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Message no. 1
From: runnerpaul@*****.com runnerpaul@*****.com
Subject: Ranges and Flux [was: Misc SR q's]
Date: Wed, 28 Apr 1999 00:38:37 -0400 (EDT)
At 04:37 PM 4/27/1999 -0400, Bai Shen wrote:
>I had already figured that out from a rules standpoint, but I'm
looking
>at it from a physics standpoint. How does the van get the commands
from
>a CRD which can only transmit to 250m?
>


At 04:51 PM 4/27/1999 -0400, Marc Renouf wrote:
> Technical question: if Joe's CRD has a range of 250m, does
that
>not more or less mean that he must stay within 250m of his repeater
(in
>this case the van) to command the drones? He may be able to receive
the
>simsense signals from farther away (out to the 2km range of the van's
>transmitter), but he wouldn't be able to send a signal strong enough
to be
>received by the van and thus relayed to the drones.
> Or am I missing something? Does increasing your Flux
magically
>increase the range at which you can *receive* signals as well as
transmit
>them? I realize that "Flux" is a necessarily abstract concept, but
some
>clarification would be helpful.
>


At first, I was confused on this too (after all, doesn't the rule on
p.30 of R2 specifically read "The ranges of ... remote control decks
are determined by the power output of the system's transmitter."?),
but here goes with my explanation/take on the matter:

The radio signal broadcast from the flux 0 CRD does not just
evaporate/vanish at 250m. That's just the point at which the signal
becomes too weak to become useable; The weak signal continues on
outward well past 250m, but it's lost energy to the point where a
normal receiver can not pick it out from the background noise.

Now when this too-weak signal is picked up by the antennas of
something with a higher flux rating, the same signal amplifiers used
to pour on the power for outgoing transmissions can also amplify weak
incoming signals back up to the point where they are useable again.

The reason this fact isn't considered in other parts of the rules is
mainly for simplicity's sake; using a high-flux RC deck as a Server
for a CRD is listed as one of the "Advanced Rules", after all. :)

Even without using the advanced rules, however, it's safe to assume
that amplification of incoming signals would have to occur. Picture a
rigger using a RC Deck equipped with Signal Amplifiers so that it has
a Flux of 8. The range of such an RC Deck would be 20km. Now say the
rigger is using the RC Deck to control a small, electric-powered, Body
0 drone. Now there doesn't seem to be a Flux rating listed for the
transmitters that are included in the Remote Control Adaptation
package that comes standard on drones, but a Body 0 drone would not by
any means be able to put out much of a signal, right? However,
everything in the rules seem to indicate that you can operate that
drone out to the 20km range, and still receive a full telemetry and
simsense broadcast from the drone.


There are some very important things to consider if you allow high
flux devices to be able to amplify weak incoming signals. There's the
fact that when you amplify incoming signals, you're also amplifying
the background noise. Even with the sophisticated noise filtering
circuits and pattern recognition software that'd be available by SR
time, you'd probably need to know exactly what frequency to look on
and know exactly which rigger protocol to look for.

When you set up a high flux RC deck as a server for a CRD, you know in
advance what frequencies and protocols you'll be using. Signal
interception is another matter entirely. When you're attempting to
intercept another rigger's signals, unless you've done some _serious_
legwork, you won't know those things in advance.

This is why normally the rule for signal interception is that you must
be within the range of the least powerful device. Sure you could set
up a higher flux receiver outside the effective range of the
interception target, and try to amplify the signal, but it would be
needle in a haystack time. Even when you're inside both ranges, you
have to make a test to find the frequencies the target is broadcasting
his rigger channels on; this would be much harder if the signal is so
weak that you have to amplify everything just to be able to pick it
out from the background noise.

There are other tricks to consider, but some of them depend on what
the Flux rating of the Remote Control Adaptation's
transmitter/receiver is. I'm going to ask Mr. Szeto about that in
another post.

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Message no. 2
From: JonSzeto@***.com JonSzeto@***.com
Subject: Ranges and Flux [was: Misc SR q's]
Date: Wed, 28 Apr 1999 11:15:17 EDT
runnerpaul@*****.com wrote,

> At first, I was confused on this too (after all, doesn't the rule on
> p.30 of R2 specifically read "The ranges of ... remote control decks
> are determined by the power output of the system's transmitter."?),
> but here goes with my explanation/take on the matter:
>
> The radio signal broadcast from the flux 0 CRD does not just
> evaporate/vanish at 250m. That's just the point at which the signal
> becomes too weak to become useable; The weak signal continues on
> outward well past 250m, but it's lost energy to the point where a
> normal receiver can not pick it out from the background noise.

