Tokyo Keiki Company Limited

Yoshio Numaho

Tetsuro Ogawa

Hiroshi Okada

Yoshio Kato

Kiyoshi Arima

A PPI radar apparatus is constructed such that even when a transmission time cycle of radio waves is varied by switchover of a distance range to any of short, middle and long distance ranges, a sweep display time cycle of a radar video signal received in any of the distance ranges is maintained constant at all times; the sweep display time cycle is determined to meet the middle distance ranges, in the short distance ranges in which the reception time of radio waves is short, the video signals are written in storage means in real-time and then displayed by readout of the video signals at a low speed in synchronism with the sweep time cycle, in the long distance ranges in which the reception time of radio waves is long, the video signals are written in storage means in real-time and then displayed by a number of readouts in one sweep display time cycle; and the video signals written in a plurality of storage means are parallelly read out and a mean value or peak of the read-out video signals is obtained by arithmetic operation to thereby enhance the signal-to-noise ratio of the radar image.

PPI radar apparatus

A sweep termination generating circuit adopts an octagon boundary for sweep termination which is set by combining a plurality of comparators so as to be circumscribed about the display screen of a circular CRT. When the sweep position is deviated from the center of the display screen for the purpose of displaying a radar image by PPI sweep, the circuit allows the comparators to detect that a scanning signal for scanning an electron beam from the off-center sweep position has reached the boundary for sweep termination and thereby generates a sweep termination signal.

Sweep termination signal generating apparatus for radar system

A PPI display apparatus allows a radar image or bearing marker to be displayed on a circular CRT screen through sweeping on the basis of a plan position indicator system. In the apparatus, the generation of a radar antenna angle signal, generation of a bearing angle signal representing the angle of a bearing cursor, generation of an antenna angle signal corrected by adding a deflection angle to the antenna angle, and generation of sine and cosine signals corresponding to the antenna angle or bearing angle are all carried out through digital processing.

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Tokyo, Japan

Yoshio Numaho