CN105049081A - Long-code spread spectrum signal rapid capturing method adaptive to high dynamic environment - Google Patents

Abstract

The invention discloses a method for quickly capturing long code spread spectrum signals adapted to high dynamic environments. The method includes: using an analog-to-digital converter to sample the spread-spectrum signal, and then obtaining a complex baseband signal through a digital down-converter; then in the first dwell stage, using code phase compression and fast Fourier transform to realize time-frequency two Dimensional search to determine the approximate pseudo-code phase compression interval and estimated frequency offset; in the second dwell stage, use the traditional coherent accumulation algorithm to search each code phase in the code phase compression phase interval one by one. The present invention is characterized in that: the code phase compression correlator is used for large-scale search in the time domain, and the fast Fourier transform is used for parallel search in the frequency domain, which can quickly capture large dynamic spread spectrum signals; at the same time, the method has low complexity , can save a lot of hardware resources.

Description

A Fast Acquisition Method of Long Code Spread Spectrum Signal Adapted to High Dynamic Environment

technical field

The invention relates to a method for quickly capturing long code spread spectrum signals adapted to high dynamic environments in a radio communication and navigation system.

Background technique

In direct sequence spread spectrum systems, pseudo code acquisition plays a very important role in establishing a good communication link. In a high dynamic environment, the spread spectrum receiver and the transmitter have a relatively large speed of motion, and considering factors such as anti-interference and anti-interception, a longer spread spectrum code is often used, so for the receiver, the acquisition phase requires The searched code phase and Doppler frequency offset range is very large, and the acquisition time required by the traditional serial acquisition method is very long, which cannot meet the requirements of fast acquisition in a high dynamic environment.

At present, there are three main types of fast acquisition methods for spread spectrum signals under high dynamic conditions: (1) using fast Fourier transform/inverse fast Fourier transform to realize pseudo-code phase capture, changing the serial search of code phase into parallel search, However, Doppler frequency shift and symbol flip have a great impact on its acquisition performance, and the acquisition algorithm requires a long Fourier transform resource when capturing long codes. (2) Use fast Fourier transform to capture Doppler frequency offset, combining multiple partial matched filters and fast Fourier transform, the capture speed is very fast, but as the period of the pseudo code becomes longer and the signal Oversampling will consume a lot of hardware resources. (3) Two-dimensional compressed correlation acquisition method, the acquisition algorithm is aimed at the rapid acquisition of the spread spectrum system in the case of large frequency offset and long code, and the compression search of code phase and Doppler frequency offset is completed within the unit dwell time Yes, this method saves at least half the time compared with the traditional method. However, the acquisition algorithm increases the demand for hardware resources in the process of frequency compression, and the acquisition bandwidth of a single dwell is limited by the number of frequency compression channels.

Contents of the invention

In view of the above-mentioned problems in the prior art, the object of the present invention is to provide a fast acquisition method for high dynamic long code spread spectrum signals based on code phase compression and fast Fourier transform. Its characteristics are as follows: (1) In the time domain, the code-phase compression correlator is used for large-scale search, and in the frequency domain, the fast Fourier transform is used for parallel search. Compared with the two-dimensional compression correlation acquisition method, this method can further reduce Acquisition time; (2) By reasonably selecting the length of the code phase compression correlator, high dynamic signal acquisition with multiple Doppler frequency deviations can be completed; (3) Compatible with matched filters or fast Fourier transform/inverse fast Fourier transform Compared with the pseudo-code capture method of the present invention, in the case of a long pseudo-code period, the complexity of the method of the present invention is lower, and a large amount of hardware resources can be saved.

The object of the present invention is achieved through the following technical solutions:

A long code spread spectrum signal fast acquisition method based on code phase compression and fast Fourier transform, characterized in that it includes:

A. Use the analog-to-digital converter to sample the spread-spectrum signal received by the receiver, and then use the digital down-converter to obtain the complex baseband signal;

B. Use code phase compression and fast Fourier transform to realize time-frequency two-dimensional search, determine the approximate pseudo-code phase interval and frequency offset interval, and record it as the first dwell stage;

C. Use the traditional coherent accumulation algorithm to search one by one for the phase points in the optimal compressed code phase interval obtained in the first dwell stage, which is recorded as the second dwell stage.

