Abstract: A method for system acquisition for a subscriber unit (112) in a satellite communication system (100) maximizes life of a battery (320) of a battery-powered subscriber unit. A receiver (304) of the subscriber unit is energized only when ring bursts are expected from satellites in the system, serving to minimize consumption of battery power. During just two scans, the subscriber unit acquires enough information to enable it to identify the best beam for monitoring for a ring alert and to predict the nearby beams most likely to carry a ring alert targeted for the subscriber unit. From the received information, the subscriber unit can also perform necessary processes such as passive geolocation. The subscriber unit then enters a low-power standby mode, energizing the receiver only long enough to detect the best beam to scan for a ring alert targeted for the subscriber unit.

Abstract: An antenna array system combines the antenna signals from separate antennas using at least one delay in the RF path of an antenna. In certain embodiments, the antenna array system combines the antenna signals in the Radio Frequency (RF) domain before analog-to-digital (A/D) conversion, thereby reducing the amount of hardware required when compared to antenna array systems where the antenna signals are combined digitally. In doing so, signals from antennas are combined with signals from a plurality of antennas to determine if they improve signal quality. Only signals determined to improve signal quality are maintained as active. In accordance with other aspects, the antenna system selects parameter settings for the antenna array to provide enhanced performance.

Abstract: Systems and methods for improved use of idle power of each satellite repeater/transponder during low-traffic periods improve the overall link performance in multi-carrier, demand-assigned satellite communication systems through dynamic control and allocation of additional power to all signal carriers passing through each repeater when the total traffic load in the repeater is below a threshold. For satellite systems already in operation, the invention can be implemented and integrated into the existing feeder earth stations. For new systems, the invention can be implemented and integrated into the transmit section of individual satellite repeaters/transponders. The invention can be applied to new satellite systems to directly reduce the required satellite payload power for a given mission, thus substantially lowering the cost of the space segment.

Abstract: A combining technique for coherently combining signals transmitted from a moving satellite that are received by separate antennas. The combining technique corrects for differential delays that are large enough to cause misalignments in the symbols of the communication signal as well as the phase of the signal. Further the combining technique tracks changes in the differential delay, keeping the phase and the symbols properly aligned for combining.

Abstract: The present invention provides a method for custom coding uplink signals and downlink beams in a satellite communications system. The method includes the step of applying, at a ground station (100), an outer code (102) to an uplink signal to produce an outer coded uplink signal. Next, the ground station (100) applies a selected reduced complexity inner code (104) to the outer coded uplink signal to produce a concatenated coded uplink signal. The ground station (100) transmits the concatenated coded uplink signal to a satellite (110). At the satellite (110), the inner code of the concatenated coded uplink signal is decoded (116) to produce an outer coded satellite data stream. Next, the satellite (110) applies a selected inner code (120) to a portion of the outer coded satellite data stream to produce a concatenated coded satellite data stream. The satellite (110) then transmits the concatenated coded satellite data stream in a downlink beam to a destination ground station (126).

Abstract: The satellite communications system of this invention provides high-gain coverage to a wide geographic area with a minimum number of satellites. The satellites each include a high-gain antenna that periodically sweeps the satellite's service area to receive the messages from remote terminal units within the entire service area. In order to provide high gain, the antenna is designed to have a narrow beamwidth in at least one dimension. To cover the entire area, the antenna's field of view is swept across the entire service area. In the preferred embodiment, the antenna's field of view is essentially rectilinear, having a narrow beamwidth in one dimension and a beamwidth that extends across the entire service area in the other dimension, such that the sweeping effect is akin to that of a common push-broom. Because of the high gain of the satellite antenna, communications via the satellite can be accomplished using a low-gain wide-beamwidth antenna at the remote terminal unit.

Abstract: A method and system for combining signals in a receiver employing antenna diversity. If the interference exceeds a predetermined threshold, interference rejection combining (IRC) is used. If the interference does not exceed the predetermined threshold, maximum ratio combining (MRC) is used. The diversity combining technique can be selected, and the signals combined every burst, half-burst, or other suitable interval.

