JPS6476404A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To prevent erroneous recognition and loss of effective data by comparing a reference waveform amplitude with the the output waveform amplitude of a waveform equalizer at each time of detecting a tone pattern having a certain logic and controlling the correction so that the error is minimized. CONSTITUTION:A signal Tone-N is inputted at each time of detecting thetone pattern. Switches SW1 and SW2 are controlled by the combination between a logic circuit 12 and a multivibrator 11. Then, a capacitor C3 is charged or discharged when the output of the circuit 12 is in the high level or the low level. The terminal voltage of the capacitor C3 is a lead signal A from a waveform equalizer 3, and a delay signal C is controlled by tap gain circuits C-1 and C+1, and they become signals AR and CR, and they are inputted to a sum circuit SIGMA together with a neutral signal B. The circuit SIGMA performs addition/subtraction of input signals, and the calculated output is compared and corrected by an automatic gain circuit 4, a floating amplifier 5, a differentiating circuit 13, and a comparator 6c. The error of the calculated value of the circuit SIGMA is minimized, and this value is outputted as peak data Q. When data Q is outputted, the tone pattern is synchronously detected again.