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Meet Drone Shield, an Ambitious Idea For a $70 Drone Detection System

Posted by samzenpus on from the I-can-hear-you dept.

An anonymous reader writes "Here's an Interesting idea of how to use a Raspberry Pi and a few other inexpensive items to make a low cost detection system. From the article: 'The Drone Shield would combine a Raspberry Pi, a signal processor, a microphone, and analysis software to scan for specific audio signatures and compare them against what known drones sound like. (Because obviously a Predator drone is going to sound very different than a small quadcopter.) Once a match is found, the Drone Shield then sends an e-mail or SMS to its owner...'"

32 of 159 comments (clear)

  1. Range by Dan+East · · Score: 4, Insightful

    A Predator has an operating ceiling of 25,000 feet. You think a raspberry pi and mic is going to hear a Predator drone in cruise mode that's 5 miles above? You can't even hear a massive passenger jet at that altitude! Now a quadcopter is a different story, as they are as loud as can be, but saying this system would work on something like a Predator is a stretch.

    --
    Better known as 318230.
    1. Re:Range by Anonymous Coward · · Score: 5, Interesting

      Yeah, you'll need some bigger tools for that.

    2. Re:Range by multiben · · Score: 3, Insightful

      Just because you can't hear it doesn't mean a microphone can't pick it up. I am not going to google this because I am lazy, but I would not be surprised at all if a good quality, well aimed, highly directional mic could pick up enough of a noise to run an analysis.

    3. Re:Range by Anonymous Coward · · Score: 5, Funny

      So now the highly directional microphone has to be pointed toward the undetected drone in order to detect it? That makes perfect sense.

    4. Re:Range by BitZtream · · Score: 2

      The basic hellfire missile (which are the ones they've acknowledged on the drones) has an operational range of 5 miles, 25k feet is less than 5 miles, so it depends on your definition. That would certainly be towards the maximum range, but gravity would help you get some more distance out of it.

      Of course, thats just what the government has ACKNOWLEDGED to exist. That basic hellfire spec comes from a missile made in 1985, not sometime in the last 10 years. Between upgrades and the fact that they don't tell us about their most impressive technology, I would say that hitting you from 25k feet is a walk in the park.

      Keep in mind, the hellfire for instance has both laser and radar guided variants. Not only can it see the target from 25k feet, it can read the newspaper, tell you the date, and tell you which comma its going to impact with first. The laser guided variant will hit where you aim the laser assuming it can get there before it runs out of fuel. The real question is, can you get the laser painter to the target. The laser painter being something that a rangers team would carry in to the target area and use to site the target and guide the drone's missile in.

      --
      Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
    5. Re:Range by flayzernax · · Score: 2

      Hehe, yeah, but a whole bunch of these all over the place in a distributed network that all dumped to one database could make a very interesting historical map of drone flight paths.

    6. Re:Range by fluffy99 · · Score: 4, Interesting

      So now the highly directional microphone has to be pointed toward the undetected drone in order to detect it? That makes perfect sense.

      If you're sophisticated and have multiple microphones in a well planned array, then you can aim your microphone in software and sweep the sky looking for the signature. Look up acoustic beam-forming. If the array is large enough you can estimate distance as well as angle. The bonus is that you get actual tracking instead of just detection.

      The problem would be processing power though. Simple implementations could range from 4 microphones that you sum/subtract to look at quandrants, up the way to something approaching what the US Navy does with its towed arrays. I doubt the PI could handle the processing of the signals in both the time domain to get tracking, and the frequency domain to do target qualification.

      Of course you also have the question of what do you do when you detect one? Aim a camera at it? Fire off your green laser? (no not suggesting you commit a felony).

    7. Re:Range by Cryacin · · Score: 4, Funny

      Dusts off old chestnut

      Sounds like you need a beowulf cluster for that!

