CN105301610A - Anti-symbol-hopping novel GPS L5 signal fast acquisition method - Google Patents

Abstract

The invention discloses an anti-symbol-hopping novel GPS L5 signal fast acquisition method. According to the method, in a GPS L5 signal pseudo code full phase parallel searching process, zero-padding processing and cycle grouping are orderly carried out on a received signal and a pseudo code; a cycle correlation operation process is divided into two small-scale cycle secondary correlation processes; the impact of a symbol hopping edge on an acquisition result is eliminated; the computational complexity is reduced; the efficiency of an algorithm is enhanced; the method can be used by a satellite control terminal and a navigation receiver to fast acquire a GPS L5 signal and similar signals without any auxiliary measure; and the problem of acquisition performance loss, which is caused by base code symbol hopping, is solved. Compared with a traditional fast acquisition method, the method provided by the invention has the advantages that the computational complexity is effectively reduced; the efficiency of the algorithm is enhanced; and signal to noise ratio deterioration after correlation integration is avoided.

Description

Novel GPS L5 signal rapid acquisition method capable of resisting symbol hopping

Technical Field

The invention relates to the technical field of satellite measurement and control and navigation signal acquisition, in particular to a novel symbol-hopping-resistant GPSL5 signal fast acquisition method, which is used for realizing the GPSL5 signal fast acquisition in the technical field of measurement and control and navigation.

Background

In the process of GPS modernization, a civil signal newly increased at the frequency point of L5 has the following new characteristics compared with the traditional GPSL1C/A signal: (1) the transmitting power is higher, and a longer pseudo code (the code length is 10230) is adopted, so that a better cross-correlation characteristic is obtained; (2) QPSK modulation is adopted, an auxiliary channel (without modulation data information) is added, and long-time integration can be realized to improve the sensitivity of the receiver; (3) and base code modulation (NH codes with the period of 10 and 20) is added, so that data synchronization is facilitated. The length of the code element of the base code is equal to a pseudo code period, the rate is far lower than the pseudo code rate, and after being added with the pseudo code modulo 2, a longer pseudo code is generated. The base code modulation improves the navigation performance, increases the signal capture difficulty, and changes the search space from two-dimension (frequency and pseudo code phase) to three-dimension (Doppler frequency, pseudo code phase and base code phase). The base code is mainly used in the application environment (e.g. indoor, forest) for capturing weak signals, and together with the doppler frequency, it limits the integration time length. Under the condition of low sensitivity requirement, the GNSS receiver can complete signal capture by using carrier Doppler and pseudo code phase information only, and simultaneously realize synchronization of the base code.

If the receiver does not utilize the base code information in the whole acquisition process, when a pseudo code-phase search (pcs) is performed, the coherent integration result may be sharply reduced due to the objective existence of the base code jump (the jump edge is located in the middle of the pseudo code of the adjacent period, which may also be referred to as a symbol jump edge), which may cause the algorithm to fail. Currently, there are several different types of methods that can overcome the symbol transition edge effect.

In the prior art, a simple and effective method for overcoming the influence of symbol jump edges is as follows: double zero padding + PCS algorithm; the method continuously collects the received signals of two pseudo code periods and the local signals with equal length (consisting of a local replica code of one period and zero padding of one period) to carry out circular correlation (pseudo code full-phase parallel search: PCS), and can effectively avoid the influence of symbol jump edges. The disadvantage of this method is that the computational complexity is multiplied and the efficiency is low, half of the computational effort in the cyclic correlation process is useless.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a novel GPSL5 signal fast acquisition method resisting symbol jump, which is used for quickly acquiring a GPSL5 signal and similar signals under the condition of no auxiliary measures by a satellite measurement and control terminal and a navigation receiver, solves the problem of acquisition performance loss caused by base code jump (jump edge is positioned in the middle of pseudo codes of adjacent periods and can also be called as symbol jump edge) in pseudo code full-phase parallel search of a GPSL5 signal, and effectively reduces the calculation complexity and improves the algorithm efficiency compared with the traditional fast acquisition method.

