| 摘要 |
<p>A plan position indicator contains a CRT, a deflector system, a deflector timing circuit generating deflection signals, an intensity modulation circuit for the tube and a video amplifier producing, from the input video signal, a picture signal for the tube having an amplitude lying within a defined envelope. During the sweep time the envelope amplitude of the signal, which is formed from the modulation and picture signals and influences the ray intensity, increases with time so that the brightness of the targets and concentric circles diminishes towards the screen's edge. Alternatively, the envelope amplitude may vary linearly with time or may be constant, in which case the intensity modulation amplitude increases.</p> |
