From:	scott@**********.com (Scott Harrison)
Subject:	Radio Spectrum (Was: Re: Hacking a Smartlink in SR4)
Date:	Mon, 3 Oct 2005 17:56:46 -0400

On Oct 3, 2005, at 17:17, pentaj2@********.edu wrote:
> 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?

It all depends on the technology used. However, if you were to
attempt to do this realistically you would have a big problem. For
example, ever try to use a wireless network device and a typical
cordless telephone in the same area. One of the signals if not both
will probably suffer. This is because the 2.4 GHz signal is used for
both devices. Now imagine that you have a PAN which has a bunch of
devices all broadcasting at the same frequency. This can get rather
bothersome. So assume you shift the frequency of each device a little
bit. This will help, but you have to remember that each device will
want to use some bandwidth. This is an amount of frequency that cannot
be used by another device, so the next device needs to be shifted by
the amount the last device uses. For example, classic voice as used in
a telephone uses about 4KHz of bandwidth while an NTSC television
broadcast uses about 6MHz of bandwidth. If you look at a normal
television cable coming from some company like Comcast or Adelphia you
see a 900MHz signal which basically can allow about 150 normal
channels. If you were to take those NTSC signals and make them digital
you can save some bandwidth and provide more channels or other features
like interactive television. As a side note there was a big uproar
when people started going digital and the companies decided not to give
high definition signals because they took up all the old bandwidth, and
instead gave normal television in digital form taking up less bandwidth
so they could use the other bandwidth to make more money.

If you assume that SR4 core is correct and that virtually any amount
of data can be uploaded instantly you are talking about a lot of
bandwidth. From a radio perspective this means a wide signal which
means there are not too many places you can put the signal to start
with. For example if you need to broadcast a 1GHz signal you cannot
start in the ELF ranges since the width of your signal will blast
everything up to 1GHz in frequency. Of course a very low power signal
will not interfere with things far away, but that is yet another
problem. So you need to move this signal into a much higher frequency.
This is problematic as well since you run out of radio frequency and
start getting into things like light. Also, with the higher frequency
being transmitted you start getting into some radical things that
happen to your body as it makes connection with the transmission.
Putting a cell phone to your head is bad enough now, but with newer
frequencies who knows what havoc we can wreak.

Basically, SR4 has not got a grasp on reality as we know it in this
regard. You can get all sorts of fancy with spread spectrum, frequency
hopping, etc. but it still will not help with what they are suggesting.
In our real world would you attempt to download a 9GB movie file over
your cell phone, or would you go to your cable modem? I want FIOS but
unfortunately cannot get it yet. Fiber yields much faster rates than
copper. Don't try it through the atmosphere though.

If you want to be able to do more with limited bandwidth look at
something like World of Warcraft. The bandwidth they use is not that
much compared to the experience you have. However, they do this by
having a specific set of protocols that are transmitted over the net
and have a lot of intelligence at the client side. You can do this
with your PAN in a limited way, but it requires a limited set of
protocols and smart clients. This is a decker's nightmare since there
are no ways in assuming the protocols are set up well.

By the way, SR has never gotten this anywhere near right, so you
should just take it with a mountain of salt. My personal favorite was
the one-way SAN. How would a decker be able to send a persona through
one when the signal could not come back to the decker? Just play it
and do not worry about reality too much.

--
·𐑕𐑒𐑪𐑑
·𐑣𐑺𐑦𐑕𐑩𐑯 Scott
Harrison