| 摘要 |
A video signal processing circuit and method for the insertion of a blanking data signal including blanking pulse, horizontal sync and color burst signal components into an input video signal to provide a modified video signal. The modified video signal is subjected to signal shaping to reduce the slopes of the front and rear edges of the blanking pulse portion in order to suppress transient overshoot and ringing distortion when the resultant output video signal is transmitted through a low pass filter. The signal shaping is preferably provided by a voltage controlled amplifier whose gain control terminal is connected to a control voltage which varies during the blanking pulse and is provided at the output of a slew limited amplifier or a non-linear low pass filter with a sine squared pulse response. The input of the slew limited amplifier is connected to an electronic switch operated by a timing circuit for selectively switching between different gain voltage sources. The timing circuit also applies a switching signal to another electronic switch providing a blanking data insertion means which selectively applies the input video signal or the blanking data signal to the input of the voltage controlled amplifier. An analog to digital converter can be employed to convert the input video signal to a digital signal for storage in a memory and further processing before insertion of digital blanking data.
|
