Testing a new form of Data modulation.

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kylehotchkiss

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While playing with my Arduino, I decided it would be neat to attach my headphones to the serial out to see if anything could be modulated with it. Turns out that the sound bandwidth on that serial data is about 500hz, and that it could probably be connected to a radio and transmit with some success to another arduino!

Now the question is if I'm *allowed* to test this on a radio. Like I said, the bandwidth of the sound I'm hearing is 350hz-750hz, and not breaking any rules as far as that goes. I was just wondering if I could legally hook this up to my radio, broadcast my callsign with morse, and test this on the experimental frequencies of the 144mhz band.
 

zz0468

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Depending on the band in use, the rules regarding data transmission are a lot more relaxed than they were in past days. I'd suggest that you, yourself, look into Part 97 and see what it says.

Don't expect it to actually work, though. The serial port output might modulate a transmitter with it's square wave data, but what comes out the other end is likely to not be a square wave, and it's not likely to come out at the proper level for the serial input to deal with it.

Another issue is the spectral output you get when applying a square wave to an FM or PM transmitter. It's not pretty, it's not neighborly, and it's probably not legal. That's why data circuits use modems.
 
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