Importance

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Abstract

Symbology is written on a radar plan position indicator display with a rotating beam deflection field. The PPI radar range is quantized into range increments and digital data representative of the symbology to be written are inserted into a shift register which is clocked in synchronism with the range sweeps to provide interleaved digital data to the video input of the display. The normal radar video data is combined with the symbology data so that the symbology and normal radar returns are simultaneously written in real time. A portion of the symbology generating apparatus provides a manual acquisition marker comprising a range ring and an azimuth geometric figure. A range switch gates a clock pulse signal into a range up/down counter for incrementing and decrementing the number therein, the digital output of the counter being representative of the range of the range ring. The decoded digital output of the range counter is loaded into the shift register for bit serial application to the video input to the display. A manually operated azimuth switch similarly increments and decrements an azimuth counter, the digital output of which being compared to the radar antenna azimuth signal for positioning the azimuth geometric figure in azimuth. The symbology writing apparatus also includes a portion for providing alphanumeric or other localized symbology. These symbols are stored in a character table in the various orientations required for the plan position indicator display and written via the output shift register at azimuth and range coordinates provided by the system, the data therefor being interleaved with the data for the manual acquisition marker.

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First Claim