Re: FT Sensor Rules -- Request for Comments [LONG]

On Sunday 24 October 2004 02:55, Laserlight wrote:
> I don't think you understood Doug's point.  Let's take the example of
> three battleships, Asad ed Din (actively searching) and Saif ed Din
> (passively searching) versus Fernando Poo (passively searching), and
> assume they're all equally reflective and have equal sensor suites.
>
> Asad is putting out an amount of energy which has to be sufficient to
> get to Fernando, reflect off Fernando, get back to Asad, and still be
> above detection threshold.  Because the distance from A-to-F-to-A is
> twice the distance from A-to-F, the inverse square law means the
> reflected signal strength A hears is one quarter the signal strength F
> hears (assuming F is a perfect mirror).  Therefore Fernando is going
> to detect Asad a long time before Asad detects Fernando.
>
> OTOH, Fernando and Saif will detect each other at the same time.

In this case, if the signal strength of Asad's active search is eight
times the strength of Fernando's passive signature, then Asad will
detect Fernando before Saif would.

Asad has given away its position to everyone else, but that is because
it's just lit itself up like a light house. For Fernando, a passive
sensor will detect Asad before any active sensors will.

Assuming Fernando is running quiet, it may not be giving much away
that can be detected on passive except at very short range, so active
may be the only way to see it at longer ranges.

Going back to Doug's torch/tower example, if the tower is dark, at
night you're not going to see *anything* with passive sensors. Turn
the torch into a huge spotlight, you can (a) see the tower with your
active sensor, and (b) everyone can also see you.

Cue argument about whether it's possible to have stealthy ships in
space.

-- 
Be seeing you,				   http://www.glendale.org.uk/
Sam.					jabber: samuel.penn@jabber.org