[600MRG] Unidentified intermittent signal observed near 475.970 kHz

[John Langridge]

Good morning:

Last week I began seeing an intermittent signal near 475.970 kHz
(474.2 kHz + 1770 Hz on your WSPR waterfall).  The signal looked
vaguely like On-Off keying at times but seems to show up in bursts
followed by a wider band component that fans out either side of the
main frequency.

My first thought was that it was a very short QRSS with a clicky CW ID
that originated from keying a square wave but at times the signal is
audible and it appears to be neither CW nor QRSS.  It some type of
wider band digital modulation, I think, and appears as a burst.

KE7A, about 40 miles NNW of me here in the Dallas area, can also see
it and indicates that it appears to be on an East / West line from
him.  From my station it appears to be about 90 degrees,  but because
of antenna beam width is could be +/- 30 degrees.  It seems to be
coming from somewhere in East Texas.

I've seen weird signals like this show up from time to time over the
last few years included one that when you transmitted on top of it, it
would dissolve and disappear for a few days.  This occurrence is the
first in a few years.

Anyone have any ideas?  Utilities playing with something?  Anyone else
see it?  its very intermittent so you may have to watch it for 20
minutes before you see something but the interval seems to change..
Ive seen it as close together as either 2-3 minutes.  The longer
spacing seems more rare, however.

Thanks for any observations ...73!

John KB5NJD..