QPSK

  Direct sequence spread spectrum (DSSS) communication systems has been widely used in these years for its advantage of wide spectrum, low working Signal-to-Noise ratio (SNR), anti-interference, anti-multipath effect and capability of LPI and LPD. They are increasingly replacing conventional communication forms and obtaining extensively applications in modern military and commercial communication systems, for example, CDMA communication system, GPS , measuring and control system, satellite chain, identification of friend or foe and etc. Therefore, corresponding DSSS electronic counter technique becomes a big problem to solve in electronic warfare domain. DSSS electronic counter technique including blind detection, blind parameter estimation and spreading sequences estimation. For the issue of DSSS electronic counter technique of DSSS/QPSK signal damaged by strong additive white Gaussian noise (AWGN), the main research content in this dissertation as follow.