Andy Shaw wrote:
>
> Hi Folks,
> I'm sure one of you out there will know the answer to this one.
>
> Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
> water. I build model subs and I know that standard 40MHz Radio control gear
> works well down to ten feet or so. I'm thinking of mounting a black and
> white TV camera on a sub. I've seen a transmission system that uses the
> 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
> will work.
>
> So any help would be much appreciated - Oh and it is not that off topic the
> Sub has two PICs in it, one for depth/attitude control the other for speed
> control!
>
> Andy

Hi, Andy

the loss of 1.3 GHz in Water is very high (up to 70dB). The loss of
400MHz is only about 15 dB. I4ve tried to transmit with an RFM HX200
(916,5MHz) out of water and I had no success, after that i changed the
frequency to 433.92 MHz and it was much better. Remember: a microwave
oven works at 2.4GHz and most of the output will absorbed by water.

Thomas