Detection And Parameter Estimation Of DS Signal In Data Link

As the tools and measure to transmit information for army’s command, control andintelligence system, data link is an important communication mode in information war.With the special military background, signal in data link must have the ability ofanti-jamming and low intercept. DSSS signal using the working mechanism ofinformation sequence directly multiplied by the pseudo random sequence, with whichextends signal spectrum and makes the signal power spectral density lower, has thefeature of concealing, confidentiality, anti-jamming, therefore, DS signal has beenwidely applied to the data link. Along with the increasingly complicated militaryenvironment, it has very important theoretical and practical significance to carry out thestudy on detection and parameter estimation of DS signal in data link.Under the background of DS signal in data link, based on the research of directsequence spread spectrum mechanism, signal separation of DS signal is deeply studiedbased on the JADE blind source separation algorithm. In order to detect DS signal underthe condition of Low SNR, focusing on orthogonal correlation detection algorithm andcepstrum detection algorithm, and the two kinds of algorithms are compared andanalyzed; Further, the parameter estimation technology of DS signal is studied, with theestimated parameters including carrier frequency, PN code rate and modulation mode.During the research, we focused on the carrier frequencies estimation with the improvedsquare of frequency doubling method, PN code rate estimation with delay andmultiplication method, automatic modulation recognition algorithm based on featureparameter decision. On the basis, the algorithms in detail are simulated with MATLAB7.1simulation platform as well. The simulation results verify the correctness andeffectiveness of the algorithms. Besides, based on the theory and simulation results ofalgorithms, carrying out hardware design of the key modules of DS detection system,DS signal generation module, orthogonal correlation detection front-end processingmodule, carrier frequency estimation module and PN code rate estimation module aredesigned through Virtex4-sx35series FPGA development platform, the functionalsimulation is verified with ModelsimSE6.5b software.