"pervect" wrote in message
...
On Sat, 20 Dec 2003 18:15:56 +0000, ess (phil
hunt) wrote:

On Fri, 19 Dec 2003 13:43:49 -0500, Ray Drouillard
wrote:

Also, since it's not encrypted, it can be spoofed using a local
transmitter

That doesn't logically follow; it's possible to make non-encrypted
data that can't be faked, you just use a digital signature.

If you don't go to spread-spectrum, your radio links will probably be
jammed. (Solution - go to spread spectrum).

Spread spectrum signals will be difficult to separate from noise,
except at very close range, where the total power level is noticable
above the broadband noise.

I'd still rate a radio location system using spread spectrum
transmitters as rather vulnerable, because the transmitters have to
remain in a fixed location for the system to work, and would be prime
targets.

You don't necessarily need stationary transmitters. After all, the GPS
transmitters aren't stationary.

If the transmitters transmit their locations to the receivers, the
receivers can do the necessary calculations to get a fix.


Ray Drouillard