A receiver apparatus adapted to be synchronized with a link transmitter to identify and isolate a transmitted, modulated carrier signal from other RF transmissions by obtaining A/D samples at each integer π zero crossing of a transmitted signal and at the half Hertz cycles (π/2 and 3 π/2) of the modulated carrier signal. The integer π A/D samples are at the carrier signal zero crossings and thus contain only the other RF and noise in the receiving antenna. The half Hertz cycle A/D samples contain both the carrier signal and the other RF being received at that instant. The analytical methods of the invention use the integer π A/D samples to compute estimates of the other RF in the half integer π A/D samples in order to separate it for the detection of the transmitted signal, thereby benefiting narrow band signals with constant zero crossing that are directly coded on the carrier frequency as DC balanced symbols, and enabling higher data rates than are typically achievable by passband filtering the receiving antenna waveform.