To the best of my knowledge(PTC-II handbook), the PTC-II does NOT use
analog filters for RTTY/AMTOR/Pactor.
73 de Goetz
dj3iw@t-online.de
----- Original Message -----
From: <f6irf@free.fr>
To: <rtty@contesting.com>
Sent: Thursday, April 22, 2004 12:30 PM
Subject: [RTTY] poor signals and soundcards performance/calibration
> For having done some tests with an HF channel simulator, and parallel tests
> from real live signals I personaly don't have any doubt about the fact that
DSP-
> based decoders really outperform decoders with conventional analog filters
> (like the PK232, PTC2, etc)...
> This was pointed out a few years ago by K6STI in articles about RITTY(for
> example the importance of the ATC, an the big difference it can make)
>
> But I also confirm what Phil has mentionned here
> >I also suspect that the processing power of your PC, and maybe even the
> >soundcard, might be a contributing factor in some cases.
>
> For the processing power, I don't know, but for the soundcard I am sure!
> -A good soundcard with low noise line input (like you can find on "home
studio"
> quality soundcards) can make a difference with Cheap soundcards having just
> a microphone input. One obvious reason, is the substantial amount of noise
> added to the signal, when using the microphone input...
> -Many amateurs never thought about the calibration of their soundcard...By
> experience I know that a baddly calibrated sound-card card can really make
the
> best decoder deaf like a stone (*).
> Of course many other factors, starting from the receiver itself may also
play a
> role, especialy when approaching the theoretical limit, but in general if
your
> PK232 outperforms MMTTY, I think that you should first look at the a/m
points.
>
> CU in the SP-test - 73's Patrick
>
>
> (*)For more details, refer to the MMTTY manual chapter "getting things to
> work"
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>
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