| 摘要 |
PURPOSE:To obtain a tracking controlling circuit which does not make any malfunction at the time of drop-out and to eliminate a blind section, by detecting frequencies of large and small azimuth loss effects and discriminating whether it is a blind section or drop-out by using both detected pulses. CONSTITUTION:When a head traces a track A1, on which the pilot signal of frequencies fP and fB of large and small azimuth loss effects is recorded, one level is added to a terminal 18 and an AND circuit 16 is turned on. Then the crosstalk component of adjacent tracks appears in the output of an LPF4 and BPF10 in addition to the fP and fB of the A1 track. Outputs of the LPF4 which detects the fP and the BPF10 which detects the fB are compared with thresholds at comparators 15 and 12 through envelope detecting circuits 5 and 11 and the voltage of a supply voltage 23 is outputted as an erroneous voltage by selecting the 24B side of a switch by outputs of fall detecting circuit 19 and rise detecting circuit 13 through an RS latch 22. When the pilot signal lacks due to a scratch, etc., the RS latch 22 is not reset and previous data are held.
|
