| Direct sequence spread spectrum signal has wide bandwidth, low SNR, low interception rate and high anti-interference and so on .It has been widely used for military communications, satellite communications, mobile communications and other fields. With the electronic warfare and information warfare development, the DS signal detection has become a hot topic in the field of communications.This paper takes DS BPSK modulated signals for example to research on detection of DS-SS signals and parameter estimation of PN sequence. It introduces a direct sequence spread spectrum communication system and the pseudo-random sequence of the basic principles of the basic knowledge. It uses the square harmonic detection method in the detection area of Carrier frequency. We derive an algorithm square multiplier method and the theoretical simulation. We use multiply delay and cyclic spectrum to detect the signal for the DS PN code rate, and show derivation and simulation results of the algorithm and analyzes their advantages and disadvantages of two methods. The paper adopts quadratic power spectrum and cepstrum method to estimate the PN code period, for the shortcomings of both methods has been improved, based on delay-related second power spectrum method provides a good solution on the long PN code period the estimation. Despreading without the code has done some work on the analysis of the local method of interception of the signal, and the mathematical theory is derived.Simulation results show that the use of the square of carrier frequency harmonic noise ratio assay detection threshold is -22dB. For the delay with multiplication and cyclic spectrum, PN code detection rate of detection threshold SNR is -20dB and -16dB. In estimate of the PN code period, the second power spectrum and cepstrum SNR detection threshold is -14dB and -15dB. Delay related to the second power spectrum method has solved the estimate of the long code period, but the corresponding SNR detection threshold increases to -12dB. |
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