Described step A further comprises:

A1, the sampling frequency of setting digital-to-analog converter is f _s , and its value is S times of pseudo-code rate;

A2. The spread spectrum signal received by the receiver is sampled by an analog-to-digital converter and digitally down-converted to obtain a complex baseband signal.

Said step B further comprises:

B1. Set the code phase compression factor as K, and perform a code phase compression correlation on the code compression sequence formed by the local pseudocode of K continuous phases and the complex baseband signal, and perform a quick and rough search on the code phase interval;

B2. Fast Fourier transform is performed on the output of the code phase compression correlator to realize the parallel capture of the Doppler frequency offset.

Said step B1 further comprises:

B11. Define K consecutive code phases as a code phase compression interval, and assume that the entire pseudo-code length can be divided into L code phase compression intervals. Let a certain code phase compression interval be [τ+iK,τ+iK+K-1], where i=0,1,2,3,...L-1, that is, i represents the segment number of the code phase compression interval , τ+iK represents the initial phase of the code phase compression interval, and c(τ+iK) represents the pseudo-code sequence whose phase is τ+iK. Then by summing the bipolar local pseudo-codes in the code phase compression interval, the code compression sequence is obtained

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; iK</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; iK</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

B12, setting the chip number M corresponding to the integration time of the code phase compression correlator, and the corresponding sampling point number SM;

B13. Set the segment number of the local pseudo-code as i=0, perform compression correlation integration on the obtained code compression sequence and the complex baseband signal, and obtain a compression correlation value.

Described step B2 further comprises:

B21, setting the threshold value of the first dwelling stage as T ₁ ;

B22. Take the compressed correlation values for P consecutive times, and use the P-order delay line to delay the compressed correlation values;

B23, performing fast Fourier transform of N (N>P) points for each output of the P-order delay line;

B24. Determine the maximum value of the modulus of the N-point fast Fourier transform output value and its corresponding channel number K _max ;

B25, if the maximum value of the modulus value of the output value is less than the preset threshold value T ₁ , then take i=i+1, and set the next compressed code phase interval [τ+iK,τ+iK+K-1] , and then repeat the search step of the first dwell stage until the maximum value of the modulus value of the output value is greater than the threshold value of the first dwell stage;

B26. If the maximum value of the modulus value of the output value is greater than the preset threshold value T ₁ , then the optimal compressed code phase interval [τ ₀ ,τ ₀ +K-1] and the optimal compressed code interval can be determined. The initial phase τ ₀ , and the approximate value of the Doppler frequency offset can be estimated by using the channel number corresponding to the maximum value of the modulus value of the output value K _max f _s /(NSM), and the Doppler frequency offset corresponding to The frequency is fed back to the digital down converter, the search of the code phase in the first dwell stage is suspended, and the second dwell stage is entered.

Said step C further comprises:

C1, setting the threshold value of the second dwelling stage as T ₂ ;

C2. In the optimal compression code phase interval [τ ₀ ,τ ₀ +K-1] of the local pseudo code, first use the local pseudo code sequence whose code phase is the optimal compression code phase τ ₀ to perform correlation integration with the complex baseband signal ;

C3. Obtain the relevant value of the relevant integral;

C4. If the correlation value of the correlation integral is less than the preset threshold value T ₂ , verify the next code phase in the optimal compressed code phase interval until the entire optimal compressed code phase interval is searched;

C5. If the correlation value is greater than the threshold value T ₂ , it is considered that the capture is successful.

As can be seen from the above-mentioned technical solutions provided by the present invention, the present invention uses a code compression correlator in the time domain, and uses fast Fourier transform in the frequency domain to perform parallel capture, further shortening the capture time; and by reasonably selecting the code phase The compressed correlation length can realize the capture of Doppler frequency deviation; meanwhile, the invention is relatively simple and flexible in hardware implementation, and can save a lot of hardware resources.

