Abstract: A system determines a voicing measure as a measure of the degree of signal periodicity and uses the determined voicing measure to quantize the spectral magnitude of the slowly evolving waveform (SEW) and the modeling of the SEW and rapidly evolving waveform (REW) phase spectra.

Abstract: A system and method of blind channel estimation to receive a signal burst over a communications channel; divide the signal burst into a prescribed number of groups of symbols; hypothesize all possible transmitted data sequences or each group; generate a corresponding channel estimate for each possible data sequence; determine an error measurement for each corresponding channel estimate; select a number of the corresponding channel estimates for each group from amongst the corresponding channel estimates, the number of the corresponding channel estimates being selected for having smaller error measurements than remaining corresponding channel estimates not selected; identifying a best channel estimate for each group from amongst the number of the corresponding channel estimates having been selected for each group; and reviewing the best channel estimate having been identified for each group and reidentifying best channel estimates for some of the groups so as to increase smoothness of a curve in two-dimensiona

Abstract: A requesting terminal includes an interface that allows a user to select whether data downloaded from a network (such as the Internet) is transmitted to the requesting terminal via a high-speed link, such as a satellite link, or a lower speed link, such as a terrestrial link. Preferably, the terrestrial link (which may comprise a conventional dial-up Internet connection) is a two-way link, wherein the requesting terminal transmits data requests to the network via the terrestrial link. The data requests generated by the requesting terminal are modified to designate whether the requested data should be downloaded from the network via the terrestrial link or the satellite link. The terrestrial link may also be automatically selected for certain applications.

Abstract: A satellite telephony communication system is used to provide a method of delivering service voice announcements to remote ground transceivers in the satellite telephony system. A relatively small portion of the satellite's bandwidth is dedicated to broadcasting periodic service voice announcements. When an announcement is desired, the remote ground transceiver tunes to the announcement frequency and retrieves the desired announcement in the broadcast sequence. Preferably, the announcements are broadcast in bursts, with a control data burst repeated periodically among the announcement bursts. The control data burst notifies the ground transceiver about the location and duration of each broadcast announcement, thus allowing the transceiver to time its voice path connection to the announcement frequency such that it starts at the beginning of the desired announcement and terminates at the end of the desired announcement.

Abstract: A method of detecting double talk in an echo canceller is provided. The method includes determining far end, near end and echo signal cancelled power, determining the presence of near end, maybe near end and far end speech, and controlling an echo suppressor and filter coefficient updates in an echo canceller.

Abstract: A circuit board guide and retaining apparatus to facilitate the alignment and installation of a circuit board within an electronic assembly chassis is disclosed. The circuit board guide and retaining apparatus includes a combination of alignment structures for aligning the circuit board in a prescribed orientation parallel to the base of the electronic assembly chassis and retention structures for preventing the circuit board from substantial displacement in lateral and/or vertical directions during and after the installation of the circuit board.

Abstract: A signal classifier and a echo suppressor for a facsimile calls in an echo prone network. The signal classifier quickly and reliably differentiates facsimile calls from voice and modem calls. The echo suppressor suppresses echo and has a variable hangover time which avoids attenuating and distorting a return transmission signal.

Abstract: A circuit for use with a data processing circuit having a transport chip for routing data is provided. The circuit includes a discrete digital logic circuit for sampling digital input signals and for generating a digital output timing signal based on the state of the digital input signals at any given point in time. The circuit minimizes default timing conditions in the transport chip.

Abstract: A preferred embodiment provides a radio port controller in a wireless personal communications system including a first interface module in communication with a radio port, a second interface in communication with a digital switch, and at least one switching transcoder module in communication with the first and second interface modules. A further preferred embodiment provides that the switching transcoder module includes a digital signal processor. The radio port controller preferably has a communication backplane including a plurality of slots, and each slot is preferably adapted to selectively receive either a T1 card interfacing to a T1 line or an E1 card interfacing to an E1 line.

Abstract: A method and system for synchronizing transmission TDMA frames in a mobile satellite communication system are disclosed herein. The method of synchronizing a transmitted frame timing in a mobile satellite communication system comprises the steps of broadcasting a frame timing offset from a satellite to a mobile terminal having a timer, receiving the frame timing offset information transmitted by the satellite in the mobile terminal, and adjusting the timer in the mobile terminal based on the timing offset information.

