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Mailing List Logs for ShadowRN

Message no. 1
From: Paul Gettle <RunnerPaul@*****.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Thu, 8 Oct 1998 21:18:53 -0400
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At 04:33 AM 10/8/98 -0400, Michael wrote:
>As to your wireless network ala the optical meathod, sorry but it
wouldnt
>work. Why? because the sending and recieving units would have to be
pointed
>right at each other in order to transmit

My television remote works on optical transmission, and I don't have
to point it directly at the television to transmit. I'll grant you
that my remote isn't sending information in megapulse amounts, but the
principles should be somewhat similar.

I'll put it up to the Physics Gurus on the list. Since we already have
a piece of canonical hardware that can send data optically, through
open air, at a rate of 2,000 Mp per minute, as long as it's pointed in
a straight line to the reciever, would it be possible to have a
optical transmitter cover a wider area, sending data at a slower rate,
say 20 Mp per minute?

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--
-- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)
PGP Fingerprint, Key ID:0x48F3AACD (RSA 1024, created 98/06/26)
C260 94B3 6722 6A25 63F8 0690 9EA2 3344
Message no. 2
From: Robert Watkins <robert.watkins@******.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Fri, 9 Oct 1998 13:56:39 +1000
Paul Gettle writes:
> My television remote works on optical transmission, and I don't have
> to point it directly at the television to transmit. I'll grant you
> that my remote isn't sending information in megapulse amounts, but the
> principles should be somewhat similar.
>
> I'll put it up to the Physics Gurus on the list. Since we already have
> a piece of canonical hardware that can send data optically, through
> open air, at a rate of 2,000 Mp per minute, as long as it's pointed in
> a straight line to the reciever, would it be possible to have a
> optical transmitter cover a wider area, sending data at a slower rate,
> say 20 Mp per minute?

There's a question of scatter... near-visible frequencies (such as the
infrared frequency used by your TV remote) scatter quite a lot. Sometimes
this is okay: your TV remote is only sending a miniscule amount of data, and
this holds up to scatter quite well (I routinely aim my remote at the wall
next to me...). Once you start having a lot of data, this gets a bit harder
to do.

However, while cellular frequencies are pretty crowded, there would be other
frequencies not used by cellular systems that would be suitable for data
transfer like you're saying. One of these could implement such a system.
Such a system would be feasible, though the actual mechanics might need to
be changed.

--
Duct tape is like the Force: There's a Light side, a Dark side, and it
binds the Universe together.
Robert Watkins -- robert.watkins@******.com
Message no. 3
From: Starjammer <starjammer@**********.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Thu, 8 Oct 1998 23:54:04 -0400
At 09:18 PM 10-8-98 -0400, you wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>
>At 04:33 AM 10/8/98 -0400, Michael wrote:
>>As to your wireless network ala the optical meathod, sorry but it wouldnt
>>work. Why? because the sending and recieving units would have to be
pointed
>>right at each other in order to transmit
>
>My television remote works on optical transmission, and I don't have
>to point it directly at the television to transmit. I'll grant you
>that my remote isn't sending information in megapulse amounts, but the
>principles should be somewhat similar.

Your television remote is essentially an IR flashlight that pulses at
different rates to send different signals. (With NV goggles you can
actually see the beam.) The beam has a fairly wide arc, and can reflect
off of some surfaces in the home. However, you still have to have the
point-to-point LOS.

>I'll put it up to the Physics Gurus on the list. Since we already have
>a piece of canonical hardware that can send data optically, through
>open air, at a rate of 2,000 Mp per minute, as long as it's pointed in
>a straight line to the reciever, would it be possible to have a
>optical transmitter cover a wider area, sending data at a slower rate,
>say 20 Mp per minute?
>--
> -- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)

Theoretically, yes, but as was said earlier the transmitter and receiver
have to be pointed directly at each other. In an out-of-doors situation
you wouldn't have anywhere near the margin you have with your indoor remote.

All in all, digital radio is a far better medium for data transmission.

Starjammer | Una salus victus nullam sperare salutem.
starjammer@**********.com | "The one hope of the doomed is not to hope
Marietta, GA | for safety." --Virgil, The Aeneid
Message no. 4
From: Micheal Feeney <Starrngr@***.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Fri, 9 Oct 1998 02:04:36 EDT
In a message dated 98-10-08 22:09:30 EDT, you write:

<< My television remote works on optical transmission, and I don't have
to point it directly at the television to transmit. I'll grant you
that my remote isn't sending information in megapulse amounts, but the
principles should be somewhat similar. >>

Thats because the beam retains enough coherance while bouncing off the wall.
Its a simple pulse code. However, the sort of data rate your looking at would
need LOS to make sure that your not loosing data to vagrancies in the paint.
Its a protocol thing mostly. Bouncing that high a density signal off anything
but a mirror is going to result in so much signal degredation its not even
funny.
Message no. 5
From: Adam Getchell <acgetchell@*******.EDU>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Fri, 9 Oct 1998 02:04:40 -0700
>I'll put it up to the Physics Gurus on the list. Since we already have
>a piece of canonical hardware that can send data optically, through
>open air, at a rate of 2,000 Mp per minute, as long as it's pointed in
>a straight line to the reciever, would it be possible to have a
>optical transmitter cover a wider area, sending data at a slower rate,
>say 20 Mp per minute?

