Unreliability detector apparatus and reproduction apparatus provided

Abstract

An unreliability detector apparatus for generating an unreliable decision signal in response to an input signal. An input terminal receives the input signal, a first comparator unit compares the input signal with a first threshold value and a second comparator unit compares the input signal with a second threshold value. A processor is provided for carrying out a function for determining whether a curve in an X-Y plane has at least one point in common with a predetermined line in the X-Y plane. The curve in the X-Y plane is obtained by plotting time equivalent signals values of the first and second comparator output signals along the Y- and X-axis respectively of the X-Y plane, while the predetermined line in the X-Y plane is formed by a first line interconnecting a first fixed point and a second fixed point and in which half plane a third fixed point is located. The three fixed points are obtained by plotting combinations of a first through a fourth signal value along the X- and Y-axis. The processor is adapted to generate the unreliable decision signal upon detecting that the curve has at least one point in common with the predetermined line. An apparatus for reading information from a record carrier may be provided with the unreliability detection apparatus.