CN116094543B - High-precision spread spectrum signal capturing method - Google Patents

Abstract

The invention discloses a high-precision spread spectrum signal capturing method, which comprises the following steps: data sampling is carried out on the received signals; carrying out compensation correction of carrier frequency on the sampled data; performing pseudo code phase correlation despreading on the frequency-corrected sampling data to obtain correlation integral data; calculating according to the related integral data to obtain self-adaptive detection threshold, related integral peak value and side peak information; performing interpolation correction on the pseudo code phase and the carrier frequency; and comparing the corrected correlation integral peak value with the self-adaptive detection threshold to detect whether the received signal is successfully captured, and calculating to obtain the received signal to noise ratio, the spread spectrum code phase and the carrier Doppler frequency shift. The invention can rapidly, effectively and accurately capture the spread spectrum signal.

Description

A high-precision spread spectrum signal capture method

Technical Field

The present invention belongs to the technical field of wireless communications, and in particular relates to a high-precision spread spectrum signal capture method.

Background technique

The spread spectrum communication system uses pseudo-random codes to spread the spectrum of information data at the transmitting end, and despreads the received signal at the receiving end to obtain a carrier signal modulated only by the information data, and then demodulates the carrier to obtain the information data. The time-frequency synchronization of the spread spectrum signal is the core technology of the spread spectrum communication system, including two steps of capture and tracking. Signal capture is the first key link in the processing of spread spectrum received signals. The pseudo-code phase and carrier frequency of the spread spectrum signal are roughly estimated. The purpose is to make the pseudo-code phase and carrier frequency errors between the local signal and the received signal within the traction range of the tracking loop. If the error between the local signal and the received signal exceeds the traction range of the tracking loop, the tracking loop will not be able to lock normally. If the signal capture provides high-precision pseudo-code phase and carrier frequency measurement values, and the error between the local signal and the received signal is small, the tracking loop can effectively and stably lock quickly, thereby realizing data demodulation. Therefore, how to improve the capture accuracy of the pseudo-code phase and carrier frequency of the spread spectrum signal has become one of the key core technologies that need to be solved in the spread spectrum communication system.

Traditional signal capture methods are mainly divided into time domain capture method and frequency domain capture method. As a classic time domain capture method, the sliding correlation capture method has a simple algorithm principle, is easy to implement in engineering, and was widely used in the early stage, but has a long capture time, slow capture speed, and huge calculation amount. The frequency domain capture method often uses Fast Fourier Transform (FFT) to realize signal capture, which mainly includes parallel frequency capture method, parallel code phase capture method, partial matching filter and FFT capture method, etc. Based on the relationship between FFT and signal convolution, the parallel search of the spread spectrum signal pseudo code phase or carrier frequency is realized. Considering the compromise between capture accuracy, search efficiency and data calculation amount, the capture accuracy of the pseudo code phase of the traditional capture method is within the range of ±0.5 code chips, and the capture accuracy of the carrier frequency is within several hundred Hz. If the capture accuracy of the pseudo code phase and carrier frequency is improved, the search step of the pseudo code phase and carrier frequency needs to be reduced, which directly increases the data calculation amount required for all fuzzy intervals, thereby seriously affecting the capture time and search efficiency.

Therefore, traditional signal capture methods have their own technical advantages, but it is difficult to take into account the capture accuracy, capture time, search efficiency, data calculation amount and other technical indicators that influence and restrict each other, and it is impossible to accurately, quickly and effectively capture the pseudo code phase and carrier frequency of the spread spectrum signal.

Summary of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a high-precision spread spectrum signal capture method, which has the advantages of high capture accuracy, simple implementation structure and good real-time processing performance, and can quickly, effectively and accurately capture spread spectrum signals, and provide high-precision receiving signal-to-noise ratio, spread spectrum code phase and carrier Doppler frequency shift for subsequent signal processing.

