CN110830077A - A Fast Acquisition Method to Improve the Receiving Performance of Multi-channel Burst Signals - Google Patents

Abstract

A fast acquisition method for improving the receiving performance of multi-channel burst signals is used to solve the acquisition problem that a message communication user uses a special pseudo code for signal modulation. The method first collects the zero-IF data and pseudo-code, then divides the zero-IF data and pseudo-code into blocks, and uses the double-block expansion method to complete the expansion of the zero-IF data block and the pseudo-code block; According to the arrangement rule of frequency pseudo-code correlation calculation results, phase parallel search and frequency parallel search are completed, and then the acquisition of all pseudo-code phases is completed. The acquisition method of the invention greatly shortens the acquisition search time, and at the same time has excellent acquisition performance, so that this special pseudo-code structure can be applied to practical engineering.

Description

A Fast Acquisition Method to Improve the Receiving Performance of Multi-channel Burst Signals

technical field

The invention relates to a fast acquisition method for improving multi-channel burst signal receiving performance, and belongs to the technical field of spread spectrum communication.

Background technique

The signal format of the message communication receiver is short burst mode, and the signal duration is variable. The signal consists of a sync header, a service segment and a data segment. The synchronization header is composed of periodic short codes without data modulation, and is used to capture signals by the message communication receiver. The message communication receiver receives message communication signals sent by each terminal, wherein each user synchronization header part is composed of the same period short code. When multiple message communication users send inbound signals at the same time, there is a problem of user collision, and the ability to suppress multiple access between users is limited. To solve this problem, a new pseudocode is designed. The pseudo-code design is based on two short-period spreading codes, which are called the main spreading code and the secondary spreading code respectively.

The main spreading code is repeated periodically, and a special pseudo-code structure is formed by inserting sub-spreading codes of unequal lengths after each period of the main spreading code. Different from the constant cycle repeating code, a sub-spreading code sequence of several chips is inserted after each main spreading code cycle. By rationally designing the number of spreading code chips inserted after each cycle, the synchronization can be effectively destroyed. The periodicity of the header reduces the probability of simultaneous inbound collisions by different users. The specific insertion method is shown in Figure 1.

In the special pseudo-code structure design of the message communication signal, a total of X1 cycles of the main spreading pseudo-code are included. This pseudo-code structure design can solve the collision problem of multiple users entering the station at the same time, and at the same time improve the interference suppression ability between multiple users. However, for the message communication receiver, the new pseudo-code structure destroys the characteristics of periodic pseudo-code, which puts forward new requirements for the design of the acquisition system. Existing capture methods are not suitable for capture of special pseudo-code structures.

SUMMARY OF THE INVENTION

The technical solutions of the present invention are: overcoming the deficiencies of the prior art, providing a fast acquisition method for improving the receiving performance of multi-channel burst signals, realizing fast acquisition of modulated signals with special pseudo-code structure, and acquiring probability of inbound signals at any time. All are greater than 99%, and the capture time is short.

The technical solution of the present invention is:

A fast acquisition method for improving multi-channel burst signal receiving performance, comprising the following steps:

(1) Zero-IF data and pseudo-code acquisition

The acquisition start time is generated according to the acquisition start flag, and the acquisition of the zero-IF data and the pseudocode is completed at twice the pseudocode rate. After the acquisition is completed, the acquisition end flag is generated; The intermediate frequency data is stored in the data area, the collected pseudo code is stored in the pseudo code area, and the acquisition start time corresponds to the S-th main spreading code of the zero intermediate frequency data;

(2) Double block expansion

After the acquisition, according to the location where the zero-IF data is stored in the data area and the location where the pseudo-code is stored in the pseudo-code area, the zero-IF data and the pseudo-code are divided into blocks. The expansion of the code block; wherein the zero-IF data is the same as the number of blocks divided by the pseudo code;

(3) Phase parallel search

Perform FFT operation on each block of zero-IF data after expansion and each block of pseudocode, perform conjugate multiplication operation on the kth block of zero-IF data and the FFT operation result of the kth block of pseudocode, and then perform IFFT operation on the operation result, Obtain the correlation calculation result of the zero-IF data and the pseudo-code, and store in the search area; k=1, 2, .

