Measure Distance using Ultrasound Waves

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jumper1127
 
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Measure Distance using Ultrasound Waves

Post by jumper1127 »

I'm working on a project which requires to use an ultrasonic system. I have to objects and want to measure the distance between the two using ultrasound waves. One object has an emitter which sends out an ultrasound wave, and the other object has the receiver. The travel time will be recorded. The product of the travel time and speed of sound will yield the distance.

I was trying to find ultrasonic transducers online to accomplish this task. However, most of the products have certain beam patterns so they can only focus in an area. My requirements are:

(1) The emitter (receiver) can send (receive) ultrasound waves in 360 degrees.
(2) The emitter has a wide range, ideally 100 ft. The receiver should be able to detect the sound wave 100 ft away from the emitter.
(3) The result should be accurate. The calculated distance should be actual distance +/- 5 in.

I'm not sure where I can buy an emitter or receiver without a beam pattern. I only found one transducer with a range of 60 ft, but it is still not good enough. This is not my major study area so I have to learn everything from scratch, but the project has to be done as soon as possible. I'd really appreciate any help and suggestions.

Thanks!

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philba
 
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Re: Measure Distance using Ultrasound Waves

Post by philba »

sounds like a school project.

You have conflicting requirements - you want distance and a 360 degree pattern. Inverse squared rule says power falls off with the square of the distance (1/d^2). so to go 20 feet requires 4 times the power to go 10 ft. I've never seen an omnidirectional emitter, either. You might consider putting a highly directional (narrowest beam you can find) on a rotating platform and do a scan like a radar antenna. And, pump up the power out. I have no idea if that will actually work, though.

There are a ton of ultrasonic ranging projects out there for you to steal, er borrow, from.

good luck

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adafruit_support_bill
 
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Re: Measure Distance using Ultrasound Waves

Post by adafruit_support_bill »

Is there some other connection between emitter and receiver? How do you calculate the travel time unless you know both the send & receive times?

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philba
 
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Re: Measure Distance using Ultrasound Waves

Post by philba »

I thought about this some more. You could use a parabolic microphone to increase the gain of your receiver. You could use multiple emitters to create an omnidirectional effect.

jumper1127
 
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Joined: Wed Feb 08, 2012 5:26 pm

Re: Measure Distance using Ultrasound Waves

Post by jumper1127 »

Thank you very much for your replies!

Yeah, I think we would go with multiple emitters around a circle. But how to achieve the long range? I was thinking to increase the voltage across each emitter, but there must be an upper limit. Are there any other options?

The receiver has to be able to receive sound waves from all directions too. Do you think the parabolic microphone can be applied here? I feel like it should be facing the emitter, otherwise it may block the sound waves.

The emitters and receivers will be connected to some microcontrollers, which have wireless communication ability.

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