Why do FM stations usually sound better than AM stations?

satguru

I am a layman in this, but I'll have a go. The main difference is FM barely receives interference as the stronger signal covers all weaker, whereas AM receives everything at once, your station plus static and other distant stations. FM works at a consistent volume as the peaks in FM modulations are horizontal, ie frequency, whereas AM naturally peaks upwards, so any variations in sound will also peak the volume at high notes. But for speech, in a good signal area, AM is fine, and if you use 2way radio and remove the AM carrier wave, you can discern a voice at about 1/10th the level as AM as it's isolated from the carrier, which has no sound of its own, but swamps signals under about 1/2 a signal unit. I think you can guess where I learnt all this... Dec 19 03, 9:12 PM

Hamlet.

As a "layman" what you write is quite impressive, just to add to your accurate information - FM stations transmit radio waves at full power. Amplitude modulation changes the amplitude of the radio waves to inform the receiver of how much compression and rarefaction is needed from the speakers. For this reason, the AM signal never transmits at full power. FM, on the other hand, keeps it signal at full power and instead varies the frequency slightly... Dec 19 03, 9:39 PM

IndieQueen

To add to what Hamlet has said about AM never broadcasting at full power, many AM stations have to power up and down at certian intervals during the day. This means that the reach of their signal varies at certain points. At least that's how it was with the AM station where I worked. Dec 19 03, 10:16 PM

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Why do most AM radio stations have a greater range than FM stations? Why do AM and FM radio stations in the UK (and presumably worldwide) have to change their frequencies every 50 or so miles rather than keep one for the whole country? How do they determine the most popular radio stations? Why do the names of radio stations in the western part of the US start with a 'K' and the ones in the eastern part start with a 'W'?

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