1. We are sorrowed to report that one of the Founding Members has passed on. Dee (Righthand) is well remembered as contributing much to the operation of SurvivalMonkey, and is already greatly missed. Little lady, big person.

Mayor Bloomberg: Police Drones are Here, Get used to it!

Discussion in 'General Discussion' started by Mindgrinder, Mar 26, 2013.


  1. Airtime

    Airtime Monkey+++

    We had some purely academic discussion about drone defense awhile back. So just for pure academic and intellectual curiosity, we are engaging it again. I like those green laser ideas but wonder just how hard it might be to hold it on a tiny spot moving through the sky long enough to overheat and kill a CCD camera. A hobby style drone might be a 3/8 inch spot 3-400 meters away moving 20-30 mph and a more commercial one might be a 1 inch spot 7-800 meters moving 40-80 mph. Hmmmm....

    And even if the camera was taken out, many of the hobby versions now have a GPS location telemetry and autopilot and even failsafe fly home controls. So we could also jam the GPS but once it was out of range of a jammer it could restore GPS lock and a return home program. Hmmmm.....

    I'm wondering about a focused high energy microwave beam that would effectively deliver an EMP like hit to the drone. I have seen a little bit with folks taking a 1200 watt magnetron (puts out about 800 w of actual microwave energy) from a microwave oven, matching it to a highly directional wave guide antenna and attempting to create a microwave disruptor.

    I don't know the frequency of residential ovens but I recall commercial ones operated in the 900 MHz range. From days past doing EMI susceptibility testing with electronic engine controls, I know many electronics have issues with strong signals in the 300-1000 MHz range. Fields strengths of 100 volts/meter (our design goal) could often curtail proper function but not damage them permanently. We saw some die at 200 v/m but that was a long time ago and most things are better. I don't have a clue what field strength one might get from 800 watts 1000 meters away with a wave guide antenna having a directivity of say 24 db. BT? Got any ideas?

    That would be my first avenue of investigation though I admit the notion of playing with a magnetron outside of an oven scares me a bit. I would have some pretty good shielding between it and me and some field strength metering on hand during development. Just thinking and saying and certainly not plotting...

    AT
     
    Mindgrinder likes this.
  2. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    That is the thing about the Chinese Drone Program, they are ALL vulnerable to ANY Modern Air Force... That is why we fly Preditors at 30+ k feet rather than Lower, because they are so vulnerable, when used at lower altitudes. So Chinese Drones are really only effective against countries that have NO Effective Air Force, and NOT US, or Russia, or any First World Country.
     
    Airtime and Mindgrinder like this.
  3. Mindgrinder

    Mindgrinder Karma Pirate Ninja|RIP 12-25-2017

    ...is that if they stopped making iphones and ipads and switched to "war-mode" they could have an attack drone for every man, woman and child in America in....2 months?
     
  4. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    900 MHz doesn't cook anything... The microwave ovens ALL Work at 2.4 Ghz and 10Ghz but 99% are 2.4 Ghz because that is where the Hydrogen/Oxygen Bonds in water resonate, and this is how microwaves cook stuff, by pumping their power into the Water in the food, making Steam, which cooks the food. 10 Ghz is similar but not as effective. This is why our FCC set the 2.4 Ghz Band for UnLicensed Operations, and an ISM band. Long before there was ANYTHING using the 900 MHz Band, the Air Force used that Band for their White Alice Comm System, that connected all the old DEW Line Radar Stations, back to the Lower 48 States. These were Over the Horizon Troposcatter Links that were engineered to go 300-500 mile Hops. If that Frequency Band had any Water adsorption characteristics, it would not have been chosen for this System.
     
    Airtime and Brokor like this.
  5. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    Try to microwave freeze dried or fully dehydrated food.

    I'm asking. I don't own a microwave. Call it a science experiment.
     
    Mindgrinder likes this.
  6. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Not much happens, unless you add water...
     
