关键词: 通信对抗, 混合扩频, S变换, 参数估计

Abstract:

This paper addresses a new method for parameter estimation of hybrid DS/FH_BPSK signals based on a time-frequency(TF) technique known as the S transform(ST). Good performance is achieved by three stages. Firstly, a nonlinear process is used to produce the reference signal(RFS) which has the same hop parameter as the original signal and its frequencies could be estimated by the cyclic spectrum as the modification information. Then the S transform is improved by adding a Gaussian window width parameter to realize the adaptation of its time-frequency resolution and the ridge curve of ST is extracted as the instantaneous frequency of RFS. Finally, the modification information is used to reduce the estimation error in the high frequency region caused by noise. Simulation results show that the proposed method can operate effectively for hop parameter estimation. Since no prior knowledge of signals is needed, the proposed method is easily implemented in a reconnaissance receiver.

Key words: electronic countermeasures, hybrid spread spectrum, S transform, parameter estimation