CN102571136A - Correlated peak detection method of double channel pn code acquisition system - Google Patents

Abstract

A kind of correlation peak detection method of two-way pseudo-code capture system, it has four major steps: one, the spread spectrum code data of input is divided into several data sections, each data section and the local pseudo-code section of two roads same length Carry out correlation operations; and input the relevant information obtained by the main and auxiliary two-way calculations into the shift register group; 2. The shift register group is composed of upper and lower shift registers. Whenever the correlation calculation of an input data segment is completed, a new When the correlation peak is reached, the shift register performs a shift and defuzzification operation; 3. The relevant information is output; 4. After the above steps, the side lobes of the effective correlation peak are filtered out; the relevant information of the effective correlation peak is extracted to use Calculate the reset position of the local pseudo code; at the same time, the number of valid correlation peaks verified is counted, which provides a basis for the capture system to judge whether the relevant information is true or not.

Description

A Correlation Peak Detection Method for Dual-path Pseudo-code Acquisition System

technical field

The invention relates to a direct-sequence spread spectrum pseudo-code acquisition technology suitable for satellite integrated baseband equipment, in particular to a correlation peak detection method of a dual-path pseudo-code acquisition system based on local pseudo-code superposition. The invention belongs to the technical field of satellite comprehensive baseband testing.

Background technique

Satellite integrated baseband equipment refers to the terminal equipment that organically integrates multiple functions such as ranging, speed measuring, remote control, telemetry, and data transmission in the satellite measurement and control communication system. It is a satellite ranging, tracking and remote control (Telemetry, Tracking and Command , an important part of TT&C) mission, satellite pre-launch test and satellite in-orbit test. The integrated baseband equipment adopts a unified direct sequence spread spectrum measurement and control system for data transmission. The direct sequence spread spectrum (Direct Sequence Spread Spectrum, DSSS) pseudo-code signal acquisition technology is a key part of the intermediate frequency signal processing unit of the spread spectrum integrated baseband equipment. Since the integrated baseband equipment is a general satellite test equipment, it can be used for remote control of various purposes. Therefore, in order to take into account the performance and flexibility of the system, a two-way pseudo-code acquisition method based on local pseudo-code superposition is adopted. Dual-channel pseudo-code capture overcomes the possible correlation peak loss caused by data jump edges when there is data modulation, and is equivalent to performing two correlation peak verifications on the same piece of input data; Correlation peak loss may be brought about by partial correlation calculation, but at the same time, correlation peaks with the same position (called effective correlation peak side lobes) are added to the data segments on both sides of the effective correlation peak data segment, which gives real correlation information detection and The reset point calculation of the native pseudocode poses difficulties.

Contents of the invention

1. Purpose: The purpose of the present invention is to provide a correlation peak detection method of a two-way pseudo-code capture system, to overcome the deficiencies in the prior art, and it can cooperate with the capture system to realize remote control signal or ranging signal pseudo-code correlation Accurate judgment and fast capture of peaks.

2. Technical solution:

The correlation peak detection method of a kind of two-way pseudo-code capture system of the present invention, the concrete steps of this method are as follows:

其中l[·]表示本地数据，x[·]表示输入数据，M是数据段长度，c[·]是相关计算结果，n是离散时间。主路本地伪码段是以本地伪码复位后输出的码片为起点，第一个伪码段与第二个伪码段的时域叠加；辅路本地伪码段是以本地伪码复位后输出的码片为起点，第二个伪码段与第三个伪码段的时域叠加。相关运算结果中的相关峰，即相关运算结果中绝对值最大的点，若超过捕获门限，则称之为有效相关峰。将主辅两路相关计算得到的相关信息输入移位寄存器组。Step 1: Firstly, the input spreading code data is divided into several data segments, and each data segment is correlated with two local pseudo-code segments of the same length. The length of the data segment for correlation operation is the same as that of the local pseudo-code segment. The formula for its related operation is

Among them, l[·] represents the local data, x[·] represents the input data, M is the length of the data segment, c[·] is the correlation calculation result, and n is the discrete time. The local pseudo-code segment of the main road is based on the chip output after the local pseudo-code is reset, and the time domain superposition of the first pseudo-code segment and the second pseudo-code segment; the local pseudo-code segment of the auxiliary road is based on the local pseudo-code reset The output chip is the starting point, and the time domain superposition of the second pseudo-code segment and the third pseudo-code segment. If the correlation peak in the correlation operation result, that is, the point with the largest absolute value in the correlation operation result exceeds the capture threshold, it is called an effective correlation peak. Input the related information obtained by the main and auxiliary two-way correlation calculation into the shift register group.

