[RTTY] DXP38 vs Soundcard stuff
chen at mac.com
Fri Mar 12 18:31:39 EST 2004
On Mar 12, 2004, at 5:41 PM, Phil Duff NA4M wrote:
> Can we just rely on the software's built in input "overload"
> indicators if they have such? Should we adjust the audio input to the
> point just below the "overload" indication? If not where?
Somewhere in the paperwork, there should be a spec of the peak level
(either voltage, dbV or VU units) that the A/D converter saturates at.
But it is probably easiest to just find a software "oscilloscope" or
"spectrum analyser" application for your machine and look at the rig's
output through the same "sound card.".
If you want to copy both loud and weak signals that are in the same AF
passband, then the total signal cannot be allowed to clip, or you will
find it hard to decode that weaker signal. This is especially true for
the PSK ops who like to watch more than one signal in a wide passband.
If you are only interested in the case where there is a single weak
signal in the passband below the AGC threshold of the rig, then
adjusting so that that weak signal almost clips the converter should
make copy easier.
In either case, more bits in the A/D converter helps. In the latter
case, you won't have to ride the gain that often, and in the former
case you can copy signals with a larger range of signal strengths.
And, of course for the case where the QSB is very deep.
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