      --
      Science advances one funeral at a time- Max Planck
    8. Re:Range by AHuxley · · Score: 2

      Yes flay, You could build a huge network over a wide area, with wired connections to each mic. Back to a central hub for very basic noise values math.
      The best location would be in a more empty state with lots of new drone 'schools' for maintenance, new staff needing many flight hours. This would give you some open space, a wide sky to scan and that real sound over many months.
      Due to the nature of drone training, one would expect this to be away from suburbia, the big air traffic hubs. Based on video capture to give you a visual of direction, very slight changes in every mic could build up some good basic math over time.
      Another option would be to have a small cam and mic in a rock/hide and massive data card to track over a few days. Place many over a wide area making them look like some simple audio/still frame university wildlife counting project.
      You could map the location of each device, play back the sounds and try and sync them all at a later date.

      --
      Domestic spying is now "Benign Information Gathering"
    9. Re:Range by DerekLyons · · Score: 5, Informative

      Disclaimer, I was a submarine crewman and though I was a qualified sonar watchstander I was not a sonar tech. I have also studied fairly widely in the unclassified literature.

      So now the highly directional microphone has to be pointed toward the undetected drone in order to detect it? That makes perfect sense.

      If you're sophisticated and have multiple microphones in a well planned array, then you can aim your microphone in software and sweep the sky looking for the signature. Look up acoustic beam-forming. If the array is large enough you can estimate distance as well as angle. The bonus is that you get actual tracking instead of just detection.

      It's certainly simple - in theory. In reality, picking out such a faint noise from the background is Very Difficult Indeed.
       

      The problem would be processing power though. Simple implementations could range from 4 microphones that you sum/subtract to look at quandrants, up the way to something approaching what the US Navy does with its towed arrays. I doubt the PI could handle the processing of the signals in both the time domain to get tracking, and the frequency domain to do target qualification.

      Processing power, both for signal analysis (finding the faint signal) and for beamforming is on the beginning of your problems. Let's just hit the high spots:

      • The accuracy of your track is only as good as the accuracy of your microphone positioning. (You won't need surveyor grade accuracy, but you will probably need better than the three meter accuracy that WAAS/GPS provides.) You can't beamform if you don't know the relative locations of your microphones. Oh, and did I mention that sound is refracted as the temperature of the air changes? You'll have to account for that too - assuming you can get accurate enough data on current conditions.
      • You'll need some fairly clever filtering and processing to avoid the microphones being swamped by unrelated and louder background noise.
      • You also need high quality low noise amplifiers to bring the sound of Predator up to useable levels. (The highest quality commercial audiophile amplifier isn't even close. You need a supercomputer and audiophile gear by comparison isn't even as good as the throwaway calculators you get with your breakfast cereal.)
      • Speaking of the sound... different frequencies get attenuated and refracted differently. You'll have to account for that too.

      Etc... etc... The very definition of a non trivial project. You're essentially trying to replicate what the USN does with it's passive sonar systems, with dull and chipped stone knives. (You don't even have a bearskin. You don't even get a bearskin, just the aforementioned knives.)

    10. Re:Range by nospam007 · · Score: 2

      "So now the highly directional microphone has to be pointed toward the undetected drone in order to detect it? That makes perfect sense."

      Ever seen the rotating antenna of the radar on a boat? That's the reason it rotates.
      To detect undetected stuff.

      I guess if many people are ordering one of these drone detectors from a cave in Pakistan, it could be a clue that it works.

  2. Tough by Cassini2 · · Score: 5, Insightful

    It's tough to reliably detect low-level background repetitive noise without detecting all sorts of nearby domestic appliances, car engines, and such. In the modern city, we live with *alot* of noise.

    Now, if the problem is to detect jet engines in rural areas featuring mountainous terrain, then I think I know what the point of this project is.

  3. Re:Interesting... by Anonymous Coward · · Score: 2, Informative

    Ofcourse it's been done. There's a lot of military equipment that works like this.

  4. Pi fever by porkThreeWays · · Score: 2

    So, it's a project with a computer that happens to run on a slightly slower processor. If this ran on a mini-itx no one would even mention that part.

    --
    If an officer ever threatens to taze you, say you have a pacemaker.
    1. Re:Pi fever by MacTO · · Score: 2

      Of course, the Pi is also smaller and uses less power than a mini-itx board. Sticking something the size of a small tissue box in the backyard, and doesn't have an AC cord running into the house, is going to create a lot less friction with the spouse. Many people also find solving problems with constrained resources fun.

