[aprssig] 9600 Packet was RE: EB-432/PCSAT2/APRS Question

[Ralph Milnes]

John wrote:

>One of the reasons I am using the Soundmodem is that it will decode  
>1200 and 9600 baud packets simultaneously.

>I also have a 9600 baud modem that I will try tonight instead of the  
>soundmodem.  It may just be that the software demodulator needs  
>tweaking somehow (audio levels/filter response maybe).   The hardware  
>modem should (in theory, I think) be better able to cope with  
>variations.  And at least it will rule that out.

>Regards
>de John
>EI7IG


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John,

One thing to watch for with 9600 baud sound card packet is presence of
isolation transformers in your sound card interface... they shouldn't be
there. While isolation is generally a good thing, the transformers used in
most interfaces do not have the frequency response range necessary for 9600
operations. You could try a simple, un-insulated wire for receive audio and
see how that works. If that works, drop the transformers for both RX and TX
audio... and cross you fingers that isolation isn't critical for your setup.

Did you try the hardware modem yet? (I may have missed your report -- if so,
sorry.)


Ralph KC2RLM
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