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Re: NOAA warning for rf communications
- From: Marshall Eubanks
- Date: Fri Oct 24 10:24:57 2003
At NASA at least, we referred to everything above 1 GHz as microwave. I
have
never heard SHF and EHF used in practice (and I worked at 8 GHz and
above for years).
There are two basic dangers here
- the electrical grid acts as a big radio antenna and circuit breakers
may trip.
- The maximum frequency at which the ionosphere reflects radio waves
(the MUF -
http://www.hfradio.org/muf_basics.html )
will increase. Some things that depend on ionospheric reflection may
act weird, there
may be interference at higher frequencies which normally do not
reflect, but now do, etc.
- it is also possible that dispersion (frequency depend phase changes)
at higher
frequency could cut down on bandwidths of broadband systems.
The reflection frequency is almost never higher than 30 MHz anywhere on
the planet, and the effects depend on the inverse frequency squared. I
doubt that many of the bits moved by the readers of this list go at
radio frequencies as low as 30 MHz. Even the cell phone and other bands
starting about 700 Mhz are
unlikely to be affected.
Spacecraft may be effected, but this will be because they are bathed in
increased radiation. There also may be some cool low latitude aurora.
On Friday, October 24, 2003, at 09:49 AM, Keptin Komrade Dr. BobWrench
III esq. wrote:
Well, this is more than you really wanted to know, but....
ELV Exremely Low dc - 3khz
VLF Very Low Freq 3khz - 30khz
LF Low Frequency 30khz - 300Khz
MF Medium 300Khz - 3Mhz
HF High 3mhz-30mhz
VHF Very High 30mhz-300mhz
UHF Ultra High 300-3Ghz
SHF Super High 3Ghz - 30 Ghz
EHF Extremely High 30Ghz - 300Ghz
Different folks put the breaks at slightly different places (the.g.
the amatuer radio community puts the hf/vhf break @ 50Mhz and the
MF/HF break @ 1.8Khz.
And, as a side note, I can't find the URL, but the US Cong is talking
about pulling all the funding for the NASA space weather programs.
Would mean less/no warning of this sort of stuff.
We now return you to our regularly scheduled off topic discussions
Komrade
Owen DeLong wrote:
This will not likely affect point-to-point line-of-site
communications above 50Mhz.
It will likely affect non-terrestrial communications and HF
communications depending
on ionospheric reflection.
Owen
--On Friday, October 24, 2003 07:15:29 AM -0400 Todd Vierling
<[email protected]> wrote:
On Thu, 23 Oct 2003, Roy wrote:
: "Satellite and other spacecraft operations, power systems, high
: frequency communications, and navigation systems may experience
: disruptions over this two-week period."
:
: I think you will find that 802.11b and other terrestrial microwave
LOS
: links don't meet any of those criteria and should be unaffected.
"High frequency communications"?
We *are* talking about multi-GHz frequencies here.
--
-- Todd Vierling <[email protected]> <[email protected]>
Regards
Marshall Eubanks
T.M. Eubanks
e-mail : [email protected]
http://www.telesuite.com
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