| 摘要 |
PURPOSE:To stabilize transient response by an AGC circuit for a reproduced signal varying in level according to the radius-directional position on a magnetic disk, by varying a clamping voltage for an AGC control voltage according to the reproduction position of the disk. CONSTITUTION:The output signal of a main amplifier 5 is inputted to a VAGC generating circuit 10 and compared with a clamping voltage VR to be clamped up to a constant value, and when it exceeds the constant value, an AGC control voltageAGC is outputted to an AGC amplifier 4. When a squelch signal is inputted to set an initial squelch period, the AGC control voltage AAGC is fixed at a constant level during the squelch period and on the squelching operation, a transient response is made. A circuit 14 consisting of resistances RN... and gates GN... is provided correspondig cylinder addresses sectioned according to the position on a disk, and the clamping voltage VR is varied according to the position on the disk. |
