| 摘要 |
PURPOSE:To normalize the level of a picture signal by detecting the size of a synchronizing signal in an input or output picture signal so as to generate an error signal and controlling a gain for the input picture signal to keep the level of the output picture signal constant. CONSTITUTION:When a synchronizing signal detecting means 21 detects the size of a synchronizing signal in the input or output picture signal of an image transmitter, and error detecting means 22 compares the size of the detected synchronizing signal with a fixed reference value and generates the error signal. Then, a gain control means 23 controls the gain of the image transmitter according to the error signal and keeps the level of the output picture signal constant. Even if the level of the input picture signal varies, the level of the picture signal in the input of a transmitter is compensated, so that the picture signal in a normal level can be equivalently obtained in a subsequent circuit.
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