| Author |
Message |
Code Warrior
Joined: 30 Dec 2004
Posts: 224
Helped: 7
|
 09 Sep 2008 8:02 RF & Modulation |
|
|
|
|
| One thing still confuse me. How different audio frequency at a same time modulate single carrier frequency. I mean a 100MHz FM transmitter is broadcasting Music, music contains audio frequency from 1KHz to 18KHz, so my question is how a multiple audio frequency modulate single RF carrier at a same time.
|
|
| Back to top |
|
 |
vfone
Joined: 10 Oct 2001
Posts: 2327
Helped: 326
|
09 Sep 2008 9:10 Re: RF & Modulation |
|
|
|
|
| http://cnyack.homestead.com/files/modulation/modfm.htm
|
|
| Back to top |
|
|
Bhanumurthy
Joined: 18 Jun 2008
Posts: 329
Helped: 102
Location: Subcontinent
|
09 Sep 2008 16:20 Re: RF & Modulation |
|
|
|
|
Hi,
Itz possible for no.of modulating frequencies to modulate a single carrier.However, the time domain and freq.domain descriptions would be a bit complex.
The modulation index is defined separately for this case and also the power and current requirements.Lotz of books in literature explain these concepts.
Regards
Bhanumurthy.
|
|
| Back to top |
|
|
mwmmboy
Joined: 18 May 2001
Posts: 145
Helped: 6
|
09 Sep 2008 17:21 Re: RF & Modulation |
|
|
|
|
In my opinion the better way to "see" the modulation process is in the time domain: so a signal (audio) modulates FM the carrier i.e.. instat for instant the phase of the carrier is changed from the modulating signal.
I hope this can help.
Bye
|
|
| Back to top |
|
|
Google
AdSense
|
09 Sep 2008 17:21 Ads |
|
|
|
|
|
|
| Back to top |
|
|
mbyoussef
Joined: 24 May 2006
Posts: 51
Helped: 6
|
09 Sep 2008 18:13 Re: RF & Modulation |
|
|
|
|
| What's wrong with having a composite signal modulating an RF carrier. An FM modulator can work quite well with a composite signal as with a single tone signal.
|
|
| Back to top |
|
|
Code Warrior
Joined: 30 Dec 2004
Posts: 224
Helped: 7
|
11 Sep 2008 20:46 RF & Modulation |
|
|
|
|
| I given FM for example. It may be any type of modulation FM, AM, SSB, PM or any other. How a different audio frequency modulates a single carrier frequency at a same time. Suppose when a carrier frequency is busy with 1KHz audio how it also dance with other audio frequency on the same time.
|
|
| Back to top |
|
|
madengr
Joined: 06 Apr 2005
Posts: 394
Helped: 84
Location: Kansas City
|
11 Sep 2008 21:19 Re: RF & Modulation |
|
|
|
|
| Code Warrior wrote: |
| One thing still confuse me. How different audio frequency at a same time modulate single carrier frequency. I mean a 100MHz FM transmitter is broadcasting Music, music contains audio frequency from 1KHz to 18KHz, so my question is how a multiple audio frequency modulate single RF carrier at a same time. |
The same way your ears hear all the frequencies at the same time. Look at 1 kHz, 3 kHz, and 5 kHz on a oscilloscope. It will look like a square wave (assuming you have the proper phasing). That waveform is simply as summation of the tones. The waveform is modulating the carrier. The modulation with subsequent demodulation is a linear process so you get the same shaped waveform out.
|
|
| Back to top |
|
|
Code Warrior
Joined: 30 Dec 2004
Posts: 224
Helped: 7
|
13 Sep 2008 3:51 RF & Modulation |
|
|
|
|
| Yes, speaker, mic, our ears response to different audio frequency at a same time thats what I want to know how it is possible.
|
|
| Back to top |
|
|