Step 2: As shown in Figure 1, the shift register group consists of upper and lower shift registers, the upper shift register includes four registers R ₁ , R ₀ , R _-1 and R _-2 , and the lower shift register includes R ₀ ′, R _-1 ′ and R _-2 ′ have 3 registers in total. Whenever the correlation calculation of an input data segment is completed and a new correlation peak is obtained, the shift register performs a shift and defuzzification operation.

Wherein, the relevant information described in step 1 includes: (1) the position of the correlation peak in the data segment is the reset point of the local pseudocode; (2) the numbering of the data segment where the correlation peak is located; (3) the effective value of the correlation peak (4) The number of times the relevant peak has been verified. Before entering the shift register bank, the number of times that the correlation peak is verified is 0.

Wherein, the shift register described in step 2 performs a shift and defuzzification operation, and its specific implementation process is as follows:

1. Register shift and main road related information setting. The operation of the upper shift register includes: R _-1 data input R _-2 , R ₀ data input R _-1 , R ₁ data input R ₀ , main road related information input R ₁ ; the operation of the lower shift register includes : The data of R _-1 ′ is input into R _-2 ′, the data of R ₀ ′ is input into R _-1 ′;

2. Auxiliary road related peak setting. Compare the reset point of the auxiliary road correlation peak with the reset point of R ₀ , if they are the same, and both the auxiliary road correlation peak and the correlation peak of R ₀ are valid, then add 1 to the verification times of R ₀ ; otherwise, enter the relevant information into R ₀ '.

3. Main road peak preprocessing. As shown in Figure 2, it is divided into 4 parts. (1) Compare R _-2 , R _-1 and R ₀ to see if the correlation peak is valid and the reset point is the same. If it is satisfied, the correlation peak of R _-2 and R ₀ Set to invalid, and set the number of verifications of R _-1 to the sum of the number of verifications of R _-1 , R _-2 and R ₀ plus 2; if not satisfied, then (2) compare R _-2 , R _-1 and Whether R ₀ ′ satisfies that the correlation peak is valid and the reset point is the same; if it is satisfied, set the correlation peaks of R _-2 and R ₀ ′ to be invalid, and set the verification times of R _{- 1} to R _-1 , R _-2 and Add 2 to the sum of verification times of R ₀ ′; if it is not satisfied, then (3) compare R _-2 ′, R _-1 and R ₀ ′ to see if the correlation peak is valid and the reset point is the same, and if so, set R _- The correlation peaks of ₂ ′ and R ₀ ′ are set to be invalid, and the verification times of R _-1 are set to the sum of the verification times of R _-1 , R _-2 ′ and R ₀ ′ plus 2; if not satisfied, then ( 4) Compare R _-2 ', R _-1 and R ₀ to see if the correlation peak is valid and the reset point is the same, if so, set the correlation peak of R _-2 ' and R ₀ to be invalid, and verify that R _-1 The number of times is set to the sum of the verification times of R _-1 , R _-2 ′ and R ₀ plus 2; if not satisfied, the peak preprocessing of the main road is ended.

4. Peak preprocessing of auxiliary roads. Replace R _-1 in the peak preprocessing step of the main road with R _-1 ′, and the rest of the operation process is the same as the peak preprocessing of the main road.

