Abstract: A method for determining the closing point of a pump piston relative to a transverse bore in a corresponding pump cylinder, the method including the steps of providing compressed air to the cylinder via the transverse bore, axially sliding the pump piston near the closing point, consecutively measuring two flow values through a throttle cross-section defined by the pump piston and transverse bore, measuring the positions of the piston corresponding to the two flow values and extrapolating the pump piston unto the closing point from the flow values and piston positions.

Abstract: Radiation is directed between moving vehicles, and the time between transmission and reception of waves, such as microwaves, is determined similarly to radar timing, to determine the spacing between the vehicles. To prevent spurious responses and ambiguities, the signal reflected from the leading vehicle to the trailing vehicle is modulated; modulation can be controlled either automatically, by providing a modulation control signal associated with a given lane of roadway or under driver-command.