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Taking Down A Drone

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  • root
    How are the new 30000 mw blue lasers?

    Something like this.

    Leave a comment:

  • Reasonable Rascal
    started a topic Taking Down A Drone

    Taking Down A Drone

    This guy seldom writes these days, but when he does it is certainly worth listening to. Old school intelligent, been there done the math and science.


    The lasers bring down the drones once the level of random IR hitting the bottom of the drone overloads the downward facing IR reflective sensors so that the unit starts thinking the ground is getting too close and forces it to go into landing mode. There are plenty of ways to take drones down if you want to, overpowering/spoofing the RF side is just one way. Faking the GPS is another. But confusing it's collision avoidance also works well, which can be done by both infrared light in the 880 to 1,100nM range, as well as Ultrasonic noise/pulses in the 35-42kHz range (a lot of the bigger units use a mix of cameras, IR sensor arrays and ultrasonic "ping" type of sensors). If you have a good random noise generator and a few 920nM luxeon Star LEDs with some good lenses you can do a lot of things with very few people able to see what you are doing. Likewise, if you can get your hands on some of the older (larger) 38, 40, 41, or 42kHz ultrasonic transducers, you can play hardball with those detection systems.

    And the reason that the green laser pointers do this is because they are actually not a green diode laser, but either an IR diode laser at 1064 nM firing into a KTP Frequency doubling crystal to bring it to 532 nM (Green), OR an 808nM IR (near IR, almost Red) laser diode firing into a ND beamsplitting element to get it to 1064 nM then through the KTP or similar to bring it 532 nM (Green) output. Either way you have "some" green output and unless there is a lot of good IR filtration on the output stages, a LOT of IR also flying out the end of your green laser pointer. Some of those "5-10mW" green laser pointers are using a 100-400mW laser diode to pump those crystals to get the output needed (each stage of the frequency doubling is around 25% efficient on a good day). If you want to see if your green laser pointer is also emitting IR laser light as well, have one person aim the laser pointer at a distant white wall and you can walk up to the wall where the green dot is, and look at it through your phone's camera (most phones don't have the best IR filtering). If your green laser pointer has poor (or next to no) IR filtering, you will see a second dot the wall that only your digital camera will see (night vision devices will see this bright as day). That second dot is the 1064nM IR laser showing through. In some really rare cases you may see TWO extra dots that only the digital camera or night vision will see, one being the 1064nM shifted beam, and the second invisible dot being the 808nM actual diode laser pump beam. Both the 808nM and the 1064nM beams will mess with the IR distance sensors on drones.

    Food for thought while on the subject: Most of the video channels coming back from the drones to the "pilot" are on 5-5.8GHz, while the control signals (remote control channels) are on 2.400-2.485GHz and run much less than a watt. The magnetron in a microwave runs rather wideband at 2.450GHz with quite a few hundred watts.

    Two superballs with holes and 10-12 inches of guitar string tied between them, fired with a slingshot also does a number on them and usually won't take out anybody in the crowd if it misses the drone. Just sayin....