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Dear Sub-9kHz'ers,
?
Marco DD7PC just made me aware of new German regulations, which also includ=
es a change of the unallocated VLF range. The latest version of the "Freqen=
zverordnung" (FreqV)=20
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 lo=
cator 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 c=
hange in the UK had been announced in this group some time ago, leading to =
the installation of some grabber windows around 8.27 kHz.=20
?
In practice, radiated powers achievable by amateurs (milliwatts at best) ar=
e ten orders of magnitudes below to that emitted by lightning events (100 m=
egawatts). The chance of amateur interference to a broadband lightning loca=
tor would thus be absolutely neglegible. Even if somebody happened to activ=
ate his kite within one kilometer from a detector station, any further effe=
ct of interference would still be suppressed by redundancy in the lightning=
location network.=20
?
Still, for publicly visible work (like claiming first contacts etc), we sho=
uld consider moving below 8.3 kHz. Of course there are disadvantages, like
- local interference eg. from railway lines seems to be much denser and str=
onger at lower frequency,=20
- 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,=20
... 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 frequ=
ency assignment.=20
?
In my location, I am mostly affected by 16.67 / 33.3 Hz modulated interfere=
nce emitted by railway overhead lines, in addition to the usual 50 Hz relat=
ed junk. To possibly identify a sweet spot with relatively low interference=
, I have temporarily shifted the frequency range of my faster VLF grabber w=
indows:
http://df6nm.darc.de/vlf/vlfgrabber.htm
Judging by the first hours, near 8280 Hz may be significantly better than 8=
270. But interference comes and goes with time, so longer observations are =
needed. Note that the heavy interference between 11 and 12 UT could have be=
en exacerbated by my noise blanker settings as it is much less severe in th=
e wideband window. At this time, I would like to encourage other receiver o=
perators to closely investigate their noise levels just below 8.3 kHz.
?
Best 73,
Markus (DF6NM)
----------MB_8D0D5D2B8541520_43C_28510_webmail-d241.sysops.aol.com
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<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"><FONT colo=
r=3Dblack face=3Darial></FONT>Dear Sub-9kHz'ers,</div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"> </di=
v>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">Marco DD7P=
C just made me aware of new German regulations, which also includes a chang=
e of the unallocated VLF range. The latest version of the "Freqenzverordnun=
g" (FreqV) <br>
<A href=3D"http://www.gesetze-im-internet.de/bundesrecht/freqv/gesamt.pdf";>=
http://www.gesetze-im-internet.de/bundesrecht/freqv/gesamt.pdf</A><br>
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 lo=
cator 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 c=
hange in the UK had been announced in this group some time ago, leading to =
the installation of some grabber windows around 8.27 kHz. </div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"> </di=
v>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">In practic=
e, radiated powers achievable by amateurs (milliwatts at best) are ten orde=
rs 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 ki=
te within one kilometer from a detector station, any further effect of inte=
rference would still be suppressed by redundancy in the lightning location =
network. </div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"> </di=
v>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">Still, for=
publicly visible work (like claiming first contacts etc), we should consid=
er moving below 8.3 kHz. Of course there are disadvantages, like<br>
- local interference eg. from railway lines seems to be much denser and str=
onger at lower frequency, <br>
- at same antenna voltage, radiated power will be 1.4 dB less,<br>
- more coil winding is required,<br>
- acoustical side-effect of transmitting may be more disturbing, <br>
... es nervt einfach!!</div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"> </di=
v>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">But then, =
one should always embrace change... positive aspects may be<br>
- lower QRN background in quiet locations,<br>
- with common international legislation, the necessity of sub-9kHz NOV's in=
the UK might become obsolescent,<br>
- EA5HVK might be motivated to provide an Opera version with flexible frequ=
ency assignment. </div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"> </di=
v>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">In my loca=
tion, I am mostly affected by 16.67 / 33.3 Hz modulated interference emitte=
d by railway overhead lines, in addition to the usual 50 Hz related junk. T=
o possibly identify a sweet spot with relatively low interference, I have t=
emporarily shifted the frequency range of my faster VLF grabber windows:<br=
>
<A href=3D"http://df6nm.darc.de/vlf/vlfgrabber.htm";>http://df6nm.darc.de/vl=
f/vlfgrabber.htm</A><br>
Judging by the first hours, near 8280 Hz may be significantly better than 8=
270. But interference comes and goes with time, so longer observations are =
needed. Note that the heavy interference between 11 and 12 UT could have be=
en exacerbated by my noise blanker settings as it is much less severe in th=
e wideband window. At this time, I would like to encourage other receiver o=
perators to closely investigate their noise levels just below 8.3 kHz.<br>
<br>
Best 73,<br>
Markus (DF6NM)</div>
<div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt"><br>
<SPAN style=3D"DISPLAY: inline-block" contentEditable=3Dfalse></SPAN></div>
<div><br>
</div>
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