(OT) Will a cellphone work under water?

[mikel...@myhouse.com]

Assuming a cellphone could be made to be water resistant, would they get
a signal under water? Obviously, no one can talk under water, so
texting would be the only option.

But I doubt that there is such a thing as a waterproof cellphone made
anyhow. My only reason to ask this is because I'm curious if a
cellphone signal will penetrate water.

Anyone know?

[hr(bob) hofmann@att.net]

Not very far

[Tony Hwang]

Hi,
If I were you, I'd experiment myself. Put the phone in a plastic bag
,aking it water tight. I can still punch the keys and ty it to see if
the signal gets out.

[Tony Hwang]

Hi,
If I were you, I'd experiment myself. Put the phone in a plastic bag

making it water tight. I can still punch the keys and try it to see if
the signal gets out.

[Ralph Mowery]

<mikel...@myhouse.com> wrote in message
news:n05198tq2un6haub5...@4ax.com...

At the frequencies the phones work, they will not work under water. Maybe a
few inches at the very most if you are next to the cell tower.

Don't ask me to explain this.But at the bottom is a number for 1 mhz of only
.25 meters. That is less than a foot and the higher in frequency,the less
the radio waves will penetrate.


>
> The formula is: depth = 1/(sqrt(PI * Freq * mu * sigma)
>
> Where:
> PI = 3.1415.....
> Freq = Freq in Hz
> mu = permeability
> sigma = conductivity
>
> But only for sigma >> 1 (which saltwater is not). The Approximate skin-
> depth for salt water is:
> 60 Hz = 32M
> 1 MHz = 0.25 M
> 1 GHz = undefined since sigma is not >> 1.
>

[harry]

On Oct 31, 3:12 am, "Ralph Mowery" <rmowery28...@earthlink.net> wrote:
> <mikeluc...@myhouse.com> wrote in message

I had a radio controlled model submarine once. That worked underwater.
Tx was above obviously and the distance was only about thirty feet. I
don't suppose it went more than a couple of feet below the surface. It
had a timed surfacing device in case things went wrong. Which they
sometimes did.

[Kurt Ullman]

In article <xl0ks.4060$zu4...@newsfe14.iad>,

All you would really need to do is to look at the signal strength at
various levels.
--
America is at that awkward stage. It's too late
to work within the system, but too early to shoot
the bastards."-- Claire Wolfe

[Felix]

Harry,

A turd in the bath tub, is not a submarine in the water.

[Robert Macy]

There are charts that supply the information for the amount of
absorption vs frequency in sea water. For the cellphone the field is
very spherical and will 'punch' through salt water much better than
the tower's rather planar field which will more follow the predictions
of skin depth, etc.

However, for fun, let's use your experience with the submarine. Assume
you had a 100mW 27MHz transmitter that went about thirty feet in
water.

Adjust for power and frequency:
Assume power scales, so 1W goes 10X further.
Assume skin effect kills your signal, so at 900Mhz your signal will be
reduced by the sqrt(900/27), or about 1/6th

Therefore the cellphone should work to an adjacent tower about 30*10/6
or 50 feet into water.

That is far deeper than I would expect, wonder what it really is.

[hr(bob) hofmann@att.net]

> That is far deeper than I would expect, wonder what it really is.- Hide quoted text -
>
> - Show quoted text -

Try your phone in a bag in a barrel of water

[Robert Macy]

On Oct 31, 8:14 am, "hr(bob) hofm...@att.net" <hrhofm...@att.net>
wrote:

> Try your phone in a bag in a barrel of water

If that's rain water, unlikely to have much noticeable attenuation at
all.

Well/city water somewhat.

Sea water will attenuate the most.

Plus, don't have cell-phone service provider.