chourysa

HI, I AM TRYING TO MAKE WIRELESS UNDERWATER CAM FOR MY SUB MODEL
DOES ANYBODY KNOW WHICH FREQ THE BEST FOR TRANSMITTING VIDEO IN THE WATER 900 MHZ OR 434 MHZ
AND IF COMPARE 900 MHZ TRANSMITTER 1000Mw AND 434 MHZ 50Mw transmitter which one can go deeper?
HOPE U GUYS CAN GIVE ME GOOD SUGGESTION TO CHOOSE THE TRANSMITTER FOR MY SUB CAM,YHANKS

JAN

LtDoc

JAN,
I'm not too sure there would be much difference between the two, actually. Of the two choices, the 400 Mhz one might give better results, I think. The reason for that is that water tends to attenuate very high frequencies more than lower frequencies. (I haven't dealt with this sort of thing so most of what I tell you will be an assumption, or the results of using frequencies much lower than the two you specified. Don't put much faith into it.) The other side of that coin is that the higher frequency of your two choices has a higher power level. I would tend to think that it would sort of 'equalize' the two, and probably have a deeper usable depth. I think it would also help a bit if the antenna for the camera's receiver were also submerged. The interface between the two mediums, water/air is where the 'single' largest loss of signal will be. Using a surface tow able camera antenna would be the 'best' choice, but probably not very practical.
I, for one, would be very interested in your results! Good luck.
- 'Doc

subhunter13

Guys,
Camera signal (wirless) looses signal typicly at about 3 in.
The best thing really to do is to lenthen the antenna.

Taxidriver

Your antennae length is dependent on your frequency. The lower the frequency the longer the the antennae. The lower the frquency the further the signal will penerate water. 2.4Ghz is the worst as it approaches the resonant frequency of water. I can reception from 36" down and 40 feet away.

CrunchyFrog

>Using a surface tow able camera antenna would be the 'best' choice, but probably not very practical.

You know, I've never seen an r/c transmitter optimized for submarines--otherwise, I wonder if it might have an antenna going straight down from the box; that way you wouldn't have to turn your control box upside down--or risk it while you're putting it over the side of the boat you're sitting in--to stick the antenna in the water.


>Your antennae length is dependent on your frequency. The lower the frequency the longer the the antennae.

Take for example the antenna in the US that's 200km long, used for sending really-low-frequency signals to submerged submarines (though I don't know its power requirements).

Good luck choosing your setup !

subhunter13

[:@] Mine is 2.4Ghz.

chourysa

WHICH ONE MUST USE LONGER ANTHENNA THE TRANSMITTER?OR THE RECEIVER?

LtDoc

Receiver
- 'Doc

chourysa

OK THAN I BETTER USE 434 MHZ 50mW OR 900 MHZ 500mW??FINALY

LtDoc

Good question! The 400 Mhz at 50mw and the 900 Mhz at 500mw are about equal in range through the air. Through water both are terrible. Wish it were different.
- 'Doc

[50mw = 1/20th of a watt. 500mw = 1/2 a watt.]