FM Synthesis Article

Counterparts · Post by **Counterparts** » Tue Oct 26, 2004 6:52 am

Before reading this article:

http://www.angelfire.com/in2/yala/2fmsynth.htm

I didn't understand anything about FM Synthesis apart from guessing that 'FM' stood for 'Frequency Modulation'.

Now, I need to lie down in a quiet, dark room for about two days...

(It is quite a good article, though - !)

Royston

BingoTheClowno · Post by **BingoTheClowno** » Tue Oct 26, 2004 10:17 am

http://www.soundonsound.com/sos/apr00/a ... ecrets.htm

Does it help to know that your common radio also uses FM to transmit in the 88.1 - 108.1 Mhz range

. The FM choice in radio was taken in order to raise the quality level of the transmitted audio (compared to AM or SW (short wave)). An AM station channel has a bandwidth of 5kHz (10kHz theorethical) which means that the audio signal's highest reproduced frequency cannot exceed 5kHz while the FM station channel bandwidth is 200kHz (which can accomodate two channels for stereo).

http://www.zonalatina.com/Zldata126.htm

[ This Message was edited by: BingoTheClowno on 2004-10-26 11:18 ]

Counterparts · Post by **Counterparts** » Tue Oct 26, 2004 11:22 am

You can't really use FM on AM-frequency range radio stations though - not enough bandwidth available, which is why amplitude modulation is used. As you get into the ~100 MHz range, FM becomes feasible.

Royston

at0m · Post by **at0m** » Tue Oct 26, 2004 12:31 pm

Great link, Royston!! I'd like to add that Aviation VHF comms use... AM modulation in the 108-13? band, just above the FM radio band

The higher freq of FM gives it it's high resolution of the radio transmission compared to AM radio. Also, if you modulate 100MHz +-20kHz, you can see why there's this FM band separation, cos the 100Mhz will be modulated and become about 99.8 to 100.2 MHz. (correct me if i'm wrong eh)

In synthesis, FM sounds similar to PM, which was easier to accomplish in the 80ies. That's part of why the DX-7, 'first FM synth', uses PM and not FM.

FM's definately worth checking out a bit more, but I haven't got around much yet except for what Flexor thought me about it this far... I know of this LPF effect as you decrease FM amount, and also this Talking Filter patch inspired me. Check out the Advanced Programming Techniques for Modular Synthesizers, there's a page on FM.

Have fun!

_________________
[url]irc://efnet/pulsarmusic[/url]

[ This Message was edited by: at0m|c on 2004-10-27 04:10 ]

[ This Message was edited by: at0m|c on 2004-10-27 04:13 ]

Counterparts · Post by **Counterparts** » Wed Oct 27, 2004 2:52 am

at0m|c wrote:
Check out http://www.cim.mcgill.ca/%7Eclark/nordmodularbook/ for more on FM.

Firefox just loads a blank page with 'Done' ?

Royston

at0m · Post by **at0m** » Wed Oct 27, 2004 3:11 am

Here also

Updated the link!

Counterparts · Post by **Counterparts** » Wed Oct 27, 2004 4:25 am

Whoa!

That's some TOC. I've downloaded the .pdf version to look at later this evening - ta!

Royston