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Re: LF: Weak signal on 137780.3

To: <[email protected]>
Subject: Re: LF: Weak signal on 137780.3
From: <[email protected]>
Date: Sun, 4 Sep 2011 14:31:33 -0400
References: <CF05C9873C704FB7B82A927A3EB3A1FE@White> <77DE9B8329834C6882925783A5F39A72@White> <001b01cc6af5$a8f74190$8d01a8c0@JAYDELL> <DDBC097970E54682B3984880BACE6DBB@White> <002001cc6b1c$d573e3a0$8d01a8c0@JAYDELL> <A1AD4570DAE040319C72CE6568D540AD@White>
Reply-to: [email protected]
Sender: [email protected]
Markus
 
Let's leave the grabbers where they are for at least one more night. The last known frequency (previous weekend) for Mitch was 780.5 but it does drift around a bit.
 
I'll start the transmitter up a bit earlier tonight.
 
Jay W1VD  WD2XNS  WE2XGR/2
 
 
----- Original Message -----
Sent: Sunday, September 04, 2011 2:00 PM
Subject: Re: LF: Weak signal on 137780.3

Ok, Jay. The effect is intruiging. The Russian line on 775 tells me that the receiver had stayed in lock all night, so it must be real.
 
Yes it would be good to try the same parameters again. There's a lot of QRN now, but the forecast says it should quiet down later tonight.
 
I'm not hooked to 780.30, just left the slot where it was after I transmitted near Chris' Loran line in Haifa. So in case we would really cause a problem for Mitch we might as well move down a tick, even a posteriori as long as it's between 774 and 781. I think Chris could do the same both in 4X and YO if required.
 
Actually after John's email I tried to look for a trace of VE3OT as well. There were some bits below the Eu Loran line 780.419, but nothing conclusive. Do you happen to know his precise QRG?
 
Best 73, and have a nice Sunday
 
Markus (DF6NM)

 
Sent: Sunday, September 04, 2011 6:08 PM
Subject: Re: LF: Weak signal on 137780.3

Markus
 
Yes ... it was a continuous transmission with no frequency step. Interesting observation on midnight crossing the middle of the path.
 
Picked 200 watts as a starting point to see how well it was received. The transmitter here is capable of 1 kW output. It appears that only your grabber was able to 'see' the signal.
 
Weather permitting, I can run further tests tonight. Do you have anything in mind? Might be interesting to do a repeat of last night's test to see if the midnight/midpoint anomoly shows up.
 
Jay W1VD  WD2XNS  WE2XGR/2 
----- Original Message -----
Sent: Sunday, September 04, 2011 9:56 AM
Subject: Re: LF: Weak signal on 137780.3

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
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