Which Radio Module should I use?

Community General Discussion
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I'm trying to control a robot from far away, like from 300 meters-1km. However, there won't be line of sight. What radio module should I use? I tried nRF401, but without line of sight the distance is limited. Should I try LoRa? Or are there other radio modules which I can try? Thanks very much

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For legal transmission in the license free bands, line of sight is more or less required. Signal repeaters are an option.

What is the plan for controlling a robot that you can't even see?

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At ground level? You're not getting 1km. You'd need a perfectly flat area, no trees, no buildings, no hundreds of other people on their phones and such. That range is expensive even from ground to air, and as @jremington hints, it's likely not a great idea to control a robot you can't see.
Using 2.4GHz Spektrum DSMX radios at ground level for a robot, I got a little more than a football field in a suburban setting.

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Thanks for the reply. I'm trying to make a wireless car that can go around my village. I've attached a FPV camera to the robot, so don't worry I can still see it. But is it possible to control my car at a distance of 50 meters without line of sight?

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No, and the FPV camera/radio generally needs line of sight, too.

distance of 50 meters without line of sight

That depends on what is in the way. A few trees, maybe OK. Large buildings, no.

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Thanks for the reply. Are there radio modules that work at 30-50 meters without line of sight?

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The only stuff I consider reliable-ish at that range are hobby grade RC transmitters and receivers. I can't speak to Arduino type radio modules that I would say do, the only time I tried with Xbee radios (who claimed 1km line of sight, 300m non iirc), I got like, 100 feet. They would drop out from my garage to my living room.
I think of it like this: who has the most to lose if they lose control? RC aircraft pilots, right? So that's what I use. Try your local hobby shop and they might have a good solution.
In general, no line of sight really depends on the obstructions. We all know guys whose wifi can't even get across the house, and guys whose wifi goes three doors down. There's no guarantees, I'm afraid.

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If you dont have line of sight how are you going to pick up the FPV video ?

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HC-12 modules have a reasonable range, better than nRF2401 but not as good as LoRa, I think.

But the only way to penetrate buildings & trees is to use low frequencies (= long wavelengths) and high transmit power (which requires licences). Even those won't penetrate hills.

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