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

A high-precision spread spectrum signal acquisition method, the method comprising:

Performing data sampling on the received signal;

Carry out carrier frequency compensation correction on the sampled data;

Performing pseudo code phase correlation despreading on the frequency corrected sampling data to obtain correlation integral data;

The adaptive detection threshold, the correlation integral peak value and the side peak information are calculated based on the correlation integral data;

Perform interpolation correction on pseudo code phase and carrier frequency;

The corrected correlation integral peak value is compared with the adaptive detection threshold to detect whether the received signal is captured successfully, and the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift are calculated.

Furthermore, the compensation correction of the carrier frequency of the sampled data specifically includes:

Dividing the carrier frequency deviation into a number of frequency subslots according to the carrier frequency deviation range;

The carrier frequency compensation correction is performed on the sampled data according to the carrier frequency deviation in a plurality of frequency subslots.

Further, dividing the carrier frequency offset into a plurality of frequency subslots according to the carrier frequency offset range specifically includes:

According to the carrier frequency offset range [f _min , f _max ], the carrier frequency offset is divided into K+1 frequency subslots, where f _min is the minimum carrier frequency offset, f _max is the maximum carrier frequency offset, and the carrier frequency offset f _k in the kth frequency subslot is f _min +k×δf, where k is the frequency subslot search round, satisfying k∈(0,1,…,K), and δ _f is the carrier frequency offset search step, satisfying δf＝(f _max -f _min )/K.

Further, the compensation correction of the carrier frequency of the sampled data according to the carrier frequency deviation in a plurality of frequency subslots specifically includes:

According to the carrier frequency deviation f _k and the sampling rate f _samp , the calculation formula CW _k = f _k × 2 ³² /f _samp is used for data conversion to obtain the carrier frequency deviation control word CW _k , CW _k is accumulated to obtain the query address, and the local carrier of the carrier frequency deviation f _k is generated through address mapping and table lookup. The local carrier of the carrier frequency deviation f _k is complex-multiplied with the sampling data to complete the carrier frequency compensation correction of the sampling data.

Furthermore, performing pseudo code phase correlation despreading on the frequency corrected sampled data to obtain the correlation integral data specifically includes:

Perform N-point fast Fourier transform on N local pseudo codes, and obtain N local pseudo code transformation data after taking conjugate;

Performing N-point fast Fourier transform on the N sampled data to obtain N sampled data transformation data, performing complex multiplication operation on the N local pseudo code transformation data and the N sampled data transformation data to obtain N complex multiplication operation data;

Perform N-point inverse fast Fourier transform on the N complex multiplication operation data to obtain N inverse transformation data, and obtain N related integral data after taking the absolute value.

Furthermore, the adaptive detection threshold, the relevant integral peak value and the side peak information calculated according to the relevant integral data specifically include:

The weighted average method is used to obtain the integral mean value V _avg of the (K+1)×N related integral data of all search subslots. Combined with the detection threshold proportional factor κ _thr , the adaptive detection threshold V _thr is obtained as κ _thr ×V _avg ;

A comparative search method is used to obtain the correlation integration peak value V _max , whose corresponding frequency index/pseudo-code phase is _kmax /τ _max , and the correlation integration value corresponding to the frequency index/pseudo-code phase of _kmax /(τ _max -δτ) is V _-δτ , the correlation integration value corresponding to the frequency index/pseudo-code phase of _kmax /(τ _max +δτ) is V _+δτ , the correlation integration value corresponding to the frequency index/pseudo-code phase of (k _max -1)/τ _max is V _-δf , and the correlation integration value corresponding to the frequency index/pseudo-code phase of (k _max +1)/τ _max is V _+δf , where N is the total number of sampled data, R _c is the spread spectrum code rate, δτ is the pseudo-code phase search step, and δτ＝R _c /f _samp is satisfied.

Furthermore, the interpolation correction of the pseudo code phase and the carrier frequency specifically includes:

The pseudo code phase is interpolated and corrected using a trigonometric relationship, and the carrier frequency is interpolated and corrected using a quadratic function.