Description of drawings

Fig. 1 is a system block diagram of the present invention

Fig. 2 is the processing flowchart of the present invention

Fig. 3 is a schematic diagram of the first resident module of the present invention

Detailed ways

The invention provides a method for quickly capturing long code spread spectrum signals in a high dynamic environment. The core of the present invention is: set the initial phase of the local pseudo code as τ _, define continuous K code phases as a code phase compression interval, and use τ as the initial phase of the bipolar local pseudo code in the code phase compression interval The codes are summed to obtain a code compression sequence. The spread spectrum signal received by the receiver is sampled by an analog-to-digital converter and digitally down-converted to obtain a complex baseband signal, and then the complex baseband signal and the code compression sequence are subjected to compression correlation integration to obtain a compression correlation value. Then, the compression correlation value is delayed by a P-order delay line, and N (N ≥ P) point complex fast Fourier transform is carried out, and then the maximum value of the modulus value of the fast Fourier transform output value is selected to compare with the threshold value, If it is less than the threshold value, then search for the next compressed code phase interval, then repeat the search steps of the first dwell stage until the maximum value of the modulus value of the output value is greater than the threshold value of the first dwell stage; if greater than the threshold value, the rough compression capture of the code phase is completed, the optimal compressed code phase interval is obtained, and the second dwell stage is entered to complete the verification of the code phases in the optimal compressed code phase interval one by one.

The system block diagram of the method for fast acquisition of long code spread spectrum signals based on code phase compression correlator and fast Fourier transform of the present invention is as shown in Figure 1, including analog-to-digital converter, digital down-converter, pseudo-code and multiple Puller frequency offset dual dwell capture module:

Analog-to-digital converter and digital down-converter: The spread-spectrum signal received by the receiver is processed through analog-to-digital conversion and digital down-conversion to obtain a complex baseband signal.

Pseudo-code and Doppler frequency offset dual-dwell acquisition module: used to complete fast acquisition based on the combination of code-phase compression correlator and fast Fourier transform, which is divided into two dwell stages: (1) in the first dwell In the remaining stage, K consecutive code phases are defined as a code phase compression interval, and the bipolar local pseudo codes in the code phase compression interval are summed to obtain a code compression sequence. Then the code compression sequence is correlated with the complex baseband signal to obtain the compressed correlation value. Then use the P-order delay line to delay the compressed correlation value, and perform N (N≥P) point complex fast Fourier transform on the output of the P-order delay line, and then select the maximum value of the modulus of the fast Fourier transform output value value is compared with the threshold value, if it is less than the threshold value, search for the next compressed code phase interval, and then repeat the search steps of the first dwell stage until the maximum value of the modulus of the output value is greater than the first dwell stage Threshold value; if it is greater than the threshold value, the code phase search in the first dwell stage is suspended, and the approximate value of the optimal compressed code phase interval and Doppler frequency offset is obtained, and the frequency corresponding to the Doppler frequency offset is fed back (2) In the second dwell stage, use the traditional coherent accumulation algorithm to carry out the phase point of the code phase in the best compressed code phase interval captured in the first dwell stage Search one by one to achieve the final capture of pseudocode.

The processing flowchart of the present invention is as shown in Figure 2, comprises the following steps:

Step 201: Sampling the spread spectrum signal received by the receiver.

Step 202: Perform digital down-conversion processing on the sampled spread spectrum signal to obtain a complex baseband signal.

Step 203: Set the compression factor of the code phase as K, the compressed code phase interval of the initial local pseudo-code and the initial phase of the local pseudo-code.

Step 204: Using the initial phase of the local pseudo-code as the initial phase in the compressed code phase interval, generate K paths of bipolar local pseudo-code sequences sequentially delayed by one code phase.

Step 205: Summing the bipolar local pseudo-code sequences delayed by one code phase in K paths sequentially to obtain a code compression sequence.

