| 摘要 |
PURPOSE:To handle only the position shift of a track magnetic head by applying a capstan motor with an output voltage corresponding to an error in the relative position of a track magnetic head after a pilot signal passes through an AGC amplifier which holds the amplitude of a color burst signal constant during reproduction. CONSTITUTION:A four-frequency signal detected by a head 101 or 102 is amplified by a playback amplifier 106, and then separated by an LPF together with a frequency component of chroma and AGC-amplified by a chroma AGC circuit 110. The chroma signal and four-frequency signal inputted to a gain control amplifier 201 are amplified, only the color burst signal is extracted by a burst gate 202 and then amplitude-detected, and a signal corresponding to an increase or decrease in amplitude 204-A is fed back to the amplifier 201, so that amplitudes of the chroma signal and four-frequency signal are made constant. The amplitude difference of a difference frequency signal is calculated to obtain an error voltage corresponding to the basic position shift of the head.
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