(4) Frequency parallel search

According to the arrangement rule of the correlation calculation result between the zero intermediate frequency data and the pseudo code in the search area, obtain the correlation result of the same pseudo code phase calculation and perform FFT operation to complete the frequency search corresponding to each pseudo code phase;

(5) Capture judgment

According to the result of the FFT operation output in step (4), the energy calculation is performed, and the power of the noise is calculated at the same time.

In the described step (1), set the zero-IF data acquisition time to be T milliseconds, then:

Assuming that the original zero-IF data contains a total of X1 main spreading codes, and a total of X2 main spreading codes are collected in T milliseconds, then X2<X1;

The pseudo code collection time is determined according to the pseudo code period. If the pseudo code period length is greater than T milliseconds, the pseudo code collection time is equal to T milliseconds; if the pseudo code period length is less than or equal to T milliseconds, the pseudo code collection time is equal to the length of a main spreading code period. .

In the step (2), the method for dividing the pseudocode into blocks is as follows:

Suppose the main spreading code is represented by s, one main spreading code period contains Q chips, and after the acquisition is completed at twice the pseudo-code rate, a total of 2Q half-chips are obtained to form a pseudo-code block;

The values of each pseudo-code block are the same, let s _k (i) represent the i-th half-chip in the k-th pseudo-code block, then:

s _k (i)=s(i)1≤i≤2Q

where s(i) represents the i-th half-chip of any pseudo-code block.

In the step (2), the method for dividing the zero-IF data into blocks is as follows:

The length of a zero-IF data block is the same as that of a pseudo-code block, including 2Q sampling data. During the acquisition time of T milliseconds, the collected zero-IF data is represented by r, and d represents the insertion of the main spreading code into the sub-spreading code. The tolerance number of , r _k (i) represents the i-th data in the k-th zero-IF data block, then

r _k (i)=r(2Qk−2Q−2d+kd+i)1≤i≤2Q.

In the described step (2), the expansion of the pseudocode block is completed according to the following method:

The extended length of the pseudo-code block is 8Q, represents the extended pseudo-code block of s _k (i), and the extension method is as follows:

s _k (i) is the i-th half-chip in the k-th pseudo-code block.

In the described step (2), the expansion of the zero-IF data block is completed according to the following method:

表示r_k(i)拓展后的零中频数据块，拓展方法如下所示：The extended length of the zero-IF data block is 8Q,

Represents the zero-IF data block after expansion of r _k (i). The expansion method is as follows:

r _k (i) is the i-th data in the k-th zero-IF data block.

In the described step (4), the implementation method of searching the frequency corresponding to each pseudo code phase is as follows:

The collected zero-IF data contains a total of X2 main spreading codes. Since the acquisition start time corresponds to the S-th main spreading code of the zero-IF data, according to the arrangement rule of the correlation calculation result between the zero-IF data and the pseudo code in the search area, The correlation values calculated by the same pseudo-code phase are shifted backward by 2*d*S phases in sequence;

Perform a traversal search on any main spread spectrum cycle of the original data corresponding to the acquisition time, select the correlation value calculated by the same pseudo-code phase, and then perform FFT calculation to complete the frequency search corresponding to each pseudo-code phase; among them, the same pseudo-code phase There are X2 correlation values in total, which are the same as the number of main spreading codes.

The number of FFT calculation points is preferably 2 to the nth power, n is an integer, 2 ⁿ -X2≥0 and takes the minimum value, if X2 is less than 2 ⁿ , after the correlation value calculated by the same pseudo code phase, add 2 ⁿ - X2 zeros are used for FFT calculation; if X2 is equal to 2 ⁿ , FFT calculation is performed directly.

