CN116719063A - Quick capturing method and system for foundation navigation signals - Google Patents

Quick capturing method and system for foundation navigation signals Download PDF

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Publication number
CN116719063A
CN116719063A CN202310691500.3A CN202310691500A CN116719063A CN 116719063 A CN116719063 A CN 116719063A CN 202310691500 A CN202310691500 A CN 202310691500A CN 116719063 A CN116719063 A CN 116719063A
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China
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signal
time
capturing
sampling
matched
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屠惠斌
黎湧
王建峰
屈志航
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University of Electronic Science and Technology of China
Yangtze River Delta Research Institute of UESTC Huzhou
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University of Electronic Science and Technology of China
Yangtze River Delta Research Institute of UESTC Huzhou
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

The application discloses a rapid capturing method and a rapid capturing system for a foundation navigation signal. The method comprises the steps of carrying out quadrature down-conversion, low-pass filtering, re-quantization and re-sampling processing on digital signals to obtain re-sampled I/Q baseband signals, carrying out capturing based on the signals, detecting by using two sets of matched filtering in one ranging code period, collecting a capturing information list by taking continuous counting of sampling points as time stamps, calculating capturing time slot values according to the time stamps to form time hopping pattern subsamples, completing capturing of the time hopping pattern, calculating signal frequency estimation according to two sets of matched filtering integral values, realizing three-dimensional quick searching of a time domain, a frequency domain and a transmitting time slot of a foundation navigation signal, and having the advantages of high capturing speed, large signal frequency estimation range and effectively inhibiting side lobe interference.

Description

Quick capturing method and system for foundation navigation signals
Technical Field
The application relates to the technical field of navigation, in particular to a rapid capturing method and system for signals of a foundation navigation system.
Background
As an important supplement to satellite navigation systems, the ground-based navigation system has unique advantages in certain aspects and can overcome the defects of weak satellite signals, susceptibility to dry resistance, incapability of indoor use and the like. In order to overcome the problem of 'near-far effect', the ground navigation system adopts time hopping/direct sequence-code division multiple access (TH/DS-CDMA) signals on a signal system, and different pseudolites transmit spread spectrum signals in different time slots by dividing time slots, namely a time division spread spectrum communication system, so that the ground navigation system can overcome 'near-far effect' and also has the ranging capability of the spread spectrum signals.
TH/DS-CDMA is not a continuous broadcast signal, and pseudolites in the system all have their own signal transmission time window, and only transmit navigation signals in a specific time slot, and generally only one pseudolite transmission window in a certain time slot is opened, and a plurality of pseudolites are broadcast signals in a time-sharing manner. Even if the time division is adopted, the distances between the receiving device and the pseudolites are unequal, and signals between the pseudolites still have time overlapping at the receiving end. Therefore, in the ground-based navigation system, the transmission window of each pseudolite is not fixed, but a known time hopping sequence with random characteristics, namely a time hopping pattern, is used for avoiding the fixed time overlap of signal reception between the two pseudolites. As in the Locata system, the super frame structure of one time hopping pattern is 200 a long, per frame time T f Within 10 time slots, each time slot having a duration T s For 0.1ms, each pseudolite selects a certain time slot of 10 time slots per frame to transmit signals, and the cycle period of the time hopping pattern is 200.
The traditional spread spectrum signal receiving technology is not applicable due to the introduction of the time hopping signal system, the problem is mainly concentrated in the capturing stage of the signal, the signal is detected in two dimensions of a time domain (code phase) and a frequency domain (Doppler) under the condition of discontinuous broadcasting of the signal, the common detection method comprises serial search, parallel search, FFT and matched filtering, the capturing time and the resource occupation are in inverse proportion, and in general, the FFT and the matched filtering occupy more software and hardware resources, but the capturing time can be greatly shortened.
The capture of the ground navigation signal has two main key problems:
(1) Capturing time hopping patterns
The capturing of the ground navigation signal is to detect the signal not only in the time domain and the frequency domain, but also in multiple transmission time slots of the signal at the same time, and matches with the known time hopping pattern, so that the capturing is the signal detection in three dimensions of the time domain, the frequency domain and the transmission time slots. As understood based on conventional spread spectrum signal acquisition techniques, when a signal is detected at a certain time-domain and a certain frequency-domain two-dimensional point, it is necessary to continue to reside for a number of time slot frames to confirm the presence of a time slot for signal transmission.
