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

John B. Stephensen kd6ozh at verizon.net
Sun Oct 31 02:57:22 UTC 2004


Is this a QAM-modulated audio subcarrier over FM or SSB?

Another approach to consider for an NBFM radio would be multi-level FSK. This
would be similar to MFSK16 on HF. 4 levels at 9600 Baud produces 19.2 kbps and 8
levels 28.8 kbps. The data can be encoded so that there is no DC component.

73,

John
KD6OZH

----- Original Message -----
From: "S. Sampson" <k5okc at cox.net>
To: "TAPR Digital Voice Mailing List" <digi-voice at lists.tapr.org>
Sent: Saturday, 30 October, 2004 23:12 UTC
Subject: Re: [digi-voice] Digital voice over high-speed packet


> 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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