Abstract: A radio ranging system has at least one receiver which receives pulses over a direct path and over a longer delayed path from each of two or more fixed repeater stations. From the reception times of pulses which have traveled over these paths at different travel times from the fixed stations, a computer calculates the hyperbolic distances separating the passive receiver and the several fixed reference stations. By interchanging the roles of the various fixed stations, the computer compares the results of timing calculations of the same distances based on the different sets of data. From this comparison, the systematic timing errors of the system can be isolated and added or subtracted from the time measuring results, leaving differential time measurements without systematic error.

Abstract: A microprocessor controls a radar trilateralization system, used on board an aircraft to provide pattern flying. A suitable hard wired board may be added to the microprocessor to enable it to read out any suitable flight pattern. A plurality of transponders are set up at known positions to establish a baseline. Then, by using known radar techniques, the system feeds radar derived, distance information into the microprocessor. The microprocessor calculates the airplane's position from these radar signals, relates that position to the X, Y grid locations in a desired flight pattern, and then gives an instrument readout. The pilot keeps a display of the instrument over an appropriate index, and the airplane flies over the entire predetermined flight pattern.

Abstract: A radar system is used to locate a vehicle's position on a predetermined X, Y grid, which could be latitude and longitude. Several paths of different lengths link the vehicle with a master station which transmits cyclically recurring pulses. Equipment on the vehicle compares the propagation time required for the pulses to travel over each of the several paths. The compared times are then used by a microprocessor to calculate the position of the vehicle. The several paths are identified by a use of repeater stations which may selectively drop predetermined ones of the cyclically recurring pulses and retransmit the rest. For example, one repeater may retransmit every second recurring pulse and another repeater may retransmit every third recurring pulse.

Abstract: A system for radar station identification depends primarily upon the encoding growing out of a pulse repetition rate of interrogation pulses. To secure the encoding, one or more pulses arm the system and succeeding pulses must be detected during an extremely narrow time of acceptance. Hence, the pulses are logically interpreted in order to reject randomly occurring stray signals.