Abstract: A digital switching system for switching messages between a plurality of subscribers located a relatively short distance from the switching system. The message format for the system comprises the serial transmission of messages of M bits of information which are transmitted from the switching system to the subscribers during one-half of a transmission frame and messages of M bits of information which are transmitted from the subscribers to the switching system during the other half of the transmission format. Addressable memory arrays are employed at the switching system for multiplexing and serial-to-parallel conversion and switching. In a preferred embodiment up to 40 telephone and/or data terminal messages are handled in 125 microsecond time frames with 8 bit voice and 8 bit data words plus a start and stop bit and 1 signalling bit message format from each of the subscribers.

Abstract: Apparatus for a monitoring and signalling system such as a home health care system includes a plurality of sensors operative to monitor the occurrence of activities performed by an individual in his or her residence and to produce binary coded signals indicative of the occurrence of the monitored activities. Each signal comprises six successive identical messages within a one-second interval, with each message including a binary word identifying the monitoring and signalling system, the particular sensor originating the signal, and the nature of the monitored activity. Each message further includes a preamble and a pair of interwords on opposite sides of the binary word.The apparatus in accordance with the invention includes a microprocessor which operates to repetitively sample each signal originating with a sensor to determine the binary content of the signal and to extract a binary word from a message while rejecting preambles, interwords and "glitches" (noise) present in the signal.

Abstract: Electrical power supply for use with apparatus which transmits a predetermined message. When an input signal is received, a source of electrical energy is connected to a power output terminal by turning a switching transistor on. A latching circuit holds the transistor on after termination of the input signal. Elements of the apparatus which are connected to the power output terminal to obtain operating power transmit the predetermined message when the electrical energy is supplied to the terminal. When the transmission is complete, the apparatus produces a termination signal to the latching circuit causing it to turn the switching transistor off and thus disconnect the source of electrical energy from the power output terminal.

Abstract: A control circuit for the current in a pair of coils, which are utilized for generating a rotating magnetic field, supplies a sinusoidal current to each coil during the normal, operate mode and a maximum DC current to the coils whenever the operate mode is initiated or stopped. Each coil is a common element in the sinusoidal and DC current supplying circuits. A transistor switch, which is open during the operate mode, is connected in series with the coil in the circuit for the DC current and is connected in parallel with the coil in the circuit for the sinusoidal current through the coil. Since the switch is open and is connected in series in the circuit for the DC current no DC current flows through the coil during the operate mode. Whenever the operate mode is initiated or stopped, the transistor switch is closed so that both the sinusoidal and DC currents flow through the switch.