modulating a carrier

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TORSKI

Joined Apr 27, 2006
1
How effiecient will be to modulate a carrier in an FM transmitter circuit using signals form the RS-232 of a computer? Is there device I need to do that effectively?
 

Papabravo

Joined Feb 24, 2006
14,255
Originally posted by TORSKI@Apr 27 2006, 09:01 AM
How effiecient will be to modulate a carrier in an FM transmitter circuit using signals form the RS-232 of a computer? Is there device I need to do that effectively?
[post=16606]Quoted post[/post]​
In bandwidth terms it will be very inefficient. A narrow band FM voce channel is about 25 kHz wide. Broadcast FM stations are separated by 200 kHz to prevent interference between adjacent stations.

For bandwidth efficiency it is hard to beat PSK31 and varicode.
 

beenthere

Joined Apr 20, 2004
15,819
Hi,

If you have a sound card, why not use its output and a standard mixer? Or pad it down a bit and just run it into the microphone input of the transmitter?
 

DAY DUDE

Joined Apr 28, 2006
2
Originally posted by TORSKI@Apr 27 2006, 06:01 AM
How effiecient will be to modulate a carrier in an FM transmitter circuit using signals form the RS-232 of a computer? Is there device I need to do that effectively?
[post=16606]Quoted post[/post]​
What are you trying to do?
 
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