brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell



Earlier tonight, I noticed that CW traffic on 40m picked way up. You get an interesting view of the band conditions when you can tune 100Khz at a time:


Even with my own wimpy antenna, it was hopping pretty good.


New gadget in the shack: an RFSPACE SDR-IQ

Well, I got a new gadget in the mail today: an SDR-IQ from It's a cute little gadget: a general purpose receiver that can deliver the quadrature signals for any 192Khz of the spectrum anywhere from 100Hz (yes, Hz) to 30Mhz. It is a small black box, with only three connectors: a USB, a regular serial port (used for rig control) and a BNC port for attaching an antenna. I fired it up, and right away started to find interesting things: for instance, here is the frequencies around 5.8Mhz:


If you look carefully, you can see that this is actually an AM signal. The carrier and a couple of sidebands are visible to each side of the received signal. If you click on the signal, and select the AM demodulator, you get the following audio:

AM modulated Morse code at 5.8Mhz, recorded around 06:30, Jan 5, 2010

A quick google of the web indicates that this is a Cuban numbers station. Pretty nifty, and probably never would have discovered it without using the RFSPACE SDR-IQ.

You'll be hearing more about this gadget in the future.

Addendum: I'm not the only person (obviously) to hear these guys.