  5. Cardinal vs. Mockingbird vs. Bluejay by girlinatrainingbra · · Score: 3, Interesting

    This is more likely to work better as a "squirrel" vs. "bird" detector, or with good/better datasets, perhaps even as a "cardinal" vs. "bluejay" vs. "mockingbird" vs. "car alarm" detector, especially if the birds are in your front or back yard. But really, the concept of hearing a predator drone is very farfetched, unless the drone is flying super low for some reason!
    .
    Better to use this as an auto-logging device for some birders falling in love with counting how many birdies are coming by, or for recording to the exact micro-second when the swallows finally make it back to San Juan Capistrano!

    1. Re:Cardinal vs. Mockingbird vs. Bluejay by ceoyoyo · · Score: 5, Funny

      Hm. That might be interesting. Build a couple and put them a distance apart, plus a remote controlled super soaker. Sit in the basement and pretend it's a sub.

      "Skipper, we have a contact on bearing 238... probable squirrel class mammal, likely a grey!"

      "Do you have a firing solution?"

      "Range and course calculated skipper! Firing solution locked in!"

      "Fire!"

      "Skipper, sudden change of aspect on the contact. I have angry squirrel sounds."

      "Nice job, everybody."

  6. Re:Interesting... by BitZtream · · Score: 5, Insightful

    It is much more developed, you just don't realize it. This sort of signal processing is used in ultrasound machines, your car, my boat, fetal heartbeat monitors, little credit card readers that attach to your phone via headphone jacks. ALL SORTS OF STUFF.

    Its all just an application of some FFTs and some weighting. It isn't even non-trivial for anyone with some basic understandings.

    Without any prior knowledge, I went from no understanding to of FFTs to writing code to detect lean fuel during runtime on my R/C airplane. A Raspberry PI is also way more CPU power than needed to do it, which means it can also do a whole bunch of other stuff too.

    --
    Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
  7. Re:Can't you just detect the RF? by Charliemopps · · Score: 2

    There are many types of drones. You're thinking of a more radio controlled type. The better ones just have a cellular chip in them and you control them over the internet. Rather than "Fly them" like an RC plane, you give it a target and it goes on its merry way. Once it has its instruction set it doesn't even need the cellular connection anymore, it can just fly back to "home base" once it has done whatever it is it was supposed to do.

  8. Re:And then what? by Black+Parrot · · Score: 2

    You run away?

    That's as much of a "shield" as a radar detector "protects" you from speeding tickets.

    OK, have it send the e-mail to your next of kin.

    --
    Sheesh, evil *and* a jerk. -- Jade
  9. Re:Interesting... by Black+Parrot · · Score: 4, Funny

    A Raspberry PI is also way more CPU power than needed to do it, which means it can also do a whole bunch of other stuff too.

    My ++ model will mine Bitcoins between drone attacks!

    --
    Sheesh, evil *and* a jerk. -- Jade
  10. Re:And then what? by AK+Marc · · Score: 3, Interesting

    The greatest use of drones is still reconnaissance. So you stop doing the illegal things until it's gone. Why run from a camera? Just hide your activities until it's gone.

    --
    Learn to love Alaska
  11. Re:Interesting... by Cryacin · · Score: 4, Funny

    Funny will be when they mount these drone shields, on drones. Then the drone shields will be warning you about other drone shields operating in the area.

    --
    Science advances one funeral at a time- Max Planck
  12. Re:Interesting... by phantomfive · · Score: 2

    Without any prior knowledge, I went from no understanding to of FFTs to writing code to detect lean fuel during runtime on my R/C airplane.

    That is fascinating. I feel motivated to go out and try myself, now

    --
    "First they came for the slanderers and i said nothing."
  13. better idea by slashmydots · · Score: 3, Funny

    You actually don't need to listen for them. If you watch really carefully, you might be able to see part of your neighborhood blow up. Then you know a drone is overhead.

  14. Re:Predators are so cheap, everyone can have one! by anubi · · Score: 2, Interesting

    Its not like we think our Government wants to spy on us because they think we intend them harm.

    I think its more down the line of : You just fixed your patio cover. Did you have a permit to do that (fee)? Did you have it inspected by the city inspector ( another fee ). We need to re-do your property tax!

