Hi guys, I need to do a project to measure the speed of sound underwater in a sewer pipe with a diameter of 11 cm and a length of 1.1 m, does anyone have any ideas? I ordered a sensor from Aliexpress JSN SR04T to test it underwater, the results are disappointing, it does not measure the distance under water, I took into account in the code that the readings in water are 4.4 times greater than in air. But alas, as soon as I place my sensor under water in the pipe at an equal distance, its readings do not change. Therefore, I wanted to ask you if it is possible to measure the distance under water with it, or if this idea is a failure, if this sensor does not fit, then tell me which one can be suitable for measuring under water or throw an idea for the implementation of my project?
Measuring in a diesel fuel pipe was done some 35 years ago, so yes, with the proper gear. Please post a (m)link to the datasheet of that sensor system.
Have you tried your sensor in an empty pipe? I don't think they are very directional so there may be lots of reflections from the walls to confuse the signal processing.
Will the pipe be full of water in operation or part full?
Hello, I haven't tried measuring in the pipe yet, but I tested the sensor by simply moving it away to a distance known to me and it displayed an almost exact value on the LCD display. I'll test it in the pipe, but I don't think anything will change in a coordinated way. Yes, I planned to fill the pipe completely with water and try to test this sensor, but before that I tried in the bathroom, placing the sensor horizontally, the length of the bathroom is about 1m, and when the readings from the sensor did not change, it gave 84 cm.
Bathroom or bath?
bath
Read what is written about under water test! It says: Failure.
The speed of sound in water would be some 4.4 x 300 m/s. 1320 m/s. If the flow changes by 1 m/s it's a change of 1 part per 1320, below the resolution of a 10 bit A/D converter that's common in Arduinos.
EDIT: It's not an anlog signal but a digital pulse. Me being too fast. Corrected below.
Yes, I read about it. That's why I asked you to recommend me other sensors from Aliexpress that will work underwater or other thoughts about my project, maybe you can offer something or there are some articles about measuring the speed of sound underwater. Because I don't find anything sensible.
Would be a great place to see how others may be doing the thing.
A search using words "diy underwater drone plans" is also a good source of info about how others are doing it.
Ultrasonic transducers intended for air do not work underwater, because the impedance match is so bad. You can buy sonar transducers for operation in water, but they are expensive.
I have tried to post a mink many times and they always fight there way out of the padded bag.
Haha. Maybe the mink will find the datasheet faster than the OP?
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