SELF-DEAGNOSTIC CIRCUIT SYSTEM FOR REGENERATIVE REPEATER

PURPOSE:To prevent the output characteristics of the regenerative repeater from deteriorating by varying the Q value of a tank circuit corresponding to the value of the parameter of the output of a parameter detection part which varies with the ambient temperature. CONSTITUTION:A diode D4 is connected in parallel to the resistance R0 of a tank circuit 8'. The output signal of the regenerative repeating LSI 9 is applied to a bipolar/unipolar converting circuit 11 through transformers T2 and T3 to convert the bipolar signal into a unipolar signal, which is applied to an error detector 12, thereby measuring the error rate of the output signal. The measured value of the error rate is applied to a CPU 13 and compared with a preset reference value; when the measured value becomes less than the reference value, a control signal is sent out to a relay driving circuit 14 to make the contact 15 of a relay in the tank circuit 15 with the control signal from the CPU 13, thereby making the Q value of the tank circuit 15 small. Consequently, a shift in the discrimination point of an eye pattern is absorbed to correct noise tolerance.