Furthermore, the interpolation correction of the pseudo code phase using the trigonometric relationship specifically includes:

The pseudo code phase corresponding to the correlation integral peak value V _max is τ _max , the pseudo code phase corresponding to the correlation integral value V _-δτ is τ _max -δτ , and the pseudo code phase corresponding to the correlation integral value V + _δτ is τ _max +δτ . According to the trigonometric function relationship of the pseudo code, the correction value ΔV _τ of the correlation integral peak value is abs(V _+δτ -V _-δτ )/2, and the correction value Δτ of the pseudo code phase is Among them, abs(·) is an absolute value operation, and min(·) is a minimum value operation.

Furthermore, the interpolation correction of the carrier frequency using a quadratic function specifically includes:

The frequency index corresponding to the correlation integral peak value V _max is _kmax , the frequency index corresponding to the correlation integral value V _-δf is _kmax -1, and the frequency index corresponding to the correlation integral value V _+δf is _kmax +1. According to the functional relationship of the coherent integral, the correction value Δk of the frequency index after the quadratic function difference correction is -b/(2a) _-kmax . After calculation, Δk is The correction value ΔV _f of the correlation integration peak is a(k _max +Δk) ² +b(k _max +Δk)+cV _max . After calculation, ΔV _f is a(2k _max Δk+Δk ² )+bΔk.

Further, the use of the corrected correlation integral peak value to compare with the adaptive detection threshold to detect whether the received signal is successfully captured, and the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift are calculated specifically including:

The received signal is detected by comparing the corrected correlation integral peak with the adaptive detection threshold, and the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift are calculated; the corrected correlation integral peak = V _max +ΔV _τ +ΔV _f , compared with the adaptive detection threshold V _thr , when / > When , it indicates that the capture is successful, otherwise the capture fails. When the capture is successful, the received signal-to-noise ratio SNR is calculated as/> The spreading code phase τ _code is τ _max +Δτ, and the carrier Doppler frequency shift f _dopl is f _min +(k _max +Δk)×δf, where L is the spreading code period.

The beneficial effects of the present invention are:

(1) The present invention uses a trigonometric relationship to interpolate and correct the pseudo-code phase, uses a quadratic function to interpolate and correct the carrier frequency, and uses the corrected correlation integral peak value to calculate the received signal-to-noise ratio. Compared with the traditional capture method, the capture accuracy of the spread spectrum signal can be further effectively improved.

(2) The present invention performs parallel despreading of the pseudo-code phase of the sampled data, uses a trigonometric relationship to perform interpolation correction on the pseudo-code phase, and uses a quadratic function to perform interpolation correction on the carrier frequency. Compared with the traditional capture method, it only requires less increase in data calculation complexity, and the algorithm structure is simple and easy to implement.

(3) The present invention can quickly process sampled data with less related calculations and uses multiple data processing branches for parallel search, which greatly shortens the data processing time. Compared with traditional capture methods, the capture speed is significantly improved and has good real-time processing performance.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic flow chart of a high-precision spread spectrum signal acquisition method provided by an embodiment of the present invention;

FIG2 is a schematic diagram of the structural principle of a time-frequency correction module according to an embodiment of the present invention;

FIG3 is a schematic diagram of the structural principle of the parallel correlation module according to an embodiment of the present invention;

4 is a schematic diagram of the algorithm principle of the interpolation correction module for correcting the pseudo code phase by trigonometric interpolation according to an embodiment of the present invention;

FIG5 is a schematic diagram of the algorithm principle of the interpolation correction module using a quadratic function to correct the carrier frequency according to an embodiment of the present invention.

Detailed ways

The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

Traditional signal capture methods have their own technical advantages, but it is difficult to take into account the capture accuracy, capture time, search efficiency, data calculation amount and other technical indicators that influence and restrict each other, and it is impossible to accurately, quickly and effectively capture the pseudo code phase and carrier frequency of the spread spectrum signal.

