Wireless communication underwater

[suniljha]

Hi!
I want to know that whether BiM2 RF Transceiver modules will work under water wireless communications or not? If yes than what would be there range as compared to air communication. If not then what would be the best alternative to control under water equipment from the surface?<p>Waiting for expert opinions..
Thanks,
Sunil

[russlk]

I don't know anything about BIM2, but underwater communication is usually done at low frequency. The US Navy communicates with submarines at 10kHz.

[Externet]

Hi.
Not expert, but experienced.
I worked in 1971-72 with the inventor of the scuba wireless intercom.
RF will not provide any useable range underwater. The attenuation in water is brutal. It is properly done with modulated ultrasonics, as any echosounder or sonar. A very selective audio filter is needed to prevent the breathing and bubbles noise to activate the vox. A special full face mask is needed. The vox is activated by a throat contact microphone in the units I know, being that, the key of the patent.
PTT systems may not use the filtering. Proper conectors must be very waterproof.
Controlling underwater devices wirelessly with data should also be done with ultrasonic carrier and transducers, and may not need filtering nor vox.
Miguel
-Scuba diver before my belly grew-

[Chris Smith]

Elf, is much lower than 10khz, the frequency that subs talk to the out side world. <p>Most underwater communicatiuons use ultra sonics, or pretty much any frequency of sound to communicate. <p>Ordinary radio waves just dont work past a few feet.

[jwax]

Your 10 mw, 433 MHz system is pretty much useless in water. Research ultrasound, or better yet, very low frequency communication.
What is it you're trying to do?
John