Abstract: According to the present invention, to drive a magnetron, a pulse voltage is applied to the gate electrode of a field effect transistor to make the field effect transistor conductive, so that a voltage stored in a storage condenser is discharged through the primary winding of a pulse transformer and the drain electrode-the source electrode of the field effect transistor. This discharge causes the voltage generated at the primary winding of the pulse transformer to be induced at the secondary winding of the pulse transformer. Thus, the magnetron connected to the secondary winding of the pulse transformer is driven.

Abstract: A detection system uses a radar apparatus for displaying conditions of the surrounding geographical and an area marker defining a selected geographical area. The area marker and conditions are displayed on an indicator. If a target is determined to be in the area marker, an alarm is activated. The area marker is indicated by specifying only two points on the screen of the indicator.

Abstract: A fish school detecting method or apparatus radiates radio search signals with their carrier frequency in the S-band frequency range, successively in different azimuthal directions through a wide angular range, receives echo signals, and displays the echo signals on the screen of an indicator in such a manner that the echo signal reflected by a bird is clearly distinguished from the other objects, thereby locating the bird and detecting a fish school under the bird.

Abstract: In a radar system with a plan position indicator, deflecting coil rotation is synchronized with antenna rotation by developing a train of pulses related to antenna rotation for driving a pulse motor controlling coil rotation. Synchronization is achieved by producing a pulse upon a predetermined displacement of the antenna.

Abstract: A push-pull switching circuit including two grounded emitter transistors 5, 6 controlled by a pair of AND gates 3, 4. The collector output of each transistor is fed back to an input of the AND gate controlling the other transistor, the remaining AND gate inputs being supplied by the Q and Q outputs of a flip-flop circuit 2. During the prolonged conduction of each transistor due to minority carrier storage, its lowered collector potential prevents the enabled AND gate for the other transistor from raising its output and initiating conduction, thereby avoiding overlapping or simultaneous transistor conduction.