Abstract: There is provided a peristaltic pump which has a base member and a rotor attached to the base member. The rotor is adapted to receive a resilient collapsible tube. The pump further includes a stator having a fixed member disposed in a permanent position relative to the rotor. A door stator is connected to the fixed stator, and the entire stator will confront the periphery of the rotor over at least uninterrupted 180.degree. concave surface. A latch is provided on the door stator, so that it may pivot outward for ease of removal of the tubing.

Abstract: Distance is measured with a tone modulated AM radio system by making a signal at the ranging tone frequency phase coherent with respect to the modulation on the RF signal at the input to the receiver by means of a product detector located ahead of the receiver of the transponder. In this way, a ranging tone phase is established which is a direct and accurate measure of the modulation phase (delayed by the propagation time) and is independent of any modulation phase shifts experienced in the receiver.