Some effects of non-linear switching and rectifier components on the driving and echo-graphic traces of NDE transceivers were analysed. Limitations of previous approaches have been overcome by means of accurate circuital models for the whole pulse-echo arrangement, showing how the non-linear devices can exert a double influence on this ultrasonic configuration:
• The first, advantageous, by avoiding the lengthening of driving pulses and the narrowing of echo signal bands, when NDE transducers are tuned by inductive components.
• The second may be harmful because, during signal reception,some elements of the inactive transmitter can induce distortions in the echoes, selectively as of a certain positive voltage value.
Therefore these non-linear devices improve system efficiency while shortening pulse lengths. But some precautions must be taken because high amplitude echo signals could suffer important distortions of an asymmetrical kind, depending on the device ‘‘on’’ thresholds.
Some effects of non-linear switching and rectifier components on the driving and echo-graphic traces of NDE transceivers were analysed. Limitations of previous approaches have been overcome by means of accurate circuital models for the whole pulse-echo arrangement, showing how the non-linear devices can exert a double influence on this ultrasonic configuration:• The first, advantageous, by avoiding the lengthening of driving pulses and the narrowing of echo signal bands, when NDE transducers are tuned by inductive components.• The second may be harmful because, during signal reception,some elements of the inactive transmitter can induce distortions in the echoes, selectively as of a certain positive voltage value. Therefore these non-linear devices improve system efficiency while shortening pulse lengths. But some precautions must be taken because high amplitude echo signals could suffer important distortions of an asymmetrical kind, depending on the device ‘‘on’’ thresholds.
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