Spread-Spectrum Signal Detection In Complex Channel

Radio system signal that adopts a spread spectrum form occupies a wide frequency band. Under existing complicated electric and magnetic environment, faults such as small power capacity at the receiver side, too many potential interference sources, interference signal's easily falling into working frequency band and high complexity of propagation channel have affected systematic performance. This paper aims to improve the system's robustness by suppressing interference, enhancing system's weak signal detection ability and constructing new detector for complex channel modeling such as multi-path propagation.Considering local optimal method's advantages like optimal performance and huge calculation quantity in dealing with weak signal, it is introduced in the detection architecture construction of the spread spectrum system to acquire amplitude-processing-based detection architecture that is more convenient in application. Corresponding simulation shows that the amplitude signal processing technology is effective in eliminating small scale non-gauss noise.Signal processing technology in amplitude domain is expanded to the frequency domain in the following steps: do FFT to the time domain sampling signal and carry through amplitude processing to its frequency domain envelop, and then apply IFFT to converse it back into time domain, and at last the signal is sent to the detector for detection. Simulation results show that frequency domain signal processing technology behaves better that time domain amplitude technology in the existence of multiple narrow-band interference.After an analysis of multiplicative channel's characteristics, observed signal is expanded from additive model to a multiplicative one, and the detection architectures and corresponding detection statistics of local optimal detection technology and amplitude-based signal processing technology in a multiplicative noise environment are given. By constructing multiplicative noise in advance, simulation work is done to draw a comparison between multiplicative channel detector and traditional square-sum detector, and to analyze multiplicative noise coefficient's impact on different detectors. The result demonstrates that the stronger the multiplicative noise, to a greater degree is the amplitude signal processing detector's advantage over traditional detectors.In the end, some aspects that are not given deep analysis and problems that might arise in practical use are presented.