Abstract: A train control system is for a train comprising at least first and second train segments including a brake pipe being separated between adjacent train segments. The train control system preferably comprises a first control subsystem for installation in a locomotive of the first train segment and a second control subsystem for installation in a locomotive of the second train segment. The first and second control subsystems communicate with one another for controlling train braking. The system also preferably includes a third control subsystem for installation in a railcar adjacent an end of the first train segment. This third control subsystem preferably includes at least one pressure transducer for sensing brake pipe pressure adjacent the end of the first train segment, and at least one control valve for controlling brake pipe pressure adjacent the end of the first train segment.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and frequency at which the RBSs can expect to receive data from the field units. A network hub or message operations center (MOC) coordinates the operation of the paging systems and RBSs from a central location. For example, the MOC determines an available HF frequency and time for a particular field unit to transmit, and then issues the request for data to the field unit using the existing paging network infrastructure. The field units make use of paging receivers, and an HF transmitter to report remote data such as a geoposition or other sensor data when requested to do so.

Abstract: A two-way communications system provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. A network hub or mission operation center (MOC) coordinates the operation of the paging systems and RBSs from a central location. The paging network infrastructure is used as an outbound link over which each of the field units is regularly provided with a outbound data message containing information on the available frequencies and time slots the field units can use to transmit inbound data messages to the RBSs. If any of the field units desires to transmit data to MOC, the field unit selects an available frequency from the outbound data message, and transmits its data at the selected available frequency and time.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and HF frequency at which the RBSs can expect to receive inbound data from the field units. A network hub or mission operation center (MOC) determines a radio frequency which is expected to be propagating and clear at the time that a particular field unit is to use the frequency as an inbound link. The MOC then issues the request for data to the field unit using an existing inexpensive wireless system such as the paging network infrastructure.

Abstract: A system and method for isolating a data or circuit signal, where the circuit signal has been frequency spread modulated with other such signals onto a beam signal and which beam signal has been frequency spread modulated onto an IF signal, using a buss for providing the entire IF signal to a bank of frequency agile tuning demodulators. Plural IF signals may be processed simultaneously where each tuning demodulator has access to each IF signal via a plurality of IF busses. Each tuning demodulator is capable of isolating any circuit signal from any IF signal.

Abstract: A local area network employs a shared control channel over which control messages between frequency agile modems for each of the user nodes of a distributed architecture-configured network are exchanged. In addition to the shared control channel, a plurality of data channel pairs is available for effecting full duplex communications between any two nodes of the network. Because all data channel assignments depend upon successful use of the control channel, a prescribed control channel contention access scheme is employed to optimize use of the control channel by all users of the network irrespective of the demand for its use. Pursuant to this scheme, each requesting node must first compare an accumulated activity measure with a traffic density threshold that is continuously optimized for the current level of control channel activity.