I'm usually silent but since i already tought of the dtmf idea a while
ago for another project and noticed it could not work, i had to say it.

The only problem with dtmf is the speed. the detectors cannot lock fast
enough to get a normal bandwidth (usually a couple of ms). A solution
would be High Speed DTMF (I heard of it but never looked it up).

I think the best way to go would be a cable to a floatin antenna. Then
you can get the equipment you want on the surface and the distance you
want. Only problem is crossing objects that are floating or submerged...
but it should work fine on the open.
+--------------------------+-----------------------+
|                          | ABL Canada inc.       |
| Jacques Audette          | 8550 Cote-de-Liesse   |
| Hardware design          | St-Laurent, Qc        |
| Video Codecs             | H4T 1H2               |
|                          | Tel: (514)344-5432    |
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> ----------
> From:         Alessandro Zummo[SMTP:azummo@ITA.FLASHNET.IT]
> Reply To:     pic microcontroller discussion list
> Sent:         Friday, March 06, 1998 7:30 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: OT: Radio Transmission in Water
>
> Il 05-Mar-98, Dennis Merrill scrisse:
>
>
> > is the best way to go in water.  The scroedinger wave equation can
> show
> > that any EM wave's propagation is a function of medium density and
> wave
> > frequency.
>
> Just and idea.. what about using DTMF underwater?
>
> yes, i know.. i'm mad :-)
>
> --
>
>    - *Alex* -
>
>   http://freepage.logicom.it/azummo/
>