(2) Acquisition of signal frequency
Because the foundation navigation system adopts a time hopping signal system, the problem that the frequency traction bandwidth and the capture bandwidth are not matched exists.
The power loss caused by incomplete frequency matching in signal detection accords with sinc 2 Attenuation: p (P) loss (Δf)＝sinc 2 (pi T.DELTA.f). T is the detection integration time, Δf is the frequency deviation, typically whenThe loss is about 3.9dB, which can be detected with a high probability for the reception strength of the ground signal, but in the subsequent signal frequency pulling, due to the system of time-hopped transmission, the adjacent transmission slots are at a frame time T f For average spacing, the frequency error range that can be resolved is about +.>I.e. the frequency pulling bandwidth is not matched to the acquisition bandwidth, which is much smaller than the acquisition bandwidth. In order to achieve a matching of the frequency pulling bandwidth and the acquisition bandwidth, the signal search can be performed with +.>Is frequency resolution, but the resulting signal power loss differences are not significant and can increase acquisition time or resource consumption.
Thus, the acquisition of the ground-based navigation signal is to spread out three-dimensional search in time, frequency and time-hopping transmit slots, and the acquisition of the signal frequency is reduced toWithin the range.
Disclosure of Invention
The technical problem to be solved by the application is to provide a rapid capturing method and a rapid capturing system for a foundation navigation signal so as to achieve rapid capturing of time domain, frequency domain and time hopping pattern of the foundation navigation signal, and the accuracy of frequency capturing is as followsWithin the range.
In order to solve the technical problems, the application firstly provides a rapid capturing method of a foundation navigation signal, which comprises the following steps:
step one, a foundation navigation digital signal sampled at a code rate higher than four times is subjected to quadrature digital down-conversion, low-pass filtering and weight treatment, resampled at a code rate of twice, and a resampled I/Q baseband signal is obtained;
step two, searching for a ground pseudolite signal in a time domain by using two sets of matched filtering with 0.5 chip as resolution based on the resampled I/Q baseband signal; wherein, the first group of matched filtering depth L-1 is before outputting the ranging code sequenceA second group of matched filter depth L+1, outputting ranging code sequence +.>The integral value of each chip, L is the period length of the ranging code sequence, and a transmitting time slot T of the foundation navigation time hopping signal s Broadcasting a ranging code with a complete period length;
step three, calculating T based on two groups of matched filtering integral values s Power value of 2L sampling points in time when the power value is larger than a set threshold P th To samplePoint continuous count value K k For time stamping, two sets of matched filter integral values I k1 /Q k1 、I k2 /Q k2 Power value P k Recording to a capture information list;
step four, calculating a capture time slot value T based on a time stamp according to the capture information list k Forming a time hopping pattern sub-sample, and completing capturing of the time hopping pattern of the signal;
step five, calculating signal frequency estimation based on the two sets of matched filter integral values according to the captured information list
Preferably, the quadrature digital down-conversion process is performed toA frequency domain search is performed on the signal for the frequency interval.
Preferably, the capture information list stores only one piece of capture information of the maximum power value for 2L sampling intervals.
Preferably, the matched filter search is performed at two consecutive frame times of 2T f If no signal is detected, exiting the search of the current target pseudolite or clearing the acquisition information list to restart the search, wherein T f Is the frame time of the time-hopping transmission of the ground navigation signal, and comprises N transmission time slots T s 。
Preferably, the acquisition time slot value T k Record time stamp K relative to first strip 1 And (3) calculating:
preferably, the signal frequency estimationThe adopted calculation method comprises the following steps:
where m is the number of records of the captured information list.
Preferably, the signal frequency estimationIs calculated after the false alarm capturing information record is deleted by the pattern capturing when the jump is completed.
