Evaluation circuit for digitally encoded signal, has shifter which switches between upper and lower threshold values used in comparator

摘要

The circuit includes a control unit (2) connected to a data signal input (1), and comprising a reference clock input (3). A counter has its input connected to the control unit and provides an output corresponding to the period (T,2T) of the digital signal. A comparator (5) coupled to the counter compares the count value with upper and lower thresholds. A shifter (9) switches between two upper threshold values (T2, 2T2) and two lower threshold values (T1, 2T1). An evaluation unit (11) is coupled to the comparator and provides an activation signal at its output if the count value lies between the thresholds.