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[digi-voice] Digital voice over high-speed packet

S. Sampson k5okc at cox.net
Sat Oct 30 23:12:51 UTC 2004


I'm working with some soundcard linux code to do QAM (had a break in
experimenting due to a very busy year), but the author thinks a standard radio
could do 14k4 bps at 3k6 baud.  I have a couple of yaesu radios with digital
jacks on them, and have connected them up to Rascal serial port interfaces,
and hope to begin long range testing in the coming months.  I also changed
over to a couple of imbedded PC's which have a built-in soundcard, so the
whole thing is about the size of a CD drive.

The one thing that excites me about QAM is that it doesn't need to work down
to DC like the G3RUH modem does.  For example 9k6 QAM fits in a
180 - 3420 Hz bandwidth, and a 14k4 would fit in about 4.5 kHz.  Heck with
that speed, you could use many Internet voice/video software packages and IP.


----- Original Message ----- 
From: "John B. Stephensen"


> However, 4.5kbps CELP sounds much better. I know that many have been using 9.6
> kbps FSK for high-speed packet in the VHF bands, but there are also 38.4 and
> 76.8 kbps modems available from Symek that can be used on our UHF bands (and
> 219-220 MHz). Has anyone tried digital voice or digital video at these speeds?
> 
> Given that the ARRL is proposing 100 kHz bandwidth digital modes for VHF and may
> extend that to 200 kHz, even the 6 meter band could be used for high-speed
> packet in the near future.






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