Excellent Jay, thanks very much! I
am really happy about this result. Attached
is a spectrum graph, showing your peak at 3:16 UT, with about 12 to 14
dB SNR in the 0.438 mHz FFT.
Do I understand you correctly in that you
transmitted a continuous carrier, without a frequency step? Then the
apparent 3.8 mHz shift must have been a transient propagational Doppler
effect. Remarkably, this lines up with observations of John Andrew's
tests in 2006, which had also shown two long stable runs, with a
dip and rapid phase change inbetween. The dip seems to roughly coincide
with midnight crossing over the middle of the path, but I'm not aware
of any simple physical explanation for this.
BTW Your transmit situation must be similar
to mine: I have about 200 W available into a Marconi antenna, which is
about 0.1 percent efficient now, and up to twice that in a cold winter
night.
Best regards, and thanks again for the test
Markus (DF6NM)
Sent: Sunday, September 04, 2011 1:27 PM
Subject: Re: LF: Weak signal on 137780.3
Markus
The mystery signal was from WD2XNS
... you have the time and frequency perfectly correct and the color DF
also provides corroborating evidence. Note that there was no break in
the transmission. The frequency is controlled by a GPS disciplined
oscillator (accuracy about 13 ppt). Transmitter power was 200 watts ...
radiated power is not known. During winter, with frozen ground,
additional radials, lower R and less foliage, the radiated power would
have been about 0.5 watt. Expect last night's test would be at least 3
- 6 dB (maybe more) below that level.
Jay W1VD WD2XNS WE2XGR/2
-----
Original Message -----
Sent:
Sunday, September 04, 2011 4:45 AM
Subject:
Re: LF: Weak signal on 137780.3
The mystery signal was received
between about 0:15 and 3:30 on 137780.310, with a 3.8 mHz downward
shift from about 1:30 to 2:15 - somewhat reminiscent of a DFCW "GM".
Greenish colour indicates southwesterly origin. The attached
screenshot was taken at 8 UT, timescale is 10 minutes per FFT.
I checked the other available TA
grabbers around 4 UT, but no trace of the mystery signal.
73, and have a nice sunday,
Markus (DF6NM)
Sent: Sunday, September 04, 2011 5:39 AM
Subject: LF: Weak signal on 137780.3
LF,
there seems to be a signal on
137780.300 Hz, about 60 nV/m here.
Wondering whose it may be...
Best wishes,
Markus
