| 摘要 |
A circuit for use in a television receiver to obtain a variable-length bar on the television screen which indicates the optimum antenna position, the circuit comprised of at least two monostable multivibrators with input terminals triggered by horizontal and vertical synchronizing pulses and with outputs coupled through an AND circuit to a video/chroma driver amplifier. The pulse length of one of the multivibrators is caused to vary in relation to the strength of an AGC signal in the video signal path of the receiver by coupling the AGC output to the time-constant-determining network of the multivibrator.
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