How to Hide From Drones: Synthetic Aperture Radar

[Music] [Music] when it comes to aerial or satellite-based reconnaissance and surveillance one of the most commonly used classes of sensors is what we like to call synthetic aperture radar so what is it well this can get a little nerdy and hard to understand so let's break it down by first looking at how a normal camera works whether it's used to take pictures of a birthday party or if it's mounted on a satellite in orbit a normal camera functions pretty much the same everywhere light gets beamed down from the sun to reflect off of an object that reflected light is then observed by the lens of the camera or taken in by the lens which passes it through an aperture to control the amount of light and finally this light gets projected from the lens onto a sensor in the days of old this sensor might be light sensitive film but in today's world this is going to be a digital sensor either way the light lands on this sensor forming the image pretty simple right well when it comes to synthetic aperture radar the process gets a bit more complicated so the first major difference is that there is no camera lens instead we've got an antenna that emits radio waves but we still keep the name beca ated so the first major difference is that there is no camera lens instead we've got an antenna that emits radio waves but we still keep the name because even in the context of radio waves this antenna array is called the aperture because the function is the same as the lens even though it's completely different technology also we don't have a sensor that is sensitive to visible light but rather a complex computer which can analyze radio waves or radar beams to form the image this system works much like a bat's echolocation or dolphin sonar in that it emits radar pulses which travel down to an object bounce back off of the object and return to the aperture or the antenna which has been listening for changes in timing signal strength and things like that now one of the cool things about this technology is that you can either have a massive antenna that can collect all of the radar returns or you can move the entire sensor over a wide area capturing trillions and trillions of different radar returns from different angles this actually works out quite well because satellites have to keep moving in order to stay in orbit and for them to even get into orbit in the first place the sensor orks out quite well because satellites have to keep moving in order to stay in orbit and for them to even get into orbit in the first place the sensor has to be pretty small so it's a win-win but it gets a little more complicated see a satellite in orbit is moving at speeds of several thousand miles per hour relative to the earth's surface so by the time a radar signal gets beamed down to an object on earth and reflected back to the satellite the satellite has moved not very much mind you these radar beams are moving at the speed of light so the lag isn't huge right but it's enough to be measurable and actually be of use synthetic aperture radar sensor platforms don't just have one aperture or antenna they have millions of them and if you arrange these bad boys in a way similar to an image sensor in which every antenna or aperture is more or less a pixel well now you start to see how we can get an image from this system so this sensor package gets rocketed into orbit where it is constantly moving around the earth beaming down radar signals and receiving the reflected returns moving around targets to capture them from different angles and when a sensor does this moves around the tar gnals and receiving the reflected returns moving around targets to capture them from different angles and when a sensor does this moves around the target object in such a way as to constantly change the angle of the radar returns we call this movement or process synthetic the sensor isn't simply receiving the returns from another object like how cameras receive light reflected from the sun sar sensor is artificially creating that signal itself and that's where everything comes together to form the term synthetic aperture radar now as confusing as that explanation was things get even more complicated when we try to examine exactly what a synthetic aperture radar sensor platform can do so rather than go down the endless list of things that this class of sensors can do let's instead just focus on the capabilities that might be of interest to the average u.s citizen from the perspective of the current times we live in by far one of the most well-known features of synthetic aperture radar is its ability to collect an image in any weather condition since we aren't relying on reflected light which can be diffused by clouds or obscured by darkness radar beams can punch through any weather ondition since we aren't relying on reflected light which can be diffused by clouds or obscured by darkness radar beams can punch through any weather or environmental conditions this might not sound like much but this matters a lot throughout history the number one go or no-go criteria for almost all military operations is weather and right now within current u.s military doctrine and actual practice there are almost zero combat operations that are conducted without some kind of overhead surveillance even among our nation's most elite special forces that pride themselves in operating without any outside support you'd be hard pressed to find a special forces unit that will leave the wire without a full isr stack granted that's definitely a reflection of our current military status of not having anybody to invade so when the next major conflict kicks off this doctrine will change but for right now even our nation's most elite special forces are to be blunt not very elite if they won't even take a visit to the portage on without a pair of 64s orbiting in a fixed wing asset on standby just to clarify this is not the mentality of the dues on the ground almost all of these dudes would ab f 64s orbiting in a fixed wing asset on standby just