Abstract: The invention relates to a radio communication system and method for minimizing co-channel interference. The system comprises a plurality of mobile stations in communication with a ground based station via an orbiting satellite. The orbiting satellite transponds a combination of signals received from the mobile stations to the ground station in coherent fashion. At the ground station, the combined signals are processing using matrix models to separate the plurality of mobile station signals. The coefficients of the matrix are chosen to minimize interference between channels. Communication in the reciprocal direction proceeds in like manner. The system and methods are applicable to, for example, landmobile communication, satellite communications system and hybrids thereof. In the landmobile or satellite communication environment, the system may include directional antennas.

Abstract: A method and apparatus for determining with high resolution the fidelity of communications over a communications channel is disclosed. Portable/mobile radios freely roaming between multiple trunked RF communications sites calculate the fidelity of communications received over current and alternate channels with comprehensive, high bit error resolution using a weighted average error dispersion procedure. The weighted average error dispersion analysis generates for each group of redundant messages (and in some instances subpreamble bits) received by a roaming radio in each message frame a weighted average error dispersion number whose incrementally increasing magnitude reflects deteriorating signal fidelity. Decisions about switching to alternate communications channels are made by the roaming radio based on the incrementally changing weighted error dispersion number so that communication channels may be selected to achieve optimum signal fidelity and continuity of communication.

Abstract: A protocol for communicating over a network, for example a wireless network, is disclosed. Protocol data units for establishing and destroying a connection, data transmission and reception control, status and error are provided.

Abstract: Information symbols spread using orthogonal or bi-orthogonal codewords are assigned a unique scramble mask that is taken from a set of scramble masks having selected correlation properties. The set of scramble masks is selected such that the correlation between the modulo-2 sum of two scramble masks with any codeword is a constant magnitude, independent of the codeword and the individual masks being compared. In one embodiment, when any two masks are summed using modulo-2 arithmetic, the Walsh transformation of that sum results in a maximally flat Walsh spectrum. For cellular radio telephone systems using subtractive CDMA demodulation techniques, a two-tier ciphering system ensures security at the cellular system level by using a pseudorandomly generated code key to select one of the scramble masks common to all of the mobile stations in a particular cell.

Abstract: In a radiotelephone system, the control channel in all cells in an area can be simulcasted. A microcell base station may be provided with a receiver to listen on the umbrella cell control channel for messages, in addition to listening on its own control channel for control information and call accesses, to facilitate the appropriate assignment of a call to a cell. Also, a microcell can share a control channel with an umbrella cell provided interference between the control channels is not excessive. Further, microcells can share a common control channel independent of the overlying macrocell structure.

Abstract: A radio access method for facilitating communication between at least one first station and a plurality of second stations is disclosed. First, each signal intended for transmission is buffered at a first station. The signals are then divided into equal length segments. The signal segments intended for a particular one of the second stations is transmitted using a corresponding time slot in a regularly repeating time multiplex frame. The signal segments transmitted by the first station are received at at least one of the second stations and the signal segments are assembled from successive corresponding time slots to reconstruct said intended signal. A transmit frequency channel uniquely associated with the corresponding receive time slot is determined at the second station.

Abstract: A radio telephone which is capable of switching between operating through a land based cellular network and an orbiting satellite system is disclosed. First antenna and radio frequency circuits receive transmitted signals from the land-based network and form first conditioned signals for subsequent numerical decoding. Second antenna and radio frequency circuits receive transmitted signals from the orbiting satellite system and form second condition signals for subsequent numerical decoding. Numerical decoders process either the first condition signals or the second conditioned signals to provide an automatic frequency control signal. Reference frequency oscillators controlled by the automatic frequency control signal provide a reference frequency signal.

Abstract: A method and a device in a homodyne receiver including a local oscillator generating an oscillator signal at a frequency of f.sub.LO, a mixer, and a reception device for receiving an input signal having a frequency of f.sub.RF, the oscillator signal and the input signal being supplied to the mixer. The oscillator signal is supplied to a first processing unit to produce a first output signal having a frequency of M*f.sub.LO, where M is an integer value. The first output signal is supplied to a second processing unit to produce a second output signal having a frequency of M*f.sub.LO /N=f.sub.LO, where N is an integer number and M.noteq.N, and the mixer and the second processing unit are integrated to minimize leakage of signals being supplied to the mixer from the second processing unit.

Abstract: A quadrature modulator for generation of complex modulated signals includes a unique pair of balanced, low-pass filters which, through a switching arrangement for switching into and out of the circuit distributed RC line sections and corresponding ground resistances are able to redress problems associated with manufacturing tolerances.

Abstract: A radio transmitter output power controller which automatically restricts the maximum transmitting time during an averaging time so that the average power remains below an acceptable level. Additionally or alternatively, the maximum transmitter output power may be automatically reduced to a lower level if and when a predetermined average power level is approached. A warning signal may be generated to inform a user that the maximum permitted power output is being approached.

