Activity on 168.125 kHz

[Bill]

     I've been hearing an ON/OFF keyed carrier on 168.125 kHz.  The ON time is
on the order of 16
seconds and OFF time is about 24 seconds.  The first 8 seconds of the ON time
appears
at full power (received here at -83 dBm), then the level shifts down 10 dB and
remains ON for another 8 seconds (-93 dBm), before going off the air for 24
seconds.  Have been hearing it since about 5AM this morning,  and it doesn't
appear to
be getting any weaker as the day progresses.

      I'm using a 180' coax loop antenna and making the measurements on a RYCOM
Model 6041.  Wonder if any others are hearing this signal or can shed any light
on it's origin or function ??

Bill Farmer  W3CSW
Rockville, Maryland