Not sure what the best subforum to post this question is, but I figured there were some people here who own radar guns and check them with tuning forks, etc.
I remember seeing a program a long time ago that supposedly let you check the accuracy of your radar gun by pointing it at a speaker. The program was just a tone generator, but the math had already been done to correlate the speed reading with the output frequency. I think it was for X-band only.
I have been searching for this for a while but can't find it. Does anyone remember this?