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  1. #1
    Power User
    Join Date
    Aug 2005
    Southlake, TX

    Default LIDAR overpass shots... accurate???

    Well I was just thinking about a LJs effectiveness against overpass shots when I got to thinking

    1) How do the LEOs get a reading from an overpass (obviously by aiming at
    the key targeting points) in the first place


    2) If they can wouldnt it be subjected to a pretty significant cosine error as the angle increases (or is cosine error a RADAR only factor), but I do realize that cosine error ALWAYS favors you by showing a slower speed on the gun, but if inaccurate why would the LEOs use that tactic to start with

    I mayy just be thinking too far into this but i'd really appreciate it if one of you big technical expert type guys would shed some light (haha ) on this matter for me, ty

  2. #2
    Suf Daddy

    Default Cosine Error and LIDAR vs radar

    Todays your day Rashi:


    RE LIDAR from overpass.

    Cosine will show a slightly slower speed on the LIDAr or Radar gun.

    Cosine is a mathematics issue. It applies to all off axis speed measuring.

    Here's the ISSUE IMHO:

    ANY cosine error (angle from the side) allows the reflected light to bounce or return from ANY portion of the car.

    SINCE the LIDAR measures distances.........adding or subtracting to those measurement calculations to determine speed CAN INCREASE or decrease your speed.

    So to have the light be able to walk up the hood to the roof (or vice versa) and to sweep or pan the entire side of the vehicle isn't to the motorists benefit IMHO......................

    Police are trained that Cosine doesn't affect them too much in measuring speed. A concept that IS WRONG IMHO in LIDAR...........

    -Suf Daddy



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