In order to solve the technical problem, the application further provides a rapid capturing system for the foundation navigation signal, which comprises:
a carrier digital controlled oscillator for generating a local reference carrier signal;
the digital down converter is connected with the carrier digital control oscillator, and is used for quadrature down-converting the input intermediate frequency sampling signal to zero intermediate frequency and outputting an I/Q baseband signal;
the low-pass filtering and re-quantizing module is connected with the digital down converter, and is used for carrying out low-pass filtering on the signal according to the code rate and re-quantizing the signal into a 2-bit I/Q signal;
sampling a digital control oscillator to generate a resampled clock signal;
the sampling point continuous counter is connected with the sampling numerical control oscillator and is used for continuously counting resampled sampling points;
the extractor is connected with the low-pass filtering and re-quantizing module and the sampling numerical control oscillator and re-samples the signal output by the low-pass filtering and re-quantizing module to obtain a re-sampled I/Q signal with double code rate;
the matching searcher is connected with the extractor, the sampling numerical control oscillator and the sampling point continuous counter and searches signals by using a matching filter;
the time hopping pattern capturing and frequency estimating module is connected with the matching searcher and is used for capturing the time hopping pattern and estimating the signal frequency based on the matching searching result;
the matched searcher includes two sets of matched filters: a first set of matched filters for outputting the ranging code sequenceI/Q integral values of L-1 sampling points of a chip; a second set of matched filters outputting the ranging code sequence +.>I/Q integration values of the l+1 sampling points of the chip;
the matching searcher further comprises a peak value recorder connected with the first group of matching filters, the second group of matching filters and the sampling point continuous counter, wherein the calculated power value is compared with a preset threshold, and if the calculated power value is larger than the threshold, a piece of information is recorded: I/Q integral value L output by first group of matched filter k1 /Q k1 I/Q integral value I of second group of matched filtering output k2 /Q k2 Power value and sampling point continuous count value K k 。
Preferably, the peak logger records only one piece of information having the maximum power value within 2L sampling points.
Preferably, the time-hopping pattern capturing and frequency estimating module is used for continuously counting the value K according to the sampling points recorded by the peak value recorder k Calculating the acquisition time slot value T k ：Sub-samples constituting a time hopping pattern are subjected to time hopping pattern capturing, and frequency estimation is calculated from I/Q integral values outputted from first and second sets of matched filters recorded by a peak recorder>
Where m is the number of entries in the peak recorder.
The rapid capturing method and system for the foundation navigation signals have the main advantages that:
(1) The three-dimensional quick search of the time domain, the frequency domain and the transmitting time slot of the foundation navigation signal is realized through matched filtering, and the signal can be captured in 5-10 subframe time;
(2) Implementation in a packet-matched filterAccurate estimation of signal frequency over a large range;
(3) Frequency domain searchingThe search number of Doppler frequency points in high dynamic application is greatly reduced for interval, and the capturing time is shortened;
(4) The range finding code sequence code phase is detected completely, so that sidelobe interference of an autocorrelation function can be effectively restrained, and a main peak can be accurately captured.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate the application and together with the description serve to explain the application. In the drawings:
FIG. 1 is a schematic diagram of time-hopping transmission of a ground navigation signal;
FIG. 2 is a flowchart of an embodiment of a method for fast capturing a navigation signal of the present application;
FIG. 3 is a schematic diagram of the rapid acquisition system of the present application;
fig. 4 is a schematic diagram of the composition of a matching searcher in an embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In a ground based navigation system, one time hopping pattern is described using superframes, subframes, and time slots. As shown in fig. 1, one period of the time hopping pattern is called a superframe, and one superframe includes M subframes, each of which is divided into N slots, each of which has a time T s Generally, the same as the ranging code period, the time T of one subframe f Namely N.T s . In a specific application, the upper limit of the deployment number of the ground pseudolites depends on N, that is, in one subframe, only one pseudolite is allowed to transmit signals in each time slot, and the transmission time slot of the pseudolite in the subframe is not fixed.
Example 1
Fig. 2 is a flowchart of an embodiment of a method for fast capturing a navigation signal. The method embodiment shown in fig. 2 mainly comprises the following steps:
step S101, a foundation navigation digital signal sampled at a code rate higher than four times is subjected to quadrature digital down-conversion, low-pass filtering and weight treatment, and resampled at a code rate twice to obtain a resampled I/Q baseband signal;
step S102, searching for an earth-based pseudolite signal in a time domain by using two sets of matched filtering with 0.5 chip as resolution based on the resampled I/Q baseband signal; wherein, the first group of matched filtering depth L-1 is before outputting the ranging code sequenceA second group of matched filter depth L+1, outputting ranging code sequence +.>The integral value of each chip, L is the period length of the ranging code sequence, and a transmitting time slot T of the foundation navigation time hopping signal s Broadcasting a ranging code with a complete period length;
step S103, calculating based on the two sets of matched filter integral valuesT s Power value of 2L sampling points in time when the power value is larger than a set threshold P th With continuous count value K of sampling points k For time stamping, two sets of matched filter integral values I k1 /Q k1 、I k2 /Q k2 Power value P k Recording to a capture information list;
step S104, calculating the capture time slot value T based on the time stamp according to the capture information list k Forming a time hopping pattern sub-sample, and completing capturing of the time hopping pattern of the signal;
step S105, calculating signal frequency estimation based on two sets of matched filter integral values according to the captured information list
In step S101, the quadrature digital down-conversion process is performed by mixing the nominal intermediate frequency of the digital signal for static or low-dynamic application, and in high-dynamic application, the quadrature digital down-conversion process is performed byPerforming frequency domain searching on the signal for the frequency interval; the sampling rate of the original ground navigation digital signal is required to be higher than four times of the code rate, so that the design of a low-pass filtering cut-off frequency index is facilitated, and a resampling clock signal with twice the code rate is generated.
