Re: Sensors

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Wed, 30 May 2001, Ryan Gill wrote:

> At 9:18 AM +0200 5/30/01, Derk Groeneveld wrote:
> >Yup. I'm just trying to remember whether there are other factors that
> >would reduce mm radar performance, other than absorbtion.
> 
> Sounds like we need to take a walk over to sci.military.moderated....

It does, doesn't it? Or dive for Skolnik's book on radar tech ;)

> >Okay; sound spretty much like what we do with phased arrays over
here;
> >even if that's a whole lot of small transmit/receive antenna's spaced
> >not-all-that-far-apart.
> >
> > > This larger lens allows a better clarity of the object. Figure two
> > > ships operating at a great distance 10-20 MU's communicating over
> > > tight whisker beam to coordinate their efforts. They'd get a very
> > > good idea of what's there.
> >
> >Does it allow for better 'clarity', or for more resolution at
> >cross-angles? Mmm.If this works anything like phased array, though,
you'd
> >need position info on your friendly ships, in the order of magnitude
of
> >your sensor wavelength, or is this not as sensitive to phase shifts?
> >
> 
> It gives you in effect a much larger telescope. A larger telescope 
> can resolve smaller objects more easily and with greater detail. 

Okay, I can see how that works, since resolution is a direct result of
your antenna diameter and signal wavelength.

> By 
> combining the data from the two widely spaced receivers you see more 
> details. This has been done by Astronomers for years. Military folks 
> are just now trying it against stealthy aircraft if I understand 
> correctly. 

Maybe, but in a way, it's what phased array radars do at much smaller
distances.

> I think the real trick is that you need a lot of 
> coordination. The internet was enough for the Astronomers to do it 
> though.

Right. Including good information on eachother's relatikve position,
speed, etc. Mmm. Time bases might also be a problem, if speeds near
relatavistic ;)

> >But tens of thousands of kilometres isn't very far, in space?
> 
> Not really. Not on the System wide scale. Remember, we're talking 
> about ships that zip in and out of systems to the FTL points on the 
> fringes (gotta get some distance between you and those gravity wells 
> before you throw the switch for the TK drives.)

Yup.
 
> >Isn't this degaussing against magnetic mines? If not, I've learnt
> >something new again :)
> 
> Helps against magnetic mines, but I'll bet you the navy does it to 
> the subs too. Probably helps reduce their magnetic signature. I 
> suspect they won't even breathe about it though.

Damn, they'll have to kill you now.

Cheers,

   Derk
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.4 (GNU/Linux)
Comment: Made with pgp4pine

iD8DBQE7FSvNJXH58oo6ncURArcOAJ4zBJ58qVpuMVm6TC+wo3F1g+Nf2wCfXZ6U
7Lz7rVkIo8rHr4VCcSIt1QU=
=78Zo