We have a project which in this case we need to mount a Sensor in our ROV Boat in detecting depth of water at least 30m(Shallow Water Operation), Our first option is using an ultrasonic Sensor. Unfortunately, we can't use an ultrasonic sensor module(e.g. Ping from parallax, us 100) because we will be submerging the sensor underwater.
In that case, We need to use the transducer found in a portable fish finder and interface it in our Arduino,I need help in hacking a Portable Fish finder and using it as an alternative for a common Ultrasonic sensor.
Question is:
Is there any means i can use an Ultrasonic Transducer below water level(e.g. modifying, waterproofing, hacking)?
How can I use the Fish Finder's Transducer to determine the depth of water.., We only need the transducer to talk with the arduino and toss all the data gathered to it to us in PC or Phone.
Ultrasound transducers for air and water are fundamentally different in design - the acoustic impedance is orders of magnitude different. You also need to avoid water damage so a sealed unit is required anyhow.
IR flavors of light usually do not penetrate the water very well so the signal might not be very strong even at 2 meters. Green light penetrates better so a green LED and a matched receiver would probably be better than IR.
Either way should be easy to test with a 2.5 meter section of pipe.
It depends on a lot of things but I would not try IR at any depth when there are green sources that will penetrate further. Think a green laser pointer. I have done calculations like how far IR gets in water but to find the references that I need in my library is not very easy.
There is a very strong reason why folks use green lasers (I forget the exact wavelength you need for max depth) because most other flavors of light die off very quickly.
So even an IR Proximity Sensor will have a difficulty in determining the depth of water.. ? I'm desperate, How far can an IR proximity sensor penetrate underwater, considering more or less 2 ft would be sufficient to me,
In air the sensor works from 10-80 cm and you want to get 2 feet ~50 cm through water??
My guess is that if you have the sensor above the water it will tell you the distance to the water, and if you put it underwater as is it short out.
I have stated a couple of times that water greatly attenuates the IR signal but you keep asking about it so I would recommend you buy one of these sensors and try to see performance you get. The sensors are pretty cheap in the US, can't say for other sources.
I spent a good chunk of my career working many aspects of IR detection and propagation and it would a lot easier for me to buy the sensor and test its performance than try to predict the performance with high accuracy. But I will say my gut feeling is this sensor will not work for at 2 feet, but you should buy and test its performance and let us know what the performance was in a future email.
in that case, i have no choice but to buy an expensive fish finder and hack through it,
unfortunately, Fish Finder's Transducer reading is between .6m-100m;(anything below .6m reads 0);
we need a reading with less than a feet up to 2ft is enough...
