Abstract: A multi-chambered piston actuator incorporates partitioned pressure chambers, each chamber delivering an actuation force to a common target object based on multiple presence signals and/or resources. The chambers are formed in part by one or more tiers, each tier having a surface area on which one or more pressure signals act. The resultant force on the tiers move the common target to control, for example, a valve.

Abstract: A method and apparatus for detecting communication network delays. In general, messages from vehicles are time stamped, and then the time stamp is compared to a time that each message is received by a central station. A processor at the central station then determines a time difference between the time stamp and the received time. The time difference is then compared to a predetermined time. If more than a predetermined number of messages is received by the central station exceeding the predetermined time, a notification is sent to an entity, such as personnel at the central station.

Abstract: A method for selectively maintaining compression state and applying a compression technique after a PPP renegotiation on a Um interface of a wireless communication network. A communication device receives packetized data transmitted from a terminal device, which is coupled to the communication device via an Rm interface. The communication device determines whether the received packetized data comprises compressed or uncompressed data. Upon determining that the received packetized data comprises compressed data, the communication device determines whether connection information identifying a compression slot is included in the compressed data. The communication device further determines whether the connection information exceeds a highest-numbered decompression slot from a plurality of decompression slots on said Um interface.

Abstract: A method and apparatus for reducing voice latency in a voice-over-data wireless communication system. In a transmitter, data frames are created from audio information by a vocoder and stored in a queue. Prior to storage, some of the data frames are eliminated, or dropped, and are not stored in the queue. In a receiver, data frames are generated from received signals and stored in a queue. Prior to storage in the receiver queue, some of the data frames are dropped. Data frames are dropped either at a single fixed rate, a dual fixed rate, or a variable rate, generally depending on a communication channel latency. By dropping data frames at the transmitter, the receiver, or both, voice latency due to data frame retransmissions is reduced.

Abstract: An electronic locking device for use by the transportation industry. The electronic locking device is used to control access to a cargo area of a vehicle, such as a tractor-trailer vehicle used in the trucking industry. The electronic locking device is controlled depending on one or a combination of factors including the location of the vehicle, the speed of the vehicle, the delivery status of the vehicle, or other factors.

Abstract: A method and apparatus for reducing voice latency in a voice-over-data wireless communication system. In a transmitter, audio information to be transmitted is first encoded using a voice encoder operating in a first mode of operation. At least one operating parameter in the transmitter is measured by a processor, the least one operating parameter proportional to a latency between the transmitter and receiver. If the at least one operational parameter exceeds a predetermined threshold, the voice encoder is instructed to operate in a second mode of operation. When the at least one operational parameter falls below a second predetermined threshold, the voice encoder is instructed to operate in the first mode of operation.

Abstract: A method and apparatus for providing coverage control for multicast service in a wireless network. The present invention comprises a central transceiver for receiving a membership report from a plurality of wireless communication devices, the membership report identifying a multicast group to which at least one wireless communication device belongs. The central transceiver transmits an indication of the multicast group identified in the membership report to at least a portion of the plurality of wireless communication devices. The wireless communication devices use the information contained within the indication to determine whether or not to transmit a membership report identifying a multicast group to which it currently belongs.

Abstract: A novel and improved dielectric lens assembly (100) includes a dielectric extension (108) on a hemispherical dielectric lens (104), to provide a dielectric lens which exhibits properties of an elliptical lens. The extended dielectric lens can be implemented with a feed antenna (112) to improve the directivity of the antenna. The extension portion (108) of the lens assembly (100) is fabricated using a plurality of dielectric wafers disposed on the bottom surface of the hemisphere, an angled extension (516), or a cylindrical extension. The entire hemispherical lens and extension assembly (508) can be a single piece of dielectric material formed into the desired shape, or the assembly can be fabricated using a plurality of dielectric components (512, 516) coupled together to form the lens assembly.

Abstract: A method and apparatus for efficient data retransmission in a voice-over-data communication system between a first wireless communication device and a second wireless communication device, without affecting existing infrastructure. When a data frame containing audio information is received in error by the first wireless communication device, n negative-acknowledgement messages are sent from the first wireless communication device to the second wireless communication device which sent the frame, each of the negative acknowledgement messages transmitted in close succession to each other. When a negative-acknowledgement message is received by the first wireless communication device from the second wireless communication device, n copies of the frame identified by the negative-acknowledgement message is transmitted by the first wireless communication device, each of the copies transmitted in close succession to each other.

Abstract: A method and apparatus for automatically creating and maintaining driver activity logs for vehicle operators. The vehicle operator is in communication with a central station using a mobile communication terminal located onboard an assigned vehicle. A vehicle operator driving status is determined at the central station when messages and position reports are transmitted from the vehicle to the central station. A driver activity log is created upon request by the vehicle operator or by authorized personnel at the central station or host facility. The driver activity log may then be transmitted to the vehicle for display.