Real-life IrDA transmission speeds are 4 megabits/second. Projected ceiling
is 16 megabits/second over a maximum range (reduced by fog, water vapor and
other strong absorbers of IR) 1.5 miles. This is already using digital
spread-spectrum techniques, which cuts signal loss somewhat.

You could probably reduce signal loss from dispersion by arranging the
packets as solitons. Still have to worry about distance attenuation and
interference.

Using an IR laser you can get 40 megabits/second. Of course, you lose
spread-spectrum capabilities and so signal failure is more error-prone. You
would have to implement Quality of Service.

All of this begs the question of what a pulse really is. Your mileage may
vary. Comparing Shadowrun results to the laser could give you some sort of
rough conversion between bits and pulses, though again, a pulse is probably
a cousin to a qubit.

> -- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)


--Adam

acgetchell@*******.edu
"Invincibility is in oneself, vulnerability in the opponent." --Sun Tzu
Message no. 6
From: Paul Gettle <RunnerPaul@*****.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Fri, 9 Oct 1998 10:28:13 -0400
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At 02:04 AM 10/9/98 -0700, Adam wrote:
>Real-life IrDA transmission speeds are 4 megabits/second. Projected
ceiling
>is 16 megabits/second over a maximum range (reduced by fog, water
vapor and
>other strong absorbers of IR) 1.5 miles. This is already using
digital
>spread-spectrum techniques, which cuts signal loss somewhat.
>
>You could probably reduce signal loss from dispersion by arranging
the
>packets as solitons. Still have to worry about distance attenuation
and
>interference.
>
>Using an IR laser you can get 40 megabits/second. Of course, you lose
>spread-spectrum capabilities and so signal failure is more
error-prone. You
>would have to implement Quality of Service.
>
>All of this begs the question of what a pulse really is. Your mileage
may
>vary. Comparing Shadowrun results to the laser could give you some
sort of
>rough conversion between bits and pulses, though again, a pulse is
probably
>a cousin to a qubit.

Lovely answer, but what I really need to know is if it's possible to
have the sort of wide beam coverage that you can get with a TV remote,
but with the sort of data transfer rate that would be practical for
use with computing in SR.

Maybe you have answered this, but I can't just pick it out through the
terminology (for instance, what's IrDA? I can guess the Ir part, but
not the rest).

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--
-- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)
PGP Fingerprint, Key ID:0x48F3AACD (RSA 1024, created 98/06/26)
C260 94B3 6722 6A25 63F8 0690 9EA2 3344
Message no. 7
From: Adam Getchell <acgetchell@*******.EDU>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Fri, 9 Oct 1998 11:34:53 -0700
>Lovely answer, but what I really need to know is if it's possible to
>have the sort of wide beam coverage that you can get with a TV remote,
>but with the sort of data transfer rate that would be practical for
>use with computing in SR.

That depends. What is the rough equivalent between bits and pulses? As I
said, 16 MB/s is the top practical rate.

If, for example, you relate a qubit to a pulse then there is no easy
correspondence between qubits and bits (well, it's exponential in the power
of 2) as a "qubyte" made up of 8 qubits could take on all bit values
simultaneously. (Utilizing this requires specific processor design). Using
long-word integers will increase the discrepancy further.

The IrDA (IR Data Association) standard uses a peak wavelength of 0.85 -
0.95 micrometers, minimum intensity 40 milliwatts/steradian, maximum
intensity 500 mW/Sr within a 30 degree cone, up to 4 MB/s. The range on
this standard is a bit low (1 meter). If you extrapolate to 16 MB/s at 1.5
miles, clearly a fair amount of spread spectrum and other techniques are
necessary. Also, the beam will have to have much less angular divergence to
achieve minimum intensity for data transfer.

Ballpark answer: sure, you can do it. I implied as much but not strongly; I
usually prefer to let facts speak for themselves. Given that Shadowrun text
files can occupy megapulses, it seems the "conversion rate" between
pulses/bytes isn't too high, barring embedded applets and multimedia
content.

Short range transmitters will be able to afford wide divergence. Longer
range repeaters will not. As I said before, you could use lasers but then
you would have signal noise and interference problems with the
monochromatic beam.

> -- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)

--Adam

acgetchell@*******.edu
"Invincibility is in oneself, vulnerability in the opponent." --Sun Tzu
Message no. 8
From: Paul Gettle <RunnerPaul@*****.COM>
Subject: Re: Wireless Networking [attn: Physics Gurus]
Date: Sat, 10 Oct 1998 00:27:10 -0400
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>Short range transmitters will be able to afford wide divergence.
Longer
>range repeaters will not. As I said before, you could use lasers but
then
>you would have signal noise and interference problems with the
>monochromatic beam.

This was the sort of answer I was looking for, whether or not a
transmitter could have a beam with wide divergence, so that
transmitter and reciever only have to be pointed in the general
direction of each other, instead of directly at each other. From the
numbers given in the post, things look iffy for my idea. I'd say it's
possible for the sort of tech I'd described, given what we've seen
already defined for the Optical Scanning Datajack, other people don't
think optical transceivers pointed just in the general direction of
each other would work as efficently as I'm giving them credit for. At
least we have some numbers to look at.


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--
-- Paul Gettle, #970 of 1000 (RunnerPaul@*****.com)
PGP Fingerprint, Key ID:0x48F3AACD (RSA 1024, created 98/06/26)
C260 94B3 6722 6A25 63F8 0690 9EA2 3344

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