Speed/radar

Archiver

I have a need to measure speed. I thought about using the polaroid
sonar mudule (I have several of these that work) from the sonar
cameras as a 'radar". Have it measure the pulses and do some
math on the ping results. Any one else ever do this?
Main thing I need is some distance/time math to do on the stamp.

I could use some help on the circuitry, too, but I have the sonars
working to measure distance to the inch but need to know how to
use the differences to measure speed.

Thanks

Doug