CN116719063A - A method and system for rapid acquisition of ground-based navigation signals - Google Patents

Abstract

The invention discloses a method and system for quickly acquiring ground-based navigation signals. Through orthogonal down-conversion, low-pass filtering, reweighting and resampling of the digital signal, the resampled I/Q baseband signal is obtained. Based on the signal, acquisition is performed and two sets of matched filters are used for detection within a ranging code period. , collect the capture information list with the continuous count of sampling points as the timestamp, calculate the capture time slot value according to the timestamp to form the time-hopping pattern sub-sample, complete the capture of the time-hopping pattern, and calculate the estimation of the signal frequency based on the two sets of matched filtering integral values to achieve It achieves rapid search in the three dimensions of time domain, frequency domain and transmission time slot of ground-based navigation signals, and has the advantages of fast acquisition speed, large signal frequency estimation range, and effective suppression of side lobe interference.

Description

A method and system for rapid acquisition of ground-based navigation signals

Technical field

The invention relates to the field of navigation technology, and in particular to a method and system for quickly acquiring signals from a ground-based navigation system.

Background technique

As an important supplement to satellite navigation systems, ground-based navigation systems have unique advantages in some aspects and can overcome the disadvantages of weak satellite signals, susceptibility to interference, and inability to be used indoors. In order to overcome the "far and near effect" problem, the ground-based navigation system adopts time hopping/direct sequence code division multiple access signal (TH/DS-CDMA) in the signal system. By dividing the time slots, different pseudolites transmit spreaded signals in different time slots. Frequency signal, that is, a split-spectrum communication system, which can not only overcome the "far and near effect", but also have the ranging capability of spread spectrum signals.

TH/DS-CDMA is not a continuously broadcast signal. The pseudolites in the system have their own signal transmission time windows, and navigation signals are only sent in specific time slots. Generally, the emission window of only one pseudolite in a certain time slot is When turned on, multiple pseudolites broadcast signals in a time-sharing manner. Even if time-sharing is adopted, for the receiving equipment, the distance to multiple pseudolites is not equal, and the signals between different pseudolites will still overlap in time at the receiving end. Therefore, in the ground-based navigation system, the launch window of each pseudolite is not fixed, but a known, random time-hopping sequence, that is, a time-hopping pattern, to avoid fixed signal reception between two pseudolites. time overlap. For example, in the Locata system, the superframe structure of a time-hopping pattern is 200 long, and 10 time slots are divided into each frame time T _f . The duration of each time slot T _s is 0.1ms. Each pseudolite is selected in The signal is transmitted in one of the 10 time slots in each frame, and the time-hopping pattern has a cycle period of 200.

The introduction of the time-hopping signal system makes the traditional spread spectrum signal receiving technology no longer applicable, and the difficulty of the problem is mainly concentrated in the signal acquisition stage, which requires discontinuous broadcasting of signals in the time domain (code phase) and frequency domain. (Doppler) two-dimensional detection signal. Commonly used detection methods include serial search, parallel search, FFT and matched filtering. The acquisition time is inversely proportional to resource usage. Generally speaking, FFT and matched filtering take up more time. Hardware and software resources, but capture time can be significantly reduced.

There are two key issues in capturing ground-based navigation signals:

(1) Capture of time-jumping patterns

The capture of ground-based navigation signals requires not only detecting signals in the time domain and frequency domain, but also detecting multiple transmission time slots of the signal at the same time to match the known time hopping pattern, so it is three times: time domain, frequency domain and transmission time slot. Signal detection in dimensions. Based on the understanding of traditional spread spectrum signal capture technology, when a signal is detected at a two-dimensional point in a certain time domain and a certain frequency domain, it needs to continue to reside for multiple time slot frames to confirm that there is a time slot for signal transmission.

(2) Capture of signal frequency

Since the ground-based navigation system adopts a time-hopping signal system, there is a problem of mismatch between the frequency traction bandwidth and the acquisition bandwidth.

The power loss caused by signal detection due to incomplete frequency matching is consistent with sinc ² attenuation: P _loss (Δf) = sinc ² (πTΔf). T is the detection integration time, Δf is the frequency deviation, typically, when The loss is about 3.9dB, which has a high probability of being detected based on the ground-based signal reception strength. However, in the subsequent signal frequency pulling, due to the time-hopping transmission system, the adjacent transmission time slots are based on the frame time T _f Average interval, for a frequency discriminator that uses the integrated values of two adjacent transmit time slots to calculate the frequency error, the frequency error range that can be resolved is approximately/> That is, there is a mismatch between the frequency traction bandwidth and the capture bandwidth. The frequency traction bandwidth is much smaller than the capture bandwidth. In order to match the frequency traction bandwidth and acquisition bandwidth, you can use/> is the frequency resolution, but the difference in signal power loss caused is not significant, and will increase the capture time or resource consumption.