In the described step (5), the implementation mode of calculating the row energy according to the result of the FFT operation output is as follows:

According to the in-direction component and quadrature component output by the FFT operation, the captured detection quantity I is calculated:

Wherein, IP _i is the i-th in-direction component output by the FFT operation, and QP _i is the i-th quadrature component output by the FFT operation;

则仅有噪声时，捕获检测量I符合标准的中心

分布；若信号存在，则捕获检测量I服从非中心

分布，非中心

分布的参数λ＝2X*snr，X等于1，snr为相干累加后的信噪比。In the presence of only noise, the noise variance is calculated according to the captured detection quantity I

Then when there is only noise, the capture detection quantity I meets the center of the standard

distribution; if the signal exists, the capture detection quantity I obeys the non-centrality

distribution, non-central

The distribution parameter λ=2X*snr, X is equal to 1, and snr is the signal-to-noise ratio after coherent accumulation.

In the step (5), the detection threshold V _t is calculated as follows:

_Pfa is the false alarm probability.

The advantages of the present invention compared with the prior art are:

(1) For the special pseudo-code structure, the main spread spectrum signal is used to accumulate energy, and the signal energy of the sub-spread spectrum code is discarded; The division uses the characteristics of the sub-spreading code inserted by the main spreading code, and the sampling rate is twice the rate of the pseudo code. The method provides conditions for the fast calculation of the subsequent FFT.

(2) Double-block expansion operation is performed on the zero-IF data block and the pseudo-code block. This expansion operation method ensures the correctness of the fast FFT calculation between the zero-IF data and the pseudo-code, and can quickly complete the parallel search of the pseudo-code phase.

(3) For the acquisition method of the special pseudo-code structure, the position of the correlation value corresponding to the same code phase calculated each time is changed, and this transformation satisfies a certain law. The start time of the captured data collection is located in the S-th main spread spectrum pseudo-code interval, and the correlation value between the zero-IF data and the same pseudo-code phase is calculated and the phase is shifted backward by 2*d*S in turn. According to this arrangement rule, the correlation results of the same pseudo-code phase calculation are read and the FFT operation is performed to complete the frequency search corresponding to each pseudo-code phase. The parallel search of frequency saves the acquisition computation time of the serial search by a large amount.

Description of drawings

Figure 1 is a special structure pseudo code structure design;

Fig. 2 is a special structure pseudo-code structure composition;

Fig. 3 is the flow chart of the present invention;

Fig. 4 message communication signal special structure pseudo code sequence;

Figure 5 is divided into zero-IF data blocks;

Fig. 6 carries out the zero intermediate frequency data block after extension;

Fig. 7 Pseudo-code block after extension.

Detailed ways

When multiple message communication users send inbound signals at the same time, there is the problem of user collision, and the multiple access suppression capability between users is limited. The spreading code shown in FIG. 2 can solve the above problem. The pseudo-code design is based on two short-period spreading codes, which are called the main spreading code and the secondary spreading code respectively. The main spreading code is repeated periodically, and a special pseudo-code structure is formed by inserting sub-spreading codes of unequal lengths after each period of the main spreading code. Each message communication user uses this special pseudo code to modulate the synchronization header information for inbound, the synchronization header contains X1 main spreading codes, one main spreading code cycle contains Q chips, and d represents the main spreading code Tolerance number for inserting subspreading codes. The message communication receiver receives the inbound information of the message communication user, and performs signal acquisition through the synchronization header. The IF signal received by the message communication receiver is sampled by AD and input to the digital down-conversion module for digital down-conversion to obtain zero-IF data and send it to the low-pass filter. The zero-IF data only contains Doppler information.

The invention is to capture and calculate the zero-intermediate frequency data processed by the low-pass filtering. The core of the capture and calculation is to solve the problem that the pseudo code of the synchronization header is inserted into the sub-spread spectrum code to destroy the periodicity of the pseudo code, and a new capture method is designed for message communication. Signal acquisition, thereby improving the performance of the message communication receiver to receive multiple burst signals.

