sensors and jammers...

A thread of 2 messages, 29 April 1992 to 1 May 1992, in the order they were sent.

#4026 sensors and jammers...

Steve Higginbotham · 29 April 1992

Scott Kellogg:

>But then we have the EMS band stuff.  Yup, that's gotta have external
>mounts.  But look at the size of the stuff in the design tables.
>It's pretty small.  Sounds like the emmitters and recievers are
>spread out in small spots over the entire hull.  That would give you
>a larger area for your antenna, so you can pick up better signal.
>When you've got the surface area of a 100 ton ship or so to put it
>on, I think you've got plenty of area.

So how big is your basic radio-telescope?  I'm sure they have
interstellar range, but not so sure about anything mush smaller.  And
how much area does a 100T ship have?  At least 590.7 square meters, to
be sure, but how much more?  Say no more than 1000 square meters
(assuming it's three meters thick).  1000 square meters lets you build
an antenna equivalent to a 35 meter dish (which is none too big for
EMS-scanning of objects 2 parsecs away).


>A question *I* have been thinking over recently is the utility of
>EMS-Jamming.  Virtually all ships that have an active EMS to jam also
>have a passive EMS system.

>Ok, scenerio.  Craft A makes an active scan of craft B.  Craft B
>doesn't particularly like this and turns on the EMS-Jammer.  Craft A
>then gets an automatic lock on Craft B by their passive EMS.  So,
>just how useful is the Jammer?

The jammer is wonderfully useful with the right platform.  My
spy-ships carry jammers in drones - self-propelled, programmable, able
to jam others from somewhere reasonably close by without actually
giving away your position.

>Ah!  What about Jamming the active sensors on incoming missiles?
>Well the missiles got home on jam stuff too!  (The TL 8 AIM-54
>Pheonix has home on Jam capablity.)

Yes, home-on-Jam exists, and yes it makes it tough on jammers, but the
real world is like that.

>I was trying to figure out how you might use the jammer to fool both,
>but I know very little about Electronic (Counter)^3 Measures.  My
>first thought was that perhaps 2 jammers working in concert could
>make things rough on the Passive EMS systems.  However it sounds that
>this is not really the case.

You don't fool PEMS by jamming it, you spoof it.  Use your AEMS to emit
just exactly the kind of signature that, when added to your natural
signature, looks JUST LIKE SOMETHING ELSE.  That's why destroyers have
that widget to make aircraft-carrier noise today.  It helps protect the
carrier, though it is kind of hard on the destroyers.
Incidently, has anyone noticed the active noise-suppression devices
being developed?  The ones that generate an out-of-phase signal to
cancel the noise?  You could do that with EMS too.  Analyse your ships
signature, generate an out-of-phase copy, and project that out your
AEMS, which should make you just about invisible to PEMS.  And if you
were sharp, you could do it t the return signal from the other guy's
AEMS and kill it too.

Later...

- -- Via DLG Pro v0.991

[email removed]

I have learned to use the word "impossible" with the greatest caution.
                                    --W. von Braun

#4049 Re: Sensors and jammers

Hans Rancke-Madsen · 1 May 1992 · reply to #4026

Scott writes:
>       I've heard folks say that superdense hulls produce a neutrino
> shadow.  I say this is garbage.  A neutrino can pass through the entire
> mass of the earth without any trouble.  If superdense was THAT tough,
> then you can forget it ever getting scratched by something as puny as a
> 250Mw laser.

But by the same token it seems to me that you'd have a hard
time getting a directional fix on a neutrino source. Or perhaps
not, I'm not very well versed in sensors. But I know that I
heartily dislike the ability to pinpoint any starship in a star
system from a game balance pov, so that's my story, and I'm
sticking to it. I impose a DM of -1 to neutrino pinpoints for
every neutrino source within range.


Steve Higginbotham writes:
> You don't fool PEMS by jamming it, you spoof it.  Use your AEMS to emit
> just exactly the kind of signature that, when added to your natural
> signature, looks JUST LIKE SOMETHING ELSE.  That's why destroyers have
> that widget to make aircraft-carrier noise today.  It helps protect the
> carrier, though it is kind of hard on the destroyers.
> Incidently, has anyone noticed the active noise-suppression devices
> being developed?  The ones that generate an out-of-phase signal to
> cancel the noise?  You could do that with EMS too.  Analyse your ships
> signature, generate an out-of-phase copy, and project that out your
> AEMS, which should make you just about invisible to PEMS.  And if you
> were sharp, you could do it to the return signal from the other guy's
> AEMS and kill it too.

Steve, are you talking about _cloaking devices_ here!? (Good
for you if you are. Efficient cloaking devices is what our
pirates need to survive ;-).

      Hans Rancke
University of Copenhagen
     [email removed]
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