^ Interesting. For those who don't read it: spoofing is not easy to do well, requires some significant means, and is also relatively easy to detect by anyone seriously looking for it.

BTW, I like that sat pic. Now *that's* a GPS satellite.

Jamming GPS, cellphone, and other signals is illegal in the US. I don't know what the legality is elsewhere.

Didn't Iran down the US spy drone with GPS spoofing? So it certainly is possible.

Spoofing GPS is not easy. Just knowing the signal format is only a beginning. Jamming is easy.

The University of Texas at Austin Radionavigation Laboratory recently demonstrated a spoof, takeover and redirection of a drone. A US military drone was captured intact by Iran last year using a spoof/redirection attack that induced the drone navigation system to land.

Spoofing currently requires only a few thousand dollars in equipment but needs considerable expertise. If the cost and skills needed come down and allow spoofing of civilian GPS from a distance of 100 feet or more by an unskilled attacker we may have a problem that dwarfs handheld lasers & airplanes.

This was an interesting incident considering the drone was also a high altitude 'Stealth' drone. So detection of the 'Stealth Drone' itself was even more sophisticated than the GPS 'Spoofing'. GPS 'Spoofing' might be more difficult than Differential GPS but probably no more sophisticated than implementing Real Time Kinematic RTK GPS based on phase measurements to get centimeter accuracy

As most Stealth aircraft will use AESA spread spectrum RADAR emitters i.e. for ground mapping imagery, I suspect that these radio signals were detected using an array of ground RADAR Warning Receivers RWR based on Software defined radio which digitises the microwave spectrum, which can give a directional information and when triangulated will pinpoint and track the AESA RADAR emitter. Its amazing what you can do with a Sony Playstation 3.

The same thing can be achieved using Networked PC Digital TV cards with firmware upgrades costing a few thousand dollars sometimes referred to as passive RADAR.

An aircraft intercept of the stealth drone with the GPS spoofing kit would then have gotten the stealth drone to follow it (follow me mode) back down to its air field.

GPS spoofing is actually an important defense area. i.e. A JDAM bomb could be redirected to behind the lines of the military who dropped it or at the very least missing its intended GPS coordinates.

The cost of this type of electronic equipment is dropping like a stone, take for example the Chinese made Tecsun PL360 radio receiver (around $45) based on the si4734 DSP chip

http://www.silabs.com/products/audiovideo/amfmreceivers/Pages/Si473435.aspx

Yes a complete digital signal Intermediate Frequency baseband processor for SW,MW,LW and Stereo FM Digital Radio Reciever!

I think there's more to that drone spoofing story. Not that I don't believe what we're told... If it was so easy it would have been a lot more than one drone by now. Or maybe it has been... It's just a drone anyway, they expect to lose them. I'm disappointed they don't have a James Bond-style "car alarm" setup, my drones would.

Speaking more generally now. What I got out of that spoofing doc linked to above was that a single spoofing source would not be enough. A modern GPS receiver should quickly ignore it. There could however be a minute or two until the receiver rejects that source, and that may be enough for the nefarious deed. Multiple signal sources *in the proper geometric locations* would normally be required.

Back to the drone: they apparently didn't have to do that, and it responded to its confusion by landing. I wonder if the Iranians made the landing place look fairly like the base where the drone would have normally landed? I thought there was always people behind the drones' control who could over-ride their autonomy.

That was a military drone presumably using an authenticated signal; it wasn't easy. There's no evidence is was the Iranians who did the spoof either.


They don't expect to lose them intact and undamaged, ready for enemy evaluation and reverse engineering to find weaknesses.


A single antenna suffices to spoof civilian GPS. Anything large enough for two GPS receivers could detect simple spoofing by comparing position solutions and known receiver separations.

A diligent GPS receiver might detect and reject a clumsy spoof but not a careful spoof takeover.


Not locations: GPS is all about *timing*. The signal sources can be anywhere you want as long as the signals arrive at the receiver with the right timing relative to each other.

With an authenticated GPS signal, where you can't change the satellite position data in the signal, you can jam the signals and send a delayed copy to the GPS receiver, tinkering with the relative timing of each satellite's signal so that the receiver solves for the position you want. It's tough to do, but apparently not tough enough.


The drones will autonomously return to base in the event of loss of command signal. A pilot is not needed.

The attack apparently jammed the command signal and then spoofed the GPS receiver so that when the drone tried to fly back to base it was really just flying in circles in Iranian airspace, and when the drone thought it was landing at home it was in fact spoofed to land at an Iranian airbase.

The Radionavigation Lab result is noteworthy as it was an entirely civilian effort by one professor and fewer than half-a-dozen students.

I would think you could _*calculate*_ what the signal including the delay as percieved by the GPS receiver should look like at any given time, in any given location. In principle, all the information is public available.



Just demonstrates my point: GPS is an open protocol, free for all to read and understand. Anyone with the proper skills in mathematics and engineering (and a little ingenuity) can get the information they need to develop spoofers and jammers.

Selective jamming of signals are indeed still a remaining issues to settle with further development of jamming system.

wireless jamming

Wow, within ONE minute of approving this member they posted spam from China. Amazing, since the spammer had been waiting for approval for almost a day.
-Blast

The newest Garmins have both US and russian satellite capability. Increases their usefulness and accuracy, too.