A wideband spread spectrum signal acquisition device based on fast lock decision feedback mechanism

Abstract

The application discloses a kind of wideband spread spectrum signal acquisition device based on fast lock judging feedback mechanism, belong to spaceflight measurement and control communication technical field.The method uses the method of parallel acquisition of pseudo code multiple ways, carrier serial search acquisition, compromise between signal acquisition time and resource consumption, and can complete the fast acquisition of carrier by fast lock judging feedback mechanism.Can complete the fast acquisition of carrier of high bandwidth spread spectrum signal under the condition of less resource consumption.The engineering implementation of the application occupies less chip resources, can use low-performance processing chip, save cost, and can be applied to low-cost application scenarios.Can find corresponding carrier frequency quickly when searching carrier frequency by fast carrier lock judging feedback mechanism, and find corresponding chip phase by pseudo code parallel search.The application is simple in design, easy to implement in engineering, and has low difficulty.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of space TT&C communication technology, in particular to a wideband spread spectrum signal acquisition device based on a fast lock judgment feedback mechanism, which is suitable for fast carrier acquisition of wideband spread spectrum signals in TT&C communication. BACKGROUND

[0002] Spread spectrum signals have strong anti-interference ability and are widely used in satellite TT&C communication fields. With the increasing demand for information rate, the bandwidth of spread spectrum signals also increases. In the face of the problem of high-bandwidth spread spectrum signal acquisition and tracking based on high pseudo code rate, a parallel processing algorithm is generally used, which uses the concept of "space for time", and carrier acquisition and pseudo code acquisition are processed in parallel to complete fast acquisition and tracking of signals. However, the more parallel paths, the higher the resource requirements for processing chips.

[0003] In some application scenarios, low-performance processing chips are used to reduce costs. Low-performance processing chips have limited resources and cannot use conventional full-parallel processing algorithms. In order to enable low-performance processing chips to process high-bandwidth spread spectrum signal acquisition, it is necessary to design a method that saves resources and can quickly achieve carrier acquisition. SUMMARY

[0004] Therefore, the present application provides a wideband spread spectrum signal acquisition device based on a fast lock judgment feedback mechanism. The present application makes a compromise between signal acquisition time and resource consumption, uses pseudo code parallel multi-path acquisition and carrier serial search acquisition, and can complete fast carrier acquisition through a fast lock judgment feedback mechanism. The present application can complete fast carrier acquisition of high-bandwidth spread spectrum signals with less resource consumption. The present application has the characteristics of low implementation complexity, resource saving, low cost, and high efficiency.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A wideband spread spectrum signal acquisition device based on a fast lock judgment feedback mechanism, comprising an AD sampling module 1, a down-conversion module 2, a filtering module 3, a carrier NCO module 4, a frequency control word search module 5, first to nth correlation modules 6-1 to 6-n, first to nth integral cleaning modules 7-1 to 7-n, first to nth parallel pseudo code modules 8-1 to 8-n, and a lock judgment module 9; wherein n is a set value;

[0007] The AD sampling module 1 is used to receive analog signals sent from a channel, convert the analog signals into digital signals, and output the digital signals to the down-conversion module 2;

[0008] The down-conversion module 2 is used to convert the digital signals from intermediate frequency signals to baseband signals by using a local oscillator signal, and output the baseband signals to the filtering module 3;

[0009] The filtering module 3 is used to filter out the twice high frequency components in the baseband signal, and outputs to the first to the nth correlation modules 6-1 to 6-n;

[0010] The carrier NCO module 4 is used to generate the local oscillator signals of sine and cosine by using the frequency control word output by the frequency control word search module 5, and outputs to the down conversion module 2;

[0011] The frequency control word search module 5 is used to search the carrier according to the maximum range of the product technical requirements , control the frequency control word to scan in the range of , and output the current frequency control word to the carrier NCO module 4 when the lock decision result is the lock state, and output the carrier frequency at the lock state to the outside;

