Re: Active vs Passive

Let's figure out how you can detect an FT ship.

PASSIVE

First of all, the Doubletalk generators. This means:
  Neutrino detection
  Warp signature
  Disturbances in the Force
  etc

Then, the PSB methods:
  Occulting background radiation (ie you detect something
  that's a little blacker than space)
  EM (usually Infra-Red) Radiation from Hull
  EM Radiation(Visible and Up) from Drive exhaust
  Particle emission (though signal/noise would be very low)
  Reflection of natural sources of radiation (ie Stars nearby)
  Very energetic EM from weapons firing.
  Moderately energetic EM from active sensors.
  Forward Mass detector (relatively low range)

ACTIVE

Doubletalk Generators:
  Tricorder readings 
  Hyperspace Radar
  Precognition etc

PSB:
  Reflected EM that could be any frequency with wavelength
  smaller than twice the length of the target.
  Reflected particles?

Active methods could include bistatic Radars/Lidars where the
easily-detectable emitters are physically separated by a large
distance from the undetectable receivers.

Virtually all of these have some form of counter: from "baffled jets"
to Radar Absorbent material, dumping heat via a tight-beam laser,
etc. And its complicated by the fact that empty space isn't:
You may be able to detect several thousand objects, one of which
is a hostile, the others innoffensive chunks of rock, ice etc.

One thing that is not easily hidden is course and velocity changes.
Also, If penetrating an enemy system, you can reasonably expect that
all significant chunks of space material have been catalogued, and
anything not in the catalogue will be investigated. Hence my story
a few weeks ago that had a penetrating mission consisting of
small ships that attached themselves like limpets on infalling
cometary material from the chaotic Oort cloud. Add some camo
nets so the ship looked just like a rock to an active sensor, and
you're effectively hidden.

Summary:
Just some thoughst on the theory. I really like the "simple simon"
sensor rules posted not long ago BTW, they make a lot of sense
from the PSB viewpoint as well as being playable.