Apparatus for converting measurement signals into digital signals, the signals having been initiated in a piezo sensor by the impacts of a hydraulic percussion device

An apparatus for converting measurement signals into digital signals suitable for processing in a microprocessor (12), with the signals having been initiated in a piezo sensor (6) by accelerations acting on the sensor during the impacts of a percussion device (1), particularly a hydraulic hammer, and being used to determine the number of work strokes that have been executed in the impact direction (arrow 3) of the percussion device (1). The conversion apparatus includes: a rectifier (8) that is connected to the output (6a) of the piezo sensor (6) and suppresses the negative component of the measurement signal; a peak-value detector (9) that is connected to the rectifier (8) and converts the remaining, positive component of the measurement signal into an envelope curve; a high-pass filter (10) that causes the envelope curves of consecutive measurement signals to be converted into intermediate signals whose amplitude respectively has a zero passage; and a comparator (11) that is disposed downstream of the high-pass filter (10) and whose output is connected to the digital input (12a) of the microprocessor (12), thereby effecting the conversion of the intermediate signals into digital signals having a rectangular amplitude response.