Step 206: Perform code compression correlation integration on the code compression sequence and the complex baseband signal to obtain a compression correlation value.

Step 207: Delaying the compressed correlation value with a P-order delay line.

Step 208: Perform N (N≥P) point fast Fourier transform on the output of the P-order delay line.

Step 209: Compare the maximum value of the modulus of the output values of the N-point FFT with the _first threshold T1.

Step 210 : If the maximum output value is smaller than the first threshold value, continue to search for the next compressed code phase interval, and return to step 205 .

Step 211: If the maximum output value is greater than the first threshold value, then an approximate value of the Doppler frequency offset can be estimated, and the frequency corresponding to the Doppler frequency offset can be fed back to the digital down-converter.

Step 212: Determine the optimal compressed code phase interval, and firstly select the local pseudocode of the first phase point in the interval.

Step 213: Perform traditional coherent accumulation on the local pseudocode at the phase point.

Step 214: Compare the maximum value of the modulus value of the traditional coherent accumulation output value with the _second threshold value T2.

Step 215: If the maximum value of the modulus of the output value is smaller than the second threshold value, then search for the local pseudocode of the next phase point within the phase interval of the optimal compressed code, and return to step 213.

Step 216: If the maximum value of the modulus of the output value is greater than the first threshold value, it indicates that the final capture of the pseudocode is completed.

The schematic diagram of the first resident module of the long code spread spectrum signal fast acquisition method based on the code phase compression correlator and fast Fourier transform of the present invention is shown in Figure 3, which includes:

K consecutive code phases are defined as a code phase compression interval, and the entire pseudo-code length can be divided into L code phase compression intervals. Let a certain code phase compression interval be [τ+iK,τ+iK+K-1], where i=0,1,2,3,...L-1, that is, i represents the segment number of the code phase compression interval , τ+iK represents the initial phase of the code phase compression interval, c(τ+iK) represents the pseudo-code sequence whose initial phase is τ+iK. Then by summing the bipolar local pseudo-codes in the code phase compression interval, the code compression sequence is obtained

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; iK</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; iK</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

Then the code compression sequence is integrated with the complex baseband signal, and the compression correlation of the entire pseudo code period is divided into multiple short-term compression correlations by using the P frequency divider. Then use the P-order delay line to delay the compressed correlation value, and perform N (N≥P) point complex fast Fourier transform on the output of the P-order delay line, and then select the maximum value of the modulus of the fast Fourier transform output value value is compared with the threshold value, if it is less than the threshold value, search for the next compressed code phase interval, and then repeat the search steps of the first dwell stage until the maximum value of the modulus of the output value is greater than the first dwell stage Threshold value; if it is greater than the threshold value, the code phase search in the first dwell stage is suspended, the best compressed code phase interval is determined, and the estimated value of Doppler frequency offset is about K _max f _s /(NSM), The frequency corresponding to the Doppler frequency offset is fed back to the digital down-converter, and at the same time enters the second dwell stage.

To sum up, the present invention provides a method for fast acquisition of long code spread spectrum signals adapted to high dynamic environments.

The above is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

1. adapt to a long code spread-spectrum signal quick capturing method for high dynamic environment, it is characterized in that, comprising:

A, utilize analog to digital converter to sample to the spread-spectrum signal that receiver receives, then utilize digital down converter to obtain complex base band signal;

B, utilize code phase to compress to realize time-frequency two-dimensional search for fast Fourier transform, determine the interval and frequency deviation interval of pseudo-code phase roughly, be designated as the first resident stage;

C, utilize traditional coherent accumulation algorithm to obtain first resident stage optimal compression code phase interval in phase point search for one by one, be designated as the second resident stage.

2. a kind of long code spread-spectrum signal quick capturing method adapting to high dynamic environment according to claim 1, it is characterized in that, described steps A comprises further:

A1, the sample frequency arranging digital to analog converter are f _s, its value is S times of pseudo-bit rate;

The spread spectrum that A2, receiver receive frequently signal obtains complex base band signal after analog to digital converter sampling and Digital Down Convert.

