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This paper addresses a new method of parameter estimation for hybrid DS/FH_BPSK signals based on S transform(ST) with an asymmetrical window. Good performance is achieved by two stages. Firstly, a nonlinear process is used to produce the reference signal(RFS) which has the same hopping parameter as the original signal. Then S transform is improved by using an asymmetrical window instead of a Gaussian one and the ridge curve of ST is extracted as the instantaneous frequency of RFS. This asymmetrical window has a sharper taper in the forward direction and a compensating slower taper in the backward direction. Thus the resolution of hopping termination times is sacrificed to improve the resolution of hopping initiation time in the resultant time-frequency spectrum. Since the onset and the offset of every hopping can provide the same parameter information, the asymmetrical S transform is better at parameter estimation for hybrid DS/FH spread spectrum signals than that which uses the symmetrical windows. The simulation results show that the proposed method can operate effectively for hopping parameter estimation.
Communications and Mobile Computing (CMC), 2010 International Conference on (Volume:2 )
Date of Conference: 12-14 April 2010