Latest on Quisk and Charleston board
tfox at knology.net
Fri Aug 6 00:29:17 CDT 2010
Hello group. James Ahlstrom just released the latest version of Quisk
(3.4.8) at pypi.python.org. I have verified that my newest code for the
Charleston board works FB with his Quisk. One of the big improvements
is that Jim has added the ability to change the decimation rate
on-the-fly via a selection menu on the Quisk Config screen. I had code
ready to do this for the Charleston board, as variable decimation was on
my to-do list, but he beat me to it on the Python code (thank goodness!).
So, with a Charleston board and Linux box, you can monitor a swath of RF
in the 0.2-30MHz spectrum that is from 48k to 480k wide (in steps), and
change the swath bandwidth without restarting the SDR, or even losing
the tuned-in frequency. This is very cool. Find a signal in the
wider-band mode, then adjust the decimation down for better frequency
resolution. And, using subsampling and a preamp, freqs up to Two Meters
can be received.
While my laptops seem to top out at 240k sampling, an older,
four-year-old Dell XPS-400 can run at 480k just fine.
A 12-bit front-end still presents a challenge, but with adequate
filtering most problems are reduced or eliminated.
My charleston code for Quisk 3.4.8 should be up on the AMRAD web site by
tomorrow, Saturday. I've also placed some possibly interesting SDR
software at my ISP web site: www.knology.net/~tfox. Mostly this is
older Linux code that Mel and I were messing with a while back. The
images are large right now, as I posted raw screen captures.
More later. 73s
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