Therefore, the capture of ground-based navigation signals requires a three-dimensional search in the time domain, frequency domain and time-hopping transmission time slots, and the capture of signal frequencies is reduced to within the range.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and system for rapid acquisition of ground-based navigation signals to achieve rapid acquisition of time domain, frequency domain and time-hopping patterns of ground-based navigation signals, and the accuracy of frequency acquisition is within within the range.

In order to solve the above technical problems, the present invention first provides a method for quickly acquiring ground-based navigation signals, which includes the following steps:

Step 1: The ground-based navigation digital signal sampled at a rate higher than four times the code rate is subjected to orthogonal digital down-conversion, low-pass filtering and weighting processing, and then resampled at twice the code rate to obtain a resampled I/Q baseband signal;

Step 2: Based on the resampled I/Q baseband signal, with a resolution of 0.5 chips, use two sets of matched filters to search for ground-based pseudolite signals in the time domain; among them, the first set of matched filters has a depth of L-1 and outputs measured before code sequence chip integral value, the second set of matching filter depth L+1, after outputting the ranging code sequence/> Chip integral value, L is the ranging code sequence period length, one transmission time slot T _s of the ground-based navigation time-hopping signal broadcasts a ranging code with a complete period length;

Step 3: Calculate the power value of 2L sampling points at time T _s based on the two sets of matched filter integral values. When the power value is greater than the set threshold P _th , use the continuous count value K _k of the sampling points as the timestamp to integrate the two sets of matched filter points. The values I _k1 /Q _k1 , I _k2 /Q _k2 , and power value P _k are recorded in the capture information list;

Step 4: According to the capture information list, the capture time slot value T _k is calculated based on the timestamp to form a time-hopping pattern subsample, and the time-hopping pattern capture of the signal is completed;

Step 5: According to the captured information list, calculate the signal frequency estimate based on two sets of matched filter integral values.

Preferably, the orthogonal digital down-conversion process is based on Perform a frequency domain search of the signal for frequency intervals.

Preferably, the acquisition information list stores only one piece of acquisition information with the maximum power value within 2L sampling intervals.

Preferably, in the matched filter search, if no signal is detected within two consecutive frames of time 2T _f , the search for the current target pseudolite will be exited or the capture information list will be cleared to restart the search, where T _f is the time-hopping emission of the ground-based navigation signal. The frame time includes N transmission time slots T _s .

Preferably, the capture time slot value T _k is calculated relative to the first recording timestamp K ₁ :

Preferably, the signal frequency is estimated to be Calculation method adopted:

Among them, m is the number of records in the captured information list.

Preferably, the signal frequency is estimated to be It is calculated after completing the time jump pattern capture and deleting the false alarm capture information record.

In order to solve the above technical problems, the present invention also provides a rapid acquisition system for ground-based navigation signals, including:

Carrier CNC oscillator generates local reference carrier signal;

A digital downconverter, connected to the carrier digitally controlled oscillator, orthogonally downconverts the input intermediate frequency sampling signal to zero intermediate frequency, and outputs an I/Q baseband signal;

A low-pass filtering and reweighting module is connected to the digital downconverter, low-pass filters the signal according to the code rate, and reweights it into a 2-bit I/Q signal;

Sampling a digitally controlled oscillator to generate a resampled clock signal;

A sampling point continuous counter, connected to the sampling numerical control oscillator, to continuously count the sampling points after resampling;

An extractor, connected to the low-pass filtering and reweighting module and the sampling CNC oscillator, resamples the signal output by the low-pass filtering and reweighting module to obtain a resampled I/Q signal with twice the code rate;

A matching searcher, connected to the decimator, a sampling numerically controlled oscillator, and a sampling point continuous counter, and uses a matching filter to search for signals;

A time-hopping pattern capture and frequency estimation module, connected to the matching searcher, performs time-hopping pattern capture and signal frequency estimation based on the matching search results;

The matching searcher includes two sets of matching filters: the first set of matching filters, before outputting the ranging code sequence The I/Q integral value of L-1 sampling points for each chip; the second set of matched filters, after outputting the ranging code sequence/> The I/Q integral value of L+1 sampling points for each chip;

The matching searcher also includes a peak recorder, which is connected to the first set of matched filters, the second set of matched filters, and a sampling point continuous counter. The calculated power value is compared with a preset threshold. If it is greater than the threshold, it is recorded. A piece of information: the I/Q integral value L _k1 /Q _k1 output by the first set of matched filters, the I/Q integral value I _k2 /Q _k2 output by the second set of matched filters, the power value and the sampling point continuous count value K _k .

