Comments on "Envelope Detector Performance for a Partially Coherent-Fading Sinewave in Noise"

The basic premise in a recent paper that the matchedfilter square-law envelope detector is generally appropriate for fastfading as well as slow-fading incoherent channels is questioned. Its inappropriateness for a fast-fading incoherent Gaussian channel is demonstrated by evaluation of probability of error for this receiver and for the optimum receiver. As a result, modifications to some of the conclusions drawn regarding attainable performance gain with increasing observation time are proposed. In addition, it is pointed out that the performance predictor adopted, viz., deflection, exhibits anomalous behavior (for at least some incoherent fading channels), thereby rendering the other conclusions questionable.