Spreading code synchronization method based on square correlation

Abstract

The invention provides a spreading code synchronization method based on square correlation. The spreading code synchronization method based on square correlation comprises the following steps of: by use of the characteristics of an autocorrelation function of signals, modifying a spread spectrum signal and a local PN code sequence signal by virtue of square operation, respectively; performing correlation calculation on the modified spread spectrum signal and PN code sequence signal on the basis of sliding correlation dispreading; next, performing secondary threshold judgment on the obtained correlation value, and adjusting the phase shifting step length of the PN code according to the judgment result until a threshold condition is satisfied; and then realizing spreading code synchronization. According to the spreading code synchronization method based on square correlation, the square operation process is added to the signal processing process so that the influence of signal symbols on the correlation operation result is eliminated, the operation time is reduced and the synchronization efficiency is improved; a secondary threshold judgment and forward-reverse shifting module is added to reduce the times of shifting in the synchronization process, and as a result, the synchronization efficiency is further improved; besides, the synchronization accuracy can be guaranteed and the requirements of a communication system can be met.

Description

technical field [0001] The invention relates to the technical field of testing, in particular to a method for synchronizing spread spectrum codes in a direct sequence spread spectrum communication system. Background technique [0002] Direct sequence spread spectrum communication is a system that spreads the spectrum of baseband signals to a wide frequency band through a pseudo-random sequence (PN code), and then transmits it. It has the advantages of strong anti-interference ability, low interception rate, and good communication concealment. It has become an important development direction in the field of communication, and has been widely used in military communication, civil communication, ranging and speed measurement and other fields. [0003] The synchronization of the spread spectrum code is a key technology in the communication system, and the data can be received and processed only after the synchronization is completed. Commonly used synchronization methods includ...

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Problems solved by technology

[0006] Compared with the matched filter method, the sliding correlation method has a simpler structure, but because the correlation operation is affected by the signal symbol, there are positive and negative correlations, so that when the sliding correlation method is used for synchronization, multiple correlations must be performed after each shift Calculate and remove the influence of the sign, and then perform an integral operation on the result of the correlation operation to obtain the correlation value, and further perform a threshold judgment to complete the synchronization process, so that the operation process is complicated and the synchronization efficiency is reduced; secondly, the sliding correlation method usually only judges through a threshold , shift according to the judgment result, only a single shift can be performed each time, the number of shifts is large, and the synchronization time is long. This problem is particularly prominent in long code spread spectrum communication

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