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[dsp] Bell 202 AX-25 in DSP

enkitec at gmail.com enkitec at gmail.com
Thu Nov 17 17:10:33 UTC 2011


On 17-Nov-11 14:25, Alejandro Santos wrote:
> Hi,
>
> I'm new on the DSP mailing list. I'm interested on developing a Bell
> 202 AX-25 receiver using DSP on simple hardware like a PC. Has anyone
> attempted on writing such program, perhaps implemented by a Goertzel
> algorithm?
>
> 73 LU4EXT
>

     Copied from another mailing list:

--------------

A few days ago I commented on the report about the UZ7HO soundcard modem 
in the
Net14 report.

At the time I had downloaded the program and was about to try it.

Over the past few days I've run the 30m APRS receiver output into the usual
AX.25-SCS soundcard program with APRS Messenger as G4HYG-10 and the UZ7HO
soundcard modem into APRSIS32 as G4HYG-11.

The results are remarkable!

AX.25-SCS always seemed to be one of the best of the 300 bd soundcard 
modems in
comparison tests with AGWPE and other programs and a Kantronics TNC but
AX.25-SCS seems deaf in comparison to the UZ7HO modem.

The new soundcard modem by UZ7HO with it's multiple receivers really 
brings in
the off frequency and noisy packets and very few that appear on the 
waterfall
miss being decoded.

I've played with the settings and I've found that running six receive 
pairs at a
spacing of 40 Hz works well at my location with this PC.

My recommendation is if you are running 300 bd HF APRS with AGWPE 
replace it now
with the UZ7HO soundcard modem as it's a direct replacement using the AGWPE
format.

I'm so impressed with it that I'm reading up on the AGWPE format in what 
spare
time I have so that I can add the UZ7HO modem (or AGWPE) as an option 
with APRS
Messenger.

73,
Chris, G4HYG

-------------------------

     73, Mark Jordan, PY3SS



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