Navigation Device

"Deco_time" <coral_city2000@NOSPAMyahoo.ca> wrote in message
news:eyhAc.43023$7H1.1454477@news20.bellglobal.com ...
> In news:Shaw New <fro@hotmail.com> typed:
> > Has anyone ever come across a navigation device for SCUBA divers
> > other than a compass?
> >
> You mean like this:
> http://tinyurl.com/26gwf
>
> If you mean a GPS type of device, no, but that would be very usefull; I
> just don't know if recieving sat signal is possible underwater.
> Anybody?
> --
> www.odysea.ca

Very doubtful that GPS works under water, as even trees can block the weak signal.

Adam

"Adam Helberg" <sendspamhere@yahoo.com> wrote in message
news:WQuAc.4988$w07.2595@newsread2.news.pas.earthl ink.net...
>
> "Deco_time" <coral_city2000@NOSPAMyahoo.ca> wrote in message
> news:eyhAc.43023$7H1.1454477@news20.bellglobal.com ...
> > In news:Shaw New <fro@hotmail.com> typed:
> > > Has anyone ever come across a navigation device for SCUBA divers
> > > other than a compass?
> > >
> > You mean like this:
> > http://tinyurl.com/26gwf
> >
> > If you mean a GPS type of device, no, but that would be very usefull; I
> > just don't know if recieving sat signal is possible underwater.
> > Anybody?
> > --
> > www.odysea.ca
>
> Very doubtful that GPS works under water, as even trees can block the weak
signal.

Only very long wave length radio works under water and it is slow. A GPS
will not work, its why they use inertial navigation systems.

Adam Helberg wrote:

> "Deco_time" <coral_city2000@NOSPAMyahoo.ca> wrote in message
> news:eyhAc.43023$7H1.1454477@news20.bellglobal.com ...
>
>>In news:Shaw New <fro@hotmail.com> typed:
>>
>>>Has anyone ever come across a navigation device for SCUBA divers
>>>other than a compass?
>>>
>>
>>You mean like this:
>> http://tinyurl.com/26gwf
>>
>>If you mean a GPS type of device, no, but that would be very usefull; I
>>just don't know if recieving sat signal is possible underwater.
>>Anybody?
>>--
>>www.odysea.ca
>
>
> Very doubtful that GPS works under water, as even trees can block the weak signal.
>
> Adam
>
>

Trees would affect it some - but it would have to be a lot of cover. It
won't work underwater without an antenna ran to the surface

>On Fri, 18 Jun 2004 05:12:22 GMT, "Adam Helberg" <sendspamhere@yahoo.com> wrote:

>
>"Deco_time" <coral_city2000@NOSPAMyahoo.ca> wrote in message
>news:eyhAc.43023$7H1.1454477@news20.bellglobal.co m...
>> In news:Shaw New <fro@hotmail.com> typed:
>> > Has anyone ever come across a navigation device for SCUBA divers
>> > other than a compass?
>> >
>> You mean like this:
>> http://tinyurl.com/26gwf
>>
>> If you mean a GPS type of device, no, but that would be very usefull; I
>> just don't know if recieving sat signal is possible underwater.
>> Anybody?
>> --
>> www.odysea.ca
>
>Very doubtful that GPS works under water, as even trees can block the weak signal.
>
>Adam

it's the water that blocks the GPS sat signal, thus when the leaves
pop out and get loaded with moisture you get decreased or lack of
coverage.

(I was told about a sat comm otr trucker coming upon an accident ...
hits the 911 button, pulls under heavy tree canopy and disappears off
the screen)

dry wood doesn't block the signal

for underwater it's compass, inertial, vlf or acoustic

short and long baseline acoustic buoys are used for relative location
of assets ... if the buoy locations are fixed and location known then
you can get absolute location. Buoys anchored directly to the
seafloor for accuracy, or surface for approximate positioning and on
movable platforms (ships) for approximate and relative positioning.

Pretty old tech, what is new is the decreasing of cost, size and
increased range and data transmission rates using uw acoustic modems
for image and data transmission. Increases are probably due to better
signal processing.

for sport diving ... fin kicks and compass skills are pretty basic and
dare I say required skills to have ... for commercial, scientific or
blackwater diving where the search grid can't use line, it's hard to
beat technology.

Most of the sport based tools are beacons for "here to there" location
and be very wary of the marketing, the distances are "best case" and
real world can cut the range significantly.

- Ed

- Ed
--
refillable drysuit talc bag $9.95 ppd
http://www.underwaterusa.com