Question 3-50F3

Cross-modulation interference occurs when a very strong, unwanted signal causes its modulation (or lack thereof) to be transferred onto a weaker, desired signal in a receiver's non-linear stages. The strong signal essentially "crosses" its modulation over to the desired frequency, making the desired signal difficult to hear or understand. This perfectly matches the description of a strong signal being "superimposed" on others. Intermodulation distortion (A) is different; it involves two or more strong signals mixing in a non-linear stage to create entirely new, spurious signals on different frequencies, which can then interfere. Receiver quieting (C) is a beneficial effect in FM receivers where a sufficiently strong *desired* signal reduces background noise. The capture effect (D) is an FM receiver characteristic where the strongest of two signals on the *same frequency* will dominate and suppress the weaker one. Neither C nor D describes interference from an *unwanted* strong station's signals being superimposed on others.