The single-channel IF signal received and sampled by the message communication receiver is:

为初始相位，C(t)为伪码，n(t_j)为第j个采样时刻的加性高斯白噪声。In the above formula, t _j is the jth sampling time, and the sampling rate of the locally received signal is twice the pseudo code rate; τ is the time delay of the signal reaching the message communication receiver; A is the signal amplitude, and f _L1 is the radio frequency carrier frequency, f _d is the Doppler shift, f _IF is the intermediate frequency carrier frequency,

is the initial phase, C(t) is the pseudo code, and n(t _j ) is the additive white Gaussian noise at the jth sampling time.

The IF signal is digitally down-converted, and the zero-IF data is sent to the low-pass filter, and finally the zero-IF data that can be used for capture is obtained. The original zero-IF data contains X1 main spreading codes in total. The collected zero-IF data It is represented by r(x), the zero-IF data only contains Doppler information, and x represents the xth data collected.

For this special pseudo-code structure, the designed fast capture method is shown in Figure 3, and the steps are as follows:

(1) Acquisition of zero-IF data and pseudo-code: The sampling start time is generated according to the capture start flag, and the collection of zero-IF data and pseudo-code is completed at twice the pseudo-code rate. The pseudo-code here is the main spreading code, It is used for the acquisition calculation of the received signal; the acquisition start time corresponds to the S-th main spreading code of the zero-IF data.

The acquisition start time is generated according to the acquisition start flag. There is no time reference, and the generated time is random. The zero-IF data contains X1 main spreading codes in total. The acquisition results are stored in the data area and the pseudo code area respectively. The storage address corresponds to a collection result, and the zero-IF data collection time is set to T milliseconds, including X2 main spreading codes, X2<X1; the pseudo code collection time is determined according to the pseudo code period, if the pseudo code period length is greater than T milliseconds, The pseudo code collection time is equal to T milliseconds; if the pseudo code period length is less than or equal to T milliseconds, the pseudo code collection time is equal to the period length of one main spreading code; after the zero-IF data and pseudo code collection is completed, the collection end flag is generated.

(2) Double-block expansion: According to the location where the zero-IF data is stored in the data area and the location where the pseudo-code is stored in the pseudo-code area, the zero-IF data and the pseudo-code are divided into blocks, where the zero-IF data and the pseudo-code are divided into blocks. The number is the same, the zero-IF data block and the pseudo-code block form a double block; according to the method of double-block expansion, the division and expansion of the zero-IF data block and the pseudo-code block are completed;

The main spreading code is represented by s. A main spreading code period is Q chips. After the acquisition is completed at twice the pseudo code rate, a total of 2Q half chips form a pseudo code block, and s(i) represents a pseudo code block. The i-th half-chip of the code block, k represents the block number of the pseudo-code block, s _k (i) represents the i-th half-chip in the k-th pseudo-code block, and all pseudo-code blocks have the same value, which is used as follows The formula says:

s _k (i)=s(i)1≤i≤2Q

The length of a zero-IF data block is the same as that of a pseudo-code block, and contains 2Q sample data. Within T milliseconds, the collected zero-IF data is represented by r, and r(x) represents the xth zero-IF data; k represents the block number of the zero-IF data block; d represents the tolerance number of the main spreading code inserted into the sub-spreading code, r _k (i) represents the i-th data in the k-th zero-IF data block, using 2Qk-2Q-2d +kd+i calculates the position of zero intermediate frequency data, which can be expressed by the following formula:

r _k (i)=r(2Qk-2Q-2d+kd+i)1≤i≤2Q

k=1, 2, ..., K, K is the total number of divided blocks of zero-IF data or pseudocode.

表示s_k(i)拓展后的伪码块，拓展方法如公式所示：The length of the zero-IF data block and the pseudo-code block after double-block expansion is 8Q,

represents the expanded pseudo-code block of s _k (i), and the expansion method is shown in the formula:

表示r_k(i)拓展后的零中频数块，拓展方法如公式所示

Represents the zero-IF block after expansion of r _k (i), the expansion method is shown in the formula

存储在搜索区中，

为主扩频码每个相位的位置。(3) Phase parallel search: perform FFT operation on each block of zero-IF data after expansion and each block of pseudocode, and perform conjugate multiplication operation on the kth block of zero-IF data and the FFT operation result of the kth block of pseudocode, Then perform IFFT operation on the operation result to obtain the correlation calculation result of zero-IF data and pseudocode

stored in the search area,

is the position of each phase of the main spreading code.