Abstract: A concave reflector is shaped to receive energy emanating from a signal source positioned at the reflector's vertex and to reflect all received energy in a uniform output direction. The reflector additionally introduces a designated constant phase shift into all reflected energy relative to unreflected energy from the signal source, regardless of where the received energy impinges upon the reflector. When the source signal is periodic, this reflector design minimizes near field interference between the reflected signals, since they all have the same phase shift relative to the unreflected source signal. Furthermore, if the reflector is designed to implement zero phase shift, reflected and non-reflected signals tend to combine additively in the far field, focusing most of the transmitted energy toward the center of the transmission pattern.

Abstract: The present invention is a system and method for providing group communication services in an existing communication system. Group communications are enabled by installing a communications manager in a data network such as the Internet. The communications manager acts as a configurable switch, allowing communications from any group member to be transmitted to all other group members. The communications processed by the communications manager take the form of data packets, suitable for transmission over the data network. The data packets are generated by communication devices operating within the communication system. The use of the communications manager further allows users of other communication systems and devices to participate in group communications with each other.

Abstract: A method and apparatus for determining whether cargo is present in a freight car. The freight car has a proximal (“rear”) end with a loading door and opposing, distal (“front”) end. One or more transmitters and receivers are mounted inside the freight car at the front end, toward the car's ceiling. The transmitters/receivers are operated by a controller, which also functions to analyze data from the transmitters/receivers and transmit related reports to a remote monitoring site. During a prescribed time period, a transmitter generates an ultrasonic signal pattern with a coverage area of prescribed radius that terminates before reaching the loading door. During the time period of transmission, or slightly later to account for signal reflection time, the controller operates the receiver to detect reflected signals originating from the transmitter.

Abstract: A system and method for generating random numbers in a wireless communication network is presented. The noise present in the signal received by a wireless receiver is extracted to form random numbers. Wireless transmitters typically are identified by a synchronization signal. In acquiring the synchronization signal, a wireless receiver generates a plurality of psuedorandom sequences, despreads an incoming signal, integrates the resulting signal, and performs an energy computation to calculate an energy measure. One or more energy measures are collected in a pool of bits, and the bits are hashed to extract random numbers.

Abstract: A method and apparatus for increasing the probability of successful data frame transmission from a transmitter to a receiver. When a data frame is generated by a processor, it is stored in a transmit queue and a copy of the data frame is stored in a secondary queue. An elapsed time device tracks the elapsed time that the data frame copy has been stored in the secondary queue. When no data frames are generated by the processor, data frame copies from the secondary queue are placed into the transmit queue, thereby increasing the redundancy of transmitted data frames and thus the probability of successful transmission to the receiver.

Abstract: The present invention comprises a system and method for gain control of individual narrowband channels using a wideband power measurement. The present invention comprises a transmit power tracking loop which controls the power of the transmitted signal by controlling the gain applied to the signal. The function of the transmit power tracking loop is to measure power, accept commands for power adjustment, and adjust the power. Gain control is performed by producing an error signal using the comparison of measurements of a total of estimated powers of each narrowband signal and a measurement of the modulated wideband signal. In addition, open loop control is performed by accepting open loop commands generated by an algorithm.

Abstract: The information signals are transferred to end users, customers, or service subscribers using at least two signal sources, generally satellites, and polarized radiation. Two polarization modes are employed, with the preferred modes being left-hand and right-hand circularly polarized radiation, although other polarization modes may be employed. The total number of channels can be divided among the polarization modes and transferred to end users either through the use of polarization switching in the receivers to selectively switch between the satellites, or by switching elements in the satellites (sources) to switch between polarization modes used for transmission.

Abstract: A method and apparatus for rejecting a request for call initialization a device capable of multi-mode communications. A user of the multi-mode wireless communication device enters one or more desired communication modes into the wireless communication device, where an indication of the selected mode(s) are stored in a memory. When a page message is received by the wireless communication device, it is examined to determine if a communication mode of an incoming call associated with the page message matches the indication of the selected communication mode(s) as stored in the memory. If a match is determined, the incoming call is accepted by the wireless communication device. If the communication mode of the incoming call does not match the indication of the selected communication mode(s), the call is rejected by the wireless communication device without interrupting the user or a call already in progress.

Abstract: A method and apparatus for providing fair access to members of a group communication system in which the members experience differing signaling delays. Members of the communication system send a transmission request to an arbitration device when they wish to communicate with other members. The transmission requests are ultimately received by the arbitration device. A time window is opened by a processor located at the arbitration device at the time an initial transmission request is received. The time window is used to treat all transmission requests that are received within the time window as having been received at the same time. Any transmission requests that are received within the time window are included in determining which member should be granted an exclusive transmission privilege.