[600MRG] Strange Signal in 630M WSPR Band

[Claude Baker]

I'm wondering if  anyone might recognize or even speculate on the origin of a signal I've been seeing for the last couple of weeks.

I'm a relatively constant presence on the 630M WSPR band. Over the last couple of weeks I've noticed a stepped signal showing up in my display. Initially I thought QRSS but as I looked more closely I noticed the use of multiple frequency steps spaced at 10 Hz intervals. When I finally noticed that they seemed to be a fairly precise 30 seconds long, I used Spectrum Lab's 30 second per dot QRSS mode to display the signal. 


I posted a screen capture taken today, 2013-09-18, that covers roughly 1500Z to 1630Z:
Flickr capture

Info about the signal reception:
    1. Relatively local to Aurora, CO - I see the signal day and night.

    2. I live in an antenna free neighborhood so I use an indoor loop, 8'x13', tacked to the back wall of my radio room. Although I have not been able to detect any real directionality as expected for a loop, it is oriented in a 105-285 degree plane.  Using Google maps to project the eastward lobe, the centerline hits the Atlantic at right on the North Carolina/South Carolina border.

    3. The signal does move but note that it frequently returns to a step at about 1530 Hz in the display - visually forming a straight line (little, if any drift ). 1500 Hz in the display corresponds to 475.700 KHz 


    4. The signal occasionally goes off for about 20 minutes and usually returns in slightly different frequency range. As I write at approximately 2000Z, the range is 1600-1650 Hz.

Earlier today I communicated with John at WG2XIQ to ask what he thought. He offered some speculation but from my perspective, his most important observation was that it might not be an intelligent communication but rather "noise" or a harmonic from some electronic system. That is not a quote of what John said but rather my summation.

Please, any ideas?


Claude Baker, AC0ZL
Aurora, CO