Abstract: An ultrasonic transducer array for transmitting and receiving ultrasonic energy in multiple two-dimensional imaging planes. The ultrasonic energy in the imaging planes is focused in elevation by the curvature of the transducer array. An imaging plane is selected from a plurality of available imaging planes by electronic switching. Each imaging plane when selected is positioned at a known angle, different from all other imaging planes, due to the known curvature of the transducer array, and the known dimensions of the transducer elements.

Abstract: A network for enabling a local area telephone system to simultaneously carry digital data and analog voice signals on the same tansmission medium. Such a system typically includes a PBX and twisted wire pairs connected to distributed telephone handsets. The network incorporates distributed station units for coupling both voice band signals from telephone handsets and RF signals from data devices to the wire pairs. The station units are physically interconnected in a star configuration with respect to a hub module preferably located in a telephone closet. The hub module includes a plurality of hub units, each uniquely connected by a wire pair to one of the station units. Each station unit and each hub unit incorporates passive filter means to separate voice band and RF band signals. A token passing procedure is used to assign network control to the multiple station units in logical sequence.