3. a kind of long code spread-spectrum signal quick capturing method adapting to high dynamic environment according to claim 1, it is characterized in that, described step B comprises further:

B1, set the code phase compressed coefficient as K, the code compressed sequence that the local pseudo-code of K road continuous phase is formed is carried out code phase to complex base band signal and compresses relevant, carry out quick, rough search to code phase is interval;

B2, to code phase compression correlator output carry out fast Fourier transform, realize the parallel capture to Doppler shift.

4. a kind of long code spread-spectrum signal quick capturing method adapting to high dynamic environment according to claim 3, it is characterized in that, described step B1 comprises further:

B11, a continuous K code phase to be defined as between a code phase compressional zone, if whole pseudo-code length can be divided between L code phase compressional zone.If between certain code phase compressional zone be [τ+iK, τ+iK+K-1], wherein i=0,1,2,3 ... L-1, namely i represents the fragment sequence number between this code phase compressional zone, and τ+iK represents the start-phase between this code phase compressional zone, and c (τ+iK) represents that phase place is the pseudo-code sequence of τ+iK.Then by suing for peace to the local pseudo-code of the bipolarity in this code phase compressional zone, obtain a yard compressed sequence

$C_c\left(i\right)=\underset{m=0}{\overset{K-1}{\mathrm{\&Sigma;}}}c(\mathrm{\&tau;}+m)=c(\mathrm{\&tau;}+\mathrm{iK})+c(\mathrm{\&tau;}+\mathrm{iK}+1)+\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;+c(\mathrm{\&tau;}+(i+1)K-1);$

B12, arrange code phase compression correlator the chip number M corresponding to the time of integration, corresponding sampling number SM;

B13, set the fragment sequence number of local pseudo-code as i=0, the code compressed sequence obtained and complex base band signal are carried out compression correlation intergal, obtain compression correlation.

5. a kind of long code spread-spectrum signal quick capturing method adapting to high dynamic environment according to claim 3, it is characterized in that, described step B2 comprises further:

B21, to arrange the threshold value in the first resident stage be T ₁;

B22, get the compression correlation of continuous P time, utilize P rank delay line to postpone compression correlation;

B23, each output of P rank delay line carried out to the fast Fourier transform that N (N > P) puts;

B24, determine the N point quick Fourier conversion maximum of modulus value of output valve and the channel number K corresponding to it _max;

If the maximum of the modulus value of B25 output valve is less than the threshold T pre-set ₁, then get i=i+1, arrange [τ+iK, τ+iK+K-1] between next compressed code phase region, then repeat the search step in the first resident stage, until the maximum of the modulus value of output valve is greater than the threshold value in the first resident stage;

If the maximum of the modulus value of B26 output valve is greater than the threshold T pre-set ₁, then optimal compression code phase interval [τ can be determined ₀, τ ₀+ K-1], and the start-phase τ in optimal compression code interval ₀, and channel number corresponding to the maximum of the modulus value of output valve can be utilized to estimate the approximation of Doppler shift for K _maxf _s/ (NSM), and by frequency feedback corresponding for this Doppler shift to digital down converter, suspend the search of the first resident stage code phase, entered for the second resident stage.

6. a kind of long code spread-spectrum signal quick capturing method adapting to high dynamic environment according to claim 1, it is characterized in that, described step C comprises further:

C1, to arrange the threshold value in the second resident stage be T ₂;

C2, optimal compression code phase interval [τ in local pseudo-code ₀, τ ₀+ K-1] in, first use code phase to be optimal compression code phase τ ₀local pseudo-code sequence and complex base band signal carry out correlation intergal;

C3, the correlation of correlation intergal;

If the correlation of C4 correlation intergal is less than the threshold T pre-set ₂, then the next code phase in optimal compression code phase interval is verified, until the search of whole optimal compression code phase interval is complete;

If C5 correlation is greater than threshold T ₂, then acquisition success is thought.