Abstract: A method and apparatus for synchronizing a system clock with a serving cell (102) associated with a first radio access technology and monitoring an adjacent cell (104) associated with a second radio access technology is provided. A communication device (100) includes a first synchronization device (205) capable of synchronization with the serving cell (102) and a second synchronization device (206) capable of independently synchronizing with the adjacent cell (104). The first synchronization device (205) and second synchronization device (206) include independent frequency correction modules (207,208). Thus, the second frequency synchronization device (206) may be corrected per the adjacent cell (104) while the first synchronization device (205) remains synchronized with the serving cell (102). Thus, the same corrected system clock may be used between two radio access technologies.

Abstract: A multimode wireless communication device capable of communicating pursuant to first and second communication protocols, including a method wherein a determination is made (530) as to whether a harmonic generated during transmission in one protocol interferes with reception in another protocol, and wherein transmission is suspended while receiving only if a harmonic generated during transmission interferes with reception. In some embodiments, the transmitter is temporarily operated in compressed mode to enable the suspension.

Abstract: A Multiple Protocol Signal Detector, MPSD (320, 500) has a mixer (406) that receives signal energy from a multi-band antenna system (324) via a low noise amplifier (402) and from a variable frequency synthesizer (408) via a first variable band pass filter (410). The output of the mixer (406) passes through a second variable band pass filter (416) to an envelope detector (418) a power detector (419) and a low resolution A/D (420) that inputs digitized samples to a binary modulation detector, BMD (422). A controller (424) configures the aforementioned devices of the MPSD (320) to detect communications using different protocols based on a scan Look Up Table (426).

Abstract: A method in a transmitter for data collision avoidance in an uncoordinated frequency hopping communication system is disclosed. The base station (104) first determines (304) that a first data set to be sent to a first device (105) and a second data set to be sent to a second device (107) are scheduled to be transmitted simultaneously on a first frequency of a frequency hop-set. The device then transmits (310) the first data set on the first frequency of the frequency hop-set. The base station delays (312) transmission of the second data set, and finally transmits (316) the second data set on a second frequency of a frequency hop-set.

Abstract: A Multiple Protocol Signal Detector, MPSD (320, 500) has a mixer (406) that receives signal energy from a multi-band antenna system (324) via a low noise amplifier (402) and from a variable frequency synthesizer (408) via a first variable band pass filter (410). The output of the mixer (406) passes through a second variable band pass filter (416) to an envelope detector (418) a power detector (419) and a low resolution A/D (420) that inputs digitized samples to a binary modulation detector, BMD (422). A controller (424) configures the aforementioned devices of the MPSD (320) to detect communications using different protocols based on a scan Look Up Table (426).

Abstract: A method and apparatus for synchronizing a system clock with a serving cell (102) associated with a first radio access technology and monitoring an adjacent cell (104) associated with a second radio access technology is provided. A communication device (100) includes a first synchronization device (205) capable of synchronization with the serving cell (102) and a second synchronization device (206) capable of independently synchronizing with the adjacent cell (104). The first synchronization device (205) and second synchronization device (206) include independent frequency correction modules (207,208). Thus, the second frequency synchronization device (206) may be corrected per the adjacent cell (104) while the first synchronization device (205) remains synchronized with the serving cell (102). Thus, the same corrected system clock may be used between two radio access technologies.

Abstract: A satellite adapted antenna system has at least spaced apart first and second elements (104, 106), the first and second elements (104, 106) having substantially a common first polarization. A third element (108) has a second polarization that is opposite the first polarization of the first element (104). An antenna mode selector system selects between operatively connecting the first and second elements (104, 106) to form a specular antenna and operatively connecting the first and third elements (104, 108) to form a diversity antenna. Each of the first, second and third elements (104, 106, 108) are quadrifilar helix antennas. The first and second elements (104, 106) are quadrifilar helix antenna having right hand circuit polarization, and the third element (108) is a quadrifilar helix antenna having a left hand circuit polarization.

Abstract: A system for rapidly acquiring a time reference for the location determination of a wireless communication device. The system includes a wireless communication device (200), a GPS satellite (202) and a communication satellite (208). The method comprises the steps of acquiring a communication satellite signal (210) and using the finite frame time to establish a course time reference. Once the course time reference is established, an absolute device time is determined by the wireless communication device, which as a result is synchronized to the absolute time of the communication satellite (208) to within ten milliseconds. The absolute device time is then used to synchronize the GPS portion of the wireless communication device with the GPS satellite system.

Abstract: A satellite communication system (SCS)(100) and method (300) are provided that provide a geographically co-located user assignment system. For unit-to-unit communication, each group of subscriber units is instructed to operate in a half-duplex unit to unit mode. The geographically co-located user assignment system comprises an assignment unit (201), a storage unit (203), and an instruction unit (205) such that a first subscriber unit (204) initiates unit to unit communication with at least a second subscriber unit (206, . . . ) in the first subscriber unit's user group utilizing a multiple access channel assigned to that group by transmitting on an assigned satellite downlink frequency of the multiple-access channel on a push-to-talk basis.

Abstract: A satellite-based, world-wide cellular messaging system transmits paging messages to pagers. The messages are transmitted at unique times, on unique frequencies, and into uniquely identified cells according to a plan which is periodically revised and transmitted in advance to the pagers. Battery resources in the satellites and pagers are thereby conserved, and interference between transmissions to adjacent cells is minimized.

Abstract: A dual function antenna structure transceives in first and second modes. A first feed (120) feeds a primary antenna element (110) for operation in the first mode. A second feed (240) connects to the first feed (120). An upper choke (150) and a metal layer (160) are tuned to a wavelength of the radio frequency energy to be transceived in the second mode. The primary antenna element (110) and the metal layer (160) thus realize a secondary antenna element for operation in the second mode. In a portable radio, dual function operation is thus possible by a compact structure by the first and second feeds (120, 140).

Abstract: A satellite-based, world-wide cellular messaging system transmits paging messages to pagers. The messages are transmitted during a guard-band time-slot of a compatible world-wide cellular telephone system. In order to achieve better penetration, the satellites boost their transmit power for paging messages. One or more paging carrier frequencies may be used to accommodate differences in paging demand among different terrestrial cells.

Abstract: A dual function antenna structure transceives in first and second modes. A first feed (120) feeds a primary antenna element (110) for operation in the first mode. A second feed (140) couples via a coupling element (130) to a portion of the first feed (120) or the primary antenna element (110) to realize a secondary antenna element. In a portable radio, dual function operation is thus possible by a compact structure by the first and second feeds (120, 140).

Abstract: A satellite-based, world-wide cellular messaging system transmits paging messages to pagers via multiple beams. A message unit monitors multiple beams, recording the visit information for each beam, and ultimately determines the optimum beam to monitor for messages. The message unit, which conserves battery resources by entering into a sleep mode, synchronizes quickly to its message block when it awakes.

Abstract: An earth station transceiver (210) is provided for communicating with at least one satellite (110, 120) in orbit. The earth station transceiver (210) has an antenna with an array of antenna elements (220, 230) and steering circuitry (240) for steering an antenna pattern created by the array of antenna elements. A position of a beam (310-330) from a satellite can be represented by a beam number. The antenna pattern can be determined without taking signal quality measurements when the beam is at an extreme elevation angle as represented by the beam number. Signal quality measurements can alternatively be made during a time slot or frame to choose an antenna pattern instead of choosing an antenna pattern based on satellite beam number when the beam is not at an extreme elevation angle. Signal quality measurements using the same antenna pattern are made to perform an intra-site handoff. Signal quality measurements using all antenna patterns are made to perform an intersite handoff.

Abstract: A constellation of satellites distributed around the earth serves as a communication network that supports global communication of subscriber units. Subscriber units may potentially transmit from any location on earth. Some locations such as radio astronomy sites may be interfered with by nearby transmissions from subscriber units. Subscriber units located within a potentially interfering proximity to radio astronomy sites are prohibited from transmitting potentially interfering signals by reception of a non-interfering beacon at radio astronomy sites. The beacon repeatedly transmits a synchronous control signal with a subscriber unit's servicing satellite's control signal. The beacon's control signal is compatible with a subscriber unit's communication receiver. Control signal information contained in a beacon control signal inhibits the subscriber unit from transmitting.

Abstract: Symbol recovery for multi-level digital signals has traditionally been difficult because of the nature of the eye pattern output by the discriminator (103), and especially its response to a noisy or impeded signal environment. This method and apparatus for recovery thresholds adjusts (411 and 417) to the current state of the discriminator (103) output of the received signal, based on an attenuated (301) version of that signal. Using a fast adjust mode and slow adjust mode, the threshold generating circuitry (331 and 361) adapts to the signal based on data from the received signal fed into lock detectors (329 and 359) which determine the mode to 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: In a system where 2-level modulation and 4-level modulation of communication signals exist, an apparatus (107) demodulates either modulation scheme by demodulating (301) a received signal under the presumption that it is a 4-level signal, and if the received signal is detected (309) to be a 2-level signal, the signal is then demodulated (319) as a 2-level signal.

Abstract: A method of synchronizing a plurality of remote site transmitters (200) in a digital simulcast transmission system is described that enables use of four-level modulation on two-level modulation systems. A synchronization signal is transmitted at a predetermined data rate from a prime site, which signal might include a synchronization pattern having a first and a second portion. The first portion of the synchronization pattern is used for synchronization, while the second portion indicates the completion of the first portion. The method includes detecting (205, 320) of the first portion of the synchronization pattern. Each remote site transmitter (200) further has a modulation clock having a phase polarity which is selected (215, 324) in response to the detection of the first portion of the synchronization signal.