Abstract: The capacity of a Mode-S ADS-B surveillance radar system is increased by sectorizing the radar system by the use of a directional array of Mode-S, quarter wavelength, single element, stub antennas. The ensemble of signals from the array of Mode-S antenna elements is processed electronically. The signal processing/receiver architecture increases the capacity of the Mode-S ADS-B system to be capable of effectively functioning within a highly congested airspace.

Abstract: An apparatus for inspecting an operational condition of a rail track from a railcar includes an antenna positioned on the railcar that directs radar signals toward the rail track and collects radar signals returned from the rail track. A radar transceiver is connected to the antenna and supplying the radar signals to the antenna. The radar transceiver receives radar returned signals from an interaction of the radar signal with the rail track. A controller is connected to the radar transceiver for controlling transmission of the radar signals from the radar transceiver and receipt of the radar returned signals. A signal processing unit is connected to the controller and a sensor unit that supplies input data to the signal processing unit. The signal processing unit processes at least the input data and the radar returned signal to produce processor output data and to determine the operational condition of the rail track.

Abstract: A communication system for communicating a modified geometric harmonic modulated (GHM) signal on a power line is described. The system includes a transmitter for transmitting a GHM signal having a plurality of carriers, a highest frequency carrier being about 630 Hz, and a receiver for receiving the transmitted GHM signal.

Abstract: A propagation delay compensation device and method provide adaptive propagation delay compensation in a time division multiple access (TDMA) communications system. The device includes a range computation unit and a delay computation unit. The range unit receives data signals to identify respective positions of a base station and a transceiver and, in response, generates a signal indicating line-of-sight range between the base station and the transceiver. The delay unit receives the range signal and, in response, generates a required delay which provides for alignment of communications signals received at the base station to arrive in alignment with assigned time slots at the base station. In one embodiment, the invention enables communication from aircraft through TDMA cellular systems using standard TDMA waveform formats.