MFSK demodulation using parallel IIR ALE with a time-varying step size factor

Infinite impulse response (IIR) adaptive line enhancers (ALEs) are employed for the task of detecting M-ary frequency shift keying (MFSK) signals. First, a new gradient search technique using a time-varying step size factor is presented which provides faster convergence rate when compared with conventional approaches. Secondly, a new parallel ALE (PALE) structure is proposed for the detection of a set or comb of frequencies which is used in frequency comb multiple access (FCMA) scheme. In FCMA, for efficient use of bandwidth, the information is carried within the phase, amplitude and frequency of each sinusoid. The proposed solution provides faster acquisition time when compared with the fast Fourier transform (FFT) method in situations where the mutual common factor of the input frequencies is small