The above object of the present invention is achieved by the following scheme:

a novel GPSL5 signal fast acquisition method resisting symbol hopping comprises the following steps:

(1) sequentially selecting Doppler frequency according to a set Doppler bin, and carrying out down-conversion on a received GPSL5 signal according to the Doppler frequency to obtain a GPSL5 baseband signal;

(2) using a set down-sampling clock f_downDown-sampling the GPSL5 baseband signal obtained in the step (1) to obtain a down-sampled signal x_d(ii) a And using said down-sampling clock f_downGenerating a local pseudo-code signal h_c；

(3) Separately for down-sampled signals x_dAnd a local pseudo-code signal h_cCarrying out data block acquisition and zero padding operation to obtain a signal data set X and a pseudo code data set H, wherein the specific implementation method comprises the following steps:

in down-sampling the signal x_dCollecting data block with length M, and supplementing N after the data block₀0 forming length N-M + N₀A signal data set X; at local pseudo-code signal h_cThe middle collection length isData of (2)Blocks and complements said data blocks0 forming length N-M + N₀The pseudo code data set H; wherein,f_codeis the pseudo-code frequency, P, of the GPSL5 signal_{n_len}The number of chips of the GPSL5 signal in one pseudo code period; n is a radical of₀＝min(N₁,N₂)，N₁Is an integer andl₁to satisfy the conditionsA minimum positive odd number of; n is a radical of₂Is an integer and $N_2=\frac{4}{3}(2^{l_2}-p)-M,$ l₂p satisfies the condition $\left(\frac{4}{3}\right(2^{l_2}-p)-M)\≥0$ And make it possible to $\left(\frac{4}{3}\right(2^{l_2}-p)-M)$ Take the minimum value,/₂Is a positive even number, and p is a positive integer;

(4) respectively carrying out the signal data set X and the pseudo code data set HPoint decomposition to obtain a first signal component x₁And a second signal component x₂And a first pseudo code component h₁And a second pseudo-code component h₂Wherein: $x_1=\[X\left(1\right),X\left(2\right),...X\left(\frac{3N}{4}\right)\];x_2=\[X\left(\frac{N}{4}+1\right),X\left(\frac{N}{4}+2\right),...X\left(N\right)\];$ $h_1=\[H\left(1\right),H\left(2\right),...,H\left(\frac{N}{4}\right),H\left(\frac{N}{2}+1\right),H\left(\frac{N}{2}+2\right),...,H\left(N\right)\];$ $h_2=\[H\left(\frac{N}{4}+1\right),H\left(\frac{N}{4}+2\right),...,h\left(\frac{N}{2}\right),h\left(\frac{N}{2}+1\right),h\left(\frac{N}{2}+2\right),...,h\left(N\right)\];$

(5) for the first signal component x₁And a first pseudo code component h₁Performing a cyclic correlation integral operation and applying a second signal component x₂And a second pseudo-code component h₂Performing cyclic correlation integral operation, and then adding the two secondary cyclic correlation integral operation results to obtain a total cyclic correlation operation result;

(6) and (5) carrying out correlation peak detection on the total cyclic correlation operation result obtained in the step (5): if the detected correlation peak value is larger than or equal to the set capture threshold, judging that the capture is successful, and entering the step (7); if the detected correlation peak value is smaller than the set capture threshold, judging that the capture fails, adjusting the Doppler frequency, and returning to the step (1) to perform the re-capture;

(7) and obtaining a signal capturing result according to the detection result of the correlation peak.

