Hello, I have few 40kHz T and R ultrasonic transduces, and don't have any info about thier beam width, can anyone let me know how to measure their beam width please?
Thanks in advance
- posted
17 years ago
Beam width!
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- posted
17 years ago
If they're like the bunch I have in my junk box... pretty wide. I used them as motion detectors for an alarm system design, and they covered a 4' hallway within a few feet away from the transducer.
"Measure"? I don't know :-(
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
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| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
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- posted
17 years ago
Measure ... lets see, if you position both of them in free space, meaning without refections from anything, and have them rotateable around 3 axis, then operating them should give you an idea. Beam width means where the signal drops off by 3dB.
Rene
-- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
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- posted
17 years ago
Hello Adam,
Basically by CW transmission and then rotating the receiving tranducer on a circular arch around the transmitter. Ideally you'd want a professional sound pressure sensor as a receiver but a crystal should do for a rough overview. Lots of web resources, such as this one:
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-- Regards, Joerg http://www.analogconsultants.com
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- posted
17 years ago
You can get a rough idea about the beamwidth of simple circular transducers with the following equation:
bw = 2*asin(lambda/(2*D))
where lambda = wavelength = c/f D = diameter of the active face of the transducer
In air at room temp, lambda is appx (345 m/s)/(40kHz) = 0.00863 m =
8.63 mm.Be sure wavelength and diameter use the same units (e.g. meters, inches, rods, ...).
If you want a slightly more accurate answer, the "2" in the equation is closer to 1.9436.
-- Mark
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- posted
17 years ago
Set up a test bench in a soundproofed room - maybe hang blankets on the walls or something, and ping the TX and move the RX around and see what you get.
Good Luck! Rich