| 摘要 |
PURPOSE:To unify a circuit constitution in one system and to reduce the scale of the circuit by controlling tracking with two difference frequency signals outputted by a multiplying means and discriminating the recording speed. CONSTITUTION:The multiplying means 18 multiplies the signal of one of frequencies f1-f4 satisfying relations f2-f1=f3-f4=fA and f4-f1=f3-f2=fB by a pilot signal to obtain the difference frequency signals of the frequencies fA and fB. Further, a differential amplifier circuit 27 and a capstan motor 28 samples the level difference between the two difference frequency signals outputted by the means 18 at a period which is 2n times (n: positive integer) as long as a period at which a rotary head scans an information signal to control the tracking of the rotary head. The discriminating circuit 34 of logic circuit constitution, on the other hand, discriminates the recording speed according to the period of at least one of the two difference frequency signals. Consequently, the circuit constitution for the tracking control and the recording speed discrimination is unified in one system.
|