Abstract: The present invention provides methods of analyzing a radio signal, including a personal handy-phone system radio signal. In accordance with a first aspect of the present invention, a method of analyzing a radio signal in a transceiver selectively coupled with a first antenna and a second antenna comprises: receiving a radio signal comprising a plurality of slots via the first antenna; first configuring the transceiver to receive via the first antenna; during the receiving of a selected slot, first determining a radio signal characteristic; following the first determining and during the receiving of the selected slot, second configuring the transceiver to receive via the second antenna; and following the second configuring and during the receiving of the selected slot, second determining a radio signal characteristic.

Abstract: A cordless telephone is arranged for operation in a frequency hopping system includes an arrangement which achieves optimum utilization of multiple cordless telephone portable units by permitting these units to simultaneously access a common base unit. A physical layer of an air interface is provided by a two channel time division multiple access protocol for supporting a two channel multiple access system for the portable units. These two channels are considered as virtual channels and not dedicated to any particular telephone line, as in the case of two line telephone products. Nor are these two channels dedicated to any particular portable unit, but rather they are available for use by any portable unit in the telephone. A signaling layer of the air interface is provided for supporting the two channel multiple access system. Two types of subframes, acquisition and traffic, are illustratively provided in the air interface for the cordless telephone.

Abstract: The prior art teachings for encoding signals and transmitting them over a plurality of antennas are advanced by disclosing a method for encoding for any number of transmitting antennas. Also disclosed is a generalized approach for maximum likelihood decoding where a decision rule is formed for all of the transmitting antennas of a transmitter, and a decision is made in favor of the transmitted symbols the minimize the equation ##EQU1## r.sub.t.sup.j is the signal received at time interval t, at receiving antenna j,h*.sub..epsilon..sbsb.t.sub.(i)j is the complex conjugate of the channel transfer function between the transmitter antenna that is transmitting symbol c.sub.i and receiving antenna j, and.delta..sub.t (i) is the sign of symbol c.sub.i in time interval t.

Abstract: A receiver and antenna selection system located at a base station preferably comprises a plurality of radio units, each connected to its own antenna. Each radio unit receives a radio message and independently derives quality metrics based on the reception quality of the radio message, as indicated, for example, by a received signal strength indication, cyclic redundancy check result, preamble correlation magnitude, and other factors. Each radio unit transfers the quality metrics as serial data to an antenna selector. The antenna selector, simultaneously for each radio unit, converts and formats the serial data into individual data words and/or bits corresponding to the quality metrics, then applies the data words and/or bits to an antenna scoring block for determining an antenna score for each antenna. A comparison block compares the antenna scores and selects the best antenna for reception and/or transmission.

Abstract: A method (400, FIG. 4) for beam management in a satellite communication system (10) which simplifies cell-to-cell hand-offs within a footprint (90) of a satellite (20) and between two or more satellites (20) is disclosed. The method includes the steps of providing multiple beam stripes (130, FIG. 2) extending across the footprint (90) in a direction corresponding to the direction of flight (60) of the satellite, grouping the beam stripes (130) into one or more beam groups (150, FIG. 3), and selectively associating hardware groups (300) comprised of hardware resources to support beam groups (150). Method (400) also can include steps (450-470) for determining and compensating for undesirable system effects arising as a result of the relative motion of the Earth (50, FIG. 1) with respect to satellites (20) of system (10). A satellite (20, FIGS. 10 and 11) designed and configured to execute method (400) also is disclosed.

Abstract: In a global satellite communication system (10) that provides antenna beams that move with respect to Earth's surface, gateways (22) send ring alerts directed to subscriber units (26) based on a list of antenna beams. The list of antenna beams is determined by a dot product between a subscriber unit's basis vector and antenna beam vectors. Ring alerts are transmitted in antenna beams when the dot product exceeds a predetermined threshold. Subscriber units listen for ring alerts in the same antenna beams of the list by calculating the list the same way the gateway calculates the list.

Abstract: An information or broadcast receiving system and a control method therefor are provided for preventing a switch noise generated during the switching of antennas of a receiver provided with a plurality of switchable antennas from deteriorating a receptive state of an other receiver. When a detector 62 of a main controller 3 detects that a radio 1 is receiving an AM broadcast, a signal output device 63 causes an FM multiplex receiver 2 to stop the switching of a main antenna 31 and an auxiliary antenna 32 by a diversity circuit 33 and to select the main antenna 31.

Abstract: The object of the invention is a method and a circuit arrangement for the processing of a signal in connection with its reception, when the signal conforms to one or more system specifications. The invention is preferably applied in receivers operating on two frequency ranges or in receivers intended to be used in two radio communication systems. Preferably the receiver is a part of a mobile station or a base station of a cellular system. An inventive idea is that before the analog-to-digital converter (324) the intermediate frequency signal (IF1, IF2) is processed on a wide band (310, 320) so that both the narrow band signal and the broadband signal are on the pass-band of the signal line. Then, when a narrow band signal is received, the signal also contains signals outside the band of the payload signal.

Abstract: A radio apparatus includes a plurality of receiving systems connected to multiple antennas providing diversity, respectively, each receiving system including an antenna terminator and a preamplifier. After one receiving system is discriminated from another receiving system based on radio signals received by the receiving systems, respectively, a controller controls the one receiving system such that an antenna terminator is inactive and a preamplifier is active and, at the same time, further controls the other receiving system such that an antenna terminator is active and a preamplifier is inactive.

Abstract: A satellite-based communications system operating at high data rates includes a plurality of satellites each having uplink and downlink antennas for transmitting and receiving a plurality of signals utilizing a plurality of spot beams to and from a plurality of coverage areas at a predetermined range of frequencies. The system also includes a plurality of user terminals for transmitting and receiving signals to and from the plurality of communications satellites at the predetermined range of frequencies and at one of the first plurality of data rates. Each of the user terminals having a steerable antenna for tracking relative movement of each of the user terminals with respect to each of the plurality of communications satellites and for tracking movement of each of the plurality of communications satellites in order to maintain communications with the plurality of communications satellites.

Abstract: A repeater system includes a plurality of repeaters, a low level combining circuit, and a tower unit for attachment to an antenna tower. The tower unit includes a linear amplifier, duplexer, filter, and low noise amplifier. The repeaters do not have final amplifiers. Instead, the low level combining circuit couples the signals from each repeater to the tower unit. The output from the linear amplifier in the tower unit is coupled to an antenna over a relatively short cable.

Abstract: Methods of and corresponding apparatus for scheduling messages on an operating channel (223) in a selective messaging system (200) for a messaging unit (235) include scheduling a first message, including a channel priority indication (511), addressed to the selective messaging unit on a first channel, and then scheduling a second message for the selective messaging unit on a second channel (225) selected as an alternative operating channel. Analogously at the selective messaging unit a method of selecting an operating channel includes monitoring the first channel for a message addressed to the selective messaging unit; detecting as part of the message the indication; and responsive thereto discontinuing monitoring the first channel and then scan for the second channel.

Abstract: A system and method for selecting and combining satellite communication signals from multiple antennas. The system includes at least two signal paths, each coupled to a separate antenna, and a combiner for combining signals from the two paths for processing by a signal processor. At least one of the two paths includes a signal delay unit. The signal processor can distinguish a signal received from a source on one of the antennas from that signal received from the source on the other antenna based on a signal delay produced by the signal delay unit. Each signal path includes a variable attenuator for selectively coupling each signal path to the signal processor. The signal processor determines the quality of the signals received along the signal paths, and provides data regarding signal quality to a control processor, which manipulates the attenuators to couple the signal path having the highest quality signal to the signal processor.

Abstract: A digital receiver (200) and transmitter (300), wherein the digital receiver includes a plurality of antennas (202) for receiving uplink radio frequency signals; a plurality of analog to digital converters (210) for converting the received radio frequency signals into digital signals; a switched digital down converter (214) for down converting one of the digital signals to a baseband IF signal; and a channel processor (228) for recovering one of a plurality of communication channels contained within the baseband IF signal.

Abstract: A satellite communications system includes hub satellite which are equipped to communicate with at least three other satellites. The hub satellites include crosslink interfaces for each of the other satellites with which it may communicate and a switching system for routing those communications between interfaces. A system of a given number of satellites may include several hubs and may be configured in a way which permits any satellite within the system to communicate with a hub either directly or after transiting one or more intervening satellites. Systems which include fewer hubs may require communication with more than one intervening satellite before a hub is reached.

Abstract: A wireless base station has a transmitter and receiver. Transmission signals are applied to an antenna through a transmit bandpass filter that is tuned for a transmit band of frequencies. Received signals from the antenna are applied to the receiver through a receive bandpass filter that is tuned for a receive band of frequencies. An RF switching array consisting of four RF switches interconnects the output of the transmitter and the input of the receiver such that normal, loopback (self-test), and scanning modes can be performed. In the normal mode, the antenna is connected to the transmitter and receiver through the transmit and receive bandpass filters, respectively. The transmit and signal paths are effectively isolated from each other by three serially-connected open switches. In the loopback mode, the transmitter output is connected to the receiver input. In the scanning mode, the antenna is connected to the receiver through the transmit bandpass filter.

Abstract: In a code division switch in a satellite communication system each of a plurality of uplink CDMA modulated RF beams, each including a plurality of uplink traffic channels, are down converted to IF and overspread with a new orthogonal code having a spreading rate N times that of the spreading code of the uplink CDMA modulated RF beam. All of the overspread beams are combined into a single combined IF stream. The individual traffic channels are extracted from the combined IF stream by de-overspreading the stream with orthogonal codes and despreading with beam and traffic channel specific orthogonal codes. All traffic channels are respread with downlink beam codes and downlink orthogonal traffic channel codes and joined onto selected ones of downlink CDMA modulated IF beams having common destinations with the included traffic channels. Downlink CDMA modulated IF beams are up converted to RF frequency and transmitted to selected destinations.

Abstract: Each of the communications satellites going around the earth is equipped with a plurality of transmitters and receivers including receiving antennas in order to be able to transmit and receive signals in a plurality of directions, and a transmitter and a receiver in order to be able to transmit and receive signals between the closest terrestrial communications equipment. Each communications satellite is equipped with a cross-connect equipment, and has a function of transmitting signals that are received from each of the receivers toward other directions by utilizing the cross-connect equipment. The communications satellites and the terrestrial communications equipment have respectively a function of transmitting and receiving signals consisting of communications frames having at their head address signals that indicate to which terrestrial communications equipment of the transmission destination they are intended for every time slot.

Abstract: A system for selecting an antenna from a diversity of antennas in a DECT, PWT, or TDMA-based telecommunication system is disclosed. The system combines multiple criteria to improve antenna diversity selections. The principal selection process is based on preamble diversity comparisons that operate in real-time. A preamble diversity switching circuit measures receive signal strength indicators (RSSI) from a plurality of antennas and selects the antenna that provides the highest RSSI value when the difference between the RSSI values exceeds a predetermined threshold. When the value of the RSSI difference falls below the predetermined threshold, a cyclical redundancy check process (CRC) and a vector detection process (SVD) are employed jointly. The CRC process decodes a CRC value from a signal's content and compares it to a predetermined threshold. If a CRC error is detected a first weighted function is calculated.

Abstract: A dual mode cellular radiotelephone subscriber unit (802) comprises a diversity receiver (812) and a controller (814). The diversity receiver (812) receives either a first radio frequency (RF) signal (808) modulated by a digital modulation method (805) or a second RF signal (810) modulated by an analog modulation method (807). In one embodiment, the controller (814) controls the diversity receiver (812) responsive to a first diversity algorithm (834) when the diversity receiver (812) receives the first RF signal (808) modulated by the digital modulation method (805), and responsive to a second diversity algorithm (836) when the diversity receiver (812) receives the second RF signal (810) modulated by the analog modulation method (836).

Abstract: A reconfigurable zonal beam forming system for an antenna on a satellite in orbit includes, in cascade, a signal splitter applying signals of equal amplitude to each channel, first variable phase-shifters and amplifiers and a Butler matrix the outputs of which are connected via second variable phase-shifters to the radiating source elements of the antenna. Varying the phase-shifts introduced by the first and second phase-shifters reconfigures the transmitted beam optimally. A preferred variant of the system further includes variable attenuators. A control device is used to apply optimization parameters. A method of optimizing the resulting configuration uses a gradient search algorithm.

Abstract: Dual program audio apparatus is provided having two or more sources of input audio program signals, switching circuitry for selecting two of the input audio signals for amplification, one or more amplifiers for amplifying the selected input audio program signals, and one or more audio speakers for enabling a listener to hear both audio programs simultaneously. Volume control circuitry is provided for selecting a higher volume level for a foreground program and a relatively lower volume for a background program and circuitry is provided for selectively interchanging the foreground and background programs either instantaneously or gradually and continuously.

Abstract: A satellite-based, world-wide cellular messaging system (5) transmits paging messages to pagers (2) via multiple beams. A pager (2) monitors multiple beams, recording the schedules for each beam, and by combining the schedules for multiple beams, ultimately determines which frames in the message groups to monitor for messages. Pager (2), which conserves battery resources by entering into a sleep mode, synchronizes quickly to its message block when it awakes.

Abstract: A diversity reception device which weights in proportion to the reception level and combines a plurality of reception signals, includes a phase demodulator for demodulating the phase of the reception signal, a converter to output the sine and cosine elements of the reception signal, a sine element adder to add up sine element of each reception signal, and a cosine element adder to add up cosine element of each reception signal. The converter fetches and outputs predetermined values on sine and cosine elements of the reception signal upon input of the reception signal's reception level and phase data that is sent from phase demodulator. Therefore, the present device does not require expensive electronic circuits and can be made of small digital circuits suitable for IC including a memory.

Abstract: Each of the communications satellites going around the earth is equipped with a plurality of transmitters and receivers including receiving antennas in order to be able to transmit and receive signals in a plurality of directions, and a transmitter and a receiver in order to be able to transmit and receive signals between the closest terrestrial communications equipment. Each communications satellite is equipped with a cross-connect equipment, and has a function of transmitting signals that are received from each of the receivers toward other directions by utilizing the cross-connect equipment. Moreover, the communications satellites and the terrestrial communications equipment have respectively a function of transmitting and receiving signals consisting of communications frames having at their head address signals that indicate to which terrestrial communications equipment of the transmission destination they are intended for every time slot.

Abstract: A satellite-based cellular telecommunications system employing a constellation of telecommunications satellites in medium earth orbit to provide multibeam radio frequency (rf) communications links for worldwide cellular telephone service with a minimum number of satellites. The telecommunications satellites are placed in a plurality of inclined orbits about the earth at an altitude of between approximately 5600 and 10,000 nautical miles. The characteristics of the orbits, such as the number of orbits, the inclination of each orbit, the number of satellites in each orbit and the altitude of the satellites, are tailored to maximize the coverage area of the satellites and their related line-of-sight elevation angles, while minimizing propagation time delays, the number of beam-to-beam and satellite-to-satellites handovers, and the total number of satellites.

Abstract: A method and apparatus for utilizing satellite update information are disclosed. In the preferred embodiment satellite update information, comprising satellite position, polarity, name, and abbreviation, are accumulated at a first location and transmitted via satellite to at least one of a plurality of satellite receivers. The satellite receiver is operable to receive and automatically utilize the satellite update information such that the end user of the satellite receiver in unaware of the automated process of updating satellite information in the satellite receiver. The satellite receiver uses a portion of the satellite update information to calculate a pulse count for positioning an antenna to receive radio signals from a satellite for which satellite update information has been received.

Abstract: Apparatus, and an associated method, for a multi-branch receiver. A receive signal is received at various receiver branches of the multi-branch receiver. Subsequent to selected processing stages of processing of the receive signal, determinations are made of the signal quality of the signal in the receiver branches. When determinations are made that the signal quality of the signal of a particular receiver branch is of poor quality, further processing of the signal in the branch is squelched.

Abstract: The present invention provides a system for simulcasting and diversely receiving radio frequency (RF) signals. The system of the present invention comprises at least one RF transceiver and a plurality of RF units each including a transmitter for simulcasting an RF signal to a user and further including one receiver which is paired with another receiver in another one of the RF units, the pair of receivers providing for diversity reception of an RF signal from the user. The implementation of diversity reception with only one instead of two receivers in each RF unit, as taught by the present invention, reduces both signal loss and required cabling in the system.

Abstract: An antenna system for a communication device which receives and/or transmits packets of data having a characteristic reception interval comprises first and second antennas which are spatially diverse. A feed circuit is coupled to the first and second antennas to connect the first and second antennas to the communication device. The feed circuit includes a switching circuit and an oscillating switch driver which periodically select the first antenna and the second antenna, with a period which is normally substantially greater than the characteristic reception interval for the communication system. For example, if the period of the switching circuit is about one hundred milliseconds, and the data packet length is only 1.22 milliseconds as in the case of Ethernet, then many packets can be transmitted during each antenna configuration state. If both states are such that neither antenna is in a multipath null then no packets are dropped.

Abstract: A multi-channel digital transceiver (400) receives uplink radio frequency signals and converts these signals to digital intermediate frequency signals. Digital signal processing, including a digital converter module (426), is employed to select digital intermediate frequency signals received at a plurality of antennas (412) and to convert these signals to baseband signals. The baseband signals are processed to recover a communication channel therefrom. Downlink baseband signals are also processed and digital signal processing within the digital converter module (426) up converters and modulates the downlink baseband signals to digital intermediate frequency signals. The digital intermediate frequency signals are converted to analog radio frequency signals, amplified and radiated from transmit antennas (420).

Abstract: In a mobile satellite system, a mobile communication system includes a user interface system, an antenna system, a transceiver system, a logic and signaling system. The logic and signaling system provides a roam function permitting the mobile communication system to roam between the mobile satellite system and a terrestrial based communication system responsive to the user selection of a primary service and an alternate service. The mobile communication system also includes a digital terminal equipment unit initiating setup and release for a data call, and a facsimile interface unit initiating setup and release for a facsimile call. The facsimile interface unit generates a line control packet responsive to a line state transition indicating transmission of information associated with a new line state over a communication channel.

Abstract: A diversity receiver system includes reception circuits connected to antennas for converting frequency of a received signal to a base band signal; a diversity branch comparison circuit for directing a base band signal to be used by comparing an intermediate frequency supplied through the reception circuit; a base band delay detection circuit for outputting a detection signal which is generated by a delay detection of the base band signal directed by the diversity branch comparison circuit; and a DPLL circuit for generating an internal clock by using the detection signal supplied from the base band delay detection circuit, thereby securing a stable reception and providing a diversity receiver system having a small circuit scale.

Abstract: In an improved diversity repeater (200), a plurality of frame sets (213) corresponding to a message are received by a time stamper (202) such that frames within each frame set are time stamped. An arrival time differentiator (204) determines arrival time differentials (217) for each frame set based on time stamps. An averager (206) averages the arrival time differentials together. The resulting averaged arrival time differentials (219) are used by a voting window determiner to determine a new voting window (221). The new voting window is used to perform voting on frame sets corresponding to a subsequent message.

Abstract: A satellite communication network (10) coordinates multiple steerable satellite beams (28) with user requests for connections requiring varying bandwidth in real-time. A control station (22) gathers user requests for connections (64) and transmits those requests (70) to a satellite (20) over an uplink (70). Requests for bandwidth (72) are processed in the satellite (20) where time slot assignments (74) and steerable beam schedules (84) are determined in response to user requests (74). Steerable beam schedule (84) and time slot assignments (74) are transmitted to subscriber units (24) and control station (22) over a broadcast downlink (86). Subscriber units (24) complete a data transfer interval of a call (62) while a steerable beam schedule (84) is executed in real-time.

Abstract: A selective diversity apparatus in which a predetection diversity system is used and branches can be switched without generating a signal error, etc., even at the time the reception of a communication physical slot having a short preamble signal zone, and a control method thereof. When a control physical slot is received in which a preamble signal zone contained in a burst received is sufficiently longer than the time necessary for selecting and switching the branches, judgment and switching of the branches are executed in the preamble signal zone, and when a communication physical slot not having a sufficient time is received, judgement of the branches is made during reception of the burst and switching of the branches is made in a guard time immediately before the burst after one frame.

Abstract: A method for use by a voter in a communication system includes the steps of receiving (201) a frame of information, wherein the received frame has a frame number. It is determined if a reference frame for the frame number exists (203). If a reference frame for the frame number does not exist, the received frame is set (205) as a current reference frame for the frame number and an output criterion is set (207) for the frame number. When the output criterion for the frame number is satisfied, the current reference frame is output (211) as the output frame for the frame number. If a reference frame for the frame number exists, the frame is voted (209) against the reference frame for the frame number, yielding the current reference frame.

Abstract: A tuner is used in common for both terrestrial and satellite television reception. A second mixing stage is switched as a mixer for signal conversion into a second intermediate frequency during terrestrial television reception and is switched as a component of a FM-PLL demodulator during satellite television reception. The tuner is particularly suitable for television receivers and video recorders which receive signals from both a terrestrial antenna/signal source and from a satellite antenna/signal source.

Abstract: A system and method communicate signals between a portable unit and a communications system. The portable device communicates with a base unit using inductive coupling. The base unit is further connected to a wider communication system such as a telephone network. Multiple, orthogonally arranged transducers are used in the base unit to provide a more complete magnetic field and to prevent mutual inductance nulls which are otherwise present in a magnetic field. The use of short-range inductive coupling minimizes the power requirements and limits interference with other sources. The inductive coupling may also be used to recharge a battery in the portable device.

Abstract: A receiver (156) includes both a coherent and noncoherent demodulator. When the confidence that estimates of the channel is high, the coherent demodulator is implemented. When the confidence that estimates of the channel is low, the noncoherent demodulator is implemented. A controlling microprocessor (162) controls the selection process and also provides a signal (158) to enable the noncoherent demodulator in instances when noncoherent demodulation would most likely be better than coherent demodulation. As an example, such an instance would be immediately after handoff of a mobile station (505) from a source base-station (503) to a target base-station (502).

Abstract: An apparatus and method for use in receiving radio frequency (RF) signals having varied frequency bands from a n-sector base station antenna, and converting the RF signals to intermediate frequency (IF) signals for allocation to all available receiver radio channels. By employing a combiner and power splitter/divider, the IF signals from the converters in each sector of the receiver can be accessed by every receiver radio channel. Accordingly, remote communications users placing calls in high traffic sectors will have access to all available radio communications channels.

Abstract: The invention concerns a method and a system for transmitting radio signals between a fixed terrestrial station and mobile user terminals via a network of satellites in inclined circular orbits having a radius less than that of geostationary orbits. The beams generated are divided into pencil beams each associated with a continuous sub-band of frequencies in increasing frequency or decreasing frequency order. The instantaneous transmission frequency is offset progressively during the call towards the frequency subband of the adjacent pencil beam, at a rate proportional to the orbital rotation speed, to enable switching between pencil beams or between satellites. Applications include transmission via satellites in non-geostationary orbit.

Abstract: A diversity reception device which weights in proportion to the reception level and combines a plurality of reception signals, includes a phase demodulator for demodulating the phase of the reception signal, a converter to output the sine and cosine elements of the reception signal, a sine element adder to add up sine element of each reception signal, and a cosine element adder to add up cosine element of each reception signal. The converter fetches and outputs predetermined values on sine and cosine elements of the reception signal upon input of the reception signal's reception level and phase data that is sent from phase demodulator. Therefore, the present device does not require expensive electronic circuits and can be made of small digital circuits suitable for IC including a memory.