Abstract: A selective call receiver receives a signal having a baud rate and comprising a number of phases. The number of phases are time division multiplexed to form the signal. The selective call receiver has selective call address information assigned thereto and includes a receiver for receiving and demodulating the signal and a memory for storing predetermined information. A demultiplexer is coupled to the receiver and the memory for demultiplexing the signal to recover one of the number of phases in response to the predetermined information and the baud rate. The selective call receiver also includes a decoder coupled to the demultiplexing means for decoding said one of said number of phases of said signal to derive a selective call message therefrom.

Abstract: A signalling protocol comprising a plurality of interleaved phases is transmitted at various baud rates, the various baud rates being multiples of a base baud rate. The signalling protocol allows a selective call receiver to decode at an operating baud rate equivalent to the base baud rate irrespective of the transmission baud rate by decoding only a portion of the transmitted signal, the portion decoded determined by the baud rate and the address of the selective call receiver.

Abstract: A radio communication system with on/off premise registration is provided. When a radio is registered with the system, incoming calls for the radio are directed to the radio via the system. When the radio is registered as off the system information is transmitted to the radio as via a wide area system. A voice mailbox is provided for storing messages when the radio is unavailable.

Abstract: The pulse communication system includes a plurality of pulse repeaters 10 for receiving and transmitting pulse signals. Each of the pulse repeaters include a frequency controller 22 for selecting one of a sequence of transmit and receive frequencies. The frequency controller 22 causes the transmit and receive frequency to change after the reception of each pulse in order to receive and transmit the next pulse on another frequency.

Abstract: An improved synchronization system for use with simulcast transmission systems is described. The invention provides a method and means for keeping the information signals for adjacent transmitters in the system in synchronization. This invention utilizes a centrally located master transmitter and control unit and a plurality of secondary transmitters disposed in an annular fashion around the master transmitter. In operation, the innermost annular band is synchronized to the master transmitter, while the remainder of the system is disabled. The next adjacent annular band is then synchronized to the innermost annular ring. The process is repeated until every annular band in the system is synchronized.

Abstract: A radio frequency transceiver is provided in which the crystal resonator and monolithic crystal filter devices therein all operate at or near the operating frequency of the transceiver, and which employs a single piezoelectric element to achieve the functions of receiver signal filtering, transmitter signal filtering, receiver local oscillator signal generation, and transmitter local oscillator signal generation. To achieve these functions, a crystal resonator and a monolithic crystal filter are situated on the same substrate of piezoelectric material. The crystal resonator portion of the piezoelectric device is employed to control the frequency at which a local oscillator generates radio frequency energy. Such crystal controlled local oscillator is shared by a receiver mixer circuit and a transmitter mixer circuit. Switching circuitry is employed to switch the crystal filter portion of the piezoelectric device from the receiver signal path to the transmitter signal path.

Abstract: A semi-duplex communication system provides high channel efficiency by having the base station transmit a reference signal which each terminal uses as a sync signal. Each unit having data to send to the base responds with a very brief signal such as a burst of silent carrier transmission during an assigned time slot in a queue of slots. Only those units which responded thus are polled during the subsequent polling cycle. During the transmission time slots, the base can be sending acknowledgments to those terminal units having sent messages during the previous polling cycle. While polling for data or acknowledgments or sending acknowledgments, the base can also be listening for the respective responses. The address code of a terminal unit is further encoded to carry other required information in both directions.

Abstract: A pager or other selectively-addressed electronic device powered by a small power cell operates in four different modes and at two power levels, depending on signals received and a timing sequence. The device can stay active continuously, be activated at intervals or remain in a powered-down state. The address code assigned to a particular device would be transmitted at a predetermined time interval following a sync signal, thus the device can be powered-down until the approximate time period in which its address code could be transmitted. The system provides increased channel efficiency since information codes are superimposed on actual address codes, and there is no dead time in a channel while there are address codes waiting to be transmitted. The system is particularly well adapted to time multiplexing.