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)
Sent: Saturday, November 02, 2013 1:59 PM
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).
...
Sent: Saturday, November 02, 2013 2:31 AM
Subject: Re: LF: Tasmania?
Stefan, Edgar,
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)
Sent: Saturday, November 02, 2013 12:24 AM
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
Am
01.11.2013 20:11, schrieb Markus Vester:
Edgar, Stefan,
yes, I think it's there. On the Orford
grabber around 15:40 UT, it looks like four dashes belonging to a "7" and
the first dash from the following "F". Also later perhaps some
more bright pixels on the same (dot) frequency
(136171.89 on the RX scale, versus 136171.9625 Hz sent by
Stefan).
The time of reception coincided with a period of good SNR from
HGA22 in Orford, whereas DCF39 happened to be in a fade.
Congratulations! Guess it's time for the two of you to open up a
bottle!
Best 73,
Markus (DF6NM)
Sent: Friday, November 01, 2013 6:39 PM
Subject: Re: LF: Tasmania?
LF,
Is there a
trace of my signal on that grabber? I can see something, very weak, and only
if you know the frequency and what letter was sent to which time. But it is
close to my QRG, a shift of maybe -35 mHz. The DFCW element length looks OK
and the DFCW shift too. But VERY weak. Could it be right or am i dreaming? Can
someone else see what i mean? https://dl.dropboxusercontent.com/u/101251787/testIDC.html
Comments?
73,
Stefan/DK7FC
Am 01.11.2013 14:47, schrieb Stefan Schäfer:
BTW,
Bob...
...did you ever try to leave a trace on the LF grabber of
Edgar J. Twining in Tasmania? We were trying this spring/fall period but, so
far, without success. I will make another attempt today though.
The path
your you would be that: http://no.nonsense.ee/qth/map.html?qth=FN12LQ&from=qe37wk
Not impossible! A bit shorter than for me and even more hops on sea water
for you!
Link to his garbber is: https://dl.dropboxusercontent.com/u/101251787/testIDC.html
A
suitable mode would be DFCW-180 or QRSS-120. Suitable frequency 136.173 kHz.
Suitable time: -3...+2 hours arround your sunrise!
Worth a
try!
73, Stefan/DK7FC
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