The recovery of distorted bandlimited almost-periodic signals

It is shown that the PQ theorem can be used to solve a certain signal recov ery problem in which the transmitted and received signals are almost period ic functions. In this problem the signal to be recovered, which is bandlimi ted, is nonlinearly distorted and then bandlimited to the original band. Re lated signal recovery results are also given. These related results, unlike the PQ theorem, are applicable in settings in which the underlying signal space is not a Hilbert space or even a space that is complete.