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Upgrading ultrasonic range finder

Posted: Wed Jun 11, 2014 2:00 pm
by markome
I have taken idea "Precision to the Last Micron" posted on and upgraded it by means of extending the distance range. First, i have obtained 40 kHz ultrasonic transducers from Farnell. I have used the same setup than the author in abovemntioned blog, but, instead of using fixed frequency of 40kHz i have created frequency sweep ranging from 39 to 41 kHz. Then i have played the sweep using the pitaya through ultrasonic transducer (tx). I have captured the delayed signal using other transducer (rx).
Then i have detected the time it took for the signal to travel from tx to rx:
I have multiplied tx and rx signals. Since sin(a)*sin(b) = 1/2(cos(a-b)-cos(a+b)) i have got signal which contained 2 spectral lines with frequency difference and frequency sum. From knowing the sweep ramp i was able to calculate the delay and from the delay and speed of sound the distance.
The setup is currently able to measure distance up to 3 m.

Re: Upgrading ultrasonic range finder

Posted: Tue Jun 24, 2014 12:20 pm
by markome
Currently i am describing the solution of ultrasonic range finder in paper which i will submit to IEEE ERK 2014 conference (

Re: Upgrading ultrasonic range finder

Posted: Wed Feb 11, 2015 11:08 am
by PatrickLafont
Your work is quite interesting.
Do you implement all signal processing operations in the ARM core of the Redpitaya, or on the computer side ? Implementing on the ARM core would be very useful, as we can make stand alone meter with the Redpitaya.

Re: Upgrading ultrasonic range finder

Posted: Tue Apr 26, 2016 9:11 pm
by jerzydziewierz
The speed of sound in air is highly dependent on things such as humidity, pressure, temperature and local air vortices,

Altough you will be able to get **resolution** in in terms of measuring the phase of the signal, think a bit about accuracy too.

Unfortunatelly, ultrasonic distance meter cannot be nearly as accurate as a laser distance meter. Unfortunatelly, because it would be so much cheaper!