| 摘要 |
<p>PURPOSE: To efficiently detect a pilot signal in a small-size circuit by recording two pilot signals to alternate tracks and scanning one track by two heads each having an overlap area when data are reproduced. CONSTITUTION: Reproducing signals including pilot signals f1 , f2 from heads 21, 22 are turned to signals (g), (h) via filters 301, 302. The signals are inputted alternately to a detection circuit 313 via an A/D converter 304 with a sampling frequency through a switch 303 controlled by an exclusive OR circuit 305. The amplitude of each signal f1 , f2 is detected in a time division multiplexing method and signals proportional to the respective amplitudes are alternately output. The output signal is delayed at a delay 413 and a difference from the original signal is obtained at a subtracter 411. Only a desired signal is outputted from a latch 412 to obtain a tracking error signal. Since the shifting direction by a track scanned by the head 21, 22 and the polarity of the output of the latch 412 are different, the code is reversed according to the track at a polarity inverter 601 and finally the tracking error signal is outputted.</p> |
