From: | pentaj2@********.edu (pentaj2@********.edu) |
---|---|
Subject: | Radio Spectrum (Was: Re: Hacking a Smartlink in SR4) |
Date: | Mon, 03 Oct 2005 17:17:22 -0400 |
From: Ice Heart <korishinzo@*****.com>
Date: Monday, October 3, 2005 2:22 pm
Subject: Re: Hacking a Smartlink in SR4
> Someone missed the class on bandwidth and how it is NOT unlimited.
> Especially radio signal bandwidth. Remember the little scandal that
> quietly rocked a few car companies a short time back because their
> keyless entry systems functioned a very narrow set of frequencies?
> So people were opening each other's cars. How about garage door
> openers, and the problems with too few freqencies.
Never mind bandwidth. What about frequency allocation?
There's just not enough spectrum, period, for all of the devices
posited to be wireless.
First, I'll provide a real-world overview of the spectrum, then pick
out where SR4's wireless matrix MIGHT be able to live on the spectrum.
An overview of the spectrum (taken from
http://en.wikipedia.org/wiki/radio_spectrum#radio_frequency_spectrum):
Lowest on the spectrum (ITU Band 1) is Extremely Low Frequency (ELF).
This is 3-30 Hz frequencies. This is used strictly by nuclear
submarines at depth, and as only a few characters can be transmitted
per minute, it's useless for our purposes.
Next up, at ITU Band 2, is Super Low Frequency (SLF). 30-300 Hz,
including 50hz and 60hz, the frequencies of AC power transmission.
Obviously, since this is where AC power lives, it's a bit full and not
really usable for anything we're thinking of.
At ITU Band 3 is Ultra-Low Frequency (ULF). 300-3000 Hz. Mostly used
for comms in mines, but the trnasmitters required are a bit big.
After that, ITU Band 4, also known as VLF or Very Low Frequency, 3-30
kHz. There's not much bandwidth on this part of the spectrum, and what
there *is* has been filled for the past century+ by radionavigation
beacons, time signals, and the like. Such creatures as PC monitors
also emit noise on the VLF band. Thus we move along.
ITU Band 5 is LF, Low Frequency, 30-300 kHz. Primarily used for
radionavigation signals (especially for trans-oceanic air traffic),
but bits of Europe also do longwave AM broadcasting here.
ITU Band 6 is Medium Frequency, 300-3000 kHz, otherwise known as AM
radio. All taken up, and SR4 indicates that AM radio lives on,
apparently.
ITU Band 7 is 3-30 MHz, also known as shortwave radio. The ranges
don't work at all for wireless PANs and the like, as shortwave can
cross the globe.
ITU Band 8 is 30-300 MHz, VHF (Very High Frequency). Used for FM radio
and TV broadcasts. However, it is a very, very crowded part of the
spectrum, used by everyone and everything.
ITU Band 9 is 300-3000 MHz, Ultra-High Frequency (UHF). used by many
TV broadcasters, Wireless LANs, and what few digital audio
broadcasting exists. UHF attenuates quite a bit through the
atmosphere, something I can only see getting worse with SR's pollution.
Keep in mind that your microwave oven also lives in UHF, at around
2450 MHz.
ITU Band 10 is microwave range.
There's more beyond that, but not much.
Now, where I figure it'd live:
First possibility is VHF. There's potential here, though I personally
don't see it.
Next up, UHF. This is the most likely part of the spectrum for SR4-ish
wireless devices. However, everybody is already using it. I wonder how
much of the spectrum is *left*.
Other than that, I'm clueless. Any radio engineers willing to throw in
their 2 cents as to where SR4's wireless stuff would live?