JPS6486373A - Pointer signal generating circuit - Google Patents

Abstract

PURPOSE:To generate a pointer signal by discriminating the waveform and polarity appearing just after the reduction in the data amplitude likely to generate a dropin or regarded to be noise or dropin so as to decide more accurately that the error may be occurred. CONSTITUTION:Since a flip-flop 7 is reset by a signal (h) and set by a signal (g), no NRZI signal (j) (figure i) is disturbed by a dropin signal g-1 (figure g) corresponding to a noise signal shown in a-1 in figure (a). In case of a signal h-4 (figure h) corresponding to a noise signal shown in a-4 in the figure (a), however, inversion i-4 shown in the figure (i) is occurred and a data inversion 1-5 corresponding to a-5 shown in the figure (a) is no longer produced. In the digital data recovery circuit (a) as above, no error data is generated in a-1-a-3 shown in the figure (a), no pointer is generated in a pointer signal generating circuit B, and a dropin data is given in a-4 shown in the figure (a) and no correct data is to be reproduced. Thus, the pointer signal generating circuit B outputs a pointer signal.