Focused Ultrasonics

@Inq

Since you're not being overburdened with responses, I'm going to lead you even farther into left field ...

Well over 50 years ago, I was attending a Science Fair where one of the exhibits was a "spy listening device" which consisted of 36 tubes about 12 mm inner diameter (1/2" to you) ranging in length from 1", 2", 3", ... 34", 35", 36" stacked together with the longest in the centre and the others wrapped around the central tube to form a device looking similar to an old Gatling gun.

At the back of this nest of tubes was a small dish with a pre-amp that led off to an amp and a set of earphones. The idea was that each tube collected its signal from the frequency range corresponding to the tube's length and that the mixed signal received and magnified by the pre-amp then reconstituted the sound back into its original state.

I was not able to test the device (access was strictly controlled, which led me to believe that it wasn't a particularly strong performer). It didn't win the Fair (and neither did I) but it made a lasting impression.

Are we talking about Elementary school Science Fairs?  I think they've done away with them here in the states.  We can't have intellectual competition anymore... everyone has to get a blue ribbon or they may feel left out.  🙄 

... or are you talking about something in Canada or something for adults?

I'm not sure what that experiment would buy you... separate the frequencies in the physical work, but recombine them in the electronic world.  I guess it would semi-digitize the input, but it would also attenuate it.  But... not every experiment has bare fruit to be beneficial.  Many a thing can be learned from failures.  Edison will certainly attest to that.

VBR,

Inq

I think that a tube of some sort would reduce the accuracy of the HC-SR04. Let think about the physics behind wave reflection. Since the wave will potentially be reflecting off of the sides of the tube instead of the target it will add to the time between the transmit and receive time. If anything I think that the sound wave may never make its way back to the sensor. I think the angles are most at play here. If the sensor is perfectly perpendicular to the shaft of the tube you may have some good results. If it is off by just a millimeter you may hit the tube walls and bounce off them until the wave either transfers all its energy to the tube or hits the receiving sensor.

I am by no means a expert. Just my ideas. I would like to see what an experiment would give us!

@inq 

I don't much care for our mainstay, the infamous HC-SR04 ultrasonic sensor.

Sonar works well for dolphins!

There are sophisticated sonar devices used in medicine such as checking an unborn baby. I remember the operator showing me the beating heart of our first child where you could see the valves open and close. They used sonar to check my heart a few  years ago. It color coded the velocity of the blood flow.

Some blind people have learned to "see" with sound using verbalized clicks. Not sure if stereo sound is also part of it using their two ears.

I have seen the HC-SR04 being used to make an impressive (in my opinion) "radar".

I will play around with the sensors to see for myself just how well they can be used to detect objects and measure rooms and report back to the forum.

https://dronebotworkshop.com/hc-sr04-ultrasonic-distance-sensor-arduino/

"the NewPing library has implemented a number of internal techniques to improve the accuracy of the sensor."

Below is one of my robots with an arrangement of 5 sonar sensors. I had intended trying other layouts.

You might note with the wooden floor a visual system could determine orientation and even use the unique textures to locate exactly where it was.

To enlarge an image, right click image and choose Open link in new window.