Re: Sensors

Ryan M Gill wrote:

> At 11:35 PM +0200 5/29/01, Derk Groeneveld wrote:
> >  > That assumes that targets are emmitting. A target at total
> >>  EMCON will presumably be relying on totally passive sensors.
> >>  Say a vessel (in space) moving ballistically and not
> >>  thrusting.
> >>
> >>  By relying on ESM systems you are looking at the various
> >>  fire control radars, navigation radars, long range
> >>  communications, search radar, weather scopes, data links,
> >>  Talk between ships radio, and other electronic garbage that
> >>  ships emmit.
> >
> >Yes. But so is any passive sensor.
> >
>
> I'm not sure what you are saying here. Is it that Passives are like
> the above ESM? I was essentially talking about Passives.

ESM is a catch-all that includes most (all?) radar/radio spectrum.

>
> >  > Further, just relying on passive sensors to recognize a
> >>  vessel will lead to funny incidents of "seeing" a harmless
> >>  tanker when in reality it is a CVA dressed up with the same
> >>  active emmissions.
> >
> >Then again, there's the same risk with active sensors. Also, you;'re
> >assuming everything CAN be disguised/masked (see below, engines
> discussion)
>
> Ahh, but with actives and passives you'll have more information to
> make your decision. Passives are using your eyes and ears in a dark
> room. Active is using a little pen light to see a specific object.
> (naturally you know this)
>
> >
> >Similarly, a sailing vessel can be given a nimitz-size reflection by
using
> >a simple retro-reflector...
> >
>
> Reflection against what? Passives?  And from what aspect? (Space is
> 3D, much harder to predict your aspect) It'll be hard to disguise a
> sailing vessel from mm wave radar. A decent mm wave set can pick out
> what style of rigging one would have.

A big plastic balloon enclosing a tinfoil shape of a carrier will fool
the mm
radar set, and if it incorporates chilled/heated surfaces, it can also
fool
passive infrared.  The deception is easily blown at firing ranges, but
if you
are that close to the decoy, it
is too late to get back to where the enemy REALLY is.

>
>
> The only thing I'd think that mm wave radar would have a hard time
> with would be a very well done Q-ship. Besides, the whole principle
> of mm-wave radar and its fine resolution is the basis for the ability
> of Enhanced and Superior sensors to figure out what the current
> status of a vessel is. ("Ok, his drives are down and geeze look at
> that big hole in his port side weapons array, he's definately weak on
> that side sir. His VLS system looks mostly popped too, so he's not
> got much fight left in him...")

This is heavily dependent on how big an mu is.	If it is thousands of
kilometers, you may have difficulty resolving two closely spaced ships
(less
than 500m apart).  Passive sensor will let you know when you have vented
compartments to space from the gas cloud itself, and the missing
insulation
(ship will lose more heat through the hole).

>
> >
> >Yes, but you're not going to do much ranging until you've acquired
the
> >target, meaning that EITHER passive sensors were good enough to
acquire
> >the target, OR you had to go active anyhow.
>
> Ranging can be accomplished with passives too.
> Inferometric/stadio-metric triangulation.
> I don't see needing Cepheid variables to figure out how far away that
> Eurie BDN is...

True, but you do need to have collected a large number of Eurie BDN
records to
be certain, or the sneaky devil will change the emissivity to fool you
into
thinking that he is nearer/closer than he really is.

>
>
> >  > So I guess the question is, what kind of drives are they?
> >>  Thats the first thing.
> >>
> >>  Second is how much passive emmissions do the ships give off?
> >>  You know something is there. How far beyond 54" do you know?
> >>  (TK drive emmissions are another thing, boy this long range
> >>  sparky stuff gets tricky...)
> >
>

This gets to the heart of the problem.	If you kept the same scale
between the
detection and combat phases of a fleet engagement (and had REALLY small
figs),
playing out the detection phase on a table would let you play the combat
phase
on a postage stamp.  The only adequite treatment I have seen of this
situation
is GDW's Star Cruiser.	The detection ranges are seldom above 30 mu. 
Long
range combat takes place at 1.0 mu, and short range combat is at 0.5mu
[Star
Cruiser is actually played on a hex map, 1.0 is adjacent hexes and 0.5
is both
firer and target in the same hex].  The detection ranges assume that
neither