(with Windows XP Home Edition), and the software I use for PSK-31 is
Digipan.
My transmit and receive frequencies are separated by about 30 Hz. One
person I communicated with on the air said that my computer sound card
samples at different rates for TX and RX, but I can't any such separate
controls.
Can any of you help me resolve this? It makes it harder to respond to a
CQ call.
Jason,
This is a sort of funny problem about Windows, or so I have been told.
The DLL that drives the sound card can result in having a slight
offset in the way it makes sound (TX drive) and inputs sound (RX).
So here's what you can do about it.
1) Check that you have not accidentally engaged your RIT. I have done
that a few times by accident and that will cause the problem you
describe.
2) I'm not sure if DigiPan lets you adjust your sample rates, but MixW
does, and I would suggest that you download and try it, it will run
fine for 10 days in a Trial mode, then you can decide if it's worth
your time and money to register it. By the way, this is not meant as a
knock against DigiPan or MultiPSK, I just know more about MixW. In
MixW there are settings for offsets on the sound card. It's a bit
beyond a simple message board posting to explain all the ends and
outs, but there are some good explanations and what not on how to
calibrate in MixW on another Yahoo group dedicated to MixW.
3) Calibrate your RX side against WWV. By using WWV, you get a nice
stable signal, and your sample rate on the RX side should be adjusted
so that you get nice strait lines. Remember you are in effect sampling
an analog with a digital sampler, sort of like timing a car with a
strobe light. Sampling too fast or too slow makes the line not strait
and you get a slanted line when you look at WWV. In MixW, you have a
place in the Sound card configuration menu to crank in some correction
factor for the differences. Again, the docs for MixW describes it
better than I can, and there are postings over on the MixW forum that
talks about it much better than I can.
4) Download a program called CheckSR. You can google search for it.
The program has instructions which will tell you more, but it
basically puts a signal out, then takes it back in via your sound card
and tells you how much of an offset you have.
I hope you find the above helpful.
73
Steve N6CRR
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/
DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion)
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