Underwater communication

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brankomer
Posts: 2
Joined: Oct 23rd, 2018, 11:45 am

Underwater communication

Post by brankomer »

Hello everybody,

I have to find a way to make communicate underwater and wireless two devices which will be distant about 10 to 15 meters maximum. One should send to the other some simple datas as depth relatively quickly. What do you think I should use?
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Bennachie
Posts: 113
Joined: Jul 6th, 2018, 11:38 am

Re: Underwater communication

Post by Bennachie »

Hi, there are really only three options and none of them are without problems.

1. Radio. Unfortunately radio signals travel very poorly through water so you'd need to use high power and low frequency/long wavelength.

2. Sound. Acoustic modems are commercially available, or you could try making your own. You'd need to source suitable ceramic transducers. Acoustic modems are prone to interference from external noise.

3. Light. If you have good water clarity you could use an optical source such as an LED and an optical receiver. You could even use a laser if your Tx and Rx units were stationary. Again, you could have problems with interference from external light, unless you are really deep or operating at night.

Your task is not an easy one to solve. Good luck!
brankomer
Posts: 2
Joined: Oct 23rd, 2018, 11:45 am

Re: Underwater communication

Post by brankomer »

Thank you for you answer. Concretely, what would be the most low-cost and easy to find components solution? I need only to send debth information from one device to other, one way direction.
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Bennachie
Posts: 113
Joined: Jul 6th, 2018, 11:38 am

Re: Underwater communication

Post by Bennachie »

That depends partly on the environment that you are working in. I'd say the light method should be cheapest but won't work if your water is not clear enough, and will work best if your devices are static and you can direct the transmitter and receiver towards each other, and if you can source a receiver that is very wavelength specific, to try to get a high signal to noise ratio.

For example, if possible I'd use a red laser source and a photo receptor that is tuned specifically for red light.

Sound might be the better option if your environment is quiet, so no waves or machinery such as propellers nearby, but it is likely to be a more difficult and expensive solution.

Radio would be my least favourite option as it would likely be the most expensive and difficult to do, but it is also the option which would probably suffer the least from external interference.

If you told us a little more detail about the environment that the task is taking place in I might be able to give you a firmer answer.
asesorplaza1
Posts: 187
Joined: Mar 4th, 2018, 6:11 pm
Location: Valverde de Júcar, Cuenca, España

Re: Underwater communication

Post by asesorplaza1 »

En el momento que hablamos de cambiar de medio, aire / agua, las señales de radiofrecuencia experimentan dos fenómenos, uno la atenuación, a las ondas les cuesta mas trabajo desplazarse por el agua, que por el aire, y el otro fenómeno es la refracción, las ondas experimentan un rebote al chocar con la superficie del agua y a demás un cambio de angulo al entrar en el agua, lo que provoca que las ondas no lleguen al receptor de la misma manera que se emiten, lo cual causa terribles problemas de comunicación a partir de los 2 metros, mas o menos.

The moment we talk about changing the media, air/water, the radio frequency signals experience two phenomena, one the attenuation, to the waves it costs more work to move by the water, that by the air, and the other phenomenon is the refraction, the waves experience A rebound when colliding with the surface of the water and other a change of angle when entering the water, causing the waves do not reach the receiver in the same way that are emitted, which causes terrible communication problems from 2 meters More or less.

para mas información consultar esta pagina

For more information see this page

https://www.fisicalab.com/apartado/refl ... contenidos
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