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[aprssig] Dayton Pilgrimage Mobile Settings

'Scott Miller' scott at opentrac.org
Thu Apr 19 20:24:48 UTC 2007


> Thanks.  Since just about all 1200 baud packet uses pre-emphasis on 
> the TX side, I wonder what is the degradation in packet success rate, 
> if any, by not using de-emphasis on the RX side.  I guess the TNC 
> could provide de-emphasis.  I have always thought that perhaps 1200 
> baud packet should be run flat.

For demodulators like the 2211, you really don't want the low tone to be
higher in amplitude.  Being off the other way doesn't make so much
difference, and that's what you get listening to the pre-emphasized signal
directly from the discriminator.  In fact, you might be better off doing it
that way anyway, because the D700 transmits flat and de-emphasis makes it
hard to decode.  The T2-135 runs a 2211 directly from the DR-135T's
discriminator and it does pretty well.

Scott
N1VG







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