Preferably, the peak recorder records only one piece of information with the maximum power value within 2L sampling points.

Preferably, the time-hopping pattern capture and frequency estimation module calculates the capture time slot value T _k according to the continuous count value K _k of sampling points recorded by the peak recorder: The subsamples that constitute the time-hopping pattern are captured, and the frequency estimate is calculated based on the I/Q integral values of the first and second sets of matched filter outputs recorded by the peak recorder/>

Among them, m is the number of records in the peak recorder.

The main advantages of the ground-based navigation signal rapid acquisition method and system implemented by the present invention are:

(1) Realize three-dimensional rapid search of ground-based navigation signals in time domain, frequency domain and transmission time slot through matching filtering, and the signal can be captured within 5 to 10 subframes;

(2) Through group matching filtering, the Accurate estimation of signal frequency over a wide range;

(3) Frequency domain search based on as the interval, which greatly reduces the number of Doppler frequency point searches in high-dynamic applications and shortens the acquisition time;

(4) Through the complete detection of the ranging code sequence code phase, the side lobe interference of the autocorrelation function can be effectively suppressed and the main peak can be accurately captured.

Description of the drawings

The drawings are used to provide a further understanding of the present invention and constitute a part of the present application. They are used to explain the present invention together with the embodiments of the present invention and do not constitute an improper limitation of the present invention. In the attached picture:

Figure 1 is a schematic diagram of time-hopping transmission of ground-based navigation signals;

Figure 2 is a flow chart of an embodiment of a ground-based navigation signal rapid acquisition method according to the present invention;

Figure 3 is a schematic diagram of the composition of an embodiment of the ground-based navigation signal rapid acquisition system of the present invention;

Figure 4 is a schematic diagram of the composition of a matching searcher in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

In ground-based navigation systems, a time-hopping pattern is described using superframes, subframes, and time slots. As shown in Figure 1, a period of the time hopping pattern is called a superframe. A superframe contains M subframes. Each subframe is divided into N time slots. The time of each time slot is T _s. Generally, it is related to ranging. The code period is the same, and the time T _f of one subframe is N·T _s . In specific applications, the upper limit of the number of ground-based pseudolites deployed depends on N, that is, within a subframe, only one pseudolite is allowed to transmit signals in each time slot, and the pseudolite's transmission time slot within a subframe is not fixed.

Example 1

Figure 2 is a schematic flow chart of an embodiment of a ground-based navigation signal rapid acquisition method according to the present invention. The method embodiment shown in Figure 2 mainly includes the following steps:

Step S101, the ground-based navigation digital signal sampled at a rate higher than four times the code rate is subjected to orthogonal digital down-conversion, low-pass filtering and weighting processing, and is resampled at twice the code rate to obtain a resampled I/Q baseband signal;

Step S102, based on the resampled I/Q baseband signal, with a resolution of 0.5 chips, use two sets of matched filters to search for ground-based pseudolite signals in the time domain; among them, the first set of matched filters has a depth of L-1 and outputs measured before code sequence chip integral value, the second set of matching filter depth L+1, after outputting the ranging code sequence/> Chip integral value, L is the ranging code sequence period length, one transmission time slot T _s of the ground-based navigation time-hopping signal broadcasts a ranging code with a complete period length;

Step S103, calculate the power values of 2L sampling points at time T _s based on two sets of matched filter integral values. When the power value is greater than the set threshold P _th , use the continuous count value K _k of sampling points as the timestamp, and combine the two sets of matched filter integrals. The values I _k1 /Q _k1 , I _k2 /Q _k2 , and power value P _k are recorded in the capture information list;

Step S104, according to the capture information list, calculate the capture time slot value T _k based on the timestamp to form a time hopping pattern subsample, completing the time hopping pattern capture of the signal;

Step S105, according to the captured information list, calculate the signal frequency estimate based on two sets of matched filter integral values.

