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Topic: Communication under water (Read 1 time) previous topic - next topic

T_Tronix

I want to create device that will interact with a pc. The device will have sensors (arduino) that will send info to the pc. What is the best way to have a PC <-> Arduino wireless interaction?

I know they have these submarine toys where a remote is interacting with the submarine so I am guessing this is possible...

CrossRoads

Use Sound. Carries very well underwater.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

T_Tronix

What if I have several of these devices will there be interference? Is there any info on using "sound"...

Grumpy_Mike

Quote
will there be interference?

Yes.
You have not specified range, data rate and environment all these have a bearing on the best solution.

T_Tronix

#4
Jul 14, 2011, 05:26 pm Last Edit: Jul 14, 2011, 05:28 pm by T_Tronix Reason: 1
Lets say a public swimming pool with 20 devices in the water. One PC receiving info from the sensors (one sensor per device). Its a rough idea at the moment as I am trying to figure out if its even feasible.

I want the PC to retrieve info from each device with the least delay possible. The PC should also be able to identify and distinguish each device .

CrossRoads

Interference? Probably.
Can you have the senders listen and only send when its their turn?
Sensor 1 pings every 10 seconds.
Sensor 2 waits to hear sensor 1, waits 1 second and pings.
Sensor 3 waits to hear sensor2, waits 2 second and pings (or pings 2 seconds after 1).
etc.

Or they wait until the PC queries:
"sensor1, transmit"
sensor1, "ok"

"sensor2, transmit"
sensor2, "ok"

Depending on the environment, there may be echos, so testing could be interesting.

Have you tried googling "underwater communication" ?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Grumpy_Mike

And are these devices submerged in the water all the time or are they on things like people or dolphins where they could be in and out of the water. Do you have control over this environment? That is could you put an inductive loop round the area of water, lets say the pool.

T_Tronix

Its a new concept I just thought of, I'll start researching more on this. Been working with arduino for several years but never something with underwater communication.

The PC interface and Arduino/Sensor are fairly straight forward at this point, its the communication between both that puzzles me a little.

I am trying to gather info now before I start investing into this new challenge...

T_Tronix


And are these devices submerged in the water all the time or are they on things like people or dolphins where they could be in and out of the water. Do you have control over this environment? That is could you put an inductive loop round the area of water, lets say the pool.


It will be in and out of the water...

Grumpy_Mike

Well that rules out anything concerned with ultra sound through the water. Inductive loop sounds right but I don't know if you have access rights to the area you want to monitor.
The problem with radio is that the water changes the wavelength so you might need two antenna, one for submerged and the other for above the water.

T_Tronix

Hmm...I see, so it might be more complex then I first thought...Also googling "arduino underwater communication" doesn't bring much help...

robtillaart

#11
Jul 14, 2011, 09:15 pm Last Edit: Jul 14, 2011, 09:19 pm by robtillaart Reason: 1
maybe search for "whale communication recording" ?

check this book - http://www.amazon.com/Underwater-Acoustic-Digital-Processing-Communication/dp/0792373049 - look inside to get the right search words.

google books shows more - http://bit.ly/nfAtIo -

And this looks fun - http://www.utc-digital.com/ -
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Magician

There are a lot of R/C submarine all over google & youtube.
It looks like a water not a problem for RF communication, assuming a few meters depth.
http://www.youtube.com/watch?v=-je3pCo2SvI

Grumpy_Mike

As I said the wavelength changes under water, if the OP had something that was constantly under water then this would be much easer. But because it can be in and out of the water the antenna would be wrong in one environment or the other. Radio waves do penetrate water but there is severe attenuation as well. Nuclear submarines communicate over 200KHz radio links but the antenna they use is over half a mile dragged out as a wire behind it.

tkbyd

What do you want to DO? What are you wanting to sense? Do you need two way communication?

If, say, you want "things" a racer touches to indicate he/she has finished a length, then a whole bunch of problems go away, a whole bunch of solutions arise. But until you explain where you are trying to go, useful discussion is difficult.

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