Research On Weak BPSK Signal Detection Based On Chaos Theory

In the modern information battlefield, the request of communication system forthe security of information transfer is more and more high, make ensure that theinformation is received by the partner safely and capture the enemy’s informationhas become a important condition to win the war. Therefore, the sender will usuallysend out the useful information in high noise background, this needs the signalreceiver has strong ability to detect low SNR signal. The detection SNR threshold oftraditional signal detection method based on linear theory of linear high than-10dB,which is hard to meet the requirements of the communication countermeasures, sowe need to find new detection methods of low SNR signals.Chaos theory is a branch of the nonlinear science, for it is immune to the noiseand sensitive to weak signals, a lot of scholars have used the chaos theory in weaksignal detection, and achieved good effects. Based on Duffing oscillator in the chaostheory, this paper is aiming to find the frequency measurement and demodulationmethod of high frequency weak BPSK signal.This paper first introduces to chaos theory, and analyzes the parameter’scharacteristic of the Duffing system, according to the different time domainwaveforms of the cycle mode and chaos mode, we put forward the maximumvariance method and sampling points’ mean square method to measure thefrequency of the signal, then measured the frequency of BPSK signal whosefrequency is between225MHz to400MHz，and presents the frequency measurementerror curves, the interval error is less than0.03%. Then this paper set the thresholdof BPSK signal demodulation based on the above two methods, restore the originalcode words of the BPSK signal and gave the bit error rate curves, from the figureshows, when the SNR is-20dB the bit error rate is at about2%, this can maintainthe basic voice communication. Finally, from the point of view of real-timedetection, this paper demonstrates the system’s hardware implementability.