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Unformatted text preview: oscillation. This AC voltage is switched through to the ceramic module by means
of a pulse generator, when the transmitting pulse is to be emitted. Distance
measurement is calculated according to the ultrasound propagation time. A ramp
generator is triggered at the time of transmission, which generates a timedependent voltage. Thereupon, the piezoceramic module is switched over to
receiving. The ultrasonic signal is reflected if an object is present in the active range
of the proximity sensor. The proximity sensor receives the signal and the ramp
generator is stopped. The voltage level is evaluated at this point and an output
signal emitted. 184 © Festo Didactic GmbH & Co. KG • FP 1110 11. Physical fundamentals D α 1
2 Near field (~D /λ) (1) 2 Far field (2) Fig. 11.3.8: Sound emission characteristic of an ultrasonic transducer An object must not be present in the sound field of the proximity sensor within the
so-called near field, as this can lead to error pulses at the proximity sensor output.
For an ultrasonic proximity sensor with a transdu...
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This note was uploaded on 11/01/2012 for the course CHEMICAL 102 taught by Professor Jamesrodriguez during the Spring '12 term at Universidad Politécnica de Cartagena.
- Spring '12