Abstract: A radiotelephone, used in a satellite radiotelephone system, has an antenna (12) with a hemispherical gain pattern (14). Since a satellite (18) can be anywhere in the sky the antenna gain pattern (14) needs to be aligned with the hemisphere above the user. This is accomplished with an antenna positioning apparatus, comprising the antenna (12) having a wedge shaped mating surface (42) affixed to an attaching surface (36) by a pin (38) and socket (44). The attaching surface (36) slopes downward from a plane (24) defined by a front face (26) of the radiotelephone (10). The combination of the wedge shaped mating surface (42) and the downward sloping attaching surface (36) positions the antenna (12) at an angle .phi. from the plane (24) when the antenna is in the active position. As a result the antenna (12) is vertically oriented when held by the user during normal use.

Abstract: The present invention includes a low-earth satellite-based paging broadcast system (100) and method (200, 300) that maximizes spectral efficiency and minimizes power expenditure for the broadcast of paging messages by broadcasting the messages to terminator- or originator-selectable portions of the total system coverage area. The terminator selects a long-term preferred geographic area (LTPGA), and optionally, a short-term preferred geographic area (STPGA). The originator provides the terminator ID, the message, and optionally provides a customized preferred geographic area (CPGA). Terminators and originators can easily modify the selectable geographic areas (SGA(s)): LTPGA(s), STPGA(s), and CPGA(s). The gateway converts the SGA(s) to addressable coverage areas (ACA(s)), and transmits a signal including the paging information, and ACA(s) to at least a first communication satellite (COM SAT).

Abstract: A digital encoding and decoding system suited for use in a mobile trunked dispatch communication system capable of error correction, error detection, and detection of loss of synchronization. The encoder comprises a cyclic block encoder, an autosynchronization sequence combiner, a convolutional encoder, and a bit interleaver to encode information to be transmitted. The decoder comprises a bit de-interleaver, a convolutional decoder, an autosynchronization sequence combiner, and a cyclical block decoder to recover the transmitted information and also indicates whether any errors are present in the recovered information.

Abstract: Apparatus and method for determining when a phase lock loop is in a state of lock is disclosed. The input frequency and the VCO frequency of a phase locked loop are combined by a difference multiplier to produce a signal having their difference frequency. The difference frequency signal is transformed into a squarewave by a limiter and the squarewave is then fed into a binary counter which counts the frequency of the squarewave pulses. Circuitry including a clock, two monostables, an AND gate, and a one cycle memory flip-flop periodically monitors the count of the binary counter and produces a signal indicating a state of unlock when the count of the binary counter exceeds a predetermined limit. An inhibit signal which prevents the binary counter from continuing to count is generated when the predetermined count limit has been reached in any one monitored time period.