Among them, the orthogonal digital down-conversion process in step S101 is to adapt to different carrier application scenarios. For static or low-dynamic applications, the nominal intermediate frequency of the digital signal is used for mixing. In high-dynamic applications, orthogonal digital down-conversion process Also with Perform a frequency domain search on the signal for the frequency interval; the sampling rate of the original ground-based navigation digital signal needs to be higher than four times the code rate, which facilitates the design of the low-pass filter cutoff frequency indicator and the generation of a resampled clock signal with twice the code rate.

Among them, the depths of the first group and the second group of matched filters in step S102 can be interchanged, the ranging code is a pseudo-random sequence, L is an odd number, and the integral lengths of the two groups of matched filters are almost equal. Suboptimal, both sets of depths are L.

Among them, step S103 calculates the power value of 2L sampling points in T _s time based on two sets of matched filter integral values, which is calculated based on the sum of the first set and the second set of matched filter I/Q integral values.

Among them, in order to further improve the suppression of autocorrelation function side lobe interference, in step S103, the acquisition information list can be constrained to only store one piece of acquisition information with the maximum power value within 2L sampling intervals. According to the uniqueness of the autocorrelation function peak, in When a higher power value is detected within 2L sampling intervals, the existing record is replaced.

Among them, in order to further improve the efficiency of signal search, if no signal is detected in the matched filter search of steps S102 and S103 within two consecutive frames of time 2T _f , the search for the current target pseudolite will be exited or the capture information list will be cleared and the search will be restarted. In highly dynamic applications, you can change the search frequency point and then start the matching filter search.

Among them, in step S104, the capture time slot value is calculated relative to the first record timestamp K _1. The first record in the capture information list is marked as time slot 0. The increment of the subsequent record sampling point count value is calculated. According to each time There are 2L sampling points in the slot, converted to the time slot value:

Among them, the signal frequency estimation in step S105 Frequency deviation is calculated independently based on each captured record/> Then find the mean:

m is the number of records in the captured information list. Since the integration time of the two sets of matched filters is approximately Therefore, the detectable range of the above signal frequency estimate is/> The signal reception power based on ground-based navigation is relatively strong and the averaging process,/> The estimation accuracy is/> within the range.

In addition, in order to further improve the accuracy of signal frequency estimation, signal frequency estimation It can be calculated after the time jump pattern capture is completed and the false alarm capture information record is deleted.

Example 2

Figure 3 is a schematic diagram of the composition of an embodiment of the ground-based navigation signal rapid acquisition system of the present invention. As shown in Figure 3, the embodiment includes: a carrier numerically controlled oscillator 120, a digital downconverter 130, a low-pass filtering and weighting module (170, 180), a sampling numerically controlled oscillator 140, a sampling point continuous counter 150, a decimator ( 190, 200), match searcher 210, time-hopping pattern capture and frequency estimation module 220.

The carrier numerically controlled oscillator 120 generates a local reference carrier signal 205. The reference carrier signal 205 is generally a 3-5 bit signal. The digital downconverter 130 orthogonally mixes the input ground-based navigation digital signal 205 and the local reference carrier signal 205, and outputs multi-bit I/Q baseband signals 211 and 212.

The I/Q baseband signals 211 and 212 pass through the low-pass filtering and reweighting modules 170 and 180 to obtain 2 to 4-bit reweighted I/Q baseband signals 213 and 214. In order to take into account quantization loss and resource consumption, preferably, the I/Q baseband signals 213 and 214 can be 2 bits.

The sampling digitally controlled oscillator 140 generates a twice code rate resampled clock signal 218. In static or low dynamic applications, the frequency of the required resampled clock signal 218 can be calculated at the nominal code rate, while in high dynamic applications, small changes in the actual code rate due to the Doppler effect should be taken into account. The sampling point continuous counter 150 performs continuous counting based on the sampling clock signal 218, and outputs a continuous count value 217 as a timestamp of the capture process.

The weighted I/Q baseband signals 213 and 214 enter the extractors 190 and 200 and are extracted with the resampled clock signal 218 to obtain the resampled I/Q baseband signals 215 and 216, and enter the matching searcher 210.

The search results 219 of the matching searcher 210 are used as inputs to the time-hopping pattern capture and frequency estimation module 220 to capture the time-hopping pattern and estimate the signal frequency.