[0012] The first to the nth correlation modules 6-1 to 6-n are respectively used to perform correlation exclusive or calculation on the filtered baseband signal and the corresponding pseudo code sequence, and output the correlation exclusive or processed signal to the first to the nth integration cleaning modules 7-1 to 7-n;

[0013] The first to the nth integration cleaning modules 7-1 to 7-n are respectively used to perform integration accumulation processing on the correlation exclusive or processed signal, and output the integration cleaned data to the lock decision module 9;

[0014] The first to the nth parallel pseudo code modules 8-1 to 8-n are respectively used to shift the pseudo code phase according to the number of parallel paths, generate the pseudo code sequence of the corresponding path number, and output to the first to the nth correlation modules 6-1 to 6-n, and output the pseudo code phase of the corresponding path number to the subsequent pseudo code tracking loop when the lock decision result output by the lock decision module 9 is the lock;

[0015] The lock decision module 9 is used to receive the integration cleaned data output by the first to the nth integration cleaning modules 7-1 to 7-n, perform corresponding decision processing, obtain the lock decision result, and output to the first to the nth parallel pseudo code modules 8-1 to 8-n and the frequency control word search module 5 respectively.

[0016] Further, the lock decision module 9 includes a BPSK / QPSK system selection module 9-1, an I / Q power statistical module 9-2, an I / Q power ratio module 9-3, an optimal sampling point detection module 9-4, a constellation statistical module 9-5, and a lock decision result output module 9-6;

[0017] The BPSK / QPSK system selection module 9-1 is used for selection of modulation system, according to the modulation system parameters BPSK or QPSK sent from the outside, receives the integration cleaned data of each branch, outputs the BPSK system signal to the I / Q power statistical module 9-2, and outputs the QPSK system signal to the optimal sampling point detection module 9-4.

[0018] The I / Q power statistics module 9-2 is used for I and Q power statistics of the BPSK system signal, and outputs I and Q power values to the I / Q power ratio module 9-3.

[0019] The I / Q power ratio module 9-3 is used for I / Q power ratio calculation of the I and Q power values, and outputs to the lock decision result output module 9-6.

[0020] The best sampling point detection module 9-4 is used for best sampling of the symbol of the QPSK system signal, and samples the I and Q values of the best symbol, and outputs to the constellation statistics module 9-5.

[0021] The constellation statistics module 9-5 is used for judging and counting the proportion of the symbol in the normal range of the QPSK constellation according to the I and Q values, and outputs to the lock decision result output module 9-6.

[0022] The lock decision result output module 9-6 is used for judging the carrier capture lock when the I / Q power ratio is greater than the set value for the BPSK system signal, otherwise, judging the carrier capture loss of lock; for the QPSK system signal, when the proportion of the symbol in the normal range of the constellation is greater than the threshold, judging the carrier capture lock, otherwise, judging the carrier capture loss of lock, and outputting the lock decision result to the first to the n parallel pseudo code modules 8-1 to 8-n and the frequency control word search module 5.

[0023] The present application has the following advantages:

[0024] 1 The present application occupies less chip resources in engineering implementation, can adopt a low-performance processing chip, saves cost, and can be suitable for low-cost application scenarios.

[0025] 2 The present application adopts carrier serial search combined with pseudo code parallel search through the fast carrier lock feedback mechanism, so that the corresponding carrier frequency is quickly found during carrier frequency search, and the corresponding chip phase is found through pseudo code parallel search.

[0026] 3 The present application is simple in design, easy to implement in engineering, and low in difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the overall block diagram of the working principle of the present application.

[0028] Figure 2 is the working principle diagram of the lock decision method of the lock decision module 9 of the present application.

[0029] Figure 3 is the corresponding constellation of the QPSK spread spectrum signal carrier pseudo code loss of lock of the present application.

[0030] Figure 4The QPSK spread spectrum signal carrier pseudo code locking time corresponding constellation of the application. DETAILED DESCRIPTION

[0031] The application will be described in detail below in conjunction with the drawings and specific embodiments.

