Hello,
I am doing a project on finding the depth of water using sonar jsn-sr04t. It calculates the distance in air in range 20 to 800 cm and the results are satisfactory .Now i tried to do in water with same code then whatever the distance maybe it shows the same duration value and distance ie., 1150 and 18cm , I tried upto 55 cm depth in water form 20 to 50 cm there is no change.
May I get any help in solving the problem
You need an underwater transducer to use sonar ranging in water. A transducer designed for air won't work.
Unfortunately, underwater transducers are expensive and generally require high voltages to drive.
hello ,
Thank you jremington for helpful reply.
Then is it waste doing with jsn-sr04t . Is there anyway to replicate it with that sonar.
I have project expo with in 4 days I have to show some output
If you can switch to wave height you can use that sensor. If you need water depth you may be able to get a fishfinder and use the fish. Finder sensor
You know the overall depth of the tank?
You know where the sensor is fixed above the water (and the whole tank depth)?
Subtract the detected surface of the water from the known tank depth?
Voila.
Now you have the depth of the water.
There is at least one report in the "online literature" claiming success using the jsn-sr04t to measure water depth. Whether that report is reliable is open to question.
There are several other reports (that seem reliable to me) claiming success with a Maxbotix sensor. See the links in post #3 and #5 here. The work summarized in post #5 seems especially compelling to me. Some here are not convinced, but the best criticism ("the waterproofing is clumsy") does not speak to the data.
Read the links and make your own judgment.
By the way, if the jsn-sr04t works in water, this...
Saichandu:
I tried up to 55 cm depth in water from 20 to 50 cm there is no change.
...is because the device can't read any closer than 20 cm in air, and since the speed of sound in water is about four times faster than in air, the device will not be able to read any water depths less than about 80 to 90 cm.
The DS1603 sensor can do just that: measure the depth of the water, when attached to the bottom of the tank. It also bounces ultrasound waves off the surface of the water. Not too expensive - RMB 85 on Taobao; around USD 25 on e-bay. So far one of the cheapest methods I've found for directly measuring water depth at this level of precision.
I have one on order - it was discussed not long ago on this forum. Very promising specs, hope it works as promised. Hope to have it by the start of next week.
wvmarle:
The DS1603 sensor can do just that: measure the depth of the water, when attached to the bottom of the tank. It also bounces ultrasound waves off the surface of the water. Not too expensive - RMB 85 on Taobao; around USD 25 on e-bay. So far one of the cheapest methods I've found for directly measuring water depth at this level of precision.I have one on order - it was discussed not long ago on this forum. Very promising specs, hope it works as promised. Hope to have it by the start of next week.
https://www.aliexpress.com/item/free-shipping-Ultrasonic-liquid-level-detecting-sensor-probe/32827257147.html
An ultrasonic sensor working at 24GHz ? ? ? ?
LOL that kind of things are so often wrong on aliexpress and taobao...
Best strategy is usually to look at the same product from 10 sellers, take the most commonly quoted (and most sensible) numbers, and normally you have the correct ones. Digging up manufacturer's spec sheets is a second strategy to the same. It's like instructables - they give you an idea of how it should be, but you have to do your due diligence.
Are those sensors for analog ‘level.’, or simply presence?
It looks like they may be on/off outputs. No proportional measurement.
Just saying... the description and photos haven’t convinced me.
The UART output is supposed to give an actual depth (and I guess the RS485 output as well - never looked that one up). The NPN and PNP outputs are indeed simple on/off outputs.
They can also be used as simple on/off switches, but I'd only use them for metal containers for that purpose. There are much cheaper ones that are capacitive based and work fine to detect water in non-metal containers.
I am using the jsn-sr04t connected with esp12F and using ESPEasy Firmware. The result is accurate for me. my tank is 15ft depth from surface. it is working fine for me.
yeskay:
I am using the jsn-sr04t connected with esp12F and using ESPEasy Firmware. The result is accurate for me. my tank is 15ft depth from surface. it is working fine for me.
Like this?
Hi,
As you are measuring it submerged, it is not in air.
The speed of sound is much quicker in water than air so I can see why you are having difficulties.
I can find no reference to it being suitable for fluids, it is waterproof, and it will be calibrated for air, not water.
The only other thing you can do has already been suggested, measure the distance from the top of the tank to the surface of the water.
Tom... 
If you weren't too insistent on knowing an EXACT level, then microswitches attached to buoyant floats at, say full, 3/4, 1/2, 1/4 and almost empty could do the same job....
Hi,
For accurate depth measurement you need a submersible pressure transducer.
https://www.ebay.com/itm/Submersible-Liquid-Level-Pressure-Transmitter-With-11m-Cable-4-20mA-G1-2/202122787850?hash=item2f0f74fc0a:g:CJcAAOSw3xVaFrB~
Tom...
