Two-Signal Cross Modulation in a Frequency-Modulation Receiver

Cross modulation of a desired signal by an undesired signal is caused by amplitude modulation on the undesired signal and appears as amplitude modulation of the desired signal. Therefore, a frequency-modulation receiver is insensitive to cross modulation, except to the extent that the undesired signal has amplitude modulation and the receiver is incidentally sensitive to amplitude modulation. It is shown that cross modulation is not caused by frequency modulation on the undesired signal and does not appear as frequency modulation of the desired signal. There still may be a kind of beat-note interference if the signals are in adjacent frequency channels. Also the desired signal may be attenuated if the undesired signal is strong enough to overload the receiver before it is filtered out.