Newsgroups: sci.electronics
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Bad News- Lasers replace Radar guns
Message-ID: <1990Jan19.164220.20457@utzoo.uucp>
Organization: U of Toronto Zoology
References: <51058@bbn.COM> <8561@nigel.udel.EDU> <1990Jan18.164315.15737@utzoo.uucp> <7333@lindy.Stanford.EDU>
Date: Fri, 19 Jan 90 16:42:20 GMT

In article <7333@lindy.Stanford.EDU> sorka@ucscb.UCSC.EDU (Alan Waterman) writes:
>Sorry but you're wrong. Halogen lights are legal. They will most likely
>jam the lasers. This will interefere with the police. Thus it is not
>illegaL

Halogen lights are legal.  I would not be so sure that they will jam the
lasers.  If I were designing such a laser system, the very least I'd do
would be a very narrow bandpass filter on the receiver, plus circuits to
ignore steady background and listen only to pulses.  There are a variety
of more sophisticated things that could be done -- see any book on radar
that talks about ECCM (Electronic Counter-CounterMeasures).  The most
your halogen lights would do is reduce the range slightly (by reducing
signal/noise ratio a bit), unless you do something elaborate and conspicuous
and less obviously legal like pulsing them.  Even that might not help, since
the laser pulses will be very short and sharp-edged and I don't think
halogen lights can imitate that very well.

The suggestion for a diffraction-grating paint job is much more clever.
It wouldn't be perfect, but it might cut the S/N ratio enough to make
things difficult.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu