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[thegrimreaper]

Need your help guys I know that a 2.4GHz signal will not penetrate water but will 1.2GHz 900-1200MHz in the form of a radio camera transmitting from a sub in the water and under the water if so what quality picture can I expect and if not what frequency do I need to be looking at to transmit through water from a submerged Sub
 
Thanks in advance
 
Mark.

[ministeve]

hi mark 5.8gig will work
regards steve

[nick_75au]

2.4 definitely does not work, but as I understand it the lower the frequency the better the penetration of the signal through water, but also the lower the frequency the lower amount of data that can be transmitted, for effective penetration Mhz frequency are the norm, think subs on the different 36-75 Mhz bands used around the world, the most effective solution that I know works is a tether to a bouy with the transmitting antenna. In salt water any normal frequency is completely blocked including the RC signal so what's done in the video has to be done


like this guy


http://www.youtube.com/watch?v=Ioc97woAXDs


Nick

[thegrimreaper]

Nice Video Nick thanks for the link problem with the cable is that it would probably get snagged by other subs or even surface craft in the pond I use hence I wanted a camera capable of transmitting through the water I have been told that 1.2GHz will do what I want I was just trying to pick a few more brains as to weather this was correct as I have seen a 1.2GHz camera with transmitter and receiver at a good price in the U.K. for good money.
 
and thanks Steve for the 5.8GHz tip I will have a look online and try to find one
 
Regards Mark

[Subculture]

Two things Mark. One anything over 1Ghz is generally a no-no for underwater use, and even if you can get it to work slightly, you'll get terrible range. 5.8Ghz will be even worse than 2.4Ghz, so don't bother with that!

Second point, the use of 1.2ghz equipment is illegal.

[thegrimreaper]

Thanks for that Andy looks like I will have to put a bigger Micro SD card in my 808 then and adapt a phone battery to get a longer run time out of the 808
aint it great how when it comes to fun its illegal
 
Regards Mark

[Subculture]

Recording to card is the best way to do things Mark.

Most phone batteries are over 1A in capacity, which will give you several hours of recording on an 808, as the onboard battery is only about a fifth of that, and gives about 40-50 minutes of recording if fully charged.

A 16Gb card would give you well over six hours of recording time, and are under a tenner now. You don't need anything over class 4.

[thegrimreaper]

Looks like that's the way to go then will have to strip down the 808 and have a look at what`s inside and what`s involved in the mod. Andy is it worth taking the original battery out or leaving it in? if I remember the original batteries have an protection circuit will I need to use that with a phone battery?
 
Thanks Andy
 
Regards Mark.

[Subculture]

Take care poking about inside, lot of electronics in there sensitive to static, so earth yourself on something metallic (e.g. radiator) before you touch the bare board.

Inside you'll see the small battery wired to the board with two small flyleads, which are colour coded red for positive and black for negative, snip these one at a time, and then solder on some extensions, so the lead can go outside the case. Heatshrink the connections and solder on a small plug to the flyleads that matches what you have on the external battery. Then you can plug in a single Lipo of your choice. The protection circuit on the battery can be recycled if you wish, or you can simply time how long the camera has been running, and turn it off before you run the battery too low.

I would remove the old battery if you're going for a larger battery.

[thegrimreaper]

Well that mod was painless Thanks to you Andy. Phone battery now connected next job 16 Gig micro SD card and a proper plug and socket for the wires
Thanks again Andy
 
Regards Mark