rank wrote:Where do you see that inference?
When I read that quote about VIP, I just understand it to mean that the unit is using the signal from patrol vehicle computer (via vip/vss cable) to compare against the patrol vehicle speed that is being generated by the radar. The radar is receiving multiple signals back and has to determine which one is patrol vehicle speed and which one is target vehicle speed and which ones are neither. When it is not sure about which radar signal is patrol vehicle speed (due to shadowing), it compares it to the patrol vehicle speed from computer and then says "this one matches so it must be the correct patrol vehicle speed" which eliminates the shadowing error.
And after reading argyll, decatur and nanuk comments, I believe that is what they are saying as well.
Of course it could also mean that it actually uses ONLY the patrol vehicle speed from computer when it gets confused and detects the shadowing error. However without putting an engineer from the manufacture on the stand, I don't think we would ever know for sure.
But regardless of how/when it uses the computer speed, there still needs to be a visual check of the speedometer with the patrol vehicle speed displayed on radar during the test, which in my opinion still makes it necessary to prove the accuracy of the speedometer with some external testing or the accuracy of the radar with external tuning forks. Just because they both match/agree does not of itself make them both accurate. It just means that they could be equally inaccurate.