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

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

 

...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?

 

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

 

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.

 

"stay off above mah lawn" meme belongs here somewhere

 

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

 

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

 

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

 

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