Abstract: A digitally controlled CRT display system providing display intensity levels having equal ratios of luminances for consecutive steps over a plurality of brightness control settings. The digital video is added to a digital brightness code and the sum is converted to an analog signal that is coupled to the cathode of the CRT. The digital-to-analog converter provides a transfer characteristic such that the consecutive gray shade steps have a constant ratio of luminance.

Abstract: A system for electronically producing and displaying target position history trails in a PPI radar. Digital target positions within a selected sector zone from all targets meeting predetermined amplitude and duration criteria are stored in a memory for single azimuth scans at predetermined intervals. The data from the scans are interleaved and read out of the memory for display with the real time PPI targets. When the memory is filled, the oldest plots from each target are dropped to make room for new plots.

Abstract: A variable range marker device for use with a PPI radar with digitized video displayed in non-real time. The position of the range marker is initially operator determined by rotation of a knob mechanically linked to an optically encoded disc. Optical sensors produce a digital output indicative of the disc rotation angle and range mark position as a distance from the center of the radar display screen. A counter is preset with the digital output at the start of each sweep and decremented once each range cell until a count of zero is reached at which time an unblanking pulse is produced. A numeric display of range is produced by dividing the number of range cells to the range mark by the range setting and displaying the result with a three digit LED display.

Abstract: A radar system having an adaptive compass drive capable of operation over a wide variety of compass outputs and supply voltages and frequencies. For compass outputs in the form of multi-phased analog signals, a digital phase detector converts the signals to a series of digital pulses which are used to operate a three-phase to UP-DOWN pulse converter. If the gyro compass output signals are in the form of overlapping digital signals, the converter changes the signals directly to a sequence of UP or DOWN pulses. The UP-DOWN pulses are used to operate a binary counter which operates the phases of a multi-phased stepper motor which is coupled to the true bearing scale of the radar system the output of which may also be used to operate a north stabilization synchro converter for the radar display.

Abstract: A radar system having the radar pulse rate controlled directly from an indicator unit. Separate modulator-transmitter-receiver and digital video processor indicator units are provided. A radar trigger pulse is produced by the processor unit in synchronism with the processor clock at a rate determined by the radar range setting. An acknowledge signal is produced in turn by the modulator-transmitter-receiver in accordance with an activating signal in the modulator and fed back to the indicator unit to start video signal digitization and the CRT sweep. Jitter between the start of the radar return signal and the radar sweep are eliminated.