Abstract: In a switching network, a single 16 slot protective chassis supports a plurality of different adaptation switch modules (ASMs) sharing a single midplane bus. Multiple, identical ASMs form redundancy groups wherein one module in a group operates as a backup. Each ASM has relays for isolation between ASMs, and repeater circuitry to strengthen signals and minimize signal interference.

Abstract: The present invention relates to a subscriber unit in a wireless personal communications system (WPCS). In one embodiment, the subscriber unit includes a digital dataport for modemless communication of digital signals. Another preferred embodiment provides for a subscriber unit having a cable television transport module for modulating and demodulating signals over unused bandwidth available on cable television lines.

Abstract: The present invention relates to a device and a method for communicating in a mobile communication system. The method provides a carrier signal having a plurality of frames. Each frame has a plurality of time slots, and each time slot comprises a plurality of transmission bits. A group of time slots are assigned to a communication channel. A traffic burst signal having a plurality of traffic symbols is transmitted over the communication channel by transmitting a first preamble over one of the assigned time slots, and transmitting a second preamble and at least one of the traffic symbols over at least one of the other assigned time slots. The second preamble occupies fewer transmission bits than the first preamble.

Abstract: A dual mode external DC power supply system for supplying DC power to an electronic device and which operates under the control of the electronic device is provided. The disclosed embodiment of the power supply system includes a first input adapted to receive an input signal of unregulated DC power, a second input adapted to receive a control signal from the electronic device, and an output adapted to provide either a constant voltage DC output signal or a constant current DC output signal depending on the magnitude of the control signal. The control signal also determines the level of constant current delivered to the electronic device when the system is operating in the constant current mode.

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 present invention relates to a radio port in a wireless personal communications system. The radio port includes a first channel in communication with a first subscriber unit, a second channel in communication with a second subscriber unit, and a switching device connecting the first channel to the second channel so that the first subscriber unit may communicate directly with the second subscriber unit. In another preferred embodiment, the radio port includes a plurality of antennas, an RF receive section, an RF transmit section, an analog port adapted for connection to an analog telephone line, a digital dataport for receiving and transmitting digital signals, and a databus interconnecting the RF receive section, RF transmit section, analog port, and digital dataport. The RF receive section includes a diversity selection unit receiving an input signal from each of the antennas. The RF transmit section generates an output signal to be transmitted over at least one of the antennas.

Abstract: A method of transporting speech information over a wireless cellular communications system is provided. By determining the existence and compatibility of the destination port with the origination port in a given telephone call, the present invention is capable of using only one compression step and one decompression step. Accordingly, voice signal degradation and delay associated with multiple compression/decompression steps may be reduced.

Abstract: A Supervisory Audio Tone (SAT) based Carrier-to-Interference (C/I) ratio measurement system uses the SAT tone to determine the desired signal to undesired interferers so that an intelligent hand-off decision can be made in a digital cellular communication system. The measurement is implemented by digital signal processors which allows additional signal processing and subsequently noise rejection over analog techniques. The received level of the desired SAT as well as the received levels of the SATs for the co-channel interferers is detected. The ratio of the desired SAT level to the sum of the undesired SAT levels provides the C/I measurement. By monitoring this C/I measurement, the base station can determine when to make a hand-off. This SAT based C/I measurement system also aids in the selection of a candidate cell to which the subscriber is handed-off. Surveillance receivers in the candidate cells make SAT based C/I measurements as well as Received Signal Strength Indication (RSSI) measurements.

Abstract: A method and apparatus for generating and navigating an on-screen program guide comprising current and future scheduling information for a plurality of different program sources. The method comprises the steps of entering a date and a time which defines a reference time for the on-screen program guide, and generating the on-screen program guide containing scheduling information for the plurality of different program sources including the user-entered reference time.

Abstract: A bit rate Codebook Excited Linear Predictor (CELP) communication system which includes a transmitter that organizes a signal containing speech into frames of 40 millisecond duration, and classifies each frame as one of three modes: voiced and stationary, unvoiced or transient, and background noise.