According to the above steps and methods, the calculation and result storage of all zero-IF data blocks and pseudo-code blocks in (2) are completed.

(4) Frequency parallel search: The acquisition start time is unknown, and the acquisition start time of zero intermediate frequency data and pseudo code is located at any position of the main spreading code. It is necessary to consider that the acquisition start time is located at any position of the main spreading code. According to the arrangement rule of zero intermediate frequency data and pseudo code correlation calculation in the area, read the correlation result of the same pseudo code phase calculation and perform FFT operation to complete the frequency search corresponding to each pseudo code phase;

The zero-IF data collected and stored contains a total of X2 periods of the main spreading code. The sampling start time is random, and the sampling start time can be located in any period of the main spreading code. The initial sampling time of the zero-IF data is at the S-th main spread spectrum, and the correlation value calculated by the same pseudo-code phase is shifted backward by 2*d*S phases in sequence. Traverse the acquisition time in any main spread spectrum period, select the correlation value calculated by the same pseudo code phase, and then perform FFT calculation; the correlation value calculated by the same pseudo code phase has a total of X2, which is the same as the main spread spectrum pseudo code period. The number is the same; the number of FFT calculation points should preferably satisfy the nth power of 2 (n is an integer, 2 ⁿ -X2≥0 and take the minimum value), if X2 is less than 2 ⁿ , enter 2 after the correlation value calculated by the same pseudo code phase ⁿ -X2 zeros are used for FFT calculation. If X2 is equal to 2 ⁿ , FFT calculation is performed directly.

(5) Acquisition judgment: According to the result of the FFT operation, the energy calculation is performed, and the power of the noise is calculated at the same time; according to the acquisition detection probability and the false alarm probability, the detection threshold is set to complete the acquisition judgment of all pseudo code phases.

According to the in-direction component and quadrature component output by the FFT operation, the captured detection quantity I is calculated:

分布。Among them, IP _i is the i-th in-direction component output by the FFT operation, and QP _i is the i-th quadrature component output by the FFT operation;

distributed.

则仅有噪声时I符合标准的中心

分布，若信号存在，则I服从非中心

分布，非中心分布参数为λ＝2X*snr(进行了

的归一化，X等于1，snr为相干累加后的信噪比)，可以得到自由度为2的中心

分布与非中心

分布的概率分布，根据检测估值理论与上述计算关系，捕获门限V_t计算如下，虚警概率P_fa为已知量。In the presence of only noise, the noise variance is calculated according to the captured detection quantity I

Then I only meet the center of the standard when there is only noise

distribution, if the signal exists, then I obey the non-centrality

distribution, the non-central distribution parameter is λ=2X*snr (performed

The normalization of , X is equal to 1, and snr is the signal-to-noise ratio after coherent accumulation), the center with 2 degrees of freedom can be obtained

Distribution and non-centrality

The probability distribution of the distribution, according to the detection evaluation theory and the above calculation relationship, the acquisition threshold V _t is calculated as follows, and the false alarm probability P _fa is a known quantity.

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail by using actual simulation data.

In the message communication project, the performance simulation verification of the above capture method is carried out, and the test conditions are as follows:

Signal center frequency: 85.9MHz

The number of pseudo-code cycles of the main spreading code N2: 50

The number of chips in one period of the main spreading code N1: 1023

Pseudo code rate: 1.023MHz

Sub-spreading code length: 1275

Inserted sub-spreading code length tolerance d: 1

Generate pseudocode rate X MHz: 1.023MHz

Pseudocode period: 1ms

Doppler frequency is 300Hz

Sampling frequency of data and pseudocode: 2.046MHz

Signal inbound frequency: 1s/time

Number of points for FFT-IFFT with double extended data and pseudocode: 8192 points

Frequency search FFT points: 32 points

The inbound mode of the message communication user is random inbound, the time to arrive at the message communication receiver satisfies the Poisson random distribution, and the ingress carrier-to-noise ratio C/N0 of the message communication receiver is 36dBHz. The synchronization header pseudo code adopts the above-mentioned special pseudo code structure, the main spread spectrum adopts the m sequence with the period length of 1023, the sub spread spectrum code adopts the m sequence with the period length of 2046, and the length tolerance d of the inserted sub spread spectrum code is equal to 1. The pseudo-code structure of Fig. 4 is shown in Figure 4, which constitutes a special-structure pseudo-code sequence of the message communication signal, and generates 100,000 inbound signals to complete the simulation verification of the above capture method.

