successful when at least N decision results in the multiple decision results indicate successful decision-making.

[0193] The specific embodiments of the present invention can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way. Therefore, those skilled in the art should understand that they still make modifications or equivalent replacements to the present invention; and all technical solutions and their improvements that do not depart from the spirit and technical essence of the present invention shall be covered by the protection scope of the present invention patent.

[0194] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A capture implementation method that takes into account both capture speed and capture sensitivity, characterized in that Including: Step 101: In the integration mode, capture satellite data of multiple satellites by using a single-channel capture method, and process the satellite data to obtain the satellite data operation result in the integration mode; Step 102: Perform a single decision on the satellite data operation result in the integration mode. If the decision is successful, it is determined that the satellite navigation signal capture in the integration mode is successful; Step 103: After the satellite navigation signal capture in the integration mode is successful, in the sub-channel mode, capture satellite data of multiple satellites by using multi-channel parallelism, and process the data to obtain the satellite data operation result in the sub-channel mode; Step 104: Perform multiple decisions on the satellite data operation result in the sub-channel mode. If the multiple decisions are successful, it is determined that the satellite navigation signal capture in the sub-channel mode is successful; In the integration mode, adopt a two-stage mixing mode. Through the circular shift algorithm in the frequency domain, change the frequency of the local carrier of the first-stage mixing. By controlling the number of circular shifts, realize the search in units of 1 KHz within the Doppler range; when adopting the sub-channel mode, at a certain search frequency point, each channel first samples for a period of time and stores it; then the system responds to the calculation requests of each channel within the given 2 ms time. After each channel calculates, the processing result is modulo and then stored. Each channel completes a non-coherent operation. At the same time, the front-end module samples another section of data for processing and accumulation to realize multiple non-coherent operations.

2. The method according to claim 1, wherein The capturing of satellite data of multiple satellites by using a single-channel capture method and processing the satellite data to obtain the satellite data operation result in the integration mode includes: Process the local carrier digital oscillator according to the local intermediate frequency carrier frequency and the local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal; Perform mixing processing on the collected satellite data to generate two paths of mixed-frequency data, and the two paths of mixed-frequency data include: in-phase (I)-channel mixed-frequency data and quadrature (Q)-channel mixed-frequency data; Under the action of the half-chip pulse signal, perform half-chip accumulation decimation processing on the two paths of mixed-frequency data, and truncate the half-chip accumulation amount to generate decimated and truncated data; Perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank; Read the mixed-frequency decimated data in the decimated data memory bank, and perform two-stage mixing processing on the read mixed-frequency decimated data to obtain two-stage mixed-frequency data, and use the two-stage mixed-frequency data as the satellite data operation result.

3. The method according to claim 1, characterized in that, The capturing of satellite data of multiple satellites by using multi-channel parallelism in the sub-channel mode and processing the data to obtain the satellite data operation result in the sub-channel mode includes: Process the local carrier NCO according to the local intermediate frequency carrier frequency and the local code frequency respectively to generate a local carrier quantization result and a half-chip pulse signal; Perform mixing processing on the collected satellite data to generate two paths of mixed-frequency data, and the two paths of mixed-frequency data include: in-phase (I)-channel mixed-frequency data and quadrature (Q)-channel mixed-frequency data; Under the action of the half-chip pulse signal, perform half-chip accumulation decimation extraction processing on the two-channel mixed-frequency data, and perform truncation processing on the half-chip accumulation amount to generate decimated and truncated data; Perform superposition and caching processing on the decimated and truncated data, and store it in the decimated data memory bank; Read the mixed-frequency decimated data in the decimated data memory bank, and perform 4096-point radix-8 FFT operation and related processing on the read mixed-frequency decimated data to obtain the IFFT calculation result; Perform non-coherent accumulation processing on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

4. The method according to claim 3, characterized in that, Performing multiple decisions on the satellite data operation result in the sub-channel mode, and determining that the satellite navigation signal capture in the sub-channel mode is successful when multiple decisions are successful, includes: Perform statistical averaging operation on the values of different phases in the non-coherent accumulation result to obtain the average power value; Obtain the peak detection threshold value according to the average power value and the pre-configured threshold; Compare the peak detection threshold value with the pre-set maximum value to obtain the decision result; Perform multiple operations and decision processing according to the multiple satellite data captured in multiple channels to obtain multiple decision results; When at least N decision results in the multiple decision results indicate successful decision, determine that the satellite navigation signal capture in the sub-channel mode is successful.