Figure 4 is a schematic diagram of the composition of the matching searcher according to the embodiment. As shown in Figure 4, it includes: delay register (310, 320), adder (330, 340), 2-divider 400, 3-bit 2L level shift register (350, 360), selector (370, 380) , 1-bit L-stage shift register 390, a first set of matched filters (410, 430), a second set of matched filters (420, 440), and a peak recorder 450.

The resampled I/Q baseband signals 215 and 216 enter the delay registers 310 and 320 to obtain delayed signals 301 and 302, and enter the adders 330 and 340 with the undelayed signals 215 and 216 to obtain the sum of the two adjacent sampling points. Signals 311 and 312, if the input resampled I/Q baseband signals 215 and 216 are 2 bits, then the signals 311 and 312 are 3 bits.

The sums 311 and 312 of the two sampling points enter the 3-bit 2L stage shift registers 350 and 360, and are divided into odd delay data groups 313 and 315 of length L and even delay data groups 314 and 316 for output, and enter the selectors 370 and 380. .

The resampled clock signal 218 passes through the 2-divider 400 and outputs a selection signal 355 whose frequency is a code rate and a duty cycle of 50%. Under the control of the selection signal 355, the selectors 370 and 380 select odd delay data groups 313, 315 or The even delay data groups 314 and 316 are used as outputs 317 and 318, and the preceding ones of 317 and 318 are The data 321 and 323 are sent to the first set of matched filters 410 and 430, and then/> The data 322 and 324 are sent to the second set of matched filters 420 and 440.

The 1-bit L-level shift register 390 stores L chips of the ranging code sequence. The first part of the sequence Each chip 351 is sent to the first set of matched filters 410 and 430, and then/> Each chip 352 is fed into the second set of matched filters 420, 440.

The integrated values 361(I _k1 ), 363(Q _k1 ) and 362(I _k2 ), 364(Q _k2 ) respectively generated by the first group and the second group of matched filters are input to the peak recorder 450 . The peak recorder 450 will first calculate the sum of the integral values of the two sets of filters, then calculate the power value, and compare it with the preset threshold. If it is greater than the threshold, record the following information: I/Q output by the first set of matched filters 410 and 430 Integral values 361, 363 (I _k1 , Q _k1 ), I/Q integral values 362, 364 (I _k2 , Q _k2 ) output by the second set of matched filters 420, 440, power value and sampling point continuous count value K _k . The peak recorder 450 only records one piece of information with the maximum power value within 2L sampling points.

The time-hopping pattern capture and frequency estimation module 220 calculates the capture time slot value T _k according to the continuous count value K _k of sampling points recorded by the peak recorder 450: Sub-samples that constitute the time-hopping pattern are captured to capture the time-hopping pattern; frequency estimation is calculated based on the I/Q integral values of the first set of matched filters and the second set of matched filter outputs recorded by the peak recorder 450/>

Among them, m is the number of records in the peak recorder.

Based on the matching filtering technology, the present invention realizes three-dimensional fast search of time domain, frequency domain and transmission time slot of ground-based navigation signals. Taking the design parameters of the Locata system as an example: the present invention can capture the target pseudolite signal within 5 to 10 ms, and search and capture all pseudolites in the system within 50 to 100 ms; the estimated signal frequency range reaches -10 to +10 kHz. For static or low dynamic applications, no additional Doppler frequency point search is required; the frequency domain search interval is 10kHz. In high dynamic applications, when the line-of-sight speed reaches 5km/s, the corresponding Doppler frequency shift range -40～40kHz, the number of search frequency points is 9, and the target pseudolite can be captured within 21～26ms in the worst case.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified. Modifications or equivalent substitutions without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of the claims of the present invention.

Claims (10)