    And gee whiz, what if someone is hanging their wash in the back yard on a clothes line instead of using a dryer!

    --
    "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]

  15. Bigger tools -- was Re:Range by kosty · · Score: 2

    "Yeah, you'll need some bigger tools for that."

    Can't we just raise money to buy/rent/bribe the "bigger tools" who keep telling us that this (drone-use) horse$hit is "legal?" Just sayin'...

    --
    "Democracy." It's just a slogan.
    1. Re:Bigger tools -- was Re:Range by KGIII · · Score: 5, Interesting

      I don't think that I disagree with your ideals. Having said that, and - really, I don't disagree with them in all likelihood, I must ask, "In which way(s) are you asserting that drones, or their use(s), illegal to start with? What, specifically, is illegal about drones? What laws are being broken with them?"

      I ask because, well, I fear that they will become so inexpensive to operate (including training) that they will be used to increase surveillance which, while against my ideals, probably doesn't (in and of itself) violate any laws. I'd like to be able to make a clear, factual, and reasonable argument against the increased use of drones but I don't have any arguments to make against it that are logical and truthful. I can only state that I'm afraid of what it may turn into.

      Even in my worst imagined fears concerning these drones, I'm unable to find any laws that are being broken. Perhaps you come from a different country than I do? I'm from the United States of America. We're not all that free here which means that there are a lot of laws. Given the number of laws it is impossible for me (I'm not a lawyer, even then it would still be impossible) to know all of the laws. However, I'm reasonably aware of the many laws that we have to protect us and I'm reasonably aware of the laws that the government must follow and I'm unable to point to anything specifically about drones (or their proposed use, or even with the uses that I'm afraid of) which are illegal.

      So, I'm not asking you to be my research assistant or the likes. You stated that drone use was illegal which isn't very specific and certainly isn't true so I'm hoping that you have something more concrete and that you can actually point out which laws being broken by these. If you could provide specifics and case law that would be most excellent too but I'm trying to not ask for too much.

      See, in my opinion, they are making their surveillance too intrusive and too easily accomplished. In this day and age we're able to be monitored in most everything we do and, while this has always been legal, it has become increasingly easy for this to be done and for this information to be shared. The use of drones by police, municipalities, and private companies to monitor, photograph, and track a person is just yet another step in the age of zero privacy. I'm quite certain that it (that portion specifically) is legal though I'm equally certain that it shouldn't be. I can vocalize, express, this as a worry and all and that may affect the opinions of some but if it is illegal then there's an even greater chance of demonstrating the harm that this can cause to society.

      I don't know... Perhaps you meant it should be illegal? I'm really unable to find anything that indicates the use of drones would be illegal in and of itself and that includes FAA regulations and the likes - I've looked. I could be missing something. Then again, this is /. and you could just be an insane zealot who thinks that anything they don't like is illegal but I'm hoping you're more honest and logical than that. Trust me on this, I've seen it here before...

      Either way, I'm hoping you have something more concrete than the generic statement that the use of drones is illegal because, well... No, no it isn't illegal in and of itself. If there's some specific manner that they're being used that is illegal then I'm quite interested in knowing what it is. Like I said, I've even met people online who thought that DST (Daylight Savings Time) was illegal so you could just be one of the crazy ones but I'm sort of hoping you're not. It would be, admittedly, amusing but it wouldn't actually be beneficial to me.

      --
      "So long and thanks for all the fish."
  16. Re:Interesting... by wonkey_monkey · · Score: 2

    little credit card readers that attach to your phone via headphone jacks.

    --
    systemd is Roko's Basilisk.
  17. Re:Interesting... by ttucker · · Score: 2

    FFTs are not used in magstrip reading software.

    But they are used extensively while processing audio signals to digital ones.

    little credit card readers that attach to your phone via headphone jacks.

    The OP specified something that plugs into the analog microphone jack of a phone to transfer digital information from a credit card, so I would say a DFT is probably occurring somewhere in there. :)

  18. Re:Interesting... by Bacon+Bits · · Score: 2

    Imagine a Beowulf cluster of these!

    --
    The road to tyranny has always been paved with claims of necessity.
  19. Obligatory xkcd by HungryMonkey · · Score: 2

    Great, because I was worried about these.