5. A capture implementation system that takes into account both capture speed and capture sensitivity, characterized in that, Including: An integrated mode operation result acquisition module, configured to capture satellite data of multiple satellites in a single-channel capture mode in the integrated mode, and process the satellite data to obtain the satellite data operation result in the integrated mode; An integrated mode capture success determination module, configured to perform a single decision on the satellite data operation result in the integrated mode, and determine that the satellite navigation signal capture in the integrated mode is successful when the decision is successful; A sub-channel mode operation result acquisition module, configured to, after the satellite navigation signal capture in the integrated mode is successful, capture satellite data of multiple satellites in a multi-channel parallel manner in the sub-channel mode, and process the data to obtain the satellite data operation result in the sub-channel mode; A sub-channel mode capture success determination module, configured to perform multiple decisions on the satellite data operation result in the sub-channel mode, and determine that the satellite navigation signal capture in the sub-channel mode is successful when multiple decisions are successful; In the integrated mode, adopt a two-stage mixing mode, change the frequency of the local carrier of the first-stage mixing through the circular shift algorithm in the frequency domain, and realize the search in units of 1KHz within the Doppler range by controlling the number of circular shifts; when adopting the sub-channel mode, at a certain search frequency point, each channel first samples and stores for a period of time; then the system responds to the calculation requests of each channel within a given 2ms time. After each channel calculation is completed, the processing result is modulo and then stored. Each channel completes a non-coherent operation, and at the same time the front-end module samples and processes and accumulates a section of data to realize multiple non-coherent operations.

6. The system according to claim 5, wherein The integrated mode operation result acquisition module includes: A carrier quantization result generating unit, configured to process a local carrier digital oscillator according to a local intermediate frequency carrier frequency and a local code frequency respectively, and generate a local carrier quantization result and a half-chip pulse signal; A two-channel mixing data generating unit, configured to perform a mixing process on the collected satellite data to generate two-channel mixing data, where the two-channel mixing data includes: in-phase (I)-channel mixing data and quadrature (Q)-channel mixing data; A downsampling truncated data generating unit, configured to perform a half-chip accumulation downsampling extraction process on the two-channel mixing data under the action of the half-chip pulse signal, and perform a truncation process on the half-chip accumulation amount to generate downsampling truncated data; A downsampling truncated data storage unit, configured to perform a superposition and caching process on the downsampling truncated data, and store it in a downsampling number memory bank; An integrated mode operation result obtaining unit, configured to read the mixed downsampling data in the downsampling number memory bank, perform a secondary mixing process on the read mixed downsampling data to obtain secondary mixing data, and use the secondary mixing data as the satellite data operation result.

7. The system according to claim 5, wherein The sub-channel mode operation result obtaining module includes: A half-chip pulse signal generating unit, configured to process a local carrier numerically controlled oscillator (NCO) according to a local intermediate frequency carrier frequency and a local code frequency respectively, and generate a local carrier quantization result and a half-chip pulse signal; A mixing data generating unit, configured to perform a mixing process on the collected satellite data to generate two-channel mixing data, where the two-channel mixing data includes: I-channel mixing data and Q-channel mixing data; A downsampling data generating unit, configured to perform a half-chip accumulation downsampling extraction process on the two-channel mixing data under the action of the half-chip pulse signal, and perform a truncation process on the half-chip accumulation amount to generate downsampling truncated data; A downsampling data storage unit, configured to perform a superposition and caching process on the downsampling truncated data, and store it in a downsampling number memory bank; An inverse fast Fourier transform (IFFT) calculation result obtaining unit, configured to read the mixed downsampling data in the downsampling number memory bank, and perform a 4096-point radix-8 FFT operation and related processing on the read mixed downsampling data to obtain an IFFT calculation result; A sub-channel mode operation result obtaining unit, configured to perform a non-coherent accumulation process on the IFFT calculation result to generate a non-coherent accumulation result, and use the non-coherent accumulation result as the satellite data operation result in the sub-channel mode.

8. The system according to claim 7, wherein, The sub-channel mode capture success determination module includes: A power average value obtaining unit, configured to perform a statistical average operation on values with different phases in the non-coherent accumulation result to obtain a power average value; A detection threshold value obtaining unit, configured to obtain a peak detection threshold value according to the power average value and a pre-configured threshold; A decision result obtaining unit, configured to compare the peak detection threshold value with a pre-set maximum value to obtain a decision result; Multiple decision result obtaining units, configured to perform multiple operations and decision processes on the multiple satellite data captured by the multi-channel to obtain multiple decision results; The sub-channel mode capture success determination unit is used to determine that the satellite navigation signal capture in the sub-channel mode is successful when at least N judgment results among the multiple judgment results indicate successful judgment.

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