It ain't that good...about as accurate (sometimes) as a recent Florida radar speeding case.
In this instance, the defendant questioned the accuracy of the radar 'gun' so...the judge adjurned the court to the courthouse front lawn, and upon further testing, an oak tree was 'clocked' at 83mph.
Case dismissed, forthwith.
I don't know how "recent" this was.....I first heard that story way back in high school, thirty some years ago.