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Thanks to Hartmut,for the spectrogram and info, and
to Bob for shifting up.
Hartmut your stronger Loran lines are from Lessay /
Sylt as usual, eg. 74610.0134 and 74609.9480 Hz. The weak one you mention
is 74614.1890 Hz from the Ejde chain on
GRI 9007 (multiples of 5.551238 Hz).
In my location, Loran is far away and weak, and the
QRM is dominated by DCF77 noise. The relative intensity of the 1
Hz peaks and the "data strips" around them can be predicted from
the Fourier transform of the known PRN sequence. Attached is a zoomed plot
of the magnitude spectrum, covering 74.50 to 74.65 kHz. For example, "sweet
spots" exist on 74504, 74552, 74604, 74623 Hz.
On a larger scale, there is a relatively
flat area between the noise lobes, eg. surrounding 74270.833 Hz
(77500-5*645.833). In the middle of these gaps, there are additional
lines from the bitclock frequency which are not shown in this
plot.
Best 73,
Markus
Sent: Thursday, December 12, 2013 11:30 PM
Subject: Re: LF: WG2XRS/4 [WG4XRS for short] will start at 2200 with
WSPR 15... "Band" selection?
Am 2013-12-12 22:48,
schrieb Markus Vester:
> Unfortunately 74613 Hz looks a bit noisier here
than 614: http://dl.dropboxusercontent.com/u/26404526/df6nm_74kHz.jpg
Markus,
I
have here not the strong DCF77 noise:
https://dl.dropboxusercontent.com/u/50178231/2013-12-12-2215_74600kHz.jpg
74613,5
Hz is looking good in your screenshot. Just above 74614 Hz is a
weak Loran
line
--
73
Hartmut
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