The novel GPSL5 signal fast acquisition method resisting symbol hopping is as follows, in step (2), f_down>2f_code。

The novel GPSL5 signal fast acquisition method resisting symbol hopping comprises the step (3) if N is₀＝N₁Then, thenIf N is present₀＝N₂Then, thenThen, in the step (5), the L-point FFT processing is adopted to realize the secondary cycle correlation integral operation, and the specific realization method is as follows:

(5a) for the first signal component x respectively₁A second signal component x₂First pseudo code component h₁And a second pseudo-code component h₂Performing L-point FFT to obtain a first signal frequency domain component X_fft,1Frequency domain component X of the second signal_fft,2First pseudo code frequency domain component H_fft,1And a second pseudo-code frequency-domain component H_fft,2；

(5b) The frequency domain component X of the first signal_fft,1And the first pseudo code frequency domain component H_fft,1Is multiplied to obtain a first secondary correlation result Y_fft,1＝H_fft,1 ^*·X_fft,1(ii) a And the frequency domain component X of the second signal_fft,2And a second pseudo code frequency domain component H_fft,2Is multiplied to obtain a second secondary correlation result Y_fft,2＝H_fft,2 ^*·X_fft,2；

(5c) The first operation result Y is used_fft,1And the result of the second operation Y_fft,2Adding to obtain Y ═ Y_fft,1+Y_fft,2；

(5d) Performing L-point IFFT on the frequency domain operation result Y, and taking the result beforeAnd taking the point as a total cyclic correlation operation result for carrying out correlation peak detection.

Compared with the prior art, the invention has the following beneficial effects:

(1) in the invention, in the process of the pseudo code full-phase parallel search of the GPSL5 signal, the received signal and the pseudo code are subjected to zero filling processing and then are subjected to cyclic grouping, and the cyclic correlation operation process is decomposed into two small-scale secondary cyclic correlation processes, so that the influence of a symbol jump edge on a captured result is eliminated, the calculation complexity is reduced, and the algorithm efficiency is improved;

(2) the signal and pseudo code grouping method adopted by the invention is simple and easy to realize, and does not involve approximate calculation, so that the signal-to-noise ratio after the correlation integration can not be deteriorated while the calculation amount is reduced.

Drawings

Fig. 1 is a flowchart of a novel symbol-hopping-resistant GPSL5 signal fast acquisition method according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

in the pseudo code full phase parallel search of the GPSL5 signal, the acquisition performance loss is caused by the jump of the base code, aiming at the problem, the invention provides a novel GPSL5 signal fast acquisition method resisting the symbol jump, the method carries out zero filling processing on a received signal and the pseudo code and then carries out cyclic grouping, and the cyclic correlation operation process is decomposed into two small-scale secondary cyclic correlation processes, thereby realizing the fast acquisition of the signal. Wherein: the zero filling processing is to eliminate the influence of the symbol jump edge, and the cyclic correlation decomposition can effectively reduce the captured operand, thereby ensuring the immunity of the invention on the symbol jump edge, and compared with the traditional pseudo code full-phase parallel search computation method (PCS), the method effectively reduces the computation complexity and improves the algorithm efficiency.

The principle of the rapid capture method of the invention is explained as follows:

the circular correlation operation in the pseudo code full phase parallel search method for representing the GPSL5 signal in a matrix form is as follows:

$y=\stackrel{\‾}{H}x;---\left(2\right)$

in formula (1), h [ n ] is represented as a pseudo code signal, x [ n ] is a data set after down-conversion, y [ n ] is a cyclic correlation operation result, and formula (2) is a matrix expression of formula (1).

If zero padding is performed on the local pseudo code, equation (1) can be modified as follows:

first, using only the first half of the correlator output, the vector y and matrix are deletedTo obtain a truncated vector y of N/2 points_TAnd a truncation matrix of N/2 × N