    Mindgrinder likes this.
  7. Airtime

    Airtime Monkey+++

    Predators used to use the Rotax 912 engine which dried up the supply for the ultralight community pissing them all off a decade ago. Then the Preditor was upgraded with the Rotax 914 which is turbocharged and again the ultralight community got pissed because those became hard to get. Unless they are modifying the engine and airhandling, as I recall the power from this engine really drops off at 24-25k feet due to the engine controls cutting the fueling back to prevent over-revving the turbo. Regardless, it is still pretty high and hard for ground fired weapons shy of heat seeking missiles to have much chance to disable one. A fighter jet on the other hand.... And there are probably drones we don't know about that fly far higher now.

    AT
     
    Mindgrinder likes this.
  8. Mindgrinder

    Mindgrinder Karma Pirate Ninja|RIP 12-25-2017

    Better question....

    How do you soak a 100m square area up to 50k feet away with ANY signal that would flood every angle.
    C:/run Sat/RF/Cell/ALL_nerf.signal+to+noise+ratio.exe
    Manual aim.
     
  9. Mindgrinder

    Mindgrinder Karma Pirate Ninja|RIP 12-25-2017

    "stay off above mah lawn" meme belongs here somewhere
     
  10. Airtime

    Airtime Monkey+++

    Maybe not and/or maybe not any more. I just had this vague recollection from 25 years ago of a discussion at work about possibly using a micro-wave to do some crude EMI testing before renting a chamber that would hold a truck. But interestingly...

    Microwave Heating

    IEEE Xplore -
    Field-Strength Measurements of Microwave-Oven Leakage at 915 MHz

    Envirowave Corporation- Frequently Asked Questions about Microwaves, scrap tires, sewage treatment. (point 15)

    Anyway, this isn't important.
    The question is could an RF energy device be created inexpensively from readily available stuff that could disable a drone? I think there is reason to at least investigate the idea for intellectual curiosity.

    AT
     
  11. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Depends on the frequency of the Drones Control System...
     
  12. Airtime

    Airtime Monkey+++

    Agreed, if we are wanting to just jam the control system communications. But I'm not thinking signal jamming, rather EMI radiated susceptibility. This is where the various connections into and out of the various electronic modules from battery power to servo drivers to GPS or gyro interfaces, pickup RF energy. This gets inside the module, and if enough is beyond the capability of filter caps to shunt adequately to ground, and the voltages induced in various circuits inside screw up it's functioning. Like years ago when you couldn't put a 100 watt amp on your VHF or UHF transceiver in your electronic injection car without stalling the engine every time you hit transmit.

    AT
     
  13. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Not going to happen on a MilSpec Drone, all those will be shielded.... On a Toy it will depend on how good the Engineering is....
     
  14. Airtime

    Airtime Monkey+++

    Electronic modules for vehicles have gotten much better. Connectors can have bypass capacitors integrated right in them and PCB layout is much better understood as well. Bypass/filter caps right at the connector, multilayer boards with ground planes on the top and bottom, etc. But on the flip side clock speeds are way up, trace sizes way down so their impedance is up and where frequencies above 1 gig used to be ignored for EMI susceptibility testing, most companies like Ford are now specing to 2 ghz and higher because they started experiencing problems above 1 ghz and there is much more RF energy there compared to just 15-20 years ago. So, maybe the 2.4 ghz magnetron becomes a viable option. Just thinkin....

    AT
     
  15. Brokor

    Brokor Live Free or Cry Moderator Site Supporter+++ Founding Member

    I know this is again off topic, but how does water heat up when it's microwaved? :oops:
     
  16. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Post #24.... You liked it, didn't you read it?
     
  17. Airtime

    Airtime Monkey+++

    Yes they are shielded. The weakness is the wires going in and out. I know from work in the past the military EMI specs were't much different than commercial (the powerplant for the M1 Bradley vs a semi truck engine.) it was easy to shut them both down with a turn of the knob of the power amp feeding the test antennas. I'll ponder this next week when back in the office with a couple guys at work that are a bit closer to this stuff than I am now.

    AT
     
survivalmonkey SSL seal        survivalmonkey.com warrant canary
17282WuJHksJ9798f34razfKbPATqTq9E7