On Tue, 2005-01-25 at 22:54 -0500, Dave VanHorn wrote:
> >
> >Nope. I recently saw an episode of Fifth Gear where they were testing
> >radar and lidar detectors, and one of the major gripes was the lidar
> >detector going off in front of certain grocery stores.
> >
> >Most of the grocery stores in my area us IR (I've seen them opened).
> 
> Passive IR won't set off a lidar detector.

They are NOT passive IR, the ones I've seen have a set of transmitters
and a receiver. Why don't you just believe me on this? Do I have to take
one apart and take pictures??

> 
> >But that's the point: the signal LOOKS like it comes from a Lidar, which
> >is why Lidar detectors are triggered. Anything that sets off a Lidar
> >detector has the good potential, if strong enough, at interfering with a
> >Lidar gun.
> 
> Primitive ones maybe. How likely is it for your video sender to interfere 
> with my cordless phone? They are both in the 2.4 GHz band.  Not at all, 
> since my cordless is direct sequence spread spectrum. I just don't "see" 
> your signal.

Bad example since you are talking about spread spectrum. Lidar usually
uses a laser diode. Laser diodes transmit a VERY narrow band of
frequencies. All you need is a transmitter on the same "frequency"
keying a certain pattern strongly enough to jam a Lidar gun. It's not
that hard to do actually, which is why the door sensors have been known
to set off the detectors.

Again, a Lidar detector is pretty much just the receiver half of a Lidar
gun, they are both "looking" for the same signal, so ANYTHING that sets
off a Lidar detector has a fair chance of interfering with a Lidar gun.
I don't know why this point is so hard to get across.
 

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