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Aircraft bands use AM rather than FM because of the FM capture effect. When there is a double transmission with FM, the receiver will lock on to one signal and

by ajosh 9y ago

Aircraft bands use AM rather than FM because of the FM capture effect. When there is a double transmission with FM, the receiver will lock on to one signal and exclude the other. With AM, you will hear both as well as, possibly, a heterodyne tone if the carriers aren't exactly the same frequency which is much preferable. FM demodulators can't really demodulate AM signals. AM demodulation can demodulate FM by tuning a bit off the carrier frequency thanks to the fall-off of the filters but the quality isn't great.

Aloha 9y ago
> FM demodulators can't really demodulate AM signals. AM demodulation can demodulate FM by tuning a bit off the carrier frequency thanks to the fall-off of the filters but the quality isn't great. By "isn't great" you mean, "I might be able to understand something with a tailwind, downhill" - right? :-P The mode of operation for an AM radio listening to FM is akin to a slope detector.