PURPOSE: To enable the display of a signal obtained from a sweep reception circuit whose sweeping time is different from the deflection time of a CRT display unit, by a method wherein a sweep reception signal is subjected to A/D conversion and stored and this stored signal is read out and sent to the CRT display unit.

CONSTITUTION: Frequency sweeping-receiving circuits 1AW1C sweep and receive electric waves in frequency bands different from each other and input reception signals 102W302 and sweep signals 101W301 in a sweep conversion circuit 3. Waveform memory circuits 3AW3C subject the reception signals to A/D conversion in A/D conversion circuits 3A2W3C2 synchronously with the sweep signals, and write them in memory circuits 3A3W3C3. When the next sweep signals come, the contents of the memory circuits 3A3W3C3 are written in memory circuits 3A4W3C4, and then the subsequent A/D conversion and writing in memories are started. In parallel with these operations, the contents of the memory circuits 3A4W3C4 are read out by a signal being synchronous with the deflection time of a CRT display unit 2, and are inputted in the CRT display unit 2 via a D/A conversion circuit 3D2.