| 摘要 |
PURPOSE:To attain the AGC amplifying operation with a proper gain corresponding to the position of a magnetic head and the variation of the ambient temperature by providing a temperature sensor and a gain control adjusting means. CONSTITUTION:The read signal of a magnetic head 10 is amplified by a head amplifier 11 and has the noise eliminated by an LPF 12 and is amplified by an AGC amplifier 13 and is differentiated by a differentiation circuit 15. A pulse signal 16 which is changed at the zero-crossing point is shaped and is outputted as a read pulse. The ambient temperature of a disk device is detected by a temperature sensor 22 and is converted by an A/D converter 23 and is outputted to a CPU 20. A gain information table corresponding to the position of the head 10 and the ambient temperature is preliminarily stored in the CPU 20, and the CPU 20 retrieves information to generate proper information. This information is converted by a D/A converter 21 and is supplied to the AGC amplifier 13. The AGC amplifier 13 amplifies the read signal passing the LPF 12 with the adjusted gain and outputs the amplification output to the differentiation circuit 15. By this constitution, a recorded data reproducing circuit is obtained which performs the read operation surely with a simple constitution.
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