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Watching the news regarding the war in Ukraine and similar conflicts and coming from an RF electrical engineering background, I'm baffled over how commercial drones can even be used in war. Shooting them down with guns is very difficult and shooting them down with military anti-air means seems quite overkill. However, jamming them out ought to be quite possible.

My question is: why isn't the military using signal jammers?

If commands, camera as well as GPS are completely blocked, then the drone can't possibly do anything meaningful but at best make an emergency landing - or alternatively fly off in a random direction. I realize there are advanced military drones with autonomous optic recognition of targets etc, but I'm talking about plain commercial drones here.

Building a wide band signal jammer for 1.6GHz, 2.4GHz or 5.6GHz bands etc isn't trivial, but not complicated either if you have the means. The only problems are that you need to jam a couple of very wide bands and that you need sufficient output power to drown every other signal. For maximum nastiness it could even spew modulated nonsense data, to make signal detection even harder compared to when getting drowned out by raw unmodulated carrier energy.

Such jammers are of course wildly illegal, but I doubt the military (or anyone else) cares about following laws or if their wifi isn't working when there are incoming hostile drowns carrying grenades. Plus you only need to activate the jammer for a short time.

A mobile military vehicle with a sufficiently large on-board antenna should be quite suitable and such vehicles already exist, though not for the explicit purpose of jamming, but rather for long distance communication and surveillance.

Am I missing something here?

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  • $\begingroup$ I just realized that the title could be wildly misinterpreted, if that's what the down vote is coming from. I fixed it now. $\endgroup$
    – Lundin
    Commented Aug 20 at 11:28
  • $\begingroup$ Distance is relevant. A jammer must be as powerful as normal signal, and with square of distance you may see: short distance you can easily win jammers (and jammers could not be too near, or you know the position of jammer). .Why do you think jammer are illegal on war operation? There are units about that, in plain sight (on organization diagrams). $\endgroup$
    – Giacomo Catenazzi
    Commented Aug 22 at 13:59
  • $\begingroup$ @GiacomoCatenazzi The scenario is that you have a mobile antenna on a vehicle in your base and wish to defend against incoming drones, so the defender would both have superior short distance and superior output power. Jamming commercial bands is illegal for most purposes and I think military drones will be using different bands. $\endgroup$
    – Lundin
    Commented Aug 22 at 14:05
  • $\begingroup$ But a jammer gives your position. it is a cat/dog problem. And military law is different. Forget "civilian law", during war. Frequencies may be listed in a appendix of a law, or just as addendum by government, so lower priority. I do not remember ITU rules, but most international laws explicitly say they do not apply during war (else countries would not accept it). Obviously various Geneva and Vienna conversions apply also during wars. $\endgroup$
    – Giacomo Catenazzi
    Commented Aug 22 at 14:11
  • $\begingroup$ @GiacomoCatenazzi The scenario is as mentioned in the question: "...when there are incoming hostile drowns carrying grenades. Plus you only need to activate the jammer for a short time." You'd only activate it when you spot hostile drones. Otherwise you'll jam out all wifi and bluetooth etc as well. The legal aspect of it all is just a side note (and probably better asked at the Law site). $\endgroup$
    – Lundin
    Commented Aug 22 at 14:18

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From the discussion in the comments

In reality radio communication is jammed, so indirectly commercial drones may lost communication.

But there are two factors which make them differently:

  • lost communication doesn't mean lost of control. Inertial system should be able to keep position information accurate for many minuted, and drone can be configured to continue straight (or according a plan) until control signals tell them otherwise. So on short range and speed, you may still be able to hit the target.

  • jamming gives hints on the position of jammers. It may be ok on long range maybe using a high power antenna, with some protection around, but on field things are more complex. Sometime jamming can be better, but then other weapons may be used. For short distances, now it is not convenient: nets are much more effective to reduce drone risks (commercial drones do not have huge inertia nor huge explosives).

Note: we are not discussing drones which you can buy on common shops, but commercial grade drones, which may be the same model, but with the possibility to better configure it. Normal shops must follows normal drone guidelines: weight, geofencing, etc. But if one has special permits, drone manufactures are happy to sell them without basic protections. Note: it is also not so uncommon: various professional uses requires it. Just it needs a lot of paperworks and planing (and the permission may be given only for one mission, you should ask for every mission, with all documentation of mitigations).

Long distance drones (and missiles) are different. Inertial system doesn't work so well on such distance (and times). Historically, see the V2 to London. So there was a lot of research on how to determine position: looking the stars, looking the terrain features (or now GPS or other radio beacons, which may be jammed), so they are much more vulnerable to jamming, and jamming can be done far away from sender and from target.

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