5. Defuzzification of the peak value of the main road. As shown in Figure 3, it is divided into two parts, (1) If the correlation peaks of R _-2 and R _-1 are valid and the reset points are the same, then it is judged that the reset points of R _-2 and R _-1 are in the data segment If the reset points of R _-2 and R _-1 are in the first half of the data segment, set the correlation peak of R _-1 to be invalid, and set the verification times of R _-2 to R _-2 , R _{- 1} The sum of the number of verifications plus 1, if the reset point of R _-2 and R _-1 is located in the second half of the data segment, the correlation peak of R _-2 is set to be invalid, and the number of verifications of R _-1 is set to The sum of the verification times of R _-1 and R _-2 plus 1; if R _-2 and R _-1 do not meet the requirement that the correlation peak is valid and the reset point is the same, then (2) compare whether R _-2 ' and R _-1 satisfy the correlation The peak is valid and the reset point is the same. If it is not satisfied, the peak preprocessing of the main road will be ended. If it is satisfied, the position of the reset point of R _-2 ′ and R _-1 in the data segment will be judged. If R _-2 ′ and R _- If the reset point of ₁ is located in the first half of the data segment, set the correlation peak of R _-1 to be invalid, and set the verification times of R _-2 ′ to the sum of the verification times of R _-2 ′, R _-1 plus 1 , if the reset points of R _-2 ′ and R _-1 are located in the second half of the data segment, set the correlation peak of R _-2 ′ to be invalid, and set the verification times of R _-1 to R _-1 , R _- Add 1 to the sum of verification times of ₂ '.

6. Peak defuzzification of auxiliary roads. Replace R _-1 in the main road peak defuzzification step with R _-1 ′, and the rest of the operation process is the same as the main road peak preprocessing.

Step 3: Output relevant information. Choose to output the relevant information that is valid for the relevant peaks in R _-2 and R _-2 ′; if both the peaks in R _-2 and R _-2 ′ are valid, then output the relevant information with the largest number of verifications, if both If the number of verifications is the same, the relevant information in R _-2 will be output. If none of the peaks in R _-2 and R _-2 ' is valid, the relevant information in R _-2 is output.

Step 4: After the above steps, the side lobes of the effective correlation peaks are filtered out; the relevant information of the effective correlation peaks is extracted to be used for the calculation of the reset position of the local pseudo code; at the same time, the number of times the effective correlation peaks are verified is counted as The capture system provides a basis for judging whether the relevant information is true or not.

3. Advantages and effects:

From the above description, it can be seen that the correlation peak detection method of the present invention has the following advantages:

(1) The function is independent from other parts of the pseudocode capture system, and the structure is simple.

(2) It overcomes the problem of ambiguity of effective correlation peaks brought about by superposition of local pseudocodes, and can accurately find real relevant information from among a set of input related information.

(3) Utilize the ambiguity of the validity of the correlation peaks brought about by the superposition of local pseudo codes, take the side lobe of the effective correlation peak and the side lobe of the auxiliary path as the verification of the effective correlation peak and record the number of verifications, and output the relevant information with more verification times first, so The false alarm probability of the capture system is reduced, and a basis is provided for the capture system to judge whether relevant information is true or not.

(4) Since the effective correlation peaks have been verified during the defuzzification operation, the capture system does not need to go through multiple dwells to verify the capture information, which reduces the capture time.

Description of drawings

Fig. 1 Schematic diagram of shift register group structure;

Figure 2 The flow chart of the peak preprocessing of the main road;

Fig. 3 main path defuzzification flow chart;

Fig. 4 schematic diagram of main and auxiliary two-way input data segment, local data segment and correlation peak position;

Figure 5 (a) is a schematic diagram of the positional relationship between the input data segment and the local pseudo-code segment when the correlation peak is located in the second half of the correlation result;

Figure 5 (b) is a schematic diagram of the positional relationship between the input data segment and the local pseudo-code segment when the correlation peak is located in the first half of the correlation result;

Fig. 6 is a flow chart of the present invention.

Detailed ways

See Fig. 6, a kind of correlation peak detection method of the two-way acquisition system based on local pseudocode superimposition of the present invention, the concrete steps of this method are as follows:

其中l[·]表示本地数据，x[·]表示输入数据，M是数据段长度，c[·]是相关计算结果，n是离散时间。主路本地伪码段是以本地伪码复位后输出的码片为起点，第一个伪码段与第二个伪码段的时域叠加；辅路本地伪码段是以本地伪码复位后输出的码片为起点，第二个伪码段与第三个伪码段的时域叠加。相关运算结果中的相关峰，即相关运算结果中绝对值最大的点，若超过捕获门限，则称之为有效相关峰。本地伪码段时域叠加的目的是在不对有效相关峰造成衰减的前提下，将相关运算的长度减半。将主辅两路相关计算得到的相关信息输入移位寄存器组。Step 1: Firstly, the input spreading code data is divided into several data segments, and each data segment is correlated with two local pseudo-code segments of the same length. The length of the data segment for correlation operation is the same as that of the local pseudo-code segment. The formula for its related operation is

