Abstract: A method and apparatus is capable of high-speed transportation of passengers and/or freight. Vehicles are operated along a guideway as a result of the interaction between vehicle lift, steering and propulsion apparatus, each of which includes coil assemblies that are mounted on the vehicle, and magnet assemblies mounted on the guideway. Vehicle propulsion is provided by the interaction of currents on the vehicle with time-varying magnetic fields that are generated along the guideway. The coils and magnets interact in accordance with the magnitude of electric current passing through the coils and the strength of the magnets' fields, to give lift and directional control to the vehicle. The lift and steering magnets provide substantially uniform magnetic fields so that the interaction between the lift coils and lift magnets, and respectively between the steering coils and steering magnets is substantially independent of positioning of the corresponding coils.

Abstract: A method and apparatus is capable of high-speed transportation of passengers and/or freight. Vehicles (22) are operated along a guideway (14) as a result of the interaction between vehicle lift, steering and propulsion apparatus, each of which includes coil assemblies that are mounted on the vehicle (22), and magnet assemblies mounted on the guideway (14). Vehicle propulsion is provided by the interaction of currents on the vehicle (22) with time-varying magnetic fields that are generated along the guideway (14). The coils and magnets interact in accordance with the magnitude of electric current passing through the coils and the strength of the magnets' fields, to give lift and directional control to the vehicle.

Abstract: A radio position determation and message transfer system is implemented using a pair of satellites in geostationary orbit for replaying interrogation and replay signals between a ground station and a user-carried transceiver. The user portion is calculated based on the arrival times of replay signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points of the earth's surface. The stored terrain map allows accurate position fixed to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.

Abstract: A radio position determination and message transfer system is implemented using a pair of satellites in geostationary orbit for relaying interrogation and reply signals between a ground station and a user-carried transceiver. The user position is calculated based on the arrival times of reply signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points on the earth's surface. The stored terrain map allows accurate position fixes to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.

Abstract: A radio position determination and message transfer system is implemented using a number of satellites in geostationary orbit for relaying interrogation and reply signals between a ground station and a user-carried transceiver. Message information can be exchanged between a given user transceiver and the ground station, as well as between different user transceivers. The user transceiver is provided with means for monitoring the quality of the radio communication link between the transceiver and one or more of the satelites, based on errors detected in the received interrogation signals. The transmission of a reply signal by the transceiver is enabled only when the link quality is found to be acceptable. The reply signal may contain message information or may constitute a request for a position fix. In the latter case, the transceiver may be configured to await favorable link quality to more than one satellite before the reply signal is transmitted.

Abstract: A system for determining the positions of a plurality of vehicles traveling on or above a defined sector of the earth's surface comprises a transponder carried by each vehicle for transmitting a uniquely coded beacon signal in response to a general interrogation signal, at least three repeater-carrying satellites at spaced orbital locations above the earth for receiving and retransmitting the beacon signals produced by the vehicles, and a ground station for periodically transmitting the general interrogation signal and for receiving and processing the beacon signals retransmitted by the three satellites in order to determine vehicle position. In order to avoid signal overlap and equipment saturation at the ground station, each vehicle transponder includes means responsive to the general interrogation signal for inhibiting the transmission of further beacon signals by the transponder for a predetermined time interval following the response of the transponder to the general interrogation signal.