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1  Using Arduino / Sensors / Re: srf08 making audible "chrimp" while ranging on: February 18, 2013, 10:08:19 am
Hi,

Thank you for your smart comment.

No i am not a dog. If you read my original post carefully you will see that my problem is human audible chrimps while sending the ping signal. Which frequency is definately in the human audible range.

Here is a video of my problem:


Sound level of the video is quite low. 
2  Using Arduino / Sensors / Re: srf08 making audible "chrimp" while ranging on: February 14, 2013, 07:59:28 pm
Thank you very much for your response and explanation. I unfortunately can't even start to comprehend all of the concepts you are talking in. But it opened my world a bit.

My level of expertise right now is about as high as choosing the right part if i know what to look for , and go/learn from there.

Maybe someone has experience with other ultrasonic sensors and can elaborate, if some of them are more silent than others? Whatever the range or accuracy or interface. Or some literature which could be useful on the subject.

Thank you!
3  Using Arduino / Sensors / Re: srf08 making audible "chrimp" while ranging on: February 14, 2013, 10:28:46 am
If DC bias would be the problem, what would one consider while designing a ultrasonic sensor from scratch? better filtering?
4  Using Arduino / Sensors / srf08 making audible "chrimp" while ranging (added video of the problem) on: February 14, 2013, 04:41:10 am
Hi,

I am using an ultrasonic rangefinder srf08 with an arduino and almost everything is working well. Signal is stable and accurate. But for my suprise every time the sensor emitts the 40khz ping it also has an audible, much lower frequecy sound to it.It is quite loud and annoying if pointed to a person. For my purposes any sound under 20khz is unacceptable. IS this a normal thing for ultrasonic rangefinders or to this particular model? Or i have a faulty model?. I can make a sound recording if needed for further analysis.

Any help is much appreciated. I have searhed the forum , and the best explanation I found is that the extra sound comes from the air moving next to the transducer. Is this true? are there quieter models out there if this would be the case?
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