to clarify this is not the mentality of the dues on the ground almost all of these dudes would absolutely be willing to go out with nothing but an mri and a tomahawk but the command structures of all military units are very risk-averse right now in some way or the other with most commands requiring isr for all missions to include sar scans of the operational area and one of the main reasons that soaking an area with isr before an operation is essential is cave detection this is particularly useful in the middle east or mountainous areas where caves are everywhere your classic imagery analyst out there will tell you that most cave detection is done with normal electro-optical sensors i.e a camera but the sharp reality that can't be denied is that one of sar's best uses is for detecting even the smallest of caves this use is actually a holdover from the cold war some of the very first uses for sar were to find and measure secret soviet bunkers submarine pins tunnels ballistic missile sites and pretty much anything that might be underground you can have the largest underground bunker in the world but you've got to get in there someh sites and pretty much anything that might be underground you can have the largest underground bunker in the world but you've got to get in there somehow and some of the most photographed objects in the world are the entrances to soviet and now russian buildings and cave structures an interesting note is that the soviets russians in particular broadly speaking don't actually use caves really that much at all but they do use buildings to hide their military hardware from prying american eyes and this leads to a very fascinating use of sar seeing inside buildings now that you know the basic operation of sar one might be able to deduce that an active radar beam or a series of thousands of beams can be bounced off of different objects to measure certain characteristics so what if we were to wait until the satellite was in the right spot and then angle the beam so that it bounces off of the ground and into the doorway of something like an aircraft hangar that could be pretty interesting this means that we can beam these different radio radar beams into doorways and see what's inside because all we've got to do is just wait for one of these signals to bounce all around all over the inside r beams into doorways and see what's inside because all we've got to do is just wait for one of these signals to bounce all around all over the inside of the structure until it hits something or until it bounces back out to the satellite obviously this is going to be very wasteful because of the sheer number of electrons involved we're talking like trillions and trillions will not make their way back out of the hangar door and will simply be absorbed by things that are inside the hangar but if we wait long enough some transmissions will bounce back out and if we or rather a supercomputer attached to the sar sensor analyzes these radar returns the timing of the returns radar beams of different frequencies and by using a whole lot of math that is really hard to understand sara can detect if something is inside that hanger or not and perhaps most importantly if the sensor is really good and if we fire a lot of beams through the door we can maybe determine what is inside the hanger now we see the real power of sar now as cool as this sounds this is a very very high level usage of this technology and most information on this capability is pretty rare to find in the open source world but ds this is a very very high level usage of this technology and most information on this capability is pretty rare to find in the open source world but there are lots of articles being written about sar because of its civilian uses and the data is out there if you're interested in learning more about this and from the civilian images one can see that the resolution for satellite-based sar is horrible the reason that we use the aircraft hangar example is that sara can't really see through a doorway smaller than a massive hangar door so that's the most common usage for satellite-based collection assets so for those of you out there that find yourself looking up to the sky and being concerned about spy satellites tracking your every move you don't really have to worry at all about the national reconnaissance office bouncing radar beams through the front door of your house this technology in our experience is not nearly that good from satellite-based platforms but when it comes to atmospheric collection things are a bit different which leads to the next topic ied detection so we pretty much know how sar works when it's on a satellite just blazing through space at 16 000 miles per hour w ds to the next topic ied detection so we pretty much know how sar works when it's on a satellite just blazing through space at 16 000 miles per hour well a few years ago and through various billion tax dollar investments the defense industry figured out how to make sar sensors small enough to put on aircraft in various drones and the effect is quite dramatic when you think about it it's pretty obvious that the closer you are to an object the better image you can take with higher resolution so a drone or an aircraft that's at an altitude of say 30 000 feet will obviously take a much better image than a satellite that's orbiting at an altitude of 400 miles so that resolution problem that the satellite has is very much reduced by moving the sensor closer to the target and here's just how much resolution that these aerial sensors can have obviously we can't talk about much of this in the open source environment but one style of sar is what's called ccd or coherent change detection we've briefly talked about this in the past but it's really hard to talk about this topic because again there just isn't very much known about this capability in the civilian world you can go down this rabbit y hard to talk about this topic because again there just isn't very much known about this capability in the civilian world you can go down this rabbit