[UK-CONTEST] PSK !!!

[ALEX LISTER]

Tks
Rob& co
Explains why my cheap replacement 2nd sound card was far superior to the the 
"Clever " device fitted by manufacturer,
I would guess apart from sampling the equalisation within some sound cards is 
half the trouble.
Still absolutely amazed that many commercial interface units are sold with TX 
audio via the microphone input.
An absolute No No unless that'sur only audio input.
I do have a SignalinkUSB from a SK which I need to check out prior to sale so 
will have a play to see how good it is !
Probably on next CW session.
Found why my PSK decode was so poor on last data event.
I had not noticed that the AFC flag had been turned on.
Whilst realising the important bandwidth considerations like most I do not like 
PSK as a contest mode, Takes far too long to sync. 

I will persevere as PSK = Points + on RSGB cc80.
Alex G8FCQ





________________________________
From: Robert Chipperfield <robert at syxis.co.uk>
To: Steve Knowles <g3ufy at blueyonder.co.uk>
Cc: uk-contest at contesting.com
Sent: Wednesday, 27 April, 2011 1:26:12
Subject: Re: [UK-CONTEST] DUMP PSK use AMTOR

On 26/04/2011 22:42, Steve Knowles wrote:
> BTW, If anyone has bothered to read this far and is having trouble 
> decoding,
> try the 'SignalinkUSB' external soundcard interface available from ML&S.
> Works brilliantly with MMTTY, Digipan and MIXW, even with Vista!!!  You do
> need to adjust the signal levels correctly - but you get physical controls
> on the box to do it!
And a similar couple of hints, for those not using interfaces with built 
in audio interfaces:

1) If you're using a laptop, the built-in soundcard's input is almost 
certainly very poor. However, even the very cheap ~£2.50 USB audio 
modules that can be found on eBay are usually much superior, and 
entirely suitable. Combining one of these with a homebrew interface for 
isolation works well, and is substantially cheaper than a MicroHam or 
similar if you're experimenting for the first time. I've not yet done a 
side-by-side comparison of performance, but it would be interesting to try!

For those who enjoy construction, Gavin, M1BXF has combined his version 
of the above with another USB-RS232 adaptor in a single box to give CIV
control; it's quite a nice project: <http://bit.ly/huiLCc>. Total cost 
~£25, I think.

2) If you're using a sound card, ensure that any driver-type DSP is 
turned off: this is variously labelled in different models, but noise 
reduction, echo cancellation, or anything that claimed to improve the 
sound is almost certainly unwanted when using the sound card for 
datamodes! This has reared its head on a number of machines I've seen 
where people were struggling to get successful decodes on DSSTV, with no 
initially obvious cause.

Cheers,
Rob, M0VFC
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