In order to solve the above technical problems, the following embodiments of a high-precision spread spectrum signal capture method of the present invention are proposed.

Referring to Figure 1, as shown in Figure 1, it is a schematic flow chart of the high-precision spread spectrum signal capture method provided in this embodiment, which is implemented by a data sampling module, a frequency deviation slotting module, a frequency correction module, a local pseudo-code module, a parallel correlation module, a peak search module, an interpolation correction module and a detection solution module.

Specifically, the data sampling module performs data sampling processing on the received signal; the frequency deviation slotting module divides the carrier frequency deviation into several frequency sub-slots according to the carrier frequency deviation range; the frequency correction module performs carrier frequency compensation correction on the sampling data output by the data sampling module according to the carrier frequency deviation in several frequency sub-slots of the frequency deviation slotting module; the parallel correlation module uses the FFT-IFFT algorithm to perform pseudo-code phase correlation despreading on the frequency-corrected sampling data; the peak search module uses the weighted average method to obtain the adaptive detection threshold for all relevant integral data, and uses the comparison search method to obtain the relevant integral peak and side peak information; the interpolation correction module uses the trigonometric relationship to perform interpolation correction on the pseudo-code phase, and uses the quadratic function to perform interpolation correction on the carrier frequency; the detection solution module uses the method of comparing the corrected relevant integral peak with the adaptive detection threshold to detect the received signal, and solves to obtain the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift.

The data sampling module performs data sampling processing on the received signal, and the total number of sampled data N is f _samp /R _c ×L, wherein f _samp is the sampling rate, R _c is the spread spectrum code rate, and L is the spread spectrum code period.

The frequency offset slotting module divides the carrier frequency offset into K+1 frequency subslots according to the carrier frequency offset range [f _min , f _max ], where f _min is the minimum carrier frequency offset, f _max is the maximum carrier frequency offset, and the carrier frequency offset f _k in the kth frequency subslot is f _min +k×δf, where k is the frequency subslot search round, satisfying k∈(0,1,…,K), and δ _f is the carrier frequency offset search step, satisfying δf＝(f _max -f _min )/K.

Referring to Fig. 2, as shown in Fig. 2, it is a schematic diagram of the structural principle of the time-frequency correction module of this embodiment. The frequency correction module performs carrier frequency compensation correction on the sampled data output by the data sampling module according to the carrier frequency deviation in several frequency sub-slots of the frequency deviation slotting module; the frequency correction module performs data conversion according to the carrier frequency deviation _fk in the frequency sub-slot of the frequency deviation slotting module and the sampling rate _fsamp using the calculation formula _CWk = _fk × ²³² / _fsamp to obtain the carrier frequency deviation control word _CWk , accumulates _CWk to obtain the query address, generates the local carrier of the carrier frequency deviation _fk through address mapping and table lookup, performs complex multiplication operation on the local carrier of the carrier frequency deviation _fk and the sampled data output by the data sampling module, and completes the carrier frequency compensation correction on the sampled data.

Referring to Fig. 3, as shown in Fig. 3, it is a schematic diagram of the structural principle of the parallel correlation module of this embodiment. The parallel correlation module uses the FFT-IFFT algorithm to perform correlation despreading of the pseudo code phase on the frequency-corrected sampling data; the first N-point FFT module performs N-point fast Fourier transform on the N local pseudo codes, and obtains N local pseudo code transformation data after taking the conjugate, the second N-point FFT module performs N-point fast Fourier transform on the N sampling data to obtain N sampling data transformation data, the N local pseudo code transformation data and the N sampling data transformation data are complex multiplied to obtain N complex multiplication operation data, the N-point IFFT module performs N-point inverse fast Fourier transform on the N complex multiplication operation data to obtain N inverse transformation data, and obtains N correlation integral data after taking the absolute value.

