Earlier quoted context omitted.
Amen! I had exactly the same reaction. (Disclosure: I'm an alumnus, twice.)
Hook 'em Horns! Sorry, conditioned response from this alum.
the wife says, "Go Pokes!" :-)
Drone hijacked by UT hackers with $1,000 spoofer
61–70 of 81 posts
Re: Drone hijacked by UT hackers with $1,000 spoofer
#62Earlier quoted context omitted.
I agree it is an area that could do with research. However, we know consumer level GPSs have no protection against spoofing (indeed, you can buy GPS jammers from various websites for defeating fleet tracking systems). You could as well use a replay attack against the pilot's control system (probably on 2.4GHz) using much cheaper hardware. There is still plenty of work to do before these class of research drones becom…
Sounds to me then like FAA should require all drones to be safe against things like GPS spoofing, GPS jammers and replay attacks before they open up the airspace for drones.
And/or jail people for using GPS jammers.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#63Earlier quoted context omitted.
1960's inertial navigation systems have better resolution than today's consumer GPS. The issue is not the technology, it's the cost, size, and weight. The small, light, and low-cost sensors fueling the current wave of UAVs are not the most accurate technology available, but that doesn't mean they aren't useful.
The concern I would have with inertial navigation over long distances is the possibility of drift. You might have good resolution over short distances, but what about hours and hours? What if your vectors are not quite right, or you get drift in your gyros (and LR gyros are prone to drift in certain circumstances)?
Which is why aircraft normally have multiple INS units. INS has been used as primary nav for endurance missions (>24hrs) in the US military for decades.
Citation: Myself, I worked on a variety of systems including INS and GPS in the military.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#64Earlier quoted context omitted.
The concern I would have with inertial navigation over long distances is the possibility of drift. You might have good resolution over short distances, but what about hours and hours? What if your vectors are not quite right, or you get drift in your gyros (and LR gyros are prone to drift in certain circumstances)?
Which is why aircraft normally have multiple INS units. INS has been used as primary nav for endurance missions (>24hrs) in the US military for decades. Citation: Myself, I worked on a variety of systems including INS and GPS in the military.
But redundant INS units protect against failure of LR gyros. They don't protect against the case where an extremely slow turn by the plan can induce drift in an LR gyro. In that case all your redundant systems will all drift together.
LR gyros are also limited by physics to a certain limit of precision, and this is the specific mechanism by which they can drift (from what I understand though building larger gyros might help). So flying for a long time.... I don't know to what extent we know how much drift might occur. It would certainly be possible to build in some checks here though since landing in Iran instead of Afghanistan would seem to show some discrepancy between the two systems.
I am just not sure you can be sure that relative position will be as accurate as absolute position over an extended period of airtime.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#65Earlier quoted context omitted.
State-of-the-art inertial navigation technology has approximately the same precision as state-of-the-art GPS. Even modern run-of-the-mill interferometer-based inertial systems are precise enough for most purposes. The unique value of inertial navigation is that it requires neither receiving nor sending a signal that can be jammed or spoofed, hence why the military uses it for everything.
Extra bonus points : if you get above the cloud cover, can also use constellations to correct accumulated errors. I heard some Russian ICBMs had a special window so that cameras can see constellations for that purpose.
And the SR71 had it from the start, too.
http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro-...
Re: Drone hijacked by UT hackers with $1,000 spoofer
#66Earlier quoted context omitted.
State-of-the-art inertial navigation technology has approximately the same precision as state-of-the-art GPS. Even modern run-of-the-mill interferometer-based inertial systems are precise enough for most purposes. The unique value of inertial navigation is that it requires neither receiving nor sending a signal that can be jammed or spoofed, hence why the military uses it for everything.
Extra bonus points : if you get above the cloud cover, can also use constellations to correct accumulated errors. I heard some Russian ICBMs had a special window so that cameras can see constellations for that purpose.
Oh wow, this is why I keep coming back to HN again and again. Thank you for teaching me something amazing!
Re: Drone hijacked by UT hackers with $1,000 spoofer
#67Earlier quoted context omitted.
Which is why aircraft normally have multiple INS units. INS has been used as primary nav for endurance missions (>24hrs) in the US military for decades. Citation: Myself, I worked on a variety of systems including INS and GPS in the military.
But redundant INS units protect against failure of LR gyros. They don't protect against the case where an extremely slow turn by the plan can induce drift in an LR gyro. In that case all your redundant systems will all drift together. LR gyros are also limited by physics to a certain limit of precision, and this is the specific mechanism by which they can drift (from what I understand though building larger gyros mig…
> But redundant INS units protect against failure of LR gyros. They don't protect against the case where an extremely slow turn by the plan can induce drift in an LR gyro. In that case all your redundant systems will all drift together.
I'm am pretty sure this is very wrong, although I'm not an expert enough to downvote you. Having multiple systems allows one to average out (statistically independent) drifts; it's not just a protection from failure. I don't think there's anything special about a "slow turn" which will cause military-quality INSs to have correlated drifts.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#68Earlier quoted context omitted.
But redundant INS units protect against failure of LR gyros. They don't protect against the case where an extremely slow turn by the plan can induce drift in an LR gyro. In that case all your redundant systems will all drift together. LR gyros are also limited by physics to a certain limit of precision, and this is the specific mechanism by which they can drift (from what I understand though building larger gyros mig…
> But redundant INS units protect against failure of LR gyros. They don't protect against the case where an extremely slow turn by the plan can induce drift in an LR gyro. In that case all your redundant systems will all drift together. I'm am pretty sure this is very wrong, although I'm not an expert enough to downvote you. Having multiple systems allows one to average out (statistically independent) drifts; it's no…
As I understand it with LR gyros, if you rotate them sufficiently slowly so that they move less than half a wavelength in the time the light transits, they re-lock on the new orientation without interference. This is a limit based on quantum physics and it's why I said that larger gyros might reduce the problem.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#69Earlier quoted context omitted.
I think he may mean that airliners transmit their GPS coordinates (which I've heard an ordinary citizen can pick up cheaply) but can't receive commands that way.
The exact opposite actually. Apparently airliners, like our mobile phones, can only receive GPS signals to track their own position, but they can't report that back to the control towers - position is calculated from ground radars, which only reach up to 200 miles from shore. That's why the location of AF447 couldn't be pinpointed quickly after the accident, for example, there are only estimates for location while ou…
Do you know why the pilots of that plane didn't use GPS to determine their altitude and speed? I read that it's suspected they slammed into the sea because they didn't know their altitude and speed, due to frozen-over measuring devices.
Re: Drone hijacked by UT hackers with $1,000 spoofer
#70Earlier quoted context omitted.
The concern I would have with inertial navigation over long distances is the possibility of drift. You might have good resolution over short distances, but what about hours and hours? What if your vectors are not quite right, or you get drift in your gyros (and LR gyros are prone to drift in certain circumstances)?
Which is why aircraft normally have multiple INS units. INS has been used as primary nav for endurance missions (>24hrs) in the US military for decades. Citation: Myself, I worked on a variety of systems including INS and GPS in the military.
There was a fratricide in Desert Storm where a bunch of Apaches drifted behind friendly lines. INS is mentioned as a contributing factor. IIRC they were hovering, but a slight wind didn't register with the INS.