Hacker News Reader

Comment by KaiserPro | Hacker News Reader

A number of things.

1) blocking GPS. 2) Electronic noise (mostly the same as blocking GPS, but needs lots more power) 3) thin nets. (bonus points for barrage balloons) 4) shotguns 5) flak (air burst anti-air shells 6) rain

Off the shelf quadcopters are fragile and not designed to cope with hostile flight. Loose a motor and your falling out of the sky.

Loose a GPS track and you'll either hover, or descend. This could be hacked to rely on dead reckoning, but that's inherently inaccurate. the sensors are designed to tell you what way up you are, how fast you are deviating from desired angle, they rarely have odometers.

A small > 250watt narrow band transmitter, Something with harmonics for 2.4gigs, or just a modified microwave magnetron with a decent directional antenna will destroy most hardware.

A thin fishing net is thin, light, cheap and almost invisible. The hardest part is keeping it in the correct place.

View on HN

Before GPS, cruise missiles used photographs of the terrain they expected to navigate and a camera. The photos were state secrets back then; today they're easily accessible for the entire planet. Miniature computers are also far more power and more capable of the processing needed for navigating using photos and a camera. It'd take some R&D to develop, but it's certainly possible.

Also, "falling out of the sky" can still be an effective weapon if you plan for it.

While certainly possible, it would take the pool of people able to build it down at least an order of magnitude. I can say so with the experience of a guy who build drones and also tried working with some vision stuff for drone indoor positioning. It simply is far harder to do. GPS guidance you can do it in an slow evening.

Most of the measures intended to stop access to explosives, weapons and generally dangerous things are not able to do so 100% but simply make the cost of that access high enough MOST malevolent actors will simply not afford it.

The problem is that virtually all those things could harm, interfere with, or annoy human activity.

GPS is used for all sorts of legitimate human activity, so blocking it would cause problems.

Electronic noise could interfere with not just drones, but all sorts of electronic devices that humans use and need.

Nets, flack, and shotguns could certainly interfere with or harm humans, depending on where they are, and if there's some place they're not to let humans pass, then drones might be able to go through the same route.

Rain is annoying to humans and so plenty of places where humans are are protected against rain, so in those places this is an inadequate defense against drones -- though maybe sprinklers would work (but they can cause their own problems to useful electronics and might even cause an electrocution hazard to humans, depending on where they're used).

The problem is that virtually all those things could harm, interfere with, or annoy human activity.

In the context of how to respond and if possible disabled a weaponized remote controlled aircraft, I think being dead or seriously wounded also interferes with human activity. These proposals aren't-I didn't get the impression at least-meant to be implemented and operated persistently, but applied into purpose-built apparatuses to disrupt a hostile remote controlled aircraft.

That's a context I'm willing to trade having my phone work for a moment if there's a DJI Phantom dropping bombs over Boston (I beg humor for the hip-hop hyperbole) being taken out of commission before someone gets hurt.

The problem I see is that jamming GPS / wifi / mobile frequencies once you see a suspicious drone is too late. When the drone is already in view, it can find its target by inertial or camera navigation alone.

But jamming 1km around every possible target, every day as a precaution is going to be too disruptive. It may actually increase risk to life - by jamming 911 calls for any ordinary accident.

You are of course spot on. You have to asses the cost of implementing vs the risk/cost of the attack

For a spurious one time threat from an unknown actor, then most of these are overkill.

However against a known adversary with an MO for doing drone attacks, these might be legitimate.

An example, a sports event: stringing a fine net from the building/all weather lights, directional GPS blocking (its RF so can trivially be localised.) is cheap and proportional. "RF snipers" with 900 watt converted microwave "guns" (or more likely a beam forming radar type affair)

To the article's credit, none of these solutions address the "high up drone dropping a grenade on you in an area you can't secure beforehand" - simply because you won't know it's there until it's too late.

But that's not uniquely a drone problem. Aren't modern mortar shells wicked accurate?the trigonometry that governs them has been known for centuries.

i can't imagine how unguided shells can be that accurate, especially if you only have one shot. trigonometry helps, but there are way too many unknowns (mainly atmospheric cconditions) for it to work perfectly.

We have guided bullets today. A guided mortar is downright trivial in comparison.

agreed, reminds me of this xkcd :)

https://xkcd.com/1958/

Reminds me of the fallacy that Autonomous vehicles need to be absolutely infallible, when in fact they only need to have fewer fatalities per mile than humans.