1. A method for quickly acquiring ground-based navigation signals, which is characterized by comprising the following steps: Step 1: The ground-based navigation digital signal sampled at a rate higher than four times the code rate is subjected to orthogonal digital down-conversion, low-pass filtering and weighting processing, and then resampled at twice the code rate to obtain a resampled I/Q baseband signal; Step 2: Based on the resampled I/Q baseband signal, with a resolution of 0.5 chips, use two sets of matched filters to search for ground-based pseudolite signals in the time domain; among them, the first set of matched filters has a depth of L-1 and outputs measured before code sequence chip integral value, the second set of matching filter depth L+1, after outputting the ranging code sequence/> Chip integral value, L is the ranging code sequence period length, one transmission time slot T _s of the ground-based navigation time-hopping signal broadcasts a ranging code with a complete period length; Step 3: Calculate the power value of 2L sampling points at time T _s based on the two sets of matched filter integral values. When the power value is greater than the set threshold P _th , use the continuous count value K _k of the sampling points as the timestamp to integrate the two sets of matched filter points. The values I _k1 /Q _k1 , I _k2 /Q _k2 , and power value P _k are recorded in the capture information list; Step 4: According to the capture information list, the capture time slot value T _k is calculated based on the timestamp to form a time-hopping pattern subsample, and the time-hopping pattern capture of the signal is completed; Step 5: According to the captured information list, calculate the signal frequency estimate based on two sets of matched filter integral values. 2. A method for quickly acquiring ground-based navigation signals as claimed in claim 1, characterized in that: The quadrature digital down-conversion process is Perform a frequency domain search of the signal for frequency intervals. 3. A method for quickly acquiring ground-based navigation signals as claimed in claim 1, characterized in that: The acquisition information list stores only one piece of acquisition information with the maximum power value within 2L sampling intervals. 4. A method for quickly acquiring ground-based navigation signals as claimed in claim 1, characterized in that: According to the matching filter search, if no signal is detected within two consecutive frame times 2T _f , the search for the current target pseudolite will be exited or the capture information list will be cleared to restart the search, where T _f is the frame time of the ground-based navigation signal jump launch. , including N transmission time slots T _s . 5. A method for quickly acquiring ground-based navigation signals as claimed in claim 1, characterized in that: The capture slot value T _k is calculated relative to the first record timestamp K ₁ : 6. A method for quickly acquiring ground-based navigation signals as claimed in claim 1, characterized in that: The signal frequency estimate Calculation method adopted: Among them, m is the number of records in the captured information list. 7. A method for quickly acquiring ground-based navigation signals as claimed in claim 6, characterized in that: The signal frequency estimate It is calculated after completing the time jump pattern capture and deleting the false alarm capture information record. 8. A rapid acquisition system for ground-based navigation signals, characterized by including: Carrier CNC oscillator generates local reference carrier signal; A digital downconverter, connected to the carrier digitally controlled oscillator, orthogonally downconverts the input intermediate frequency sampling signal to zero intermediate frequency, and outputs an I/Q baseband signal; A low-pass filtering and reweighting module is connected to the digital downconverter, low-pass filters the signal according to the code rate, and reweights it into a 2-bit I/Q signal; Sampling a digitally controlled oscillator to generate a resampled clock signal; A sampling point continuous counter, connected to the sampling numerical control oscillator, to continuously count the sampling points after resampling; An extractor, connected to the low-pass filtering and reweighting module and the sampling CNC oscillator, resamples the signal output by the low-pass filtering and reweighting module to obtain a resampled I/Q signal with twice the code rate; A matching searcher, connected to the decimator, a sampling numerically controlled oscillator, and a sampling point continuous counter, and uses a matching filter to search for signals; A time-hopping pattern capture and frequency estimation module, connected to the matching searcher, performs time-hopping pattern capture and signal frequency estimation based on the matching search results; The matching searcher includes two sets of matching filters: the first set of matching filters, before outputting the ranging code sequence The I/Q integral value of L-1 sampling points for each chip; the second set of matched filters, after outputting the ranging code sequence/> The I/Q integral value of L+1 sampling points for each chip; The matching searcher also includes a peak recorder, which is connected to the first set of matched filters, the second set of matched filters, and a sampling point continuous counter, and calculates the power value and the preset value based on the integral values of the two sets of matched filters. Threshold comparison, if it is greater than the threshold, record a piece of information: the I/Q integral value I _k1 /Q _k1 of the first set of matched filter output, the I/Q integral value I _k2 /Q _k2 of the second set of matched filter output, and the power value and sampling point continuous count value K _k . 9. A rapid acquisition system for ground-based navigation signals as claimed in claim 8, characterized in that: The peak recorder only records one piece of information with the maximum power value within 2L sampling points. 10. A rapid acquisition system for ground-based navigation signals as claimed in claim 8, characterized in that: The time-hopping pattern capture and frequency estimation module: calculates the capture time slot value T _k according to the continuous count value K _k of sampling points recorded by the peak recorder: Subsamples that constitute the time-hopping pattern are used to capture the time-hopping pattern; frequency estimation is calculated based on the I/Q integral values of the first and second sets of matched filter outputs recorded by the peak recorder/> Among them, m is the number of records in the peak recorder.