The peak search module obtains an integral mean value V _avg by a weighted average method for the (K+1)×N correlation integral data of all search subslots, and obtains an adaptive detection threshold V _thr of κ _thr ×V _avg by combining the detection threshold proportional factor κ _thr ; obtains a correlation integral peak value V _max by a comparative search method, and its corresponding frequency index/pseudo-code phase is _kmax / _τmax , and the correlation integral value corresponding to the frequency index/pseudo-code phase of _kmax /( _τmax -δτ) is V _-δτ , the correlation integral value corresponding to the frequency index/pseudo-code phase of _kmax /( _τmax +δτ) is V _+δτ , the correlation integral value corresponding to the frequency index/pseudo-code phase of ( _kmax -1)/ _τmax is V _-δf , and the correlation integral value corresponding to the frequency index/pseudo-code phase of ( _kmax +1)/ _τmax is V _+δf , wherein N is the total number of sampled data, _Rc is the spread spectrum code rate, δτ is the pseudo-code phase search step, and δτ＝ _Rc / _fsamp is satisfied.

Referring to FIG. 4 , FIG. 4 is a schematic diagram showing the algorithm principle of the interpolation correction module of this embodiment for correcting the pseudo code phase by trigonometric interpolation.

The interpolation correction module uses trigonometric relationship to interpolate and correct the pseudo-code phase; the pseudo-code phase corresponding to the correlation integral peak value V _max output by the peak search module is τ _max , that is, point A, the pseudo-code phase corresponding to the correlation integral value V _-δτ is τ _max -δτ, that is, point B, and the pseudo-code phase corresponding to the correlation integral value V _+δτ is τ _max +δτ, that is, point C; according to the trigonometric function relationship related to the pseudo-code, points A, B, and C are in an isosceles triangle. When V _-δτ ≤V _+δτ , B'C is V _+δτ -V _-δτ ,

is a parallelogram and ΔAMM ₂ is an isosceles triangle, MM ₁ is (V _+δτ -V _-δτ )/2, ΔABD and ΔMBM ₁ are similar triangles, AM ₁ is/> After calculation, it is When V _-δτ >V _+δτ , MM ₁ is (V _-δτ -V _+δτ )/2, and AM ₁ is/> After the trigonometric difference correction, the correction value ΔV _τ of the correlation integral peak is abs(V _{+ δτ} -V _{- δτ} )/2, and the correction value Δτ of the pseudo code phase is/> Among them, abs(·) is an absolute value operation, and min(·) is a minimum value operation.

5 , as shown in FIG5 , is a schematic diagram of the algorithm principle of the interpolation correction module of this embodiment using a quadratic function to interpolate and correct the carrier frequency.

The interpolation correction module uses a quadratic function to perform interpolation correction on the carrier frequency; the frequency index corresponding to the correlation integral peak value V _max output by the peak search module is _kmax , i.e. point A, the frequency index corresponding to the correlation integral value V _-δf is _kmax -1, i.e. point E, and the frequency index corresponding to the correlation integral value V _+δf is _kmax +1, i.e. point F; according to the functional relationship of the coherent integral, the three points A, E, and F are fitted into a quadratic function with an opening downward, and the quadratic function equation is set to V = ak ² + bk + c, and the coordinates of the three points A, E, and F are substituted into the quadratic function equation to obtain a = (V _-δf + V _+δf )/2-V _max ,

b＝(V _+δf -V _-δf )/2-(V _-δf +V _+δf -2V _max )×k _max , c＝V _max -ak _max ² -bk _max , the maximum point of the quadratic function must be at the vertex coordinates, and the correction value Δk of the frequency index after the quadratic function difference correction is -b/(2a)-k _max , after calculation, Δk is The correction value ΔV _f of the correlation integration peak is a(k _max +Δk) ² +b(k _max +Δk)+cV _max . After calculation, ΔV _f is a(2k _max Δk+Δk ² )+bΔk.