[0032] A wideband spread spectrum signal acquisition device based on a fast lock judgment feedback mechanism. As shown in the figure, it comprises an AD sampling module 1, a down-conversion module 2, a filtering module 3, a carrier NCO module 4, a frequency control word search module 5, first to nth correlation modules 6-1 to 6-n, first to nth integral cleaning modules 7-1 to 7-n, first to nth parallel pseudo code modules 8-1 to 8-n, and a lock judgment module 9; wherein n is a set value; wherein: Figure 1 The AD sampling module 1 is used to receive an analog signal sent from a channel, convert the analog signal into a digital signal, and output it to the down-conversion module 2.

[0033] The down-conversion module 2 is used to complete the quadrature down-conversion processing of the signal, convert the digital signal from an intermediate frequency signal to a baseband signal using a local oscillator signal, and output it to the filtering module 3.

[0034] The filtering module 3 is used to receive the baseband signal sent from the down-conversion module 2, filter out the twice high frequency component in the baseband signal, and output it to the first to nth correlation modules 6-1 to 6-n.

[0035] The carrier NCO module 4 is used to receive the frequency control word sent from the frequency control word search module 5, generate a sine, cosine local oscillator signal, and output it to the down-conversion module 2.

[0036] The frequency control word search module 5 is used to control the frequency control word to scan within a range according to the maximum carrier acquisition range of the product technical requirements

[0037] , and when the lock judgment result is a lock state, output the current frequency control word to the carrier NCO module 4, and output the carrier frequency at the lock time to the outside. The first to nth correlation modules 6-1 to 6-n are respectively used to receive the baseband signal sent from the filtering module 3 and the pseudo code sequence sent from the first to nth parallel pseudo code modules 8-1 to 8-n, perform correlation exclusive or calculation on the baseband signal and the corresponding pseudo code sequence, and output the correlation exclusive or processed signal to the first to nth integral cleaning modules 7-1 to 7-n.

[0038] The first to nth integral cleaning modules 7-1 to 7-n respectively receive the correlation exclusive or processed signal sent from the first to nth correlation modules 6-1 to 6-n, perform integral accumulation processing on the signal, and output the integral cleaned data to the lock judgment module 9.

[0039] The first to nth integral cleaning modules 7-1 to 7-n respectively receive the correlation exclusive or processed signal sent from the first to nth correlation modules 6-1 to 6-n, perform integral accumulation processing on the signal, and output the integral cleaned data to the lock judgment module 9. ​

[0040] The first to the n parallel pseudo code modules 8-1 to 8-n are respectively used for shifting the pseudo code phase according to the number of parallel paths to generate the pseudo code sequence of the corresponding path number, and output to the first to the n correlation modules 6-1 to 6-n. When the lock decision result output by the lock decision module 9 is lock, the pseudo code phase of the corresponding path number is output to the subsequent pseudo code tracking loop.

[0041] The lock decision module 9 is used for receiving the integrated and cleaned data output by the first to the n integrated and cleaned modules 7-1 to 7-n, performing corresponding decision processing to obtain a lock decision result, and output to the first to the n parallel pseudo code modules 8-1 to 8-n and the frequency control word search module 5 respectively.

[0042] As shown in Figure 2 The lock decision module 9 includes a system selection module 9-1, an I / Q power statistical module 9-2, an I / Q power ratio module 9-3, an optimal sampling point detection module 9-4, a constellation statistical module 9-5, and a lock decision result output module 9-6.

[0043] The BPSK / QPSK system selection module 9-1 is used for selection of modulation system, receives the integrated and cleaned data of each branch according to the modulation system parameters BPSK or QPSK sent from outside, and outputs the BPSK system signal to the I / Q power statistical module 9-2 and the QPSK system signal to the optimal sampling point detection module 9-4.

[0044] Common spread spectrum signals include BPSK spread spectrum signals and QPSK spread spectrum signals. For BPSK spread spectrum signals, after the carrier pseudo code is locked, the I path data is demodulation data and the Q path data is noise, and the I / Q power ratio can be used for carrier lock decision. For QPSK spread spectrum signals, after the carrier pseudo code is locked, the I path and Q path data are both demodulation data, and the I / Q power ratio cannot be used for carrier lock decision, and the position of the constellation can be used for carrier lock decision.

