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QRM here on 8280.
Prefer 8275
PA1SDB
----- Original Message -----
Sent: Friday, January 03, 2014 11:10
AM
Subject: Re: VLF: 8.275 kHz
Peter, ok. But I still have a problem with the
railway QRM on 8270, so I'd prefer either 8275 or 8280...
What do the others think? Chris, Eddie, Gerhard,
Haldór, Jim, Laurence, Lubos, Paul, Stefan ?
73, Markus
Sent: Friday, January 03, 2014 11:56 AM
Subject: LF: Re: 8.275 kHz
Oops.. forgot to tell, but that 8270 Hz is a
local experiment here.
Its a notebook PC at a wire here in my
home.
No problem with 8270 here.
----- Original Message -----
Sent: Friday, January 03, 2014 10:43
AM
Subject: VLF: 8.275 kHz
Hi Uwe,
ok, but could you make that 8275
Hz?
PA1SDB seems to be bothered by a
continuous line on 8270 and some noise on 8280. I also have significantly
more QRM around 8270.
8275 Hz is clearer, and I will retune my "6000" and "50000" grabbers
there, along with the attached opds-4H and
-32 postprocessing.
Hope that Lubos could also shift his lowest
panel from 8270 to 8275 Hz.
Good luck,
73, Markus
Sent: Friday, January 03, 2014 11:10 AM
Subject: Re: LF: Re: 8.3 kHz
OK,
Peter and all, today Ill adjust the aerial system at 8270Hz. afterwards
doing som e tests in modes carrier only and Op-4H. GL Uwe/dj8wx
Von: [email protected]Gesendet:
02.01.2014 23:09 An: [email protected]Betreff:
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.pdfhas
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.htmJudging 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)
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