Thread: What is the difference between cross-modulation and intermodulation?

Cross modulation is a form of intermodulation.
See
http://www.williamson-labs.com/480_mod.htm
If you have ever been listening to a distant FM station while driving by an AM Broadcast station's transmitting tower; you more than likely heard both stations--one on top of the other. That effect was "Cross Modulation," a form of Intermodulation.
Since an FM receiver can only receive--Demodulate--one station at a time (unlike AM which cannot separate interfering stations), that is, two stations on the same frequency, the receiver will only demodulate the stronger of the two [2].

In the scenario above, you heard both the distant FM station and the very close AM transmitter. The FM station's signal, as it was entering the receiver's "Front End," was being Modulated by the very strong AM signal. In effect, the receiver's RF Amplifier was acting as a Detector (rectifier) varying its bias point, which caused the amplifier's gain to change rapidly (at the AM transmitter modulation rate). This varying gain is effectively Modulating (Multiplying) the distant FM station's signal. By the time this "Mess" reaches the receiver's Demodulator it appears to the Discriminator as an FM signal having two audio messages superimposed one on the other.

In electronic communications, what is the difference (if there is) between cross and intermodulation?

There is definitely a difference between the two even though both are unwanted forms of distortion.

Cross modulation occurs when the carrier or some of it`s side band frequencies modulate another carrier or it`s side band frequencies.

Intermodulation occurs when frequencies within the sidebands of a single carrier modulate each other.