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Yas, Alex, Stefan,
opds decodes with correlation peaks just
above 15 dB are on the borderline, and there's always a chance for false
positives. The implicit downside of the use of a template list is that a
false detection always shows a valid callsign, known to be active on
LF.
Often the false ones don't just
come "out of the blue" (ie plain noise), and inspecting the spectrogram can be
enlightening. The bogus detection of RA3YO was probably a partial
correlation, associated with a prior strong reception from
JP1ODJ:
2013-10-27 12:17:23 RA3YO
7813km 137569.599Hz 8mHz -50.5dBOp 66% 15.4dB
2013-10-27
11:59:21 JP1ODJ 43km 137569.966Hz 4mHz -22.2dBOp
100% 21.1dB
Opds does have a built-in mechanism to suppress
such aliases. But they can still occasionally come through if opds happens
to trigger on a spurious peak contained in the skirts of the strong
signal.
2013-10-27 16:01:02 VE7BDQ 7566km
137572.172Hz 3mHz -46.2dBOp 99% 15.0dB
There seems to be a permanent line on
Yas' waterfall, but this one dosn't seem to match one of the known
Loran line frequencies for the area:
If you see strong Loran lines, and your
receiver and samplerate are very accurately calibrated, you can tell opds
to ignore them by enabling and editing the lorangri=<GRI
list> and lorantol=<tolerance> lines in
opds.ini.
Best 73,
Markus
PS: Nothing at all wrong with Mal's
opinion, everything in life is "guess-work" to some extent
;-)
Sent: Sunday, October 27, 2013 5:52
PM
Subject: Re: LF: Re: OPDS
32...
Oooh! Markus? What now?
Hopefully Mal don't see
it ;-)
73, Stefan
Am 27.10.2013 17:46, schrieb Alex R7NT:
Stefan,
Воскресенье, 27 октября 2013, 17:28 +01:00 от
Stefan Schäfer :
JA8SCD,
PM95VQ:
2013-10-27 11:52:13 UA0AET 4175km 137580.826Hz 15mHz
-44.8dBOp 95% 17.2dB
2013-10-27
12:17:23 RA3YO 7813km 137569.599Hz 8mHz -50.5dBOp 66%
15.4dB !!! ERROR :-(
2013-10-27 16:01:02 VE7BDQ
7566km 137572.172Hz 3mHz -46.2dBOp 99%
15.0dB VE7BDQ's Sunrise abt 15z
I think there is a real chance for
VE7BDQ to appear at YV7MAE! Must be best during 7...10 UTC
Looks
like RA3YO made the best distance in that mode so far (?).
73,
Stefan/DK7FC
73! Alex R7NT
136.73.ru
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