Abstract: A handheld pop-up sprinkler riser-clamp for allowing sprinkler heads to be held in upright raised positions for maintenance work. A plastic block can have a side U-shaped cut-out with a continuous slot therebetween. A midportion of the U-shaped slot can have a widened opening that is greater in diameter than the rest of the U-shaped slot. The ends of the U-shaped cut-out can be held together with a screwable member. In operation the widened opening can be slipped over the raised head of the sprinkler head, and then the narrow portion of the clamp member is slid upon the exposed barrel neck of the sprinkler head and snapped into place so that the clamp holds and restricts the sprinkler head from moving back into its' base. The screwable fastener can adjust the width opening of the U-shaped slot as needed for different diameter necks.

Abstract: A radio frequency switch which has input and output diodes and a quarter length impedance inverter interconnecting the diodes. A switch drive signal is clamped to a predetermined voltage between drive signals so that the impedance with respect to the input source remains substantially constant during the entire switch operation.

Abstract: Movement of an object (intruder) in a specified area is sensed by transmitting microwave energy from an antenna (10) that also receives energy reflected from the intruder, where the received energy is quadrature processed using Doppler techniques. Connected to the antenna (10) is a transceiver (12) that includes a quadrature mixer (48) coupled to an RF oscillator (50) through an RF switch (52). The RF switch (52) is controlled by a switch driver (54) to provide pulse energy from the antenna (10). Doppler outputs E.sub.1 and E.sub.2 from transceiver (12) are processed in the same manner except for a 90-degree phase lead applied to the Doppler output E.sub.2 by a phase lead network (18). Doppler outputs E.sub.1 and E.sub.2 (E.sub.2 90-degree phase shifted) are applied simultaneously to a sum and signature processor (24) and to a difference and signature processor (22). The sum and signature processor provides the "approach" receiving signal and processes the signature to further reduce the nuisance alarm rates.

Abstract: A multi-function information system utilizing a specialized modular information library is disclosed. In its preferred embodiment, the system is applied to the problem of teaching technicians the theory of specific apparatus and providing a tool to aid in the location and correction of malfunctions of the apparatus. In such an application, the system may comprise a video playback system and a video-cassette library containing a description of how the apparatus operates and malfunction correction procedures. Special procedures are employed in constructing the library to assure that the teaching and malfunction correction times are minimized.