On 1/25/06, Dumitru Stama <list@mirosat.com> wrote:
>
> I think 2.4 GHz is very high for underwater broadcasts.

please don't say stupid things my friend.
What epsilon have water ?

It was over the water not "in water" !

regards,
Vasile

> Under water you could get away with a low frequency transmission, even
> a sonar but i am quite sure 2.4GHz will not do the job.
>
> Dumitru Stama
>
>
> MB> Could you have some sort of antenna below the water level? I'm not su=
re what
> MB> the specifics would be, but given that sound travels so much better
> MB> underwater, it might be an option.
> MB> - Marcel
>
> MB> On 1/24/06, Enrico Schuerrer <enrico@gmx.at> wrote:
> >>
> >>
> >> -----Urspr=FCngliche Nachricht-----
> >> Von: "VULCAN20" <VULCAN20@charter.net>
> >> An: "pic microcontroller discussion list" <PICLIST@mitvma.mit.edu>
> >> Gesendet: Dienstag, 24. J=E4nner 2006 22:02
> >> Betreff: [EE] 2.4 GHz over water???
> >>
> >>
> >> > I am not knowledgeable with radio waves.  I was thinking of a project
> >> > using the Maxstream xbee Zigbee pro radios.  I need to send data fro=
m a
> >> > small rc boat to a larger full size boat  about 1000 M distance.
> >> > The big boat will have the ant about 3 to 4 M above water. The small
> >> > boat I would like to have as low as possible.  I asked an old ham ra=
dio
> >> > person about it and he said It would not work due to freq. and height
> >> > above water.
> >> > I e-mail Maxstream and all they would comment that it depended upon =
the
> >> > height above water and would not suggest min height required.
> >> > Any thoughts on this?
> >>
> >> IMHO a question of the antenna height on the smaller boat above the
> >> waterline AND the height of sea waves. From the point of free space
> >> attenuation it's only a question of transmitting power and receiver
> >> sensitivity and the used antennas. A bigger problem I assume will be i=
f the
> >> small boat is in a wave trough and so the direct visible line between =
the
> >> antennas is interrupted.
> >>
> >> >
> >> > Any other radios that could be used?  Requirements: about 1000M over
> >> > freshwater, wave height less then  1M.,
> >> >  the large boat would send signal to start data collection.  Then wh=
en
> >> > small boat had data it would send it back to larger boat.
> >> >
> >>
> >> If you use a data transmission protocol with data protection even
> >> interuptions should not be a problem.
> >>
> >> Enrico
> >> OE1EQW
> >>
> >> --
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