How Do Ultrasonic Distance Sensors Work? -- The Learning Circuit 85

How Do Ultrasonic Distance Sensors Work?

The Learning Circuit | element14 presents | Project Videos

In this video, Karen talks about ultrasonic distance sensors. These sensors use high frequency sound, above human hearing, to detect objects within their range. Unlike other no-touch sensors, they can not only detect if there is an object within range, but also how far away that object is. Check out the video to watch Karen explain more about how these sensors work.

Supplemental Content

The Learning Circuit 46: Introducing Microphones and Speakers
The Learning Circuit 79: How Accelerometers Work
Arduino Nano bot - using ultrasonic sensor by carmelito
SoundFi - Transmitting Data Using Sound (Ultrasonic Sound) by vimarsh_
PSoC ultrasonic range meter by koudelad
The specified item was not found. by Sean_Miller
1DUltraBot #3 : Finished (and working!) by dubbie

Top Comments

Parents

DAB over 4 years ago

Good presentation Karen.

One nit, I would not use c to represent the speed of sound.
c is universally used to represent the speed of light, so using it for sound could confuse some people.

DAB
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jc2048 over 4 years ago in reply to DAB

The speed of sound in mathematical notation is conventionally represented by c, from the Latin celeritas meaning "velocity".

https://en.wikipedia.org/wiki/Speed_of_sound
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DAB over 4 years ago in reply to jc2048

It is not a universally known notation as I never encountered it during my work career.
The speed of sound was usually given as a mach number with altitude.
c was always the speed of light.

So I do not know where wikipedia came up with that notation, but it was not part of my physics or engineering use.

DAB
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beacon_dave over 4 years ago in reply to DAB

"...So I do not know where wikipedia came up with that notation..."

Oxford Dictionary of Physics perhaps ?

https://www.oxfordreference.com/view/10.1093/acref/9780198821472.001.0001/acref-9780198821472-e-2875

"Symbol c or c_s. The speed at which sound waves are propagated through a material medium."
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beacon_dave over 4 years ago in reply to DAB

"...So I do not know where wikipedia came up with that notation..."

Oxford Dictionary of Physics perhaps ?

https://www.oxfordreference.com/view/10.1093/acref/9780198821472.001.0001/acref-9780198821472-e-2875

"Symbol c or c_s. The speed at which sound waves are propagated through a material medium."
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airbornesurfer over 4 years ago in reply to beacon_dave

I'm just going to jump in on this as well: In my experience, c is pretty common in aeronautical engineering and pilot-level aerodynamics as notation for the speed of sound at a given altitude. Even Mach numbers are defined as M = u/c where u is airspeed and c is the speed of sound at that density altitude.
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DAB over 4 years ago in reply to beacon_dave

I checked my physics books and c is always speed of light.
When I looked up speed of sound they used v or Vs.

So my US text book did not follow the Oxford definition, probably like me, they found it too confusing with the speed of light.

FYI, when I did a project with the Noise and Sonic Boom Information Technology office in the US Air Force, I never saw the speed of sound referred to as c.

DAB
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neuromodulator over 4 years ago in reply to DAB

There aren't that many latin + greek letters to have a single letter for each constant or variable, so of course you have to "recycle" them. The lowercase c is also commonly used for specific heat for instance.
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