Abstract: A radar return image for display on a cockpit CRT is generated by selectively accessing terrain data compressed and stored in a digital map data base and processing that data to artificially simulate a radar return image pattern on a cockpit display which effectively corresponds that which would otherwise be provided by conventional T/R equipment. Since the compressed data base contains information representative of both the elevation and cultural features of the terrain at map locations that are capable of being intercepted by the aircraft's radar beam, this data may be subjected to signal processing functions to establish pixel intensity control signals by way of which a radar image of a cockpit CRT display is generated.

Abstract: Non-linearities in the sweep output of a voltage controlled oscillator are automatically linearized by a scheme that compensates for changes in slope of the variation in frequency with time during a high accuracy calibration mode, prior to placing the VCO into real time operation. During the calibration mode the sweep rate of the VCO is slowed down as the operational frequency range of interest is divided into a prescribed number of subfrequency segments or windows. During each window, an input control code, obtained from a random access memory (RAM) and representative of the intended slope of the VCO frequency sweep (for that window of interest), is applied to a digital-to-analog converter (DAC) whose output is integrated and applied to the voltage control input of the VCO.

Abstract: A high resolution scanning system, employing non-linearly driven galvanometer deflection optics, compensates for both the non-linear rate of travel of the information pixel beam and for pixel position offset introduced by an optical subsystem (a flat field lens) that equalize pixel size and quality across the recording medium. The system employs a single high speed reference clock the output pulses of which are counted and used to address a compensation data-containing PROM (programmable read only memory). The contents of successive addresses of the PROM contain pixel location codes identifying the position on the recording medium where a pixel of interest is to be recorded. These codes are derived in accordance with the periodic non-linear rate of travel of the scanning optics across the recording medium and the measured parameters of a flat field lens disposed in the path of the scanning beam.