Linux-Hams archive - November 1998: Re: Pactor-ax25
Re: Pactor-ax25
Thomas Sailer (sfjt.hkogdqk@kerailya.tunkki.fi)
Wed, 04 Nov 1998 13:56:33 +0100
> Monitoring would probably work using a sound card, but transmitting
> is a different matter. "Advanced" hf protocols like pactor have very
> strict timing requirements (this is what makes noise reduction by
> adding/subtracting multiple retransmits possible), so emulating pactor
> probably wouldn't be a strength of linux. (Or have you already found
> some ingenious way of handling the turnaround, Thomas? ;)
Yes, using full duplex soundcards 8-) . For receiving it isn't a
problem anyway, and for transmitting it depends on the soundcard.
Measurements on some of my half duplex cards gave roughly 10ms
turnaround time, which works under some circumstances (i.e.
the link distance less than the theoretical maximum).
The bigger problem is an accurate clock source. Amtor specifies
+- 50ppm (or something in that region), which no PC builtin
clock source can do. You have to calibrate the clock source.
Tom