What is Frequency that can be useful in tracking underwater?

[patrickBugRats]

Help....

Our project is to make a device that will trigger when it submerged, once it triggers then it emit a RF signal, so that we can locate the device.

Our problem is that what RF signal that can suitable for underwater? And what devices can do this?

 

[keith1200rs]

It depends on depth. As far as I know, the higher the frequency the lower the depth penetration. There are radio controlled toy submarines that work down to a few feet using 27MHz, I believe.

Keith

 

[patrickBugRats]

100ft is our maximum depth. What frequency will do this?

 

[keith1200rs]

Why RF? Acoustics is usually used for underwater communications. See https://en.wikipedia.org/wiki/Communication_with_submarines

Even very low frequencies (3-30kHz) will struggle at 100ft.

Keith

 

[patrickBugRats]

thanks you!

 

[jiripolivka]

Why RF? Acoustics is usually used for underwater communications. See https://en.wikipedia.org/wiki/Communication_with_submarines

Even very low frequencies (3-30kHz) will struggle at 100ft.

Keith

Radio propagation under water mostly depends on water conductivity, defined by salinity.
Typically, submarines communicate under water from 12 to 50 kHz. Sound is preferable for short distances, and recently it was determined that green laser light can be used in low-turbidity water.