[linux-audio-dev] Using Jack for "Control Volt" continued

[David Olofson]

On Sunday 09 November 2003 09.11, Paul Winkler wrote:
[...]
> remember that nyquist theorem limits the frequency to half the
> sampling rate.

OTOH, if there's only one control per channel, one could just modulate 
with a "sine" at Nyqvist, and demodulate using fabs(sample). For two 
signals at half the sample rate, use the sign to determine the signal 
"subchannel" when demodulating.

However, as long as you stay digital, there should be no need for 
modulation of control signals. AFAIK, JACK doesn't process the audio 
data in any way in between clients.

You most probably *do* need to modulate if you need to go analog, 
unless you use modified sound cards or industrial AD/DA boards for 
the I/O. You'll have to use lower frequency carriers for analog I/O, 
as anything at Nyqvist will probably (should!) be totally eliminated 
by the converters.


//David Olofson - Programmer, Composer, Open Source Advocate

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