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Hi Chris, I have noted this strange effect a
few times on SpecLab. Such a bogus line looks more prominent when
the noise is strong, and seems to go away when it's quiet. My unproven theory is
that there may be a hidden n / n-1 rounding error in the
one-pixel-per-FFT-bin mapping, and the ominous line is actually calculated
as the maximum magnitude from two adjacent bins, which would make it a tad
brighter on average.
Best 73,
Markus
Sent: Tuesday, March 20, 2012 11:09 PM
Subject: Re: LF: 8.970khz
Yes - I hope that there is a trace of Henny's signal in
there.
The 8970.016 apparent line was quite a strong effect - more so on the
monitor than on the jpeg - and I'd almost convinced myself that there was
another vlf transmission - but there was no sign of anything on Eddie's or
Stefan's grabber. I've noticed that the eye tends to 'join up the dots' when
looking for signals - it's easy to believe that there is something there in the
noise.
73 Chris G3WCD
On 20/03/2012 19:41, Markus Vester wrote:
... and some "hot pixels" on 8970 which probably belong to Henny.
There's also a conspicious narrow noise enhancement on 8970.016, but
this seems to be a display interpolation artifact (something like 0.999
pixels per FFT-bin).
Best 73,
Markus
-----Ursprüngliche
Mitteilung----- Von: Stefan Schäfer <[email protected]>An:
rsgb_lf_group <[email protected]>Verschickt:
Di, 20 Mrz 2012 6:18 pm Betreff: Re: LF: 8.970khz
Am 20.03.2012
18:48, schrieb Chris Dillon:
Hi Uwe - here's a screenshot of your signal in
IO92vf Cambridgeshire.
73 Chris G3WCD
...it
shows the last K of OK2BVG too :-) 73, Stefan
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