The data collection time is generated by random numbers, and matlab randomly generates an integer less than 24 as the start time of data collection. The zero-IF data collection time is 26ms, including 25 completed main spreading codes; the pseudo-code collection time is determined according to the pseudo-code cycle, and the collection time is 1ms; the zero-IF data and the pseudo-code are completed at twice the pseudo-code rate. Acquisition, the acquisition rate is 2.046MHz; the data and pseudocode are divided into 25 blocks, the divided zero-IF data block is shown in Figure 5, and the expanded zero-IF data block is shown in Figure 6, the expanded pseudocode The data block is shown in Figure 7, and the length of the extended data block is 8184.

100,000 inbound signals are simulated and verified, and users successfully access 99,920 signals, the receiving success rate is 99.92%, and the acquisition time is about 22ms, which can quickly complete the acquisition of multi-channel random access signals. The use of this pseudo-code structure design can increase user capacity, and at the same time, the multiple access suppression capability is enhanced, which improves the receiving performance of multi-channel burst signals, and enables this special pseudo-code structure to be applied to practical engineering. At the same time, the method can be parameterized according to the specific needs of the project, and the data acquisition time and the number of FFT calculation points can be changed according to the actual needs, and it has high scalability.

The above is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention.

Contents that are not described in detail in the specification of the present invention belong to the well-known technology of those skilled in the art.

Claims (10)

1. a fast acquisition method for improving multi-channel burst signal receiving performance, is characterized in that, comprises the steps: (1) Zero-IF data and pseudo-code acquisition The acquisition start time is generated according to the acquisition start flag, and the acquisition of the zero-IF data and the pseudocode is completed at twice the pseudocode rate. After the acquisition is completed, the acquisition end flag is generated; The intermediate frequency data is stored in the data area, the collected pseudo code is stored in the pseudo code area, and the acquisition start time corresponds to the S-th main spreading code of the zero intermediate frequency data; (2) Double block expansion After the acquisition, according to the location where the zero-IF data is stored in the data area and the location where the pseudo-code is stored in the pseudo-code area, the zero-IF data and the pseudo-code are divided into blocks. The expansion of the code block; wherein the zero-IF data is the same as the number of blocks divided by the pseudo code; (3) Phase parallel search Perform FFT operation on each block of zero-IF data after expansion and each block of pseudocode, perform conjugate multiplication operation on the kth block of zero-IF data and the FFT operation result of the kth block of pseudocode, and then perform IFFT operation on the operation result, Obtain the correlation calculation result of the zero-IF data and the pseudo-code, and store in the search area; k=1, 2, . (4) Frequency parallel search According to the arrangement rule of the correlation calculation result between the zero intermediate frequency data and the pseudo code in the search area, obtain the correlation result of the same pseudo code phase calculation and perform FFT operation to complete the frequency search corresponding to each pseudo code phase; (5) Capture judgment According to the result of the FFT operation output in step (4), the energy calculation is performed, and the power of the noise is calculated at the same time. 2. a kind of fast acquisition method that improves multi-channel burst signal reception performance according to claim 1, is characterized in that, in described step (1), set zero intermediate frequency data acquisition time to be T millisecond, then: Assuming that the original zero-IF data contains a total of X1 main spreading codes, and a total of X2 main spreading codes are collected in T milliseconds, then X2<X1; The pseudo code collection time is determined according to the pseudo code period. If the pseudo code period length is greater than T milliseconds, the pseudo code collection time is equal to T milliseconds; if the pseudo code period length is less than or equal to T milliseconds, the pseudo code collection time is equal to the length of a main spreading code period. . 3. a kind of fast acquisition method improving multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (2), the method that pseudocode is divided into blocks is processed as follows: Suppose the main spreading code is represented by s, one main spreading code period contains Q chips, and after the acquisition is completed at twice the pseudo-code rate, a total of 2Q half-chips are obtained to form a pseudo-code block; The values of each pseudo-code block are the same, let s _k (i) represent the i-th half-chip in the k-th pseudo-code block, then: s _k (i)=s(i)1≤i≤2Q where s(i) represents the i-th half-chip of any pseudo-code block. 4. a kind of fast acquisition method that improves multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (2), the method that the zero-IF data is divided into blocks and processed is as follows: The length of a zero-IF data block is the same as that of a pseudo-code block, including 2Q sampling data. During the acquisition time of T milliseconds, the collected zero-IF data is represented by r, and d represents the insertion of the main spreading code into the sub-spreading code. The tolerance number of , r _k (i) represents the i-th data in the k-th zero-IF data block, then r _k (i)=r(2Qk−2Q−2d+kd+i)1≤i≤2Q. 5. a kind of fast acquisition method improving multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (2), completes the expansion of pseudo code block according to the following method: The length of the expanded pseudo-code block is 8Q, and s' _k (i) represents the expanded pseudo-code block of s _k (i). The expansion method is as follows:

