1964 Antique MODEM Live Demo

[Chris Elmquist]

On Saturday (05/30/2009 at 10:37AM +0100), Gordon JC Pearce wrote:
> 
> So, you can't see a possible set of circumstances where having the wrong
> voltage coming in the serial port could cause the frequency shift to be
> wrong?
> 
> How clever do you think the tone generator side is?

Well, as Tony replied-- I think that the RS232 input is a logic level.
It's not an analog level.  So, you are going to get either the mark tone
or the space tone and not something in between.

I think this situation was just a poor explaination of what went wrong.
Whatever miscable situation he had caused him to generate the opposite
tone of what he was expecting but not a tone that was off frequency from
one of the two possibilities.

He was also off the mark (so to speak) by attempting to explain it as
on-off keying rather than the FSK that it really is.

Chris

-- 
Chris Elmquist