Abstract: A sound enhancement system including a beamed linear array microphone system for the acoustic pickup of voice and music from substantial distances with a relatively narrow sound pickup beam and with the avoidance of acoustic feedback. The acceptance beam angle is relatively constant over the desired sound octaves. Response outside of the acceptance beam is relatively low. The system includes a microprocessor-controlled circuit for processing the signals from a multiplicity of microphone elements in the linear array for application to a loudspeaker.

Abstract: The present invention provides a combined ground and satellite system for global aircraft surveillance, navigation, landing guidance and collision avoidance which comprises a satellite subsystem consisting of both a satellite constellation and associated ground stations, and a ground subsystem consisting of a network of ground stations, together with an airborne subsystem comprised of a transponder unit located in each of the aircraft using the system. A high speed two-way data link is provided between each of the subsystems using spread spectrum technology to permit overlaying and operation of the system in an existing band of narrow channels with minimum mutual interference. The system of the invention is reliable because of the redundant subsystems, and is not subject to failure. Also, the system provides for computations to be made on the ground, rather than in the aircraft, thereby reducing the size and complexity of the airborne equipment.

Abstract: A system for viewing a lighted scene through a diffusive medium, such as rain, fog, snow, blowing dust, or sand, by overcoming the effects of light backscatter. The system uses a flash lamp which operates in response to short electric pulses at a high repetition rate to give the appearance of continuous illumination. The scene is viewed through a panel which operates as a high-speed optical shutter. The panel serves to block the reflected light (backscatter) from the nearby particles of the diffusive medium and passes the reflected light from the distant objects which make up the scene.

Abstract: An aircraft surveillance, navigation, landing, guidance and collision avoidance system is provided which takes the form of a two-way data communication link between each of a plurality of controlled aircraft and a ground station, and appropriate measuring equipment at the ground station which provides three-dimensional position data on the ground for air traffic control purposes; and which also provides three-dimensional position data in the aircraft for navigation, landing guidance and collision avoidance purposes, as well as a two-way air/ground data link for miscellaneous data and control purposes. The system of the invention comprises the combination of a ground transmitter/receiver station and airborne transponders mounted in the aircraft. The ground transmitter broadcasts discrete aircraft addressed interrogation pulses which are coded to contain position and/or other data.