WIFI Range under water

Hi,

Does anyone know what the range of a WIFI card would be under/through
water? Is it as simple as saying air is X times denser than air
therefore the range would be X times less?

Thanks

On Thu, 14 Jan 2004, Billy wrote:
> Does anyone know what the range of a WIFI card would be under/through
> water? Is it as simple as saying air is X times denser than air
> therefore the range would be X times less?

Although density and the ability to absorb (or conduct) electromagnetic energy
may be linked, it is the latter, not the former, that really matters.

Just what is it that you would be doing where a wireless device would need to be
underwater?

Billy wrote:

> Hi,
>
> Does anyone know what the range of a WIFI card would be under/through
> water? Is it as simple as saying air is X times denser than air
> therefore the range would be X times less?

RF tends not to penetrate water very well.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

Billy wrote:
> Does anyone know what the range of a WIFI card would be under/through
> water? Is it as simple as saying air is X times denser than air
> therefore the range would be X times less?

Remember that it's been found that to communicate with submerged submarines,
a signal in the KHz (thousands of cycles per second) range is necessary,
while WiFi is in the GHz range (billions of cycles per second).

I suspect that the answer to your question, given the power output of WiFi
devices, is "millimeters," although it could effectively be zero. 2.4 GHz
is a frequency at which almost all of the energy goes into heating of water
molecules, not radiation.

--
John Miller, N4VU
My email address: domain, n4vu.com; username, jsm

System restarting, wait...

John Miller wrote:
> Billy wrote:
>> Does anyone know what the range of a WIFI card would be under/through
>> water? Is it as simple as saying air is X times denser than air
>> therefore the range would be X times less?
>
> Remember that it's been found that to communicate with submerged
> submarines, a signal in the KHz (thousands of cycles per second)
> range is necessary, while WiFi is in the GHz range (billions of
> cycles per second).
>
> I suspect that the answer to your question, given the power output of
> WiFi devices, is "millimeters," although it could effectively be
> zero. 2.4 GHz is a frequency at which almost all of the energy goes
> into heating of water molecules, not radiation.

It's worse: submarine contact is done in the hz range - very, very slow.
http://hypertextbook.com/facts/2001/LisaWu.shtml
"Frequencies are 76 Hz for the US System and 82 Hz in the Russian
system".
"The transmitter facility in Michigan uses about six acres of land and
the one in Wisconsin about two acres. The operating frequency is 76 Hz."

Q

On Thu, 15 Jan 2004 10:21:30 -0700, "Quaoar" <(E-Mail Removed)>
wrote:

>"The transmitter facility in Michigan uses about six acres of land and
>the one in Wisconsin about two acres. The operating frequency is 76 Hz."

presumably it transmits either through the earth or through the air,
given the location of these states well away from the coastline of
America

Phil

I thought they stopped using that system some time ago? I head they were
sometimes sending up a floating satilite antenna.

Bill Crocker



"Quaoar" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
[clipped]
> It's worse: submarine contact is done in the hz range - very, very slow.
> http://hypertextbook.com/facts/2001/LisaWu.shtml
> "Frequencies are 76 Hz for the US System and 82 Hz in the Russian
> system".
> "The transmitter facility in Michigan uses about six acres of land and
> the one in Wisconsin about two acres. The operating frequency is 76 Hz."
>
> Q
>
>

You'll be very lucky if your signal got as far as 1 meter thru water.

Divers use very high frequency ultrasonics to carry voice chatter thru water
between each other etc.

As others have said, subs use ultra low RF frequencies for comms, though they
are slowly switching to sat comms using surface boys etc.

Under water robots use very long fibre cables between it and the ship above to
transfer video, control signals etc.

Until the human race makes the next giant leap in remote comms (other than RF),
cables are the ONLY way to transfer high speed data thru water. Although laser
can be useful, it doesn't get far either.

Clive

In article <(E-Mail Removed)>,
<(E-Mail Removed)> wrote:
:Until the human race makes the next giant leap in remote comms (other than RF),
:cables are the ONLY way to transfer high speed data thru water. Although laser
:can be useful, it doesn't get far either.

Synchronized streams of quantum pairs? Though perhaps they don't have
that working at high speed yet.
--
Disobey all self-referential sentences!

Walter Roberson <(E-Mail Removed)> wrote:
> In article <(E-Mail Removed)>,
> <(E-Mail Removed)> wrote:
> :Until the human race makes the next giant leap in remote comms (other than RF),
> :cables are the ONLY way to transfer high speed data thru water. Although laser
> :can be useful, it doesn't get far either.
>
> Synchronized streams of quantum pairs? Though perhaps they don't have
> that working at high speed yet.

Gradio.
802.11neutrio.