專利摘要：
A radar scan converter and method of mixing image. By inserting a radar scan converter (RSC) card in a personal computer, an input video such as a radar video or supersonic video can be mixed on a screen of the personal computer without deteriorating the current graphic, such as range rings, plots, tracks, and symbols. An analog-to-digital converter, a radial buffer, a decimation filter, a coordinate converter and an overlay processor are used in the radar scan converter. The overlay processor read a display memory on a display card according to a triangular coordinate generated by the coordinate converter. The read data from the display memory is then compared. When the read data do not contain either text or graphic, a data processed by the decimation filter is written into the display memory.