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Laser False Alarms
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Why am I getting laser alarms when I follow some cars?
- J.J., Michigan
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Red neon is occasionally used for the CHMSL (Center
High Mounted Stop Lamp) on new cars. We know of these
models: GM Trailblazer and Envoy, the Lincoln Mk VIII
and the latest BMW 3-series convertible.
These lights use a neon-plasma light source. The red
lens allows red visible light to pass, and also invisible
energy near infrared. The source is powered by a pulsating
voltage on a frequency that happens to be similar to the
repetition rate of legitimate laser-gun pulse trains. In
other words, the CHMSLs have an invisible energy leakage
that’s nearly identical to the beam used by traffic laser.
If we suppress the interference, we’re likely to damage
laser sensitivity.
Another source of alarms: a few new cars have cruise controls that
use laser to measure distance to the car ahead. This feature is
available on the Lexus LS430, Infiniti FX35, FX45, and QX56. This, of
course, is real laser, not a false alarm.
If you’re really bothered by these alarms, you can reprogram V1
to disable its laser reception. It’s a DIY project. Here’s a link to
the instructions on our website: http://www.valentine1.com/lab/mikeslabrpt3.asp
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