The detection and solution module uses the method of comparing the corrected correlation integral peak with the adaptive detection threshold to detect the received signal, and solves the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift; the corrected correlation integral peak = V _max +ΔV _τ +ΔV _f , compared with the adaptive detection threshold V _thr , when / > , it indicates that the capture is successful, otherwise the capture fails. When the capture is successful, the received signal-to-noise ratio SNR is calculated as The spreading code phase τ _code is τ _max +Δτ, and the carrier Doppler frequency shift f _dopl is f _min +(k _max +Δk)×δf, where L is the spreading code period.

This embodiment uses a triangular relationship to interpolate and correct the pseudo-code phase, uses a quadratic function to interpolate and correct the carrier frequency, and uses the corrected correlation integral peak solution to obtain the received signal-to-noise ratio. Compared with the traditional capture method, it can further effectively improve the capture accuracy of the spread spectrum signal. The pseudo-code phase is parallel despread on the sampled data, the pseudo-code phase is interpolated and corrected using a triangular relationship, and the carrier frequency is interpolated and corrected using a quadratic function. Compared with the traditional capture method, only a small amount of data calculation complexity needs to be increased, and the algorithm structure is simple and easy to implement. It can quickly process the sampled data, with a small amount of related operations, and uses multiple data processing branches for parallel search, which greatly shortens the data processing time. Compared with the traditional capture method, the capture speed is significantly improved, and it has good real-time processing performance.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. A high-precision spread spectrum signal acquisition method, characterized in that the method comprises: Performing data sampling on the received signal; Carry out carrier frequency compensation correction on the sampled data; Performing pseudo code phase correlation despreading on the frequency corrected sampling data to obtain correlation integral data; The adaptive detection threshold, the correlation integral peak value and the side peak information are calculated based on the correlation integral data; Interpolation correction is performed on the pseudo code phase and carrier frequency, including: The pseudo code phase is interpolated and corrected by using trigonometric relationship, and the carrier frequency is interpolated and corrected by using quadratic function; The interpolation correction of the pseudo code phase by using the trigonometric relationship specifically includes: The pseudo code phase corresponding to the correlation integral peak value V _max is τ _max , the pseudo code phase corresponding to the correlation integral value V _-δτ is τ _max -δτ , and the pseudo code phase corresponding to the correlation integral value V + _δτ is τ _max +δτ . According to the trigonometric function relationship of the pseudo code, the correction value ΔV _τ of the correlation integral peak value is abs(V _+δτ -V _-δτ )/2, and the correction value Δτ of the pseudo code phase is Wherein, abs(·) is an absolute value operation, min(·) is a minimum value operation, δτ is a pseudo code phase search step, and satisfies δτ＝R _c /f _samp , R _c is a spread spectrum code rate, and f _samp is a sampling rate; The interpolation correction of the carrier frequency by using a quadratic function specifically includes: The frequency index corresponding to the correlation integral peak value V _max is _kmax , the frequency index corresponding to the correlation integral value V _-δf is _kmax -1, and the frequency index corresponding to the correlation integral value V _+δf is _kmax +1. According to the functional relationship of the coherent integral, the correction value Δk of the frequency index after the quadratic function difference correction is -b/(2a) _-kmax . After calculation, Δk is The correction value _ΔVf of the correlation integral peak is a(k _max +Δk) ² +b(k _max +Δk)+cV _max . After calculation, _ΔVf is a(2k _max Δk+Δk ² )+bΔk, where a=(V _-δf +V _+δf )/2-V _max , b=(V _+δf -V _-δf )/2-(V _-δf +V _+δf -2V _max )×k _max , and c=V _max -ak _max ² -bk _max ; The corrected correlation integral peak is compared with the adaptive detection threshold to detect whether the received signal is captured successfully, and the received signal-to-noise ratio, spread spectrum code phase, and carrier Doppler shift are calculated. = V _max +ΔV _τ +ΔV _f , compared with the adaptive detection threshold V _thr , when / > , it indicates that the capture is successful, otherwise the capture fails. 