| 摘要 |
PURPOSE:To automatize the operation of the titled circuit and eliminate mistakes in the operation, by switching the original latter signal and color adder letter signal to each other depending on the existence of the burst of an input super signal. CONSTITUTION:A signal to be superimposed is supplied to a band pass filter 2 of a central frequency 3.58MHz through an input terminal 1 and only the chromatic component of the signal is fetched and supplied to a burst gate circuit 3. On the other hand, an input from the input terminal 4 of the signal for the burst gate is supplied to the burst gate circuit 3 and supplied to a burst detecting circuit 5. The burst detecting circuit 5 obtains an output signal converted into a DC signal depending on the existence of the burst component and supplies the output signal to a switching circuit 8. Moreover, an original letter signal and color adder latter signal are inputted through an input terminal 6 and input terminal 7, respectively, and they are supplied to the switching circuit 8. They are fetched after switching to the original letter signal when the burst component exists and to the color adder letter signal when no burst component exists. |
