[OZAPRS] 10MHz HF Gateway -Re: New to list

Hamish Moffatt hamish at cloud.net.au
Fri Aug 31 10:12:27 EST 2007

On Thu, Aug 30, 2007 at 09:51:57PM +0200, Mike Zwingl oe3mzc wrote:
> Gday,
> just one comment on HF-APRS Gateway operation:
> in practice it is not the signal to noise ratio that decides about
decode or 
> nodecode of an APRS beacon on 10Mhz.
> More important is to use a TNC that allows some frequency drift, like
> DSP-TNC from SCS.
> The DSP-TNC is currently the only hardware that will simultaneously
> several APRS signals at same time in a 800Hz wide channel!
> So the frequency offset of a mobile station can be plus/minus 400Hz and 
> still have successful decode on 10.147,6 USB (10151LSB)
> See the result at VK6UZ-4 and VK8ZAB-4, Fritz and Alan are using these
> Most other TNCs/Soundcards require 30Hz accuracy in frequency, which is 
> almost impossible to achive.
> www.scs-ptc.com/datasheets/scs_datasheet_tracker_english.pdf

A sound card demodulator could certainly implement multiple decoders,
probably even more than the DSP-TNC if that was useful given that your
PC would have more processing power.

I have been meaning to experiment with this but have not found time.
Also I don't have an antenna tuned for 30m.

Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>
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