The depth of the first set and the second set of matched filtering in step S102 may be interchanged, the ranging code is a pseudo-random sequence, L is an odd number, and the integration lengths of the two sets of matched filtering are nearly equal. Suboptimal, both sets of depths are L.
Wherein step S103 calculates T based on the two sets of matched filter integral values s The power value of the time 2L sampling points is calculated according to the sum of the first group of matched filtering I/Q integral values and the second group of matched filtering I/Q integral values.
In step S103, the list of acquisition information may be constrained to store only one piece of acquisition information with the maximum power value in 2L sampling intervals, and the existing record is replaced when a higher power value is detected in 2L sampling intervals according to the uniqueness of the peak value of the autocorrelation function.
Wherein, to further improve the efficiency of the signal search, the matched filter search of steps S102, S103 is performed at two consecutive frame times 2T f If no signal is detected, the search of the current target pseudolite is exited or the search is restarted by clearing the acquisition information list, and in the high-dynamic application, the matched filtering search is restarted after the search frequency point is replaced.
In step S104, the capture time slot value is compared with the first record time stamp K 1 Calculating, wherein the first record mark of the capture information list is time slot 0, calculating the increment of the count value of the sampling points of the subsequent records, and converting the increment into a time slot value according to 2L sampling points of each time slot:
wherein the signal frequency estimation in step S105Independently calculating frequency deviation based on each acquisition record>Then, the average value is calculated:
m is the number of entries of the captured information list. The integration time due to the two sets of matched filtering is approximatelyThus, the detectable range of the above signal frequency estimation is +.>Signal receiving power based on ground navigation is relatively strong and averaging is carried out, and the signal receiving power is +.>The estimation accuracy of (2) is +.>Within the range.
In addition, to further improve the accuracy of signal frequency estimation, signal frequency estimationThe calculation can be performed after the jump time pattern capture is completed and the false alarm capture information record is deleted.
Example 2
FIG. 3 is a schematic diagram of the fast acquisition system of the present application. As shown in fig. 3, the embodiment includes: the carrier digital controlled oscillator 120, the digital down converter 130, the low pass filtering and re-quantization modules (170, 180), the sampling digital controlled oscillator 140, the sampling point continuous counter 150, the decimator (190, 200), the match searcher 210, the time hopping pattern acquisition and frequency estimation module 220.
The carrier digitally controlled oscillator 120 generates a local reference carrier signal 205, the reference carrier signal 205 typically being a 3-5 bit signal. The digital down converter 130 quadrature mixes the input ground navigation digital signal 205 with the local reference carrier signal 205, outputting multi-bit I/Q baseband signals 211, 212.
The I/Q baseband signals 211, 212 are subjected to low pass filtering and weighting modules 170, 180 to obtain 2-4 bit weighted I/Q baseband signals 213, 214. To achieve both quantization loss and resource consumption, the I/Q baseband signals 213, 214 may preferably be 2 bits.
The sample numerically controlled oscillator 140 generates a double code rate resampling clock signal 218. In static or low dynamic applications, the frequency of the desired resampling clock signal 218 may be calculated at a 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 continuously counts with reference to the sampling clock signal 218, and outputs a continuous count value 217 as a time stamp of the capturing process.
The re-quantized I/Q baseband signals 213, 214 enter decimators 190, 200, decimate with a re-sampling clock signal 218, obtain re-sampled I/Q baseband signals 215, 216, and enter match searcher 210.
The search result 219 of the match searcher 210 is used as input to the time hopping pattern acquisition and frequency estimation module 220 to perform acquisition of the time hopping pattern and estimation of the signal frequency.