s _k (i) is the i-th half-chip in the k-th pseudo-code block. 6. a kind of fast acquisition method improving multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (2), completes the expansion of zero intermediate frequency data block according to the following method: The extended length of the zero-IF data block is 8Q, and r' _k (i) represents the zero-IF data block extended by r _k (i). The extension method is as follows:

r _k (i) is the i-th data in the k-th zero-IF data block. 7. a kind of fast acquisition method for improving multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (4), the realization method of searching the frequency corresponding to each pseudo code phase as follows: The collected zero-IF data contains a total of X2 main spreading codes. Since the acquisition start time corresponds to the S-th main spreading code of the zero-IF data, according to the arrangement rule of the correlation calculation result between the zero-IF data and the pseudo code in the search area, The correlation values calculated by the same pseudo-code phase are shifted backward by 2*d*S phases in sequence; Perform a traversal search on any main spread spectrum cycle of the original data corresponding to the acquisition time, select the correlation value calculated by the same pseudo-code phase, and then perform FFT calculation to complete the frequency search corresponding to each pseudo-code phase; among them, the same pseudo-code phase There are X2 correlation values in total, which are the same as the number of main spreading codes. 8. The fast acquisition method for improving multi-channel burst signal receiving performance according to claim 7, wherein, the number of FFT calculation points preferably satisfies the nth power of 2, ⁿ is an integer, and 2n-X2≥ 0 and take the minimum value, if X2 is less than 2 ⁿ , add 2 ⁿ -X2 zeros to perform FFT calculation after the correlation value calculated by the same pseudo code phase; if X2 is equal to 2 ⁿ , directly perform FFT calculation. 9. a kind of fast acquisition method improving multi-channel burst signal receiving performance according to claim 1, is characterized in that, in described step (5), the realization mode of energy calculation according to the result row of FFT operation output is as follows: According to the in-direction component and quadrature component output by the FFT operation, the captured detection quantity I is calculated: Wherein, IP _i is the i-th in-direction component output by the FFT operation, and QP _i is the i-th quadrature component output by the FFT operation; In the presence of only noise, the noise variance is calculated according to the captured detection quantity I

Then when there is only noise, the captured detection quantity I conforms to the standard central χ ² distribution; if the signal exists, the captured detection quantity I obeys the non-central χ ² distribution, and the parameter λ=2X*snr of the non-central χ ² distribution, X is equal to 1 , snr is the signal-to-noise ratio after coherent accumulation. 10. The fast acquisition method for improving multi-channel burst signal reception performance according to claim 9, characterized in that, in the step (5), the detection threshold V _t is calculated as follows:

_Pfa is the false alarm probability.

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