[Skimmertalk] New Problems with SDR-IQ and CW Skimmer: Ideas?

Jeff Maass jmaass at k8nd.com
Fri Dec 2 13:54:16 PST 2011

I have been using CW Skimmer with SDR-IQ receivers for a few years now, but
ran into a problem at the PJ2T CQWW CW operation just past.

We were planning to use two on-site Skimmers, for 160- and 80-meters, using
the two PJ2T Beverage antennas run to two SDR-IQ receivers. In the days
prior to the contest, we noted that the Skimmers we set up on my laptop (the
same used for several previous contests from PJ2T) were not posting any
spotted stations although we could hear stations on the station transceivers
and see signals on the display.

The visual representation on CW Skimmer seemed to show CW elements that were
not as crisp as normal, and when listening to the signals from Skimmer on
the laptop speakers, they sounded "mushy". I tried each of the three SDR-IQ
receivers I had with me, and the problem was the same on each. I tried
versions 1.6 and the same version 1.4 installations that had been used in
previous contests, but that made no difference.

With much head-scratching, I noted that there was a subdirectory named 'bal'
under the installed directory for each of the three instances of CW Skimmer
installed on the laptop. In each of those directories was a file
'IQBalance-96-sdrWAV.dat'. It seemed that when that file was deleted, the CW
Skimmer instances would work OK for a short time, and then stop. Can someone
explain what this file is intended to do or signify?

After much more head-scratching, Jim W8WTS deleted all instances of CW
Skimmer from my laptop, and reinstalled. Everything worked OK for a short
time, and then the video and audio from on-air stations became "mushy" and
were not translated. He eliminated running tasks one-by-one, but was never
able to restore normal operation of CW Skimmer on my laptop.

He then connected the SDR-IQ receivers to his own laptop, essentially the
same Dell model as mine, but with a little faster processor. Everything
worked fine, and continued to work fine throughout the contest weekend!

My laptop has proven itself to have plenty of 'horsepower' to handle CW
Skimmer in contests in the past. Something has changed which degrades the
operation of CW Skimmer to uselessness.

Any ideas where else to look? I'd like to keep my laptop ready to be used
with CW Skimmer in the future!

73,  Jeff K8ND


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