a plurality of detected data generators respectively corresponding to a plurality of antennas installed at different positions, for generating detected data represented by a polar coordinate system using detected signals from the respective antennas;

a plurality of drawing address generators respectively corresponding to the plurality of antennas, for setting drawing addresses represented by a rectangular coordinate system corresponding to respective antenna relative positions, using azimuth information from the respective antennas, draw start point position information corresponding to the installed positions of the respective antennas, and distance information from a draw start point to a draw position;

an address selector for selecting the drawing addresses set by the plurality of drawing address generators, and outputting the drawing addresses as drawing addresses or read addresses to a plurality of image data storing memories;

a plurality of correlators for subjecting the detected data from the respectively corresponding detected data generators to a correlation process, and storing the resultant data in an internal memory as correlated data represented by a rectangular, true motion coordinate system based on the addresses set by the address selector;

a specific area configurator corresponding to a specific antenna, for setting an area in which detected data obtained by the specific antenna is drawn, using azimuth information from the specific antenna, draw start point position information corresponding to the installed position of the specific antenna, and distance information from a draw start point to a draw position;

a display image data selector for, among the correlated data output from the plurality of correlators in accordance with a drawing address obtained from one predetermined antenna, selecting and outputting correlated data from a correlator corresponding to the specific antenna to a display image data storing memory, for the area set by the specific area conflaurator, based on a mask image memory associated with said antenna, and selecting and outputting correlated data from a correlator corresponding to an antenna other than the specific antenna to the display image data storing memory, for another area; and

the display image data storing memory for storing display image data represented by the set true motion display coordinate system; and further, wherein there are more antennas than drawing address generators such that each antenna connected to a drawing address generator is a master antenna, and further wherein at least one master antenna has an associated slave antenna whose scanning and detection cycles are synchronized with said master antenna.