Direct Sequence Spread Spectrum Signal Parameter Estimation Method And Its Application

Direct sequence spread spectrum (DSSS) communication systems has been widely used in modern military and commercial communication systems these years for its anti-interference and anti-multipath effect, so the corresponding DSSS electronic counter technique becomes a exigent problem to solve in electronic warfare domain. After the modulation type is estimated through carrier squre method, the parameters which include the carrier frequency, the symbol rate, the chip rate, the PN code length, can be estimated. DSSS/PSK communication system often changes in a wide range of these parameters, in the premise of this; the main results are as follows.Based on the parameter estimation algorithm that has been existed, considering how to implement the algorithm, the parameters are under the condition that the chip rate changes from 1Mbps to 25Mbps, the PN code length changes from 511 to 2047. The existing algorithms can not be applicated well. So a method about selecting the number of segments and a biased estimation method are proposed in the subject to estimate the chip period. Combining a method named Split-Symbol Moments Estimator (SSME) with a method named Projection Approximation Subspace Tracking with deflation (E-PASTd), a new method named Blind synchronization-SSME method is proposed to estimate the PN code length. When the PN code length and the chip period are estimated, the chip rate is estimated by dividing these two numbers. This method avoid comb peaks at the integer multiple of the chip rate, which appearing when using the traditional chip rate estimation method.Through software simulation, the accurate estimation of the parameters is obtained. This demonstrates the feasibility of the algorithm. Throuth hardware-in-loop simulation and the SIMULINK simulation, the parameters are well estimated too. This demonstrates that the algorithm can be applied to implemention platform.