| 摘要 |
PURPOSE:To easily set up a frequency correcting coefficient by a simple circuit constitution by adding a frequency characteristic correcting reference signal to a horizontal or vertical blanking period and detecting the reference signal. CONSTITUTION:A reference signal generating circuit 3 generates a reference frequency signal in a frequency band to be corrected such as sub-carrier frequency to be added to a prescribed position of a horizontal blanking period. The reference frequency signal outputted from the circuit 3 is added to an input video signal by an adder 2 and the added signal is impedance-reduced through an impedance converter 4. An output from the converter 4 is inputted to a smoothing amplifier 8 and a wide band amplifier 9 through a coaxial cable 5. A multiplier 9 is controlled in its multiplication rate in accordance with the level of the reference frequency signal set up in a setter 17 and multiplies respective video signals outputted from both amplifiers 8, 9. Consequently a frequency correcting coefficient can easily be set up by the simple circuit constitution.
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