$y_T={\stackrel{\‾}{H}}_{T}x---\left(5\right)$

The decomposition of the compound of formula (5),is decomposed intoThe decomposition method comprises the following steps: will be provided withElement h [ n ] of (1)]Is set to zero, where N/4<n<N/2-1, the remainder being kept unchanged, to giveWill be provided withElement h [ n ] of (1)]Is set to zero, wherein 0<n<N/4-1, the remainder being kept unchanged, to giveNamely:

irrespective of the last column, matrixEach containing N/4 columns of zeros. After removing all zero columns, a matrix is obtainedSimultaneously removing the corresponding row of x to obtain the vector x₀、x₁. As shown in formula (7), y_TIs a vector of N/2 points and,is a matrix of N/2 × 3N/4, x₀、x₁Is a vector of 3N/4 points:

finally, from equation (7), the matrixHave a cyclic character between the row vectors. Thus, the matrix can be converted into a circulant matrix by expanding the rows. As shown in equation (8), for the matrixNewly adding N/4 rows:

after expansion, equation (7) can be modified to the following form:

wherein, y_MIs a vector of points 3N/4,circulant matrix, x, of 3N/4 × 3N/4₀、x₁Is a vector of points 3N/4. y is_MFrom an initial vector y_TN/2 points in, and vector y_DN/4 point composition (to be discarded). The multiplication in equation (9) is replaced by FFT, resulting in the following expression:

$y_M=IFFT\left(\stackrel{\&OverBar;}{FFT\left(h_0\right)}FFT\left(x_0\right)\right)+IFFT\left(\stackrel{\&OverBar;}{FFT\left(h_1\right)}FFT\left(x_1\right)\right)=IFFT\left(\stackrel{\&OverBar;}{FFT\left(h_0\right)}FFT\left(x_0\right)+\stackrel{\&OverBar;}{FFT\left(h_1\right)}FFT\left(x_1\right)\right)---\left(10\right)$

wherein:

from the above equation, the number of points discarded by the new algorithm is reduced by half of the calculated output ((N/2)/N), to one third ((N/4)/(3N/4)).

Recall from the publication (7) that notes the matrixThe last column of (a) is all zeros. Then all zero rows are summed with vector x₀、x₁The last element in (a) can be removed without affecting the calculation result. Thus, can beModified to a circulant matrix of (3N/4-1) × (3N/4-1), x₀、x₁、y_MIs a vector of (3N/4-1) without affecting the useful calculation result y_TOnly the useless result y is affected_D(becomes a vector of (N/4-1)). Further, the method can be used for preparing a novel materialWe can also be in the matrixIs added p all zero columns and all zeros are added after the last column of (x) vector₀、x₁P arbitrary elements are added at the end of (a), so that the secondary correlation length of the signal becomes (3N/4+ p).

Based on the principle of the method, the flow chart of the novel symbol-hopping-resistant GPSL5 signal fast acquisition method is shown in FIG. 1, and the specific implementation steps of the method are as follows:

(1) sequentially selecting Doppler frequency according to a set Doppler bin, and carrying out down-conversion on a received GPSL5 signal according to the Doppler frequency to obtain a GPSL5 baseband signal;

(2) using a set down-sampling clock f_downDown-sampling the GPSL5 baseband signal obtained in the step (1) to obtain a down-sampled signal x_d(ii) a And using said down-sampling clock f_downGenerating a local pseudo-code signal h_c. Wherein, set f_down>2f_codeThe down-sampling clock frequency is set to satisfy the sampling law and take full consideration of reducing the computing resources.

(3) Separately for down-sampled signals x_dAnd a local pseudo-code signal h_cCarrying out data block acquisition and zero padding operation to obtain a signal data set X and a pseudo code data set H, wherein the specific implementation method comprises the following steps:

in down-sampling the signal x_dCollecting data block with length M, and supplementing N after the data block₀0 forming length N-M + N₀A signal data set X; at local pseudo-code signal h_cThe middle collection length isAnd supplementing after said data block0 shapeLength of N-M + N₀The pseudo code data set H; wherein, among others,f_codefor the pseudo code frequency of the GPSL5 signal, the number P of chips of the GPSL5 signal in one pseudo code period_{n_len}＝10230；N₀＝min(N₁,N₂)，N₁Is an integer andl₁to satisfy the conditionsA minimum positive odd number of; n is a radical of₂Is an integer and $N_2=\frac{4}{3}(2^{l_2}-p)-M,$ l₂p satisfies the condition $\left(\frac{4}{3}\right(2^{l_2}-p)-M)\&GreaterEqual;0$ And make it possible to $\left(\frac{4}{3}\right(2^{l_2}-p)-M)$ Take the minimum value,/₂Is a positive even number, and p is a positive integer;

(4) respectively carrying out the signal data set X and the pseudo code data set HPoint cycle decomposition to obtain a first signal component x₁And a second signal component x₂And a first pseudo code component h₁And a second pseudo-code component h₂Wherein: $x_1=\&lsqb;X\left(1\right),X\left(2\right),...X\left(\frac{3N}{4}\right)\&rsqb;;x_2=\&lsqb;X\left(\frac{N}{4}+1\right),X\left(\frac{N}{4}+2\right),...X\left(N\right)\&rsqb;;$ $h_1=\&lsqb;H\left(1\right),H\left(2\right),...,H\left(\frac{N}{4}\right),H\left(\frac{N}{2}+1\right),H\left(\frac{N}{2}+2\right),...,H\left(N\right)\&rsqb;;$ $h_2=\&lsqb;H\left(\frac{N}{4}+1\right),H\left(\frac{N}{4}+2\right),...,h\left(\frac{N}{2}\right),h\left(\frac{N}{2}+1\right),h\left(\frac{N}{2}+2\right),...,h\left(N\right)\&rsqb;;$

wherein, $H(\frac{N}{2}+1)=H(\frac{N}{2}+2)=...=H\left(N\right)=0$

(5) for the first signal component x₁And a first pseudo code component h₁Performing a correlation integral operation and applying a second signal component x₂And a second pseudo-code component h₂Performing correlation integral operation, and then adding the two correlation integral operation results to obtain a total correlation operation result; the specific implementation method comprises the following steps:

(5a) for the first signal component x respectively₁A second signal component x₂First pseudo code component h₁And a second pseudo-code component h₂Performing L-point FFT to obtain a first signal frequency domain component X_fft,1Frequency domain component X of the second signal_fft,2First pseudo code frequency domain component H_fft,1And a second pseudo-code frequency-domain component H_fft,2(ii) a Wherein: if N is present in step (3)₀＝N₁Then, thenIf atN in step (3)₀＝N₂Then, then

(5b) The frequency domain component X of the first signal_fft,1And the first pseudo code frequency domain component H_fft,1The conjugate values of the first and second sub-correlation results are multiplied to obtain a first result Y_fft,1＝H_fft,1 ^*·X_fft,1(ii) a And the frequency domain component X of the second signal_fft,2And a second pseudo code frequency domain component H_fft,2The conjugate values of the first and second sub-correlation results are multiplied to obtain a second result Y_fft,2＝H_fft,2 ^*·X_fft,2；

(5c) The result of the first secondary correlation operation Y is obtained_fft,1And the result Y of the second secondary correlation operation_fft,2Adding to obtain a total frequency domain correlation result Y ═ Y_fft,1+Y_fft,2；

(5d) Carrying out L-point IFFT on the frequency domain correlation result Y and taking the result beforeAnd taking the point as a total cyclic correlation operation result for carrying out correlation peak detection.

(6) And (5) carrying out correlation peak detection on the total correlation operation result obtained in the step (5): if the detected correlation peak value is larger than or equal to the set capture threshold, judging that the capture is successful, and entering the step (7); if the detected correlation peak value is smaller than the set capture threshold, judging that the capture fails, adjusting the value of the Doppler frequency, and returning to the step (1) to perform the re-capture;

(7) and obtaining a capturing result according to the detection result of the correlation peak.

