Author Topic: Radio hack for underwater robot  (Read 898 times)

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Offline submarinerTopic starter

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Radio hack for underwater robot
« on: October 30, 2010, 08:48:01 AM »
I'm building an underwater robot with various sensors and other features. The number of controls (channels) I'll need (in the 40 Mhz band,) is quite a lot more than is normally available in a set commercially.

There are obviously a number of options here:

a) buy a commercial radio control set and modify ('hack')  it to take the extra channels (in practice, maybe just using the transmitter portion);

b) find an electronics self build rc kit/design and adapt that;

c) find ready made tx/rx 40 MHz modules and use those as the basis for the design.

Note that I have fair electronics knowledge but to save time and effort and not to reinvent the wheel (also to ensure a legal radio setup) I'd rather invest in a soundly designed tx.

As another issue, it would be very handy to have a bidirectional link, that is, receive sensor and other data back from the robot, again, in the model 40 MHz band.

It's a long time since I have played with model rc, so I don't know the market for this kind of stuff very well. I've found some gear in the 2.4 GHz band range, but this is unsuitable for underwater reception.

Has anyone experience in this area, know a business that offers self build 40 MHz radio kits or have any other helpful pointers?

Offline SilverMedalMan

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Re: Radio hack for underwater robot
« Reply #1 on: October 30, 2010, 10:44:50 AM »

Hi I have a fair bit of experience in Radio. I assume from your post that you actually want to control the robot whilst it is underwater and you are above the water.

You will find that in the world of Radio it is extremely difficult to penetrate a great depth of water using the frequencies you are referring to. Generally the higher the frequency the more attenuation you will have. At 40 Mhz you would have to have a very powerful transmitter to penetrate more than 5 meters. If the water is sea water, the salt content makes it even more difficult. You may have to seek special high power licence from off-comm For UK   (FCC for USA). The only other way would be to have a water proof coaxial cable which runs to the surface which attaches to a floating antenna. Either way you are looking at specialist equipment which I would not think will be available in the usual remote control shop outlets.

Best regards

SMM

Offline submarinerTopic starter

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Re: Radio hack for underwater robot
« Reply #2 on: October 30, 2010, 11:08:24 AM »
Thanks SMM,

I'm familiar with those issues, and they will not be stoppers in this application. I'm just trying to find the route of least resistance for the tx/rx by finding an off-the-shelf solution or easy hack, rather than having to build myown tx/rx in addition to everything else.

For example in today's world of multilayer smt boards, how easy is it to trace and tap into a commercial rc radio to use just the tx/rx portion -is that too impractical or are there some manufacturers who still use double sided boards?

 


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