Hardware implementation for blind demodulation method for chaotic direct sequence spreadspectrum signals

Abstract

In this paper, we design a field-programmable gate array (FPGA)-based hardware implementation for blind demodulation method for chaotic direct sequence spread spectrum (CD3S) signals. Both transmitter and receiver are designed. The transmitter can produce ten chaotic maps as the spreading sequence. In the receiver, the mathematic model of unscented Kalman filter (UKF) chaotic fitting is built and simplified for hardware implementation. The hardware structure of the receiver is based on this simplified model. For real time fitting different chaotic maps, a dynamic adjustment strategy of range-differentiating factor is proposed. The additove white Gausian noise (AWGN) and multipath channel experiments verify the anti-noise and anti-multipath performance of the UKF chaotic fitting method on one hand. On the other hand, the experiments verify the method can demodulate CD3S signals spread by all ten chaotic maps effectively.