Among them, l[·] represents the local data, x[·] represents the input data, M is the length of the data segment, c[·] is the correlation calculation result, and n is the discrete time. The local pseudo-code segment of the main road is based on the chip output after the local pseudo-code is reset, and the time domain superposition of the first pseudo-code segment and the second pseudo-code segment; the local pseudo-code segment of the auxiliary road is based on the local pseudo-code reset The output chip is the starting point, and the time domain superposition of the second pseudo-code segment and the third pseudo-code segment. If the correlation peak in the correlation operation result, that is, the point with the largest absolute value in the correlation operation result exceeds the capture threshold, it is called an effective correlation peak. The purpose of the time-domain superposition of the local pseudo-code segment is to halve the length of the correlation operation without attenuating the effective correlation peak. Input the related information obtained by the main and auxiliary two-way correlation calculation into the shift register group.

Step 2: As shown in Figure 1, the shift register group consists of upper and lower shift registers, the upper shift register includes four registers R ₁ , R ₀ , R _-1 and R _-2 , and the lower shift register includes R ₀ ′, R _-1 ′ and R _-2 ′ have 3 registers in total. Whenever the correlation calculation of an input data segment is completed and a new correlation peak is obtained, the shift register performs a shift and defuzzification operation.

Wherein, the relevant information described in step 1 includes: (1) the position of the correlation peak in the data segment is the reset point of the local pseudocode; (2) the numbering of the data segment where the correlation peak is located; (3) the effective value of the correlation peak (4) The number of times the relevant peak has been verified. Before entering the shift register bank, the number of times that the correlation peak is verified is 0.

Wherein, the shift register described in step 2 performs a shift and defuzzification operation, and its specific implementation process is as follows:

1. Register shift and main road related information setting. The operation of the upper shift register includes: R _-1 data input R _-2 , R ₀ data input R _-1 , R ₁ data input R ₀ , main road related information input R ₁ ; the operation of the lower shift register includes : The data of R _-1 ′ is input into R _-2 ′, the data of R ₀ ′ is input into R _-1 ′;

2. Auxiliary road related peak setting. Compare the reset point of the auxiliary road correlation peak with the reset point of R ₀ , if they are the same, and both the auxiliary road correlation peak and the correlation peak of R ₀ are valid, then add 1 to the verification times of R ₀ ; otherwise, enter the relevant information into R ₀ '.

3. Main road peak preprocessing. As shown in Figure 2, it is divided into 4 parts. (1) Compare R _-2 , R _-1 and R ₀ to see if the correlation peak is valid and the reset point is the same. If it is satisfied, the correlation peak of R _-2 and R ₀ Set to invalid, and set the number of verifications of R _-1 to the sum of the number of verifications of R _-1 , R _-2 and R ₀ plus 2; if not satisfied, then (2) compare R _-2 , R _-1 and Whether R ₀ ′ satisfies that the correlation peak is valid and the reset point is the same; if it is satisfied, set the correlation peaks of R _-2 and R ₀ ′ to be invalid, and set the verification times of R _{- 1} to R _-1 , R _-2 and Add 2 to the sum of verification times of R ₀ ′; if it is not satisfied, then (3) compare R _-2 ′, R _-1 and R ₀ ′ to see if the correlation peak is valid and the reset point is the same, and if so, set R _- The correlation peaks of ₂ ′ and R ₀ ′ are set to be invalid, and the verification times of R _-1 are set to the sum of the verification times of R _-1 , R _-2 ′ and R ₀ ′ plus 2; if not satisfied, then ( 4) Compare R _-2 ', R _-1 and R ₀ to see if the correlation peak is valid and the reset point is the same, if so, set the correlation peak of R _-2 ' and R ₀ to be invalid, and verify that R _-1 The number of times is set to the sum of the verification times of R _-1 , R _-2 ′ and R ₀ plus 2; if not satisfied, the peak preprocessing of the main road is ended.

4. Peak preprocessing of auxiliary roads. Replace R _-1 in the peak preprocessing step of the main road with R _-1 ′, and the rest of the operation process is the same as the peak preprocessing of the main road.

