| 摘要 |
PURPOSE:To prevent disturbance, by detecting the unnecessary video signal in a video signal after setting said video signal to a definite level and detecting the distance difference with an objective video while transmitting the same to a tracking loop when it is judged that said distance difference exerts adverse influence upon tracking. CONSTITUTION:A video signal is suppressed to definite amplitide by a video level limiter 15 and an unnecessary video signal is detected by a second video gate part 16 and a video detecting part 19 while a second signal change-over circuit 20 is changed over. In addition, a signal proportional to the distance difference with an objective video is sent to an error signal detector circuit 18 and, when it is detected that the unnecessary video approaches a distance exerting adverse influence upon an objective video, a signal showing the presence of disturbance is sent to a change-over circuit 20 and an OR circuit 21 to operate a first signal change-over part 7. Further, a control signal applied to a distance gate control part 3 is changed over to the regeneration signal from a regeneration speed signal generating part 9 from the error signal from a distance error detecting part 6 and change-over is continued until disturbance is eliminated. |
