An Ultrasonic-Or-Optical Pulse Sensor For Precise Distance Measurements.pdf

SIcon/05– Sensors for Industry Conference
Houston, Texas, USA, 8-10 February 2005
An Ultrasonic/Optical Pulse Sensor for Precise Distance Measurements
Darold Wobschall, Ming Zeng and Bhooma Srinivasaraghavan
Department of Electrical Engineering, University at Buffalo, Amherst, NY 14260
and
Esensors, Inc., Amherst NY 14226
Abstract - bined ultrasonic transit time and optical time. Wind and other atmospheric disturbances usually
pulse method described here is an improvement over the limits the range to about 1 to 5 meters with an uncertainty
standard ultrasonic echo by providing a lower signal loss and of 1-5 cm for head-on echoes.
more precise location of sensor reference points, specifically We describe here a sensor bines ultrasonic
the transmitting and receiving transducers. transit time and an optical pulse method. It is an
The ultrasonic transit time sensor described here uses only a
one-way ultrasonic pulse. The transit time, typically to 50 improvement over the standard ultrasonic echo method by
ms, is proportional to the distance between the ultrasonic providing a much lower signal loss and more control of the
transmitter and receiver transducers. There are three ultrasonic transmitter and receiver signal shapes.
advantages: (1) the ultrasonic signal loss is much less, (2) the
location of the transducers is well defined, and (3) the