5. Defuzzification of the peak value of the main road. As shown in Figure 3, it is divided into two parts, (1) If the correlation peaks of R _-2 and R _-1 are valid and the reset points are the same, then it is judged that the reset points of R _-2 and R _-1 are in the data segment If the reset points of R _-2 and R _-1 are in the first half of the data segment, set the correlation peak of R _-1 to be invalid, and set the verification times of R _-2 to R _-2 , R _{- 1} The sum of the number of verifications plus 1, if the reset point of R _-2 and R _-1 is located in the second half of the data segment, the correlation peak of R _-2 is set to be invalid, and the number of verifications of R _-1 is set to The sum of the verification times of R _-1 and R _-2 plus 1; if R _-2 and R _-1 do not meet the requirement that the correlation peak is valid and the reset point is the same, then (2) compare whether R _-2 ' and R _-1 satisfy the correlation The peak is valid and the reset point is the same. If it is not satisfied, the peak preprocessing of the main road will be ended. If it is satisfied, the position of the reset point of R _-2 ′ and R _-1 in the data segment will be judged. If R _-2 ′ and R _- If the reset point of ₁ is located in the first half of the data segment, set the correlation peak of R _-1 to be invalid, and set the verification times of R _-2 ′ to the sum of the verification times of R _-2 ′, R _-1 plus 1 , if the reset points of R _-2 ′ and R _-1 are located in the second half of the data segment, set the correlation peak of R _-2 ′ to be invalid, and set the verification times of R _-1 to R _-1 , R _- Add 1 to the sum of verification times of ₂ '.

6. Peak defuzzification of auxiliary roads. Replace R _-1 in the main road peak defuzzification step with R _-1 ′, and the rest of the operation process is the same as the main road peak preprocessing.

Step 3: Output relevant information. Choose to output the relevant information that is valid for the relevant peaks in R _-2 and R _-2 ′; if both the peaks in R _-2 and R _-2 ′ are valid, then output the relevant information with the largest number of verifications, if both If the number of verifications is the same, the relevant information in R _-2 will be output. If none of the peaks in R _-2 and R _-2 ' is valid, the relevant information in R _-2 is output.

Step 4: After the above steps, the side lobes of the effective correlation peaks are filtered out; the relevant information of the effective correlation peaks is extracted to be used for the calculation of the reset position of the local pseudo code; at the same time, the number of times the effective correlation peaks are verified is counted as The capture system provides a basis for judging whether the relevant information is true or not.

The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

As shown in Figure 4, it is assumed that k-1, k, k+1 and k+2 are 4 consecutive input data segments, wherein the kth input data segment has a complete image in the local pseudo-code segment of the main road, and the kth input data segment has a complete image in the local pseudo-code segment of the main road. The +1 input data segment has a complete image in the local pseudo-code segment of the auxiliary road, while the k-1 and k+1th data segments have incomplete images in the local pseudo-code segment of the main road, and the k-th and k-th data segments have incomplete images The +2 data segment has an incomplete image in the local pseudo-code segment of the auxiliary road, so the kth data segment of the main road and the k+1th data segment of the auxiliary road will produce a complete correlation peak with the same position and correct data segment information , the k-1th and k+1th data segments of the main road and the k and k+2th data segments of the auxiliary road will produce attenuation correlation peaks with the same position and wrong data segment information, thus causing the effective correlation peak to be blurred . When the signal-to-noise ratio is high and the correlation peak position is close to the midpoint of the data segment, the 4 consecutive input data segments may have at most 6 effective correlation peak input shift register groups; when the signal-to-noise ratio is low or the correlation peak position is close to the data segment When the segment edge is reached, the 4 consecutive input data segments may have at most 4 effective correlation peak input shift register groups.

其中l[·]表示本地数据，x[·]表示输入数据，M是数据段长度，c[·]是相关计算结果。假设k-1、k和k+1为连续3个输入数据段，其中捕获数据段k能够产生最大相关峰，它经过计算得到的复位位置是正确的，当门限值接近二分之一个最大相关峰时，(a)中的第k+1个数据段和(b)中的第k-1个数据段的相关峰低于门限值从而是无效相关峰；(a)中的第k-1个数据段和(b)中的第k+1个数据段会在数据段k同样的位置产生有效相关峰，但计算得到的复位位置相对于正确复位位置分别向前和向后偏移了一个数据段，因此必须将其滤除。当连续几个捕获数据段都在同一位置产生相关峰时，可以通过其峰值的位置来解模糊：Consider the case of one local pseudocode, as shown in Figure 5(a) and Figure 5(b), the formulas for the related operations are

