Automatic dependent surveillance ? broadcast

All well and good until GPS is disrupted - which /does/ happen regularly.

There used to be (and maybe still are) regular NOTAMs stating that aviators should not rely on GPS around Aberystwyth.

I've heard stories of pilots seeing Boscombe Down airfield a mile off their port wing, while their satnav stated they were directly over the runway.

And, of course, there's Sochi, where ships teleport

ent.

a satellite navigation and periodically broadcasts it, enabling it to be tr acked. The information can be received by air traffic control ground statio ns as a replacement for secondary surveillance radar, as no interrogation s ignal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation.

he dinosaur, another technology being replaced by vastly improved performan ce of GPS.

Were those GPS faults or mapping errors?

Deliberate spoofing.

Tests around Aberystwyth, since it was occasional and dates/times were notified in advance.

Boscombe Down is a military aircraft testing site.

Sochi is Russian; ask them :)

I suspect that military radar satellites track every plane and ship and maybe truck on Earth, but they don't want to reveal that capability.

A cubesat company down the street uses zillions of cheap satellites to track and talk to cooperating ships.

The ADS-B system has been around for a while, small planes mandated to include ADS-B OUT, etc., as well. What's new is "Aireon's space-based ADS-B will make global air traffic surveillance a reality." for planes flying across the world's oceans, using the Iridium satellite system, 66 now, 75 later.

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via satellite navigation and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stat ions as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraf t to provide situational awareness and allow self-separation.

the dinosaur, another technology being replaced by vastly improved perform ance of GPS.

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Who the heck is spoofing ADS-B in Wales???

FAA claims