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I would like to control a simple, ground-based vehicle wirelessly, at ranges up to 5-6 km. The communication would be bi-directional (to get a feedback of "command received") but would only require binary states, just as if I wanted to remotely switch a small number of switches.

I hoped that this day and age there would be plenty of such devices available for USB. I searched for long range USB radio transponders, and got nothing of interest. Most RC toys use high frequency, have a very limited range, and rarely have a USB connection. Wi-fi routers have amazing speeds, but even less range. Normal walky-talkies would have the range, but I just couldn't find readily available devices or ICs which just send a few bits to remotely trigger a few switches.

Does this mean I would need to build the antenna and all the electronics myself, or are there readily available solutions hiding under a (for me at least) unknown term?

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  • \$\begingroup\$ For that kind of range, you pretty much need to use a licensed service. For example, you could get an amateur radio license, or you could use a device (such as a cell network module) that has the license embodied in it. \$\endgroup\$ – Dave Tweed Jan 18 '15 at 0:43
  • \$\begingroup\$ What's your operating environment? 5-6km in a hilly built up area with no line of sight is significantly more challenging than 5-6km line of sight from a cliff top over water. \$\endgroup\$ – markt Jan 18 '15 at 0:59
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    \$\begingroup\$ How about a cell phone? \$\endgroup\$ – George Herold Jan 18 '15 at 1:13
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Long-ish range radios are becoming more readily available. Recently I used a few of these:

Digi 900mhz modules

They use the xbee footprint, so can be used easily with many arduino shields and other cheap hardware.

You can set two units up to be a transparent link. This can carry data via serial port, or it can mirror GPIO pins between the two. (I have used this feature on the 2.4ghz ones, but not these)

If you set the master with an input, and the slave with an output, toggling the pin on the master should toggle the pin on the slave automagically

Don't believe the 28 mile claim though! Line of sight with a high gain antenna might get you half that. Maybe.

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you can buy GPRS modules for < USD$50. They will typically have a UART you can interface with. If you plan on operating your vehicle within range of a cell tower, this should be enough.

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    \$\begingroup\$ GPRS has terrible latency, this would be pretty hard to control. \$\endgroup\$ – pjc50 Jan 18 '15 at 0:56

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