Patent ID: 6737981
Filing Date: 2004-05-18
Classification: G01D,H03M

Abstract:
An apparatus for converting measurement signals into digital signals, with the measurement signals having been initiated in a piezo sensor by accelerations acting on the sensor during the impacts of a percussion device and being used to determine the number of work strokes that have been executed in the impact direction of the percussion device with the digital signals being suitable for processing in a microprocessor, said apparatus comprising:a rectifier that is connected to the output of the piezo sensor and suppresses the negative component of a measurement signal produced by the piezo sensor; a peak-value detector connected to the output of the rectifier and converting a remaining, positive component of the measurement signal into an envelope curve; a high-pass filter connected to receive the envelope curve produced by the peak value detector and causing the envelope curves of consecutive measurement signals to be converted into intermediate signals whose amplitude has a respective zero passage; and a comparator, whose input is connected to the output of the high-pass filter and whose output is connected to a digital input of the microprocessor, for comparing the intermediate signals provided by the filter with a reference signal to effect the conversion of the intermediate signals into digital signals having a rectangular amplitude response.