[aprssig] AGWPE Pro sound card calibration

Julian, G4ILO julian.g4ilo at gmail.com
Tue Feb 22 03:56:45 EST 2011

Does anyone know if it is possible to change the sample rate in AGWPE
Pro to compensate for clock errors?

I have several USB sound devices that I use to interface with radios
for various purposes. They all tend to have sample rate errors which
affect the baud rate of packet transmissions. I have particularly
become aware of this since getting the Kenwood TH-D72 which seems
particularly sensitive to baud rate.

Using MixW to  monitor using another receiver with a pretty accurate
sound card I can measure the baud rate and it was 1208baud. There
seems to be no way in AGWPE to change the sample rate. There is a
number you can change on the configuration dialog but I can't get the
value to "stick" between restarts, nor does it seem to affect the baud
rate when I change it by editing the .ini file. Using TrueTTY I can
get the correct baud rate on one sound card by setting the sample rate
to 11050Hz and on another one by setting it to 11100Hz. Most digital
mode programs have the facility to fune tune the sample rate. I am
surprised AGWPE doesn't - or am I missing something?

Julian, G4ILO
G4ILO's Shack: www.g4ilo.com

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