JPS6423405A - Data discriminating circuit for digital magnetic recorder - Google Patents

Abstract

PURPOSE:To remarkably improve the accuracy of data discrimination by using a low pass filter built in a variable frequency oscillator so as to eliminate completely the jitter included in an output signal of a zero cross circuit. CONSTITUTION:An input analog signal S1 is supplied to a differentiation circuit 1, where the signal is converted into a signal S2 representing a zero cross point corresponding to the peak point of the signal S1, and the result is given to a zero cross circuit 2, from which a signal S3 whose level changes from a high to a low level at the zero cross point is supplied. The significant part of the signal S3 as a data is a part descending to a low level from a high level, and since jitter is included in the significant part, the signal S3 is supplied to a variable frequency oscillator 3 incorporating a low pass filter, where the jitter is eliminated and the resulting signal S4 is given to a discrimination logic circuit 5. Simultaneously the signal S1 is fed to an amplitude detection circuit 4, from which a high level signal S5 is given to the circuit 5 and a discriminated signal S6 is obtained.