Today Stefan and I got a long wav recording from Edgar J. Twining, starting 2013-11-01 16 UT, shortly after the potential reception of dashes from DK7FC in Orford, Tasmania. Signals from all three EFR utility transmitters (DCF49, HGA22, DCF39) could be found in the recording. Using the same default samplerate and LO settings that Edgar applies on his grabber, the idle frequency from HGA22 appeared to be centered on 5429.95 Hz audio, which is about 72 mHz lower than expected from the actual transmit frequency.

 

This offset is in good agreement to the observed -75 mHz offset on the DK7FC signals, showing that this was indeed a real reception.

 

Best 73,

Markus (DF6NM)

 

 

From: Markus Vester

Sent: Saturday, November 02, 2013 1:59 PM

To: [email protected]

Subject: Re: LF: Tasmania?

...

From my point of view, the best contribution to a "proof" would now be verifying the receiver's frequency calibration offset. On yesterday's screenshots, the HGA22 line seemed to be just half a pixel below the tick. Simply by zooming in on it you could measure the offset much better, even though the line is spread by some tens of milliHz due to the FSK modulation. Last year I took some effort to measure HGA's idle frequency in detail against a calibrated Rubidium source. The result was 135430.022 Hz, with only very little variation of a milliHz or so (see attached).

 ...

From: Markus Vester

Sent: Saturday, November 02, 2013 2:31 AM

To: [email protected]

Subject: Re: LF: Tasmania?

Stefan, Edgar,

 

the inset was taken from a local grabber screenshot http://dl.dropboxusercontent.com/u/26404526/df6nm_Eu_131101_1710.jpg, which was reduced in width to 50% to account for different scrolling speeds, and aligned horizontally solely by the 15 UT timestamp. The matching "7" came out as a result afterwards.

 

In my opinion this is a valid detection. It would be very unlikely that pure noise would produce such a result, and there has not been any indication of a spurious carrier on this frequency in Orford.

 

The small offset in the frequency calibration (about -75 mHz) is surely within expected tolerances of the receiver's free running crystal oscillator. This is in accordance with the Orford HGA spectrum, which shows the peak also very slightly below the 135430.0 Hz grid line.

 

Best 73,

Markus (DF6NM)

 

From: Stefan Schäfer

Sent: Saturday, November 02, 2013 12:24 AM

To: [email protected]

Subject: Re: LF: Tasmania?

Hello Markus, LF!

Yes, i saw these 3 dashes (which are "dits" on that QRG and time) in one line. And if they are from me, it must be the end of the 7. And i was transmitting the 7 just to that time.
Did you place your grabber image overlay onto Edgar's image so it fits the 3 dashes or did you place it so that the time stamp fits to your time?

If "we" call this a valid ID and detection, then these 16833 km are a new #3 world record distance on 2200m! (according to http://136.73.ru/h_qso/index.htm )
Do "we"? Would others agree/disagree?

73, Stefan/DK7FC