Ultrasonic sensor and Prop

Cenlasoft

Hello,
I have a pair of ultrasonic sensors (Tx,Rx) I bought from Jameco. Can one of the senors be used for both TX and RX? Is there a difference? I know you have the Ping, but I want to learn how to manually make an ultrasonic transducer for subsurface analysis of metals. I am thinking one could send a 40 KHz pulse and listen for the signal. Amplify it with a 741 OPAmp maybe.
Thanks,
Curtis

Mike Green

The transducer rings for a while after the pulse of sound is generated and the ringing would prevent its use as a receiver as well as a transmitter for a while after transmission. This would limit the range possible when used as a distance sensor. Usually the transducers are the same and either of a pair could be used for transmitting or receiving. For many applications (like fish locators and medical ultrasound) the range during operation is such that a single transducer can be used.

Cenlasoft

Thanks Mike,
I see on the Ping that the two sensors are side by side. Is that because the sound wave is propagated in the material and any where on the surface reflect back? Should they be at 45 degrees to reflect back?
Thanks,
Curtis

Toby Seckshund

45 degrees would imply that the surface is very close to both the sender and receiver.

There has to be a minimum distance to the reflective surface to mask the Rx from the trasmission still leaving the transmitter, wait a while whilst things settle down and get ready for the wanted reflection to arrive back, which will be at a vastly reduced level, all at the speed of sound.

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Mike Green

There's a chart in the PING))) documentation that shows the sensitivity of the PING to objects relative to their off-axis position.