PURPOSE: To stabilize the operation, and facilitate high-degree integration by using digital signal processing technology when a radar video signal is reproduced from a composite video signal.

CONSTITUTION: Digital data E obtained by carrying out A/D conversion (1) on a composite video signal is stored once in a memory circuit 2. A correction data extracting circuit 3 carries out histogram analysis (31) on this data E, and outputs respective data on the maximum level (c), on the minimum level (a) and on the standard level (b) from a histogram where the created axis of abscissa represents frequency and the axis of ordinate represents voltage. Subtraction (32) is carried out on these levels (c) and (a), and they are averaged (33), and are given to a coefficient multiplier 5, and the level (b) is also averaged (34), and is given to an adder 4. The data E in the circuit 2 becomes data (E±b)/(c-a) by correcting a direct current component and gain after passing through the adder 4 and the coefficient multiplier 5, and a D/A converter 6 converts this into a video signal, and detects (7) a synchronous trigger signal and an antenna azimuth angle signal simultaneously. Thereby, a radar video signal can be reproduced by digital processing.