hole and nerd out over ccd but the basic explanation of how it works is as follows so instead of a satellite we've got a drone flying overhead and it's beaming down these radar signals much the same as a satellite albeit with a much smaller footprint because it's closer to the earth and because of this the resolution is terrifyingly good we're talking so good that the radar beams can detect the difference in distance of a few millimeters or even much less detecting the difference in distance between two different grains of sand remember sar works by measuring the time it takes for a radar beam to bounce off of an object and return so if you multiply this up a bit sar can detect that these grains of sand are a bit lower or further away from the aircraft than these grains of sand and when we rotate this around and we look from the top down and overlay the real image we can see that this is a human footprint but we can go even smaller what about land mines or ieds as most people can guess land mines and ieds work best when they are in f s a human footprint but we can go even smaller what about land mines or ieds as most people can guess land mines and ieds work best when they are in fact hidden so the standard general operation of landmines around the world is to dig a hole plant the landmine wherever you're going to plant it cover the hole fill it in and then camouflage the area so that you can leave that's the general gist of how landmines are planted and over time through natural weathering the ground above them will settle and if the weathering is extreme it will be very easy to spot landmines like this simply with the human eye but for the most part this weathering will still not make it obvious that a mine or an ied has been planted there but not to a sar sensor a radar sensor with extreme accuracy can detect those different grains of sand and dirt that indicates there has been a disturbance in the ground now you might be asking how does the sar sensor know that this land mine isn't say a rock or something and the answer is it doesn't it can only detect ground that has been disturbed which means that unless someone is planting a whole field of rocks evenly spaced in a field somewhere it's pretty easy to use that has been disturbed which means that unless someone is planting a whole field of rocks evenly spaced in a field somewhere it's pretty easy to use other sources and common sense to figure out what that object might be sar and specifically coherent change detection can only detect the changes in the earth between two different collection periods so you fly a sensor overhead and you wait a certain amount of time not too long because then you're just going to detect natural weathering and the accuracy will suffer but you fly the mission again and compare the radar returns to the first image if a mine has been planted in between the two collections then you'll be able to see it very easily so this is a very useful technology and actually has a lot of civilian uses which is where you'll find most of the development for this technology occurs in the civilian world they aren't so concerned with hunting land mines but if that land mine were for example an ancient temple or an old roman road you can see the pretty useful civilian applications of such a technology and if you're hunting for massive temples in the jungle and not ied command wires in the desert you don't really need to fly t ns of such a technology and if you're hunting for massive temples in the jungle and not ied command wires in the desert you don't really need to fly the mission multiple times you can just go off of the ever so slight depressions in the earth that can't really be seen with the human eye but are definitely visible by such a sensor there are countless other uses for this technology from detecting the viability of temporary airfields by measuring the density of earth and detecting any patches of mud or detecting submarines by measuring the almost microscopic wake that submarines leave on the ocean surface when they are motoring along beneath the waves and as one might notice a theme with all of these different collection efforts they aren't perfect a rainstorm can ruin weeks of coherent change detection efforts a really big aluminized fabric sheet can completely negate decades worth of efforts and trillions of dollars worth of satellites and the sheer expense rarity and cost of using these sensors in the first place means that unless you're hiding an icbm silo in your backyard your privacy is pretty safe from these sensors by and large but as always the capability is definitely there 're hiding an icbm silo in your backyard your privacy is pretty safe from these sensors by and large but as always the capability is definitely there and in years to come as this technology becomes available to lower and lower levels of authority to include everyday citizens and corporations being aware of this technology right now is absolutely critical for establishing a mindset and changing your patterns before these sensors become mainstream remember the dji phantom 1 the first real mass-produced consumer grade quadcopter was only released in 2013 and now every blogger and youtube has some kind of drone and almost every single police department has one too and not just the consumer grade ones but the ones equipped with flir as standard that's an insane explosion of technological growth so we fully expect sore sensor packages to become mainstream on consumer grade devices very very soon which is something to be aware of so that's all we have for today and let us know what you think about this technology in the comments below and as always a special thank you to our supporters on patreon and teespring and everywhere else who make it possible for us to provide this content to ever always a special thank you to our supporters on patreon and teespring and everywhere else who make it possible for us to provide this content to everyone thanks again for watching and we will see you next time and as always fight in the shade [Music] you