🚀 go-pugleaf

In article <keating.722030848@galena13> keating@rtsg.mot.com (Edward Keating) writes:
>dag@col.hp.com (David Geiser) writes:
>
>>> sees at least ond diode.  Modulate the power supply with a little noise (like
>>> ignition noise) and the officer won't be able to get a reading that makes any 
>>> sense to his machine.
>
>>On second thought, it's fairly easy to descriminate the
>>reflections.  In fact, it's probably really necessary given all
>>the regular IR stuff out there like your fan blade chopping the
>>engine heat, vibrations of the car body due to resonance or 500W
>>woofers, etc.
>
>Perhaps it may be easier than you think. All we'll need is the expected 
>modulating frequency of the laser and then send back a much more intense
>bandswept signal to drown out the reflection. Sorta like trying to 
>stargaze during the noonday sun. Does anyone really have the hard spec's on
>the wavelength involved and what IR leds would come close to that spec?

I have read that the laser is not actually "modulated", it is simply 
pulsed and that the speed measurement is made by comparing succesive
distance readings to a timebase rather than using the Doppler effect
like RF radars.  Given this, a continuous emission would prevent it
from "seeing" its own pulses rendering it useless.  All you need is
lights of about the right "color" and to turn them on and leave them on.
I doubt it if the detector is as narrow as the output of the laser so
I assume you wouldn't need to use laser sources.  You would have to
make sure your light beamed directly into the unit however, this could
be tough.

-- 
Erik van Bronkhorst KC6UUT DoD#4342585443 AMA#[classified]
"Truth is false and logic lost, now the fourth dimension is crossed..."