Fig. 4 is a schematic diagram of the composition of an embodiment matching searcher. As shown in fig. 4, includes: delay registers (310, 320), adders (330, 340), 2 dividers 400, 3-bit 2L stage shift registers (350, 360), selectors (370, 380), 1-bit L stage shift register 390, first set of matched filters (410, 430), second set of matched filters (420, 440), peak logger 450.
The resampled I/Q baseband signals 215, 216 enter delay registers 310, 320 to obtain delayed signals 301, 302, and the undelayed signals 215, 216 enter adders 330, 340 to obtain signals 311, 312 of the sum of adjacent sampling points, and if the input resampled I/Q baseband signals 215, 216 are 2 bits, the signals 311, 312 are 3 bits.
The sums 311, 312 of the sampling points are input into 3-bit 2L stage shift registers 350, 360, output into odd delay data groups 313, 315 and even delay data groups 314, 316 of length L, and input into selectors 370, 380.
The resampling clock signal 218 is passed through a frequency divider 400 to output a selection signal 355 having a frequency of 50% of the code rate duty cycle, and under the control of the selection signal 355, the selector 370, 380 selects either the odd delay data group 313, 315 or the even delay data group 314, 316 as the output 317, 318, and the front of 317, 318Data 321, 323 is sent toFirst set of matched filters 410, 430, post->The data 322, 324 is fed into a second set of matched filters 420, 440.
A 1-bit L-stage shift register 390 holds the L chips of the ranging code sequence, the first of the sequenceThe chips 351 are fed into a first set of matched filters 410, 430, post +.>The chips 352 are fed into a second set of matched filters 420, 440.
The integrated values 361 (I) k1 )、363(Q k1 ) And 362 (I) k2 )、364(Q k2 ) Is input to peak logger 450. The peak value recorder 450 will calculate the sum of the integrated values of the two sets of filters, then calculate the power value, compare with the preset threshold, and record the following information if the value is larger than the threshold: the I/Q integrated values 361, 363 (I) output from the first group of matched filters 410, 430 k1 、Q k1 ) The I/Q integration values 362, 364 (I k2 、Q k2 ) Power value and sampling point continuous count value K k . Peak recorder 450 records only one piece of information with the maximum power value in 2L sample points.
The time hopping pattern capturing and frequency estimating module 220 is used for capturing and estimating the continuous count value K of sampling points according to the peak value recorder 450 k Calculating the acquisition time slot value T k ：Forming sub-samples of the time hopping pattern, and capturing the time hopping pattern; calculating a frequency estimate from the I/Q integration values of the first set of matched filters, the second set of matched filters recorded by peak recorder 450>
Where m is the number of entries in the peak recorder.
The application realizes the three-dimensional quick search of the time domain, the frequency domain and the transmitting time slot of the foundation navigation signal based on the matched filtering technology. Taking the design parameters of the Locata system as an example: the application can capture the target pseudolite signal within 5-10 ms, search and capture all pseudolites in the system within 50-100 ms; the estimated range of the signal frequency reaches-10 to +10kHz, and for static or low dynamic application, no additional Doppler frequency point search is needed; the frequency domain searching interval is 10kHz, and in the high dynamic application, when the line-of-sight speed reaches 5km/s, the corresponding Doppler frequency shift range is-40 kHz, the number of searching frequency points is 9, and in the worst case, the target pseudolite can be captured within 21-26 ms.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application, which is intended to be covered by the scope of the claims of the present application.

Claims (10)

1. The quick capturing method of the foundation navigation signal is characterized by comprising the following steps of:
step one, a foundation navigation digital signal sampled at a code rate higher than four times is subjected to quadrature digital down-conversion, low-pass filtering and weight treatment, resampled at a code rate of twice, and a resampled I/Q baseband signal is obtained;
step two, based on resampled I/Q baseband signal, the method uses 0.5 chipFor resolution, searching for ground pseudolite signals in the time domain using two sets of matched filtering; wherein, the first group of matched filtering depth L-1 is before outputting the ranging code sequenceA second group of matched filter depth L+1, outputting ranging code sequence +.>The integral value of each chip, L is the period length of the ranging code sequence, and a transmitting time slot T of the foundation navigation time hopping signal s Broadcasting a ranging code with a complete period length;
step three, calculating T based on two groups of matched filtering integral values s Power value of 2L sampling points in time when the power value is larger than a set threshold P th With continuous count value K of sampling points k For time stamping, two sets of matched filter integral values I k1 /Q k1 、I k2 /Q k2 Power value P k Recording to a capture information list;
step four, calculating a capture time slot value T based on a time stamp according to the capture information list k Forming a time hopping pattern sub-sample, and completing capturing of the time hopping pattern of the signal;
step five, calculating signal frequency estimation based on the two sets of matched filter integral values according to the captured information list
2. A method for rapid acquisition of a ground navigation signal as claimed in claim 1, wherein:
the quadrature digital down-conversion processA frequency domain search is performed on the signal for the frequency interval.
3. A method for rapid acquisition of a ground navigation signal as claimed in claim 1, wherein:
the capture information list stores only one piece of capture information of the maximum power value for 2L sampling intervals.
4. A method for rapid acquisition of a ground navigation signal as claimed in claim 1, wherein:
the matched filtering search is performed at 2T of two continuous frame time f If no signal is detected, exiting the search of the current target pseudolite or clearing the acquisition information list to restart the search, wherein T f Is the frame time of the time-hopping transmission of the ground navigation signal, and comprises N transmission time slots T s 。
5. A method for rapid acquisition of a ground navigation signal as claimed in claim 1, wherein:
the acquisition time slot value T k Record time stamp K relative to first strip 1 And (3) calculating:
6. a method for rapid acquisition of a ground navigation signal as claimed in claim 1, wherein:
the signal frequency estimationThe adopted calculation method comprises the following steps:
where m is the number of records of the captured information list.
7. The method for quickly capturing a navigation signal of a foundation of claim 6, wherein:
the signal frequency estimationIs calculated after the false alarm capturing information record is deleted by the pattern capturing when the jump is completed.
8. A rapid acquisition system for a ground navigation signal, comprising:
a carrier digital controlled oscillator for generating a local reference carrier signal;
the digital down converter is connected with the carrier digital control oscillator, and is used for quadrature down-converting the input intermediate frequency sampling signal to zero intermediate frequency and outputting an I/Q baseband signal;
the low-pass filtering and re-quantizing module is connected with the digital down converter, and is used for carrying out low-pass filtering on the signal according to the code rate and re-quantizing the signal into a 2-bit I/Q signal;
sampling a digital control oscillator to generate a resampled clock signal;
the sampling point continuous counter is connected with the sampling numerical control oscillator and is used for continuously counting resampled sampling points;
the extractor is connected with the low-pass filtering and re-quantizing module and the sampling numerical control oscillator and re-samples the signal output by the low-pass filtering and re-quantizing module to obtain a re-sampled I/Q signal with double code rate;
the matching searcher is connected with the extractor, the sampling numerical control oscillator and the sampling point continuous counter and searches signals by using a matching filter;
the time hopping pattern capturing and frequency estimating module is connected with the matching searcher and is used for capturing the time hopping pattern and estimating the signal frequency based on the matching searching result;
the matched searcher includes two sets of matched filters: first, theA set of matched filters for outputting the ranging code sequenceI/Q integral values of L-1 sampling points of a chip; a second set of matched filters outputting the ranging code sequence +.>I/Q integration values of the l+1 sampling points of the chip;
the matching searcher further comprises a peak value recorder connected with the first group of matching filters, the second group of matching filters and the sampling point continuous counter, and is used for comparing the calculated power value based on the integral values of the two groups of matching filters with a preset threshold, and recording a piece of information if the calculated power value is larger than the threshold: I/Q integral value I output by first group of matched filter k1 /Q k1 I/Q integral value I of second group of matched filtering output k2 /Q k2 Power value and sampling point continuous count value K k 。
9. A rapid acquisition system for a ground navigation signal according to claim 8, wherein:
the peak logger only records one piece of information having the maximum power value within 2L sampling points.
10. A rapid acquisition system for a ground navigation signal according to claim 8, wherein:
the time hopping pattern acquisition and frequency estimation module: according to the continuous count value K of sampling points recorded by the peak value recorder k Calculating the acquisition time slot value T k ：Forming sub-samples of the time hopping pattern, and capturing the time hopping pattern; calculating a frequency estimate from the I/Q integration values of the first and second sets of matched filters recorded by the peak recorder>
Where m is the number of entries in the peak recorder.
CN202310691500.3A 2023-06-13 2023-06-13 Quick capturing method and system for foundation navigation signals Pending CN116719063A (en)

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