Among them, l[·] represents the local data, x[·] represents the input data, M is the length of the data segment, and c[·] is the related calculation result. Assume that k-1, k and k+1 are 3 consecutive input data segments, among which the captured data segment k can generate the largest correlation peak, and its calculated reset position is correct. When the threshold value is close to one-half When the maximum correlation peak is reached, the correlation peaks of the k+1th data segment in (a) and the k-1th data segment in (b) are lower than the threshold value and thus are invalid correlation peaks; the k+1th data segment in (a) The k-1 data segment and the k+1th data segment in (b) will generate an effective correlation peak at the same position of the data segment k, but the calculated reset position is forward and backward respectively relative to the correct reset position A data segment was moved, so it must be filtered out. When several consecutive captured data segments generate correlation peaks at the same position, the position of the peak can be used to resolve the ambiguity:

1. When two consecutive capture data segments generate correlation peaks at the same position, and the correlation peak is located in the second half of the correlation result, the peak value of the second data segment is the true value;

2. When two consecutive capture data segments generate correlation peaks at the same position, and the correlation peak is located in the first half of the correlation result, the peak value of the first data segment is the true value;

3. When the signal-to-noise ratio is high and the position of the correlation peak is close to the midpoint of the data segment, it is possible that three consecutive data segments will produce valid correlation peaks at the same position. At this time, the correlation peak in the middle is selected as the true value.

Example 1. In a high SNR environment, assume that the length of the input data segment is 8192 points, and the position of the correlation peak is 5000. As shown in Figure 4, due to the influence of the modulation data jump edge, the correlation of the kth data segment of the main road is The peak is invalid, so the correlation peak information input into the shift register group is shown in the following list 1, where 1 represents a valid correlation peak, 0 represents an invalid correlation peak, and the positions of the 5 valid correlation peaks are the same. Assume initially that there are no valid correlation peaks in the shift register bank. The following is the actual detection data processing process, which only lists the part involving effective correlation peaks in the operation process of shifting and defuzzification:

data segment k-1 k k+1 k+2 main road 1 0 1 0 side road 0 1 1 1

Table 1

1. Input of related information of k-1 data segment: Input R ₁ of related information of main road of k-1 data segment.

2. K data segment related information input: R ₁ related information input R ₀ ; k data segment auxiliary road correlation peak is valid, its reset point is the same as R ₀ ’s reset point, and the correlation peak information of R ₀ is valid, so R ₀ The number of verifications plus 1 is equal to 1.

3. Input related information of k+1 data segment: input R ₀ related information into R _-1 , input R ₁ related information into R ₀ , input main road related information of k+1 data segment into R ₁ ; k+1 data segment The correlation peak of the auxiliary road is valid, but the correlation peak information of R ₀ is invalid, so the relevant information of the auxiliary road of the k+1 data segment is input into R ₀ ′.

4. Input related information of k+2 data segment: input related information of R _-1 into R _-2 , input related information of R ₀ into R _-1 , input related information of R ₁ into R ₀ , input related information of R ₀ ′ into R _{- 1} ′; the auxiliary path correlation peak of the k+2 data segment is valid, and its reset point is the same as that of R ₀ , and the correlation peak information of R ₀ is valid, so the verification times of R ₀ plus 1 is equal to 1; R _-2 , The correlation peaks of R _-1 ' and R ₀ are both valid and the reset points are the same, so the correlation peaks of R _-2 and R ₀ are set to be invalid, and the verification times of R _-1 ' are set to R _-2 , R ₀ and R _- The sum of the verification times of ₁ ′ plus 2 is equal to 4;

5. K+3 data segment data segment related information input: R ₋₁ ′ related information input R ₋₂ ′; R ₋₂ ′ related information output.

From the above analysis, it can be seen that the shift register group filters out the side lobes of the effective correlation peak, and outputs the correct result, that is, the auxiliary path related information of the k+1th data segment, and completes the other 4 effective correlation peaks with the same position as a reference to it. validation statistics.

Example 2. In a low signal-to-noise ratio environment, suppose the length of the input data segment is 8192 points, and the position of the correlation peak is 3000, as shown in Figure 4, due to the influence of the modulation data jump edge, the k+1th data segment of the auxiliary road The correlation peak is invalid, and the k-1th correlation peak of the main road and the kth correlation peak of the auxiliary road are invalid. In this way, the correlation peak information input into the shift register group is shown in Table 2 below, where 1 represents a valid correlation peak, 0 represents an invalid correlation peak, and the positions of the three valid correlation peaks are the same. Assume initially that there are no valid correlation peaks in the shift register bank. The following is the actual detection data processing process, which only lists the part involving effective correlation peaks in the operation process of shifting and defuzzification:

data segment k-1 k k+1 k+2 main road 0 1 1 0 side road 0 0 0 1

Table 2

1. Input relevant information of the k-1 data segment.

2. Input related information of k data segment: input R ₁ of main road related information of k data segment.

3. Input related information of k+1 data segment: input related information of R ₁ into R ₀ , input related information of main road of k+1 data segment into R ₁ .

4. K+2 data segment related information input: R ₀ related information input R _-1 , R ₁ related information input R ₀ ; k+2 data segment auxiliary road correlation peak is valid, its reset point is the same as R ₀ reset point The same, and the correlation peak information of R ₀ is valid, so the number of verifications of R ₀ plus 1 is equal to 1.

5. Input relevant information of k+3 data segment: input relevant information of R _-1 into R _-2 , input relevant information of R ₀ into R _-1 , input relevant information of R ₁ into R ₀ , because R _-1 and R _-2 The correlation peaks are all valid, the reset point is the same, and the reset point is in the first half of the data segment, so the correlation peak of R _-1 is set to be invalid, and the verification times of R _-2 are set between the verification times of R-2 and R _-1 Adding 1 to the sum is equal to 2; the relevant information of R _-2 is output.

From the above analysis, it can be seen that the shift register group filters out the side lobes of the effective correlation peak, and outputs the correct result, that is, the main channel related information of the kth data segment, and completes the other two effective correlation peaks with the same position as its Verify statistics.

Claims (3)

1. a correlation peak detection method of a two-way pseudo-code capture system, is characterized in that: the method concrete steps are as follows: Step 1: first divide the input spreading code data into several data segments, each data segment performs correlation operation with two local pseudo-code segments of the same length; the length of the data segment for correlation operation is the same as the local pseudo-code segment , and its related formula is

Among them, l[·] represents local data, x[·] represents input data, M is the length of data segment, c[·] is related calculation result, n is discrete time; The output chip is the starting point, the time domain superposition of the first pseudo-code segment and the second pseudo-code segment; Superimposed with the time domain of the third pseudo-code segment; the correlation peak in the correlation operation result, that is, the point with the largest absolute value in the correlation operation result, if it exceeds the capture threshold, is called an effective correlation peak, and the main and auxiliary two-way correlation The calculated relevant information is input into the shift register group; Step 2: The shift register group is composed of upper and lower shift registers, the upper shift register includes four registers R ₁ , R ₀ , R _-1 and R _-2 , and the lower shift register includes R ₀ ', R _{- 1} ' and R _-2 ' have 3 registers in total; whenever the correlation calculation of an input data segment is completed and a new correlation peak is obtained, the shift register performs a shift and defuzzification operation; Step 3: Correlation information output; choose to output the relevant information of one of the valid correlation peaks in R _-2 and R _-2 '; if both R _-2 and R _-2 ' are valid, correlate the one with the larger number of verifications Information output, if the verification times of the two are the same, output the relevant information in R _-2 ; if the peak value in R _-2 and R _-2 ' is invalid, output the relevant information in R _-2 ; Step 4: After the above steps, the side lobes of the effective correlation peaks are filtered out; the relevant information of the effective correlation peaks is extracted to be used for the calculation of the reset position of the local pseudo code; at the same time, the number of times the effective correlation peaks are verified is counted as The capture system provides a basis for judging whether the relevant information is true or not. 2. the correlation peak detection method of a kind of two-way pseudo-code capture system according to claim 1 is characterized in that: the relevant information described in step 1 includes: (1) the position of the correlation peak in the data segment is the local The reset point of the pseudo code; (2) the number of the data segment where the correlation peak is located; (3) the validity of the correlation peak; (4) the number of times the correlation peak has been verified, before the input shift register group, the correlation peak is verified The number of passes is 0. 3. the correlation peak detection method of a kind of two-way pseudo-code capture system according to claim 1, is characterized in that: the shift register described in step 2 carries out the operation of shifting and defuzzification, and its specific implementation process is as follows : 1) Register shift and information setting related to the main circuit: the operation of the upper shift register includes: R _-1 data input R _-2 , R ₀ data input R _-1 , R ₁ data input R ₀ , main channel related Information input R ₁ ; the operation of the lower shift register includes: R _-1 'data input R _-2 ', R ₀ 'data input R _-1 '; 2) Auxiliary road correlation peak setting; compare the reset point of the auxiliary road correlation peak with the reset point of R ₀ , if both are the same, and both the auxiliary road correlation peak and the correlation peak of R ₀ are valid, then add 1 to the verification times of R ₀ ; Otherwise, input relevant information into R ₀ '; 3) Main road peak preprocessing; it is divided into 4 parts, (a) compare whether R _-2 , R _-1 and R ₀ satisfy whether the correlation peak is valid and the reset point is the same, if so, then R _-2 and R ₀ The correlation peak of is set to be invalid, and the verification times of R _-1 is set to the sum of the verification times of R _-1 , R _-2 and R ₀ plus 2; if not satisfied, then (b) compare R _-2 , R Whether _-1 and R ₀ ' satisfy that the correlation peak is valid and the reset point is the same; if so, set the correlation peak of R _-2 and R ₀ ' to be invalid, and set the verification times of R _-1 to R _-1 , R Add 2 to the sum of verification times of _-2 and R ₀ '; if not satisfied, then (c) compare R _-2 ', R _-1 and R ₀ ' to see if the relevant peak is valid and the reset point is the same, if satisfied, then Set the correlation peaks of R _-2 ' and R ₀ ' to invalid, and set the verification times of R _-1 to the sum of the verification times of R _-1 , R _-2 ' and R ₀ ' plus 2; if not satisfied , then (d) compare whether R _-2 ', R _-1 and R ₀ satisfy whether the correlation peak is valid and the reset point is the same, if so, set the correlation peak of R _-2 ' and R ₀ to be invalid, and set R _- The verification number of ₁ is set to the sum of the verification times of R _-1 , R _-2 ' and R ₀ plus 2; if not satisfied, then end the peak preprocessing of the main road; 4) Peak preprocessing of the auxiliary road; replace R _-1 in the peak preprocessing step of the main road with R _-1 ', and the rest of the operation process is the same as the peak preprocessing of the main road; 5) Main road peak defuzzification; it is divided into two parts, (a) if the correlation peaks of R _-2 and R _-1 are valid and the reset point is the same, it is judged that the reset point of R _-2 and R _-1 is in the data position in the segment, if the reset points of R _-2 and R _-1 are in the first half of the data segment, set the correlation peak of R _-1 to be invalid, and set the verification times of R _-2 to R _-2 , R The sum of the verification times of _-1 plus 1, if the reset point of R _-2 and R _-1 is located in the second half of the data segment, the correlation peak of R _-2 is set to be invalid, and the verification times of R _-1 Set to the sum of the verification times of R _-1 and R _-2 plus 1; if R _-2 and R _-1 do not meet the requirement that the correlation peak is valid and the reset point is the same, then (b) compare whether R _-2 ' and R _-1 Satisfied that the correlation peak is valid and the reset point is the same, if not satisfied, then end the peak preprocessing of the main road, if satisfied, then judge the position of the reset point of R _-2 ' and R _-1 in the data segment, if R _-2 ' and If the reset point of R _-1 is located in the first half of the data segment, the correlation peak of R _-1 is set to be invalid, and the number of verifications of R _-2 ' is set to the sum of the number of verifications of R _-2 ', R _-1 and then Add 1, if the reset points of R _-2 ' and R _-1 are located in the second half of the data segment, set the correlation peak of R _-2 ' to be invalid, and set the verification times of R _-1 to R _-1 , Add 1 to the sum of the verification times of R _-2 '; 6) Defuzzification of the peak value of the auxiliary road; replace R _-1 with R _-1 ' in the peak defuzzification step of the main road, and the rest of the operation process is the same as the peak preprocessing of the main road.

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