Abstract: A method and system for controlling a fluid valve are described that avoid the effects of hysteresis. In hysteresis, the power signals associated with a valve position are different on the upstroke and downstroke. As a result, predicting the valve position can be difficult if you only know the current power signal. Instead of using upstrokes and downstrokes, a valve can momentarily be set to zero power, or a rest position when receiving a new command signal. This way the command signal is applied from a zero power or rest position, making the valve position more predictable and accurate.

Abstract: A hybrid satellite communications system provides communications, particularly Internet access, to computer users. The hybrid satellite communications system includes a satellite system and a terrestrial communications system. The satellite system includes two transceivers. The first transceiver receives and transmits a first set of signals received from the terrestrial communications system to a plurality of user units. In reverse fashion, the satellite systems second transceiver receives a second set of signals in a second frequency band from the user units and transmits those signals back to the terrestrial communications system. The first set of signals (downlink signals) are of much higher frequency than the second set of signals (uplink signals). Preferably, the first set of signals are relayed by a Direct Broadcast System (DBS) satellite in a frequency band between 12.2 GHz and 12.9 GHz, while the second set of signals are relayed by a Mobile Satellite System (MSS) satellite operating between 1.

Abstract: A hybrid satellite communications system provides communications, particularly Internet access, to computer users. The hybrid satellite communications system includes a satellite system and a terrestrial communications system. The satellite system includes two transceivers. The first transceiver receives and transmits a first set of signals received from the terrestrial communications system to a plurality of user units. In reverse fashion, the satellite systems second transceiver receives a second set of signals in a second frequency band from the user units and transmits those signals back to the terrestrial communications system. The first set of signals (downlink signals) are of much higher frequency than the second set of signals (uplink signals). Preferably, the first set of signals are relayed by a Direct Broadcast System (DBS) satellite in a frequency band between 12.

Abstract: A hybrid satellite communications system provides communications, particularly Internet access, to computer users. The hybrid satellite communications system includes a satellite system and a terrestrial communications system. The satellite system includes two transceivers. The first transceiver receives and transmits a first set of signals received from the terrestrial communications system to a plurality of user units. In reverse fashion, the satellite systems second transceiver receives a second set of signals in a second frequency band from the user units and transmits those signals back to the terrestrial communications system. The first set of signals (downlink signals) are of much higher frequency than the second set of signals (uplink signals). Preferably, the first set of signals are relayed by a Direct Broadcast System (DBS) satellite in a frequency band between 12.2 GHz and 12.9 GHz, while the second set of signals are relayed by a Mobile Satellite System (MSS) satellite operating between 1.

Abstract: Methods for operating a wireless communications system provided for reducing the use of the system by unauthorized users by establishing the geographical location of selected user, comparing this location with the known locations of authorized users and denying service to the selected user if the selected user's location does not correspond to the known location of authorized users. Seamless hand-over of a user between nodes of the communication system is effected by periodically recomputing a algorithm which determines a preferred node for communication with the user. When the algorithm indicates that another node is preferred, a call initiation handshake is established between the user and the preferred node, while still maintaining communication with the original node. Communication between the user and the first node is not interrupted until the user establishes a communication "lock" with the second node.

Abstract: A mobile communications system provides communications with mobile users in the interference zones of communications services having priority of use of the frequency band in which the mobile user operates. The frequency band has been previously allocated for use by the other services, such as fixed microwave service (FMS); however, by means of the invention, the mobile user is able to conduct communications operations on a subband or subbands in that frequency band. A position locating system determines the position of the mobile user and if the user is within an interference zone, the mobile user is assigned subbands for operation in the previously allocated frequency band that are outside the subbands of operation of the FMS. A memory accessible by the processor selecting the frequency band of operation of the mobile user includes descriptions of the transmit and receive interference zones of each FMS.

Abstract: Apparatus and a corresponding method for controlling the attitude of a space vehicle during operation of its propulsion engines, without gimbaling of the engines. Two engines are differentially throttled, one above and one below a nominal thrust setting of the engines, in response to an error signal indicative of the difference between an actual attitude angle and a desired attitude angle. Three or four engines can be used to control attitude about two orthogonal axes, or a greater number of engines can be used for redundancy.