2. The high-precision spread spectrum signal capture method according to claim 1, wherein the compensation correction of the carrier frequency of the sampled data specifically comprises: Dividing the carrier frequency deviation into a number of frequency subslots according to the carrier frequency deviation range; The carrier frequency compensation correction is performed on the sampled data according to the carrier frequency deviation in a plurality of frequency subslots. 3. The high-precision spread spectrum signal acquisition method according to claim 2, wherein the dividing the carrier frequency deviation into a plurality of frequency sub-slots according to the carrier frequency deviation range specifically comprises: According to the carrier frequency offset range [f _min , f _max ], the carrier frequency offset is divided into K+1 frequency subslots, where f _min is the minimum carrier frequency offset, f _max is the maximum carrier frequency offset, and the carrier frequency offset f _k in the kth frequency subslot is f _min +k×δf, where k is the frequency subslot search round, satisfying k∈(0,1,…,K), and δ _f is the carrier frequency offset search step, satisfying δf＝(f _max -f _min )/K. 4. The high-precision spread spectrum signal capture method according to claim 3, wherein the compensation correction of the carrier frequency of the sampled data according to the carrier frequency deviation in a plurality of frequency subslots specifically comprises: According to the carrier frequency deviation f _k and the sampling rate f _samp , the calculation formula CW _k = f _k × 2 ³² /f _samp is used for data conversion to obtain the carrier frequency deviation control word CW _k , CW _k is accumulated to obtain the query address, and the local carrier of the carrier frequency deviation f _k is generated through address mapping and table lookup. The local carrier of the carrier frequency deviation f _k is complex multiplied with the sampling data to complete the carrier frequency compensation correction of the sampling data. 5. The high-precision spread spectrum signal acquisition method according to claim 1, wherein the step of performing pseudo code phase correlation despreading on the frequency-corrected sampled data to obtain the correlation integral data specifically comprises: Perform N-point fast Fourier transform on N local pseudo codes, and obtain N local pseudo code transformation data after taking conjugate; Performing N-point fast Fourier transform on the N sampled data to obtain N sampled data transformation data, performing complex multiplication operation on the N local pseudo code transformation data and the N sampled data transformation data to obtain N complex multiplication operation data; Perform N-point inverse fast Fourier transform on the N complex multiplication operation data to obtain N inverse transformation data, and obtain N related integral data after taking the absolute value. 6. The high-precision spread spectrum signal acquisition method according to claim 4, characterized in that the step of calculating the adaptive detection threshold, the correlation integral peak value and the side peak information based on the correlation integral data specifically comprises: The weighted average method is used to obtain the integral mean value V _avg for the (K+1)×N related integral data of all search subslots. Combined with the detection threshold proportional factor L _thr , the adaptive detection threshold V _thr is obtained as L _thr ×V _avg ; The comparative search method is used to obtain the correlation integral peak value V _max , whose corresponding frequency index/pseudo-code phase is _kmax /τ _max , and the correlation integral value corresponding to the frequency index/pseudo-code phase of _kmax /(τ _max -δτ) is V- _δτ , the correlation integral value corresponding to the frequency index/pseudo-code phase of _kmax /(τ _max +δτ) is V _+δτ , the correlation integral value corresponding to the frequency index/pseudo-code phase of (k _max -1)/τ _max is V _-δf , and the correlation integral value corresponding to the frequency index/pseudo-code phase of (k _max +1)/τ _max is V _+δf , where N is the total number of sampled data. 7. The high-precision spread spectrum signal acquisition method according to claim 6, characterized in that when the acquisition is successful, the received signal-to-noise ratio SNR obtained by the calculation is The spreading code phase τ _code is τ _max +Δτ, and the carrier Doppler frequency shift f _dopl is f _min +(k _max +Δk)×δf, where L is the spreading code period.