Boots – shoes – and leggings
Patent
1990-02-26
1992-11-10
Lall, Parshotam S.
Boots, shoes, and leggings
364569, 377 20, G01B 1702
Patent
active
051630133
ABSTRACT:
A device for measuring ultrasound transit times in workpieces disposed over an HF pulse generator which generates high-frequency wave trains with few oscillations periods and which is connected with an ultrasound transmitter/ultrasound receiver, whose output signal acts upon a comparator. The comparator generates pulses on zero crossings of the ultrasound echo. Between a gate circuit and a counter there is provided an AND-gate, whose second input is acted upon with the output signal of the comparator. The time gate of the gate circuit can be positioned, computer controlled, a quarter-wavelength of the ultrasound before the maximum of the envelope curve signal of the amplified ultrasound echo, so that it always equal-lying steepest zero crossing triggers the start or stop impulse of the counter. The time gate is positioned at a fixed time spacing to the time point A given by the threshold value, so that through the envelope curve transit time variations affecting as a whole, for example in the case of a conical widening of the workpiece to be detected, the time gate still surely detects the zero crossing to be separated.
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Herzer Rudiger
Schneider Eckhardt
Casimano Edward R.
Fraunhofer-Gesellschaft zur Forderung der ange-wandten Forschung
Lall Parshotam S.
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