dont know what to call this (has to do w/ audio)

[zachtheterrible]

I'm afraid that I'm not going to get this the first time, but here goes:

Say you've got an FM signal. The only thing that varies in an FM signal is the frequency (right?). There are two things that make up an audio signal, frequency and amplitude (how loud the sound is). How is this reproduced in an FM signal, since the only thing that is varying is the frequency? Also, how does it work in an AM signal, since the only thing varying is the amplitude?

 

[vaineo]

Take a look at this, i think it explaines it pretty good. **broken link removed**

 

[Roff]

Also, do a search for "AM detector" and FM discriminator" to see how AM and FM are demodulated. Remember, AM and FM don't "happen" to the audio; The audio modulates (varies) either the amplitude or the frequency of a high frequency carrier signal. In the AM broadcast band, the carrier frequency is somewhere between 530 and 1700 kHz, depending on the station's assigned frequency. In the FM broadcast band, the carrier frequency is somewhere between 88 and 108 MHz, again depending on the assigned frequency. The maximum allowed deviation in the FM broadcast band is +/- 75kHz from the center frequency of the carrier.
FM signals are less susceptible to noise interference, because most sources of noise cause amplitude modulation, and FM discriminators are more or less immune to amplitude modulation.