That is correct. The transmission range is determined largely by the
inverse-square law, and also by the logarithmic scale of decibel
measurement. (For the liberal arts majors, a decibel is defined as the
logarithm of a given signal, divided by a certain baseline. It's used not
only in acoustic (sound) measurements, but also in RF signal technology.)

This is also why I chose a table to model the Flux transmission ranges
rather than a simple formula, to emphasize the non-linear curve of Flux.
However, the table doesn't follow the curve exactly, because a strict
logarithmic-inverse square curve results in a HUGE jump at Rating 1,
followed by very small incremental changes thereafter. So I "massaged" the
numbers a bit to make them a little more manageable.

> Now when this too-weak signal is picked up by the antennas of
> something with a higher flux rating, the same signal amplifiers used
> to pour on the power for outgoing transmissions can also amplify weak
> incoming signals back up to the point where they are useable again.
>
> The reason this fact isn't considered in other parts of the rules is
> mainly for simplicity's sake; using a high-flux RC deck as a Server
> for a CRD is listed as one of the "Advanced Rules", after all. :)

This is generally what happens in a remote control deck. If you wanted to
be absolutely strict about it, the transmission range of an RC deck should
depend on the Flux of BOTH the RC deck AND the RC interface on the drone.
However, I felt that this adds an extra level of unwanted complication.
("Drone A can only be within 2 km of the deck, while drone B can only be
within 250 meters of the deck, but drone C can go out as far as 10 km.
However, if I incorporate a retrans module, I can have drone B no more than
2 km from drone C, so if drone C is 60 degrees west of the RC deck at a
distance of 6 km and moving at a bearing of 175 degrees at 120 kph, this
means drone B can only be....")

> There are some very important things to consider if you allow high
> flux devices to be able to amplify weak incoming signals. There's the
> fact that when you amplify incoming signals, you're also amplifying
> the background noise. Even with the sophisticated noise filtering
> circuits and pattern recognition software that'd be available by SR
> time, you'd probably need to know exactly what frequency to look on
> and know exactly which rigger protocol to look for.

At this point you have to be careful. Reception ability can be a
potentially murky gray area. When you start talking about filtering and
pattern recognition, you start to cross the line into an electronic
device's "normal" Rating (which measures the relative sophistication of the
tech involved, and things like filtering and pattern recognition would fall
into this).

As far as RC decks are concerned, though, it's assumed that receptivity,
WRT range at least, is high enough across the board so as not to be an
issue. So the question of range falls back to only one variable,
transmission strength (Flux).

> When you set up a high flux RC deck as a server for a CRD, you know in
> advance what frequencies and protocols you'll be using. Signal
> interception is another matter entirely. When you're attempting to
> intercept another rigger's signals, unless you've done some _serious_
> legwork, you won't know those things in advance.

There are also issues such as frequency hopping, frequency and time CDMA
(code division multiple access), ATM (asynchronous transmission mode) and
packet switching, and so on. RC decks are implied to incorporate all these
more or less to varying degrees. But you're right, the bottom line is that
it should be DAMN difficult to intercept an RC signal.

> There are other tricks to consider, but some of them depend on what
> the Flux rating of the Remote Control Adaptation's
> transmitter/receiver is. I'm going to ask Mr. Szeto about that in
> another post.

Also answered in this message for convenience.... :-)

> The Remote Control Interface package that comes standard on drones and
> can be added to other vehicles has a radio transmitter/receiver to
> allow it to access the RC Network, correct?

That is correct. Note, however, that the space and weight of the interface
is small enough as to be negligible (0 CF, 0 Load). So there isn't a lot of
space or weight available for transmission power.

> What is the Flux rating of that transmitter/receiver? Would it be
> based off of the Body statistic?

The Flux Rating for the interface was largely ignored, as it had no
appreciable effect in the game rules. (Per the rationalization explained at
length above.) If it is abolutely necessary to know what the Flux for the
device, the interface has a Flux of 0, plus whatever boosts may be provided
by the vehicle/drone's engine (see p. 30 of R2). You can also add signal
boosters (p. 139 of R2) to boost the Flux, but again, per the rationale for
RC decks, this isn't necessary. For SIGSEC (signal security) reasons, the
Flux may not exceed that of the RC deck.

-- Jon

Further Reading

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