modem DAC

[Chris Shepley]

Kristjan Varnik wrote:
> 
> I have an old 8088 computer, I was thinking if there was
> something interesting to do with it. So I started to
> dream ...
> 
> I believe the phone lines are analog, the signal is sent
> through a DAC(modem) into the computer and then back out
> a DAC back through the phone.
> 
> Now, instead of streaming modem conversations, what if I were
> to send in music of some sort. Then the music would be
> in the computer and digitally processed.
> 
> Now, I know very little of the details on how this works,
> but would it be possible to manipulate the data coming in
> and out of the modem, turning my old machine into a
> sampler.
> 
> Just an idea,
> Kristjan

No, this would not be possible for a few reasons...

1)  The analog data of a modem is sent at basically to frequencies to
determine a set or not set bit.

2) second the audio range of phone lines is quite limited.

It would be possible to make a sampler with extra circuitry but not with
a stock modem and computer...  Although the sample speed would be
sooooooo with an 8088's UART that the maximum sample rate would be about 
2.4khz