I don't have much experience with a VIP cable I'm guessing this is specific to Genisis II Select . However Stalker uses a VSS cable which I am assuming is the same as a VIP which does the following : (directly from Stalker)
Moving traffic radar systems measure the patrol car's speed by tracking the radar return off the road surface in front of the patrol car (ground speed). Occasionally a radar can be "mislead" when the patrol car is following another vehicle that is moving at a speed that is substantially different from the patrol car's speed. When this happens, the radar will see the speed differential between the vehicles and pick that as the patrol car's speed. This is called "Shadowing."
The radar may get signals from many sources while a patrol car is moving; ground speed, closure speeds from oncoming vehicles, and relative speed differentials of multiple vehicles ahead of the patrol car. Sometimes the radar just needs a little help in picking which speed is the actual ground speed. With conventional radars it is up to the operator to make sure that the radar has made the correct decision on which signal is the ground speed. The Stalker DSR solves the problem by using the VSS signal to tell the radar which radar signal is the ground speed.
All modern vehicles have a VSS sensor (Vehicle Speed Sensor) attached to the transmission or an axle that generates a speed signal. This signal is used by the speedometer, cruise control, and some of the engine and transmission computers. By tapping into this electronic signal the Stalker DSR can monitor the patrol vehicle's speed as measured by the car's VSS sensor.
Once the VSS cable is wired and attached to the Stalker DSR, and the radar is operated in the moving mode, the DSR performs an "Auto-Calibration" sequence. This sequence matches the VSS signal to the radar ground speed. This patent pending automatic synchronization routine overcomes concerns that tire wear could impact accuracy and allows the radar to be effortlessly switched betweens vehicles.