The invention can eliminate the influence of the symbol jump edge, reduce the calculation complexity and improve the algorithm efficiency. In this embodiment, the traditional symbol-hopping-resistant PCS method is compared with the method of the present invention at the same down-sampling frequency, and the comparison result is shown asShown in table 1. Compared with the prior art, the FFT point number of the method is half of that of the traditional PCS algorithm when the down-sampling frequency is between 20.46MHz and 21 MHz. Consider that an N-point FFT requires approximately (N/2) log₂Multiplication (N), then the conventional PCS algorithm needs to be about 3(N/2) log₂(N) + N multiplications, however, the method of the invention requires only 5(N/2) log₂(N) +2N multiplications. For example, when the down-sampling frequency is 21MHz, the FFT count of the conventional PCS is 65536, whereas the FFT count of the present invention is only 32768. Since the number of sampling data points is 42000, the conventional algorithm needs to be zero-padded to 65536 points, while the present invention only needs to be zero-padded to 43692 points. In this case, the amount of calculation of the present invention is reduced by at least 20%. The quantity of the second half section of the FFT output point of the invention is 16384 points, while the quantity of the second half section of the FFT output point of the traditional algorithm is 32768 points, and the second half section is useless because of the influence of symbol jump and needs to be discarded.

Therefore, the invention has less useless calculation amount and less resource waste.

TABLE 1 comparison of the calculated quantities of the conventional PCS Algorithm and the present invention

(20.46 MHz-21 MHz as down-sampling frequency, 0.54MHz as Doppler search frequency range)

After the method and the traditional PCS algorithm are realized through the FPGA, the resource consumption statistical result is shown in the table 2, wherein the statistical result refers to XILINXVirtex-4XC4VSX55, and the statistical result is only a circular correlation calculation part. As can be seen from the statistical results of table 2: the method of the invention requires more resources, however, as the FFT length used by the method of the invention is halved, the FFT processing time is halved, and the data acquisition time is also correspondingly reduced, the acquisition time of the receiver is lower than half of that of the traditional algorithm. Therefore, the total amount of hardware resources consumed by the method is about the same as that of the traditional PCS algorithm (the consumed RAM resources are reduced), and therefore the method is more efficient.

TABLE 2 statistical results of resource consumption for the conventional PCS algorithm and the method of the present invention

	Xtreme DSP slices	Block RAM(18Kb Blocks)	Latency(μs)
				Traditional PCS algorithm	6	18	2622.488
The method of the invention	9	14	1246.168

Wherein, an XtremeDSPslice comprises an 18 multiplied by 18 multiplier, an adder and an integral accumulator.

The above description is only one embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Those skilled in the art will appreciate that the invention may be practiced without these specific details.

Claims (3)

1. A novel GPSL5 signal fast acquisition method resisting symbol hopping is characterized by comprising the following steps:

(1) sequentially selecting Doppler frequency according to a set Doppler bin, and carrying out down-conversion on a received GPSL5 signal according to the Doppler frequency to obtain a GPSL5 baseband signal;

(2) using a set down-sampling clock f_downDown-sampling the GPSL5 baseband signal obtained in the step (1) to obtain a down-sampled signal x_d(ii) a And using said down-sampling clock f_downGenerating local pseudo-codeSignal h_c；

(3) Separately for down-sampled signals x_dAnd a local pseudo-code signal h_cCarrying out data block acquisition and zero padding operation to obtain a signal data set X and a pseudo code data set H, wherein the specific implementation method comprises the following steps:

in down-sampling the signal x_dCollecting data block with length M, and supplementing N after the data block₀0 forming length N-M + N₀A signal data set X; at local pseudo-code signal h_cThe middle collection length isAnd supplementing after said data block+N₀0 forming length N-M + N₀The pseudo code data set H; wherein,f_codeis the pseudo-code frequency, P, of the GPSL5 signal_{n_len}The number of chips of the GPSL5 signal in one pseudo code period; n is a radical of₀＝min(N₁,N₂)，N₁Is an integer and $N_1=\frac{4}{3}(2^{l_1}+1)-M,$ l₁to satisfy the conditions $\left(\frac{4}{3}\right(2^{l_1}+1)-M)\&GreaterEqual;0$ A minimum positive odd number of; n is a radical of₂Is an integer and $N_2=\frac{4}{3}(2^{l_2}-p)-M,$ l₂p satisfies the condition $\left(\frac{4}{3}\right(2^{l_2}-p)-M)\&GreaterEqual;0$ And make it possible toTake the minimum value,/₂Is a positive even number, and p is a positive integer;

