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Hi Gary,
If, by chance, you have a screenshot of the SR detector (with the
main tab and the tab with the 'scope', which shows the squared MSK
baseband signal) I'd like to find out what went wrong there.
Possibly just the maximum frequency error, which was to be preset
to 5 ppm - possibly too critical if the sampling rate had not been
pre-calibrated at least once.
73,
Wolf DL4YHF (just back from DF0WD after testing new
switching-mode 'linear' PA on MF; there is lightning just
overhead...)
Am 03.01.2014 17:53, schrieb Gary - G4WGT:
Marcus, LF,
Ref : My split 8270Hz & 8970Hz grabber.
I had difficulty getting the sample rate detector running,
getting message frequency too far off or similar, SL version
v2.79 b04.
I gave up in the end & re-started using an older version of
SL (which I have no problem with) & is detecting MSK
reference OK, SL version v2.78 b05.
73, de Gary - G4WGT
MF-LF-VLF Grabber : http://myweb.tiscali.co.uk/wgtaylor/grabber2.html
Web : http://myweb.tiscali.co.uk/wgtaylor/index.html
.
On 03/01/2014 13:27, Markus Vester wrote:
Gary
great, thanks for pointing this
out. I really like that side-by-side comparison. Assuming
you are using nonresonant input circuitry and equal
brightness settings, 8.27 kHz seems a tad noisier than 8.97.
But it looks like 8270 is
least QRM free.
Best 73,
Markus (DF6NM)
Sent: Friday, January 03, 2014 2:15 PM
Subject: Re: LF: Re: 8.3 kHz
My grabber at 8270 is loading. Lets
see what QRM does here between 8234 and 8305 Hz
(did just start it at 23h00)
----- Original Message -----
Sent: Thursday, January
02, 2014 1:12 PM
Subject: VLF: 8.3 kHz
Sorry, first email was corrupted because I had
forgotten to fill in the subject line. 73, Markus
-----Ursprüngliche Mitteilung-----
Von: Markus Vester <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Do, 2 Jan 2014 2:07 pm
Dear Sub-9kHz'ers,
Marco DD7PC just made me aware of new German
regulations, which also includes a change of the
unallocated VLF range. The latest version of the
"Freqenzverordnung" (FreqV)
http://www.gesetze-im-internet.de/bundesrecht/freqv/gesamt.pdf
has become effective already on August 27, 2013, and
includes an allocation of 8.3 to 9 kHz to the passive
weather observing service (ie. lightning locator
networks). Strictly speaking, this would make 8.97 kHz
transmissions illegal in Germany (although there may be
a loophole with national footnote 2 regarding
"Induktionsfunkanlagen"). If I recall right, a similar
legal change in the UK had been announced in this group
some time ago, leading to the installation of some
grabber windows around 8.27 kHz.
In practice, radiated powers achievable by
amateurs (milliwatts at best) are ten orders of
magnitudes below to that emitted by lightning events
(100 megawatts). The chance of amateur interference to a
broadband lightning locator would thus be absolutely
neglegible. Even if somebody happened to activate his
kite within one kilometer from a detector station, any
further effect of interference would still be suppressed
by redundancy in the lightning location network.
Still, for publicly visible work (like claiming
first contacts etc), we should consider moving below 8.3
kHz. Of course there are disadvantages, like
- local interference eg. from railway lines seems to be
much denser and stronger at lower frequency,
- at same antenna voltage, radiated power will be 1.4 dB
less,
- more coil winding is required,
- acoustical side-effect of transmitting may be more
disturbing,
... es nervt einfach!!
But then, one should always embrace change...
positive aspects may be
- lower QRN background in quiet locations,
- with common international legislation, the necessity
of sub-9kHz NOV's in the UK might become obsolescent,
- EA5HVK might be motivated to provide an Opera version
with flexible frequency assignment.
In my location, I am mostly affected by 16.67 /
33.3 Hz modulated interference emitted by railway
overhead lines, in addition to the usual 50 Hz related
junk. To possibly identify a sweet spot with relatively
low interference, I have temporarily shifted the
frequency range of my faster VLF grabber windows:
http://df6nm.darc.de/vlf/vlfgrabber.htm
Judging by the first hours, near 8280 Hz may be
significantly better than 8270. But interference comes
and goes with time, so longer observations are needed.
Note that the heavy interference between 11 and 12 UT
could have been exacerbated by my noise blanker settings
as it is much less severe in the wideband window. At
this time, I would like to encourage other receiver
operators to closely investigate their noise levels just
below 8.3 kHz.
Best 73,
Markus (DF6NM)
No virus found in
this message.
Checked by AVG - www.avg.com
Version: 2014.0.4259 / Virus Database: 3658/6971 - Release
Date: 01/02/14
No virus
found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4259 / Virus Database: 3658/6971 - Release
Date: 01/02/14
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