Amplitude detector for signals having a periodical character, recorded on a recording medium, and optical tape recorder comprising such an amplitude detector

An optical tape reproducer comprising:

• means for reading signals having a periodical characteristic from an optical tape;
• an amplitude detector for the periodical signals, including:
• first and second delay lines, each delaying the output of a stored value for a predetermined detection period;
• means for storing an average value of the maximum value of a detected signal during a detection instant in the first delay line in a different location for each of a predetermined number of detection instants within the detection period, the average being for the same instant in the detection period over multiple detection periods;
• means for storing an average value of the minimum value of the detected signal in the second delay line in a different location for each detection instants, the average being for the same instant in the detection period over multiple detection periods;
• means for determining an average level between the average maximum and minimum values for each detection instant depending on the output signals of the two delay lines;
• and
• means for comparing a detected signal for a detection instant with the average level for the detection instant so as to provide a detection signal.