Abstract: An end-of-train (EOT) unit that comprises an enclosure housing its monitoring, control, and communication equipment and systems, an arm that positions and supports at least one auxiliary wheel on a rail of a track to rotate electrical generator coupled to the auxiliary wheel while the train is moving.

Abstract: A radio for determining the occupancy of a variable width channel for secondary use, the variable width channel with a bandwidth equal to an integer multiple of the bandwidth of a plurality of narrowband channels in an RF frequency band. The radio decides whether the variable width channel in the RF band is occupied by whether classifying each of the narrowband channels corresponding to the variable width channel and each of a plurality of sub-bands with bandwidths of narrowband channels but center frequencies shifted by one-half of the bandwidth of the narrowband channel and overlap with the bandwidth of the variable width channel as containing signal or noise based on measured energy levels.

Abstract: A railroad communication system includes a radio transmitter for generating radio communications signals and a length of railroad rail coupled to the radio transmitter. The length of rail is disposed on a set of nonconductive railroad ties to form a transmission line for radiating the radio communications signals to a radio receiver in a vicinity of the length of railroad rail.

Abstract: A method of exchanging application messages generated by an applications with a format specified by a predetermined protocol and then encapsulating the message with a railroad edge messaging protocol (EMP) header and a railroad Class D messaging transport header to form a packet for transmission across a railroad communications system.

Abstract: A method of exchanging messages between a railroad communications system radio operating in accordance with a host-radio exchange protocol and a railroad messaging system. A communications manager of the railroad messaging system, operating in accordance with the host-radio exchange protocol, transmits a request to the radio requesting registration as a host of the radio. The communications manager is selectively registered with the radio as a primary host. The radio sends a message to the primary host identifying an available wireless link between the radio and another radio of the railroad communications system. Data messages, which include data being exchanged between the primary host and the primary host of the another radio across the wireless link, are exchanged between the radio and the primary host in accordance with the host-radio exchange protocol.

Abstract: A method of linearizing a relationship between a signal to an amplifier and an output signal from the amplifier includes applying an inverse of a transfer function of the amplifier to the signal prior to presenting the signal as the amplifier input. The inverse transfer function is represented by a polynomial defined by a set of coefficients. The transmitter output signal is measured by the idle receiver in a time division duplex system. The output signal is filtered to isolate intermodulation products of a selected order and the peak power of the isolated intermodulation products is then estimated. An adaptive algorithm is applied in response to the estimate of the peak power to update the set of coefficients of the polynomial representing the inverse of the transfer function of the amplifier.

Abstract: A method of exchanging centralized train control (CTC) messages in a railroad communication system includes generating a message having a format defined by a protocol with an application running on a sending one of a railroad wayside system and a railroad dispatch system. A railroad edge messaging protocol (EMP) header and a railroad Class D messaging transport header are appended to the message to generate a packet. The packet is transmitted to a receiving one of the railroad dispatch system and the railroad wayside system across the railroad communications system.

Abstract: A railroad communication system includes a radio transmitter for generating radio communications signals and a length of railroad rail coupled to the radio transmitter. The length of rail is disposed on a set of nonconductive railroad ties to form a transmission line for radiating the radio communications signals to a radio receiver in a vicinity of the length of railroad rail.

Abstract: A method of linearizing a relationship between a signal to an amplifier and an output signal from the amplifier includes applying an inverse of a transfer function of the amplifier to the signal prior to presenting the signal as the amplifier input. The inverse transfer function is represented by a polynomial defined by a set of coefficients. The transmitter output signal is measured by the idle receiver in a time division duplex system. The output signal is filtered to isolate intermodulation products of a selected order and the peak power of the isolated intermodulation products is then estimated. An adaptive algorithm is applied in response to the estimate of the peak power to update the set of coefficients of the polynomial representing the inverse of the transfer function of the amplifier.

Abstract: A railroad communication system includes a radio transmitter for generating radio communications signals and a length of railroad rail coupled to the radio transmitter. The length of rail is disposed on a set of nonconductive railroad ties to form a transmission line for radiating the radio communications signals to a radio receiver in a vicinity of the length of railroad rail.

Abstract: A method of messaging in a communications system includes generating a message at an application layer. The message and associated message handling codes are passed to a transport layer and the message fragmented. The fragmented message and the message handling codes are passed to a network layer and the fragmented message selectively segmented as indicated by the message handling code. The selectively segmented message and the message handling code are passed to a link layer and formed into a packet including packet type information and data parts. The packet is passed to a physical layer and a preamble is added. The preamble and packet are transmitted with a radio.

Abstract: A method of messaging in a communications system includes generating a message at an application layer. The message and associated message handling codes are passed to a transport layer and the message fragmented. The fragmented message and the message handling codes are passed to a network layer and the fragmented message selectively segmented as indicated by the message handling code. The selectively segmented message and the message handling code are passed to a link layer and formed into a packet including packet type information and data parts. The packet is passed to a physical layer and a preamble is added. The preamble and packet are transmitted with a radio.

Abstract: A radio receiver including a memory storing a reference sample sequence and a synchronizer. The synchronizer receives a data packet, samples and modulates symbols from the data packet and then generates phase-information samples from the modulated samples. The phase-information samples are low-pass to generate a filtered phase-information sample sequence. Samples of the filtered phase-information sample sequence are selectively compared with samples of the reference sample sequence and bit synchronization is established when a selected number of samples of the filtered phase-information sample sequence match a selected number of samples of the reference sample sequence.

Abstract: A method for implementing communications in a railroad communications system having a base station radio and remote radios, the remote radios including a mobile radio and a wayside radio. The method includes assigning a common radio communications channel for allowing a remote radio to connect with the base station radio using a carrier sense multiple access (CSMA) communications protocol and assigning a local channel for allowing communications between the radio base station and the remote radios and between the remote radios, wherein communications on the local channel utilizes a selected one of fixed time division multiple access (FTDMA) and dynamic time division multiple access (DTDMA) communications protocols.

Abstract: An interface device for interfacing a set of wayside systems with a radio transmitter includes a plurality of input ports each having at least one input for receiving a signal representing a state of a corresponding wayside system and first and second parallel data paths coupled to the plurality of input ports. Each data path includes input protection circuitry coupled to the inputs of the input ports for preventing short-circuit and open-circuit conditions from triggering a false input state, a multiplexer for selecting between the input port; and a processor for scanning the input ports with the multiplexer to determine the state of current signals appearing at the inputs. In response to determining the state of the current signals appearing at the inputs, the processor generates a message communicating a current state of the wayside systems for delivery to the radio transmitter.

Abstract: A method for exchanging information within a radio communications system includes establishing communications between radio systems utilizing a carrier sense multiple access mode during a period of lower traffic load on the radio communications system and establishing communications between the radio systems utilizing a time division multiple access mode during a period of higher traffic load on the radio communications system.

Abstract: A communications system includes a plurality of operational nodes and a plurality of data distribution systems. A data distribution system operating in an active mode manages exchanges of data between the operational nodes and further operable to periodically transmit go passive messages commanding at least one other of the data distribution systems to operate in a passive mode. A data distribution system operating in the passive mode waits for receipt of one of the go passive messages, continues to operate in the passive mode after receiving one of the go passive messages within a predetermined time out period, and transitions to the active mode after the time out period has expired without receipt of one of the go passive messages.