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After watching a video demonstrating a jet-powered RC aircraft, I started to wonder about the maximum range available with modern RC equipment.

What is the maximum range currently available, and which technology does it implement?

On which frequencies does it operate?

If you have any data regarding the control-response lag (delay), please include it too.

I'm more interested in controller-based distances, and not FPV.

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  • $\begingroup$ This question would definitely benefit from some more specific information. As it is, it is a very broad question. For example ¨what is the maximum range¨ would depend on frequency, interference, and a lot of other things and the question ¨which technology does it implement¨ could mean almost anything. And for the questions regarding frequencies and lag, those both are very dependent on a large variety of things. $\endgroup$
    – Jacob B ♦
    Commented Apr 30, 2020 at 4:05
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    $\begingroup$ Do you mean for controls or FPV? $\endgroup$
    – ifconfig ♦
    Commented Apr 30, 2020 at 4:05
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    $\begingroup$ @JacobB Yes, I've intentionally left it non-specific, because I'm trying to understand the limits of current technology, without restricting it to a specific one. $\endgroup$
    – Amazon Dies In Darkness
    Commented Apr 30, 2020 at 4:17
  • $\begingroup$ @ifconfig Great question. I mean for controls, and updated the question accordingly. Thanks. $\endgroup$
    – Amazon Dies In Darkness
    Commented Apr 30, 2020 at 4:17
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    $\begingroup$ @ifconfig Yep, I tend to upvote right away (unless I happen to be out of votes), and then wait a while until I accept an answer. I do this to not discourage other answers. The exception is when there is an absolute definitive answer (like, does 1+1=2 ?), in which case I'll accept the correct answer the moment I read it. Thank you again for your helpful answer. $\endgroup$
    – Amazon Dies In Darkness
    Commented Apr 30, 2020 at 4:30

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The control range depends on the frequency, power and how the transmitter sends the data (the 'mode'.)

Power

More power gives longer range (much like a brighter light can be seen from further away.) However, as the frequencies are shared there are laws in each country1 which limit the maximum power you can use; this prevents it becoming a 'free for all' for who can push the most power out, which would cause interference issues for everyone. This is also more costly on battery life, so there is a trade off particularly on the airborne segment.

Frequency

There are a selection of frequencies available for use on commercial drones - again, this varies slightly by country1. Common frequencies these days include 5.8 GHz and 2.4 GHZ, but 870 MHz, 35 MHz and others are widely available.
A higher frequency allows you to send more data in the same time span (this is why 5.8GHz WiFi is faster than 2.4 GHz WiFi) but drone control is not usually data rate limited - although, this is why FPV kit usually uses 5.8 GHz as you can get move video data through for higher quality and/or lower latency. Lower frequencies will travel further (for the same power), but also require larger antennas on the drone for optimum performance.

Mode

Digital communication is more resilient than analog, which will extend the range for all other variables being equal. There are also variations in the digital modes used; if a manufacturer builds greater redundancy into their signal the range will be better.

Indirect options

For much longer ranges, you can exploit larger infrastructure to carry your signal. Common technologies used for this are cellular (i.e. mobile phone) networks or satellite communications. This adds lag and can make manual control impractical, but can be combined with other technologies - for example, the satellite and cellular controlled drones I've flown only provide telemetry and autopilot waypoint adjustments over the satellite link due to several seconds of lag, but have a direct RF link for local/manual flight control.

[1] As an example, this page contains information from the UK communications regulator on radio use for RC models.

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    $\begingroup$ "A higher frequency allows you to send more data in the same time span" - this is simply false. You send more data at higher frequency because your channel bandwidth is (typically) higher.If you have the same channel BW and modulation using carrier frequency of 2.4GHz and 5.8 GHz you will have exactly the same data rate. $\endgroup$
    – jpou
    Commented Jun 8, 2020 at 18:41
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If you are not interested in hard, real-time control and can accept some autonomy in the drone, then your best choice is satellite communication. The iridium based modules are lightweight, (45 grams), and are easy to integrate (they have USB and Serial connections). One example is RockBlock. You pay per message, and one message (50 bytes) is just about enough to send coordinates of the next way-point and to get status information from the drone.

EDIT: In response to the comment about LEO: if your drone is about to go further than low-earth orbit, take a look at this S-Band transceiver. Perfect choice at 194 grams. However, you will need to build your own tracking station, but then even the sky is no longer the limit.

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    $\begingroup$ Technically correct, but what do you use if you want to go beyond low-earth-orbit? ;-) $\endgroup$
    – Robin Bennett
    Commented Apr 30, 2020 at 10:59
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    $\begingroup$ @RobinBennett updated for even more options when considering range UP. $\endgroup$
    – jpou
    Commented Apr 30, 2020 at 12:13
  • $\begingroup$ I think we've ventured into thought-experiment territory... :) $\endgroup$
    – ifconfig ♦
    Commented Apr 30, 2020 at 20:34
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To my knowledge, the most readily available consumer long-range RC control system is the Crossfire ecosystem from Team BlackSheep. It makes use of the 868 MHz/915 MHz band and supports RF transmission powers from 10 mW to 2000 mW.

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Under good conditions and given well thought out antenna orientations, TBS Crossfire can achieve some truly ludicrous ranges for RC gear in the neighborhood of several kilometers. It's decently expensive and works best with RC transmitters running the OpenTX firmware, but is considered the best in the business for consumer RC.

FPV video systems are far more limited in terms of range capabilities, no matter whether or not you chose an analog or a digital system (e.g. DJI, FatShark Bytefrost). These systems most often use the 5.8 GHz band and thus have range capabilities which severely limit the long-range capabilities of most RC control links. The community doesn't have terribly good solutions for long-distance FPV video transmission.

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    $\begingroup$ To whoever is interested - be sure to study the law regarding the permissible emitter power and licensing requirements in your location. $\endgroup$
    – jpou
    Commented Apr 30, 2020 at 7:23

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