A sum-of-products model for effective coherent modulation filtering

Modulation filtering is a technique for filtering slowly-varying envelopes of frequency subbands of a nonstationary signal, ideally without affecting the signal´s phase and fine-structure. Coherent modulation filtering is a promising subtype of such techniques where subband envelopes are determined through demodulation of the subband signal with a coherently detected subband carrier. In this paper we demonstrate how modulation filtering, when done coherently, is far more effective than standard incoherent methods. We show that empirical results can be made to be almost ideal, and significantly better than previous coherent attempts, as long as fine-structure information is retained as side information and the filterbank reduces subband interference.