Visual odometry and visual SLAM is absolutely mature enough for drone state estimation and control. It’s not off-the-shelf technology quite yet, but a skilled adversary could concoct something I’m sure. I imagine drone attacks today are likely going to be FPV, and then jamming of the video feed is possible again.

See Skydio As an example of a company doing this off the shelf already

This is quite impressive:

https://www.youtube.com/watch?v=USYlt9t0lZY

https://arxiv.org/abs/1705.02550

And it's solving a somewhat harder problem - it's done with no maps apart from what it's generating in real time.

An accelerometer and gyroscope may not make for a precise dead reckoning system, but if all you need is to get into a 1m blast radius, they might be good enough. Pair that with a smartphone with face/feature detection like those used for AR, and you might be able to navigate pretty much anywhere, no need for GPS.

IIRC exactly this was the basis of removing selective availability on GPS signals for civilian use. The original GPS spec had two bands / channels / something: one that was encrypted, for military use, and a "fuzzy" version for civilians that would vary ±100 meters in accuracy.

Once inertial guidance for missiles became more accurate than ±100 meters, there wasn't a point to reducing the civilian accuracy anymore, so they disabled SA in 2000 and went all-in on availability in 2007.

https://www.gps.gov/systems/gps/modernization/sa/

The V2 guidance system was an integrating accelerometer and a gyroscope. They could barely hit a target the size of London. The lack of accurate guidance made it a militarily ineffective weapon.

To be fair the V2 rockets never hit anything useful prinarily because the British had turned every german spy and were feeding them false information about the results of the attacks.

The rocket guidance system was not capable of hitting something more precise than "London", and of course the British tried to stop even that from happening.

Also interception by drone.

I know somebody who was having a nuisance/peeping tom issue with a neighbor and a drone. They had an unfortunate accident where their cheapo drone somehow collided with the neighbors.

Or a HERF gun...

https://hackaday.com/2011/03/21/herf-gun-zaps-more-than-your...

Most of these can be countered by having hundreds if not thousands of cheap, fast and autonomous drones launching grenades from high or very low altitude. The swarm can loose a couple because of a fishing net or anti-air flak, but they can try another attack vector, loose a couple because of shotgun and try something else again.

Could a similar technique be used for defense? Program hundreds of drones to track and collide with enemy drones at high speed?

I don't know, you can build a racing drone for $200 https://www.youtube.com/watch?v=6MwKdHZ8OlM these go at 100mph and can change directions multiple times in one second.

It's worse, actually. There are motoless gliders that fly up to 545 mph, and then there are tiny jet planes that go up to 465 mph. You can jam the signal, but as soon as someone can put an autonomous vision system on them, it will become an extremely powerful weapon. You don't even need an explosive at these speeds, it can cut your target in half

https://youtube.com/watch?v=MoaWlKC3wIM

Frau Farbissina: We have developed the perfect assasination weapon! A silent glider capable of Mach 0.7!

Scott Evil: Great, now we just need to get the Venezualan President to give a speech at Torrey Pines or the backside of some other world class dynamic soaring hill...

Gliders can be dropped off balloons or airplanes. Their advantage is they are simple and cheap.

Yep - you won't get 500+mph out of that though. And the 500+mph dynamic soaring "gliders" are neither simple nor cheap.

(That's only relevant to this sub-thread's discussion, your point is completely valid in the context of the top level thread... Having said that - needing balloons or planes to get your home-brew autonomous weapons above your target is a whole extra level of logistics and opportunities to get observed/caught compared to launching consumer-grade drones.)

That's how the drone wars started.

If you know its coming. And if you have enough. What about 10 hardware-store drones with a few grams of explosive each, operating on dead-reckoning to reach their target? What about 20 of them? 100?

Id imagine a very directional antenna (or multiple ones to cover more bands and polarisation) with a 14 15 dbi plus a beefy wifi transmitter would be one possibility.

Just don't aim it like a rifle the side lobes might get nasty

A microwave magnetron and a satellite tv dish...

900-ish Watts of 2.4GHz will upset most off-the-shelf drones at quite some distance...

Nets would work to arrest and capture the drone, but to stop it you could probably get better results with a confetti like shot of something stringy and sticky. I bet long thin cotton or nylon thread would quickly tangle in the propeller, and sticky tape shards would disrupt the airflow properties of the propeller.

Reply on news.ycombinator.com