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How well will an RC radio signal transmit through an underground tunnel?

I want to take one of those overbuilt monster truck RC cars from WalMart and stick a camera and a bunch of lights on it, then drive it down drainage tunnels to see where they go. Why? I'm nuts, that's why.

My question is this: how will being in an underground tunnel effect the RC transmission? In a cement tunnel it seems to me that it would have increased range because the signal would bounce down the tube without getting lost in the air or degraded by other signals, resulting in improved signal range. Is this hypothesis true? I would be thrilled if I could get 100 feet of signal range in a tunnel.

Any ideas?

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ddemayo5 years ago
radio waves will penetrate the ground and even the cement tunnel and you could go quite a ways if you simply walked along above the tunnel with the RC car. A good thing to do is to find an RC car with the shortest wavelength possible as a smaller wave length can penetrate things better than a longer waver length
onrust ddemayo5 years ago
Does that mean an AM controller would work better than an FM in this situation?....thanks
ddemayo onrust5 years ago
an AM signal can travel farther but not necessarily does that mean that AM waves are smaller you can send an AM and FM wave at the same frequency.
onrust ddemayo5 years ago
Thank you, that helps :)
Its difficult to say offhand how well it will work. It will depend on how much and what type of material is between the transmitter and the reciever.

If it is deep under soil, which could be moist, then higher frequency (shorter wavelength) signals will be more attenuated. I wouldn't try to use a high frequency based remote control (hundred of MHz). If you are trying to use a cheaper off the shelf RC item, they often use something inthe 54MHz range, which would be better.

If the tunnels are concrete or something non metalic, they will not reflect the waves significantly. Of course, concrete structures usually contain steel mesh reinforment inside, but I couldn't speculate on how much that would reflect your signals. I wouldn't count on any improved range because you are within a tunnel.

It seem like with RC stuff you eventually get to a place where you lose contact. If the tunnel is someplace you can't venture into , then you may lose your vehicle if it goes out of range. You said you would be pleased with 100ft range, so it doesn't sound like you are intending to venture into some vast labyrinth of tunnels.

However, 100 feet isn't terribly far. At that distance, you could have a rope attached to the vehicle to pull it out if you lost contact.
ilpug (author)  LargeMouthBass5 years ago
Huh, interesting to know, thanks. I need a system like this to save me time and energy. I do draining, which is a form of urban exploration that can be summed up as: morons crawling around through drainage tunnels.

It seems that recently every time I find a promising tunnel mouth it goes in about 50 feet and then either ends in a ditch or an un-navigable tunnel. If I had a cheap little car set-up like this, I would be able to see how promising the first part of a tunnel is without having to suit up, go in, and find that it goes nowhere.