[0045] The I / Q power statistical module 9-2 is used for receiving the BPSK system signal sent from the system selection module 9-1, performing I path and Q path power statistics, and outputting the I path and Q path power values to the I / Q power ratio module 9-3.

[0046] The I / Q power ratio module 9-3 is used for receiving the I path and Q path power values sent from the I / Q power statistical module 9-2, performing I / Q power ratio calculation, and outputting to the lock decision result output module 9-6.

[0047] The optimal sampling point detection module 9-4 is used for receiving the QPSK system signal sent from the system selection module 9-1, sampling the I value and the Q value of the symbol best, and outputting to the constellation statistical module 9-5.

[0048] The constellation diagram statistics module 9-5 is used for receiving the I value and the Q value sent by the best sampling point detection module 9-4, judging and counting the proportion of the symbols in the normal range of the QPSK constellation diagram, and outputting to the lock decision result output module 9-6.

[0049] The lock decision result output module 9-6 is used for judging that the carrier capture is locked when the I / Q power ratio is greater than 5 dB for the BPSK system signal, otherwise, judging that the carrier capture is lost. For the QPSK system signal, when the proportion of the symbols in the normal range of the constellation diagram is greater than 2 / 3, judging that the carrier capture is locked, otherwise, judging that the carrier capture is lost, and outputting the lock decision result to the first to the n parallel pseudo code modules 8-1 to 8-n and the frequency control word search module 5.

[0050] For the BPSK spread spectrum signal, after the carrier pseudo code is locked, the I channel data energy is greater than the Q channel data energy in the conventional satellite-ground link, and when the I / Q power ratio is greater than 5 dB, it can be determined that the carrier pseudo code is in the locked state.

[0051] For the QPSK spread spectrum signal, when the carrier pseudo code is locked, the absolute values of the I channel data and the Q channel data are taken, and the constellation points of the four quadrants in the constellation diagram are converted to the first quadrant, and then the positions of the constellation points are counted. When the carrier pseudo code is lost, the constellation points are a circle, as shown in FIG. 6; when the carrier pseudo code is locked, the positions of the constellation points are concentrated near 45 degrees, as shown in FIG. 7. The phase of the counted constellation points between 15 degrees and 75 degrees is considered as an effective constellation point, and the others are invalid constellation points. In the 90-degree range of the first quadrant, the 60-degree range between 15 degrees and 75 degrees is the effective constellation point, accounting for 2 / 3 of the total range. When the probability of the constellation points between 15 degrees and 75 degrees is greater than 2 / 3 in the carrier pseudo code decision, it is considered that the carrier pseudo code is locked, otherwise, it is considered that the carrier pseudo code is lost. Figure 3 Figure 4

[0052] In summary, the present application adopts the method of parallel pseudo code multi-path capture and serial carrier search capture. The time of signal capture and the consumption of resources are balanced, and the fast capture of the carrier can be completed through the fast lock decision feedback mechanism. The fast capture of the carrier of the high-bandwidth spread spectrum signal can be completed under the condition of less resource consumption. The present application occupies less chip resources in engineering implementation, and a low-performance processing chip can be used to save cost and be suitable for low-cost application scenarios. Through the fast carrier lock decision feedback mechanism, the carrier serial search is combined with the parallel pseudo code search, so that the corresponding carrier frequency can be quickly found in the carrier frequency search, and the corresponding code phase can be found through the parallel pseudo code search. The present application is simple in design, easy to implement in engineering, and low in difficulty.​​