(4) respectively carrying out the signal data set X and the pseudo code data set HPoint decomposition to obtain a first signal component x₁And a second signal component x₂And a first pseudo code component h₁And a second pseudo-code component h₂Wherein: $\begin{array}{cc}{x}_1=\&lsqb;X\left(1\right),X\left(2\right),...X\left(\frac{3N}{4}\right)\&rsqb;;& x_2=\&lsqb;X(\frac{N}{4}+1),X(\frac{N}{4}+2),...X\left(N\right)\&rsqb;\end{array};$

$h_1=\&lsqb;H\left(1\right),H\left(2\right),...,H\left(\frac{N}{4}\right),H(\frac{N}{2}+1),H(\frac{N}{2}+2),...,H\left(N\right)\&rsqb;;$

$h_2=\&lsqb;H(\frac{N}{4}+1),H(\frac{N}{4}+2),...,h\left(\frac{N}{2}\right),h(\frac{N}{2}+1),h(\frac{N}{2}+2),...,h\left(N\right)\&rsqb;;$

(5) for the first signal component x₁And a first pseudo code component h₁Performing a cyclic correlation integral operation and applying a second signal component x₂And a second pseudo-code component h₂Performing cyclic correlation integral operation, and then adding the two secondary cyclic correlation integral operation results to obtain a total cyclic correlation operation result;

(6) and (5) carrying out correlation peak detection on the total cyclic correlation operation result obtained in the step (5): if the detected correlation peak value is larger than or equal to the set capture threshold, judging that the capture is successful, and entering the step (7); if the detected correlation peak value is smaller than the set capture threshold, judging that the capture fails, adjusting the Doppler frequency, and returning to the step (1) to perform the re-capture;

(7) and obtaining a signal capturing result according to the detection result of the correlation peak.

2. The method of claim 1 for fast acquisition of a novel symbol hopping-resistant GPSL5 signal, wherein the method comprises the following steps: in step (2), f_down>2f_code。

3. The method of claim 1 for fast acquisition of a novel symbol hopping-resistant GPSL5 signal, wherein the method comprises the following steps: in step (3), if N is present₀＝N₁Then, thenIf N is present₀＝N₂Then, thenThen, in the step (5), the L-point FFT processing is adopted to realize the secondary cycle correlation integral operation, and the specific realization method is as follows:

(5a) for the first signal component x respectively₁A second signal component x₂First pseudo code component h₁And a second pseudo-code component h₂Performing L-point FFT to obtain a first signal frequency domain component X_fft,1Frequency domain component X of the second signal_fft,2First pseudo code frequency domain component H_fft,1And a second pseudo-code frequency-domain component H_fft,2；

(5b) The frequency domain component X of the first signal_fft,1And the first pseudo code frequency domain component H_fft,1Is multiplied to obtain a first secondary correlation result Y_fft,1＝H_fft,1 ^*·X_fft,1(ii) a And the frequency domain component X of the second signal_fft,2And a second pseudo code frequency domain component H_fft,2Is multiplied to obtain a second secondary correlation result Y_fft,2＝H_fft,2 ^*·X_fft,2；

(5c) The first operation result Y is used_fft,1And the result of the second operation Y_fft,2Adding to obtain Y ═ Y_fft,1+Y_fft,2；

(5d) Performing L-point IFFT on the frequency domain operation result Y, and taking the result beforeAnd taking the point as a total cyclic correlation operation result for carrying out correlation peak detection.