[aprssig] APRS speed and Cosine Rule?

[Chris Hoffman]

Every Law Enforcement Department is different, but cosine compensation is
probably not as important as many other features available to law
enforcement these days, Bob:

https://www.lasertech.com/LaserSoft-SpeedCapture-App.aspx

Perhaps, one day, we'll be 'lucky' enough to have the
complete telemetry and video captured by the arresting officer's device
streamed by the patrol unit, through their central collection facility, to
our own smart phone and/or in-car smart AV device(s) in real-time. That
way, as our car's dashboard lights up to alert us that we have been caught
speeding, with a video of ourselves in the act and a small notice that a
fine has been posted to our vehicle registration number at the DMV should
we choose not to avail ourselves of the automated justice system to contest
the resulting ticket. the ID of which is also flashing in the video output
we can wave at ourselves... if only to gauge the amount of delay in the
stream.

/ch
N6QR

Oh... and always be ready to compare the vehicle's onboard sensor package
readings to that reported from the patrol unit's detectors, should we want
to suggest that one or the other be calibrated more closely as we pay the
fine.


On Mon, Jun 8, 2020 at 1:07 PM Robert Bruninga <bruninga at usna.edu> wrote:

> APRS speed related?
>
> Have cop radars implemented the Cosine rule?  IE, it should be possible to
> include a magnetic compass in a handheld radar gun and to initialize it in
> the direction perpendicular to the road with just a button push...
>
> Then the gun can display the actual speed using the cosine rule as the cop
> sweeps to keep up with your car, (or statically when the cop is at an
> angle to the line of approach) and not just the relative speed (which
> approaches zero) as the car goes past the perpendicular point.
>
> Curious as to whether I need to consider this when speeding past a
> radar...
>
> Bob, WB4APR
>
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