Claims

1. A broadband spread spectrum signal acquisition device based on a fast lock-in feedback mechanism, characterized in that, It includes an AD sampling module (1), a down-conversion module (2), a filtering module (3), a carrier NCO module (4), a frequency control word search module (5), first to nth correlation modules (6-1) to (6-n), first to nth integration cleaning modules (7-1) to (7-n), first to nth parallel pseudocode modules (8-1) to (8-n) and a lock decision module (9); where n is a set value; The AD sampling module (1) is used to receive the analog signal sent from the channel, convert the analog signal into a digital signal, and output it to the downconversion module (2). The downconversion module (2) is used to convert the digital signal from the intermediate frequency signal to the baseband signal using the local oscillator signal and output it to the filter module (3). The filtering module (3) is used to filter out twice the high frequency component in the baseband signal and output it to the first to nth related modules (6-1) to (6-n). The carrier NCO module (4) is used to generate sine and cosine local oscillator signals using the frequency control word output by the frequency control word search module (5), and output them to the downconversion module (2). The frequency control word search module (5) is used to determine the maximum carrier acquisition range according to the product's technical requirements. The frequency control word is in Scan within the range, and when the lock decision result is locked, output the current frequency control word to the carrier NCO module (4), and output the carrier frequency when locked to the outside; The first to nth related modules (6-1) to (6-n) are respectively used to perform correlation XOR calculation on the filtered baseband signal and the corresponding pseudocode sequence, and output the signal after correlation XOR processing to the first to nth integration and cleaning modules (7-1) to (7-n). The first to nth integral cleaning modules (7-1) to (7-n) are respectively used to perform integral accumulation processing on the signals after XOR processing, and output the integrated cleaned data to the lock decision module (9). The first to nth parallel pseudocode modules (8-1) to (8-n) are used to shift the pseudocode phase according to the number of parallel paths, generate the corresponding number of pseudocode sequences, and output them to the first to nth related modules (6-1) to (6-n). When the locking decision module (9) outputs the locking decision result as locked, it outputs the corresponding number of pseudocode phases to the subsequent pseudocode tracking loop. The locking decision module (9) is used to receive the integrated cleaned data output by the first to nth integration cleaning modules (7-1) to (7-n), perform corresponding decision processing, obtain the locking decision result, and output it to the first to nth parallel pseudocode modules (8-1) to (8-n) and the frequency control word search module (5).

2. The broadband spread spectrum signal acquisition device based on a fast lock-in feedback mechanism according to claim 1, characterized in that, The locking decision module (9) includes a BPSK / QPSK system selection module (9-1), an I / Q power statistics module (9-2), an I / Q power ratio module (9-3), an optimal sampling point detection module (9-4), a constellation diagram statistics module (9-5), and a locking decision result output module (9-6). The BPSK / QPSK mode selection module (9-1) is used to select the modulation mode. Based on the externally sent modulation mode parameters BPSK or QPSK, it receives the data after integration and cleaning of each branch, outputs the BPSK mode signal to the I / Q power statistics module (9-2), and outputs the QPSK mode signal to the optimal sampling point detection module (9-4). The I / Q power statistics module (9-2) is used to perform I-channel and Q-channel power statistics on BPSK signal and output the I-channel and Q-channel power values ​​to the I / Q power ratio module (9-3). The I / Q power ratio module (9-3) is used to calculate the I / Q power ratio of the I-channel and Q-channel power values ​​and output it to the lock decision result output module (9-6). The optimal sampling point detection module (9-4) is used to perform optimal sampling of the symbols of the QPSK system signal, sample the optimal I and Q values ​​of the symbols, and output them to the constellation diagram statistics module (9-5). The constellation diagram statistics module (9-5) is used to determine and count the proportion of symbols within the normal range of the QPSK constellation diagram based on the I and Q values, and output the result to the lock decision output module (9-6). The lock decision output module (9-6) is used to determine carrier acquisition lock when the I / Q power ratio is greater than the set value for BPSK system signals, otherwise it determines carrier acquisition lockout; for QPSK system signals, it determines carrier acquisition lockout when the proportion of symbols in the constellation diagram within the normal range is greater than the threshold, otherwise it determines carrier acquisition lockout, and outputs the lock decision result to the first to nth parallel pseudocode modules (8-1) to (8-n) and the frequency control word search module (5).

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