Abstract: A method of placing a calling account card telephone call on a call by call basis using one of a plurality of carrier networks is disclosed. The method includes the steps of storing a plurality of data sets in accordance with requirements for use of the carrier networks, detecting the initiation of each telephone call by recognizing a first predetermined sequence input by the user and detecting the initiation of each calling card call by recognizing a second predetermined sequence input by the user, the second predetermined sequence being different than the first predetermined sequence, retrieving one of the stored data sets responsive to the detected second predetermined sequence, and automatically initiating a telephone call in accordance with the retrieved stored data sets responsive to inputting of the second predetermined sequence. An apparatus for automatic execution of a telephone calling card call on a call by call basis using one of a plurality of carrier networks is also provided.

Abstract: A hinge configuration particularly suitable for use with a radiotelephone includes: an arcuate hinge body having a predetermined body length, a predetermined body thickness and a predetermined radius of curvature; and a pair of arms, a respective one of which is attached to and extends away from a respective end of the arcuate hinge body, the pair of arms each having predetermined arm lengths and predetermined arm thicknesses. The arms are pivotally mounted on a housing such that the arms twist upon pivotal movement of the arcuate hinge body relative to the housing. At least one of the predetermined body length, predetermined body thickness, predetermined radius of curvature, predetermined arm lengths and predetermined arm thicknesses should be selected to induce preferential deflection in the arcuate hinge body relative to the pair of arms upon twisting thereof during pivotal movement of the hinge body so that the arms resist fracture during such repeated pivotal movement.

Abstract: A digital communications receiver provides joint MLSE equalization and diversity combining. A plurality of diversity branches are processed to produce complex receive data samples and synchronization information. Channel estimators then form channel estimates from the data samples and synchronization information. The data samples and channel estimates are then used by pre-processors to produce metric multipliers. Finally, the metric multipliers are combined with hypothesized data sequences to generate and accumulate metrics using a sequence estimation algorithm to produce a demodulated data stream.

Abstract: An arrangement for duplex transmission in a radio or similar device with a transmitter and receiver comprises a transmitter filter, receiver filter and preferably a transmitter/receiver device. The receiver filter may be a surface acoustic wave filter, and the transmitter filter and receiver filter are connected via a circulator. The arrangement also comprises a power detecting device for detecting the power into the receiver filter, and the power detecting device provides a feed-back signal to an arrangement for controlling the power out from a power amplifier arranged in front of the transmitter filter.

Abstract: An extremely compact, full featured portable radio architecture conserves power by allowing a processor to sleep except when it needs to perform tasks. A lower power processor which acts principally as an interrupt controller but which performs other functions as well (e.g., tone decode, synthesizer lock monitoring, etc.) so the main processor can sleep as much as possible and yet is assured of being awoken promptly when its processing power is required. The resulting portable radio has extremely low power consumption (e.g., on the order of 75 milliamperes during trunked mode operation)--thereby permitting even a relatively small battery pack to provide nearly 8 hours of continuous operation. The portable radio with battery is small and lightweight enough to fit into a front shirt pocket.

Abstract: A method and system are provided for adaptively reducing noise in frames of digitized audio signals that may include both speech and background noise. Frames of digitized audio signals are processed to determine what attenuation (if any) should be applied to the current frame of digitized audio signals. Initially it is determined whether the current frame of digitized audio signals includes speech information, this determination being based upon an estimate of noise and on a speech threshold value. An attenuation value determined for the previous audio frame is modified based on this determination and applied to the current frame in order to minimize the background noise which thereby improves the quality of received speech. The attenuation applied to the audio frames is modified gradually on a frame-by-frame basis, each sample in a specific frame is attenuated using the value calculated for that frame.

Abstract: A system and method are disclosed for correlating rf communications in a multi-site, trunked rf communication system which includes a plurality of site controllers for controlling radio unit rf communications in corresponding geographical site areas and at least one multi-site coordinator for monitoring messages from each site controller and establishing and removing rf communication channels. Information from the multi-site coordinator including channel assignments and channel drops generated for each communication originated from or received by each radio unit is obtained from the multi-site coordinator. RF communication resources used by each radio unit are then correlated and used to generate bills detailing for each radio unit specific instances and types of rf communication resources used.

Abstract: A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions.

Abstract: Binary signals that are transmitted by Manchester coding and frequency modulation are demodulated based on the behavior of the phase or complex vector value of the received signal. The polarities of the information bits may be determined by measuring the phase excursions in the middles of the Manchester symbols. A phase reference is established from a plurality of candidate phase references as a basis for comparison of the mid-symbol phase. The phase can be measured at the start-points and end-points of the symbols and averaged, or measured a plurality of times during each symbol period to generate a reference phase.

Abstract: Digitally trunked radio transceivers are permitted to roam over an extended coverage area including two or more digitally trunked radio frequency communication networks. Each network includes at least one digital repeater site having a corresponding site coverage area and serving digitally trunked radio transceivers disposed within or near the site coverage area. Each network also includes a local multisite switch for routing communications between the digital repeater sites within the networks. Site adjacency information is established for each site and communicated between the networks. Each digitally trunked transceiver maintains a site adjacency list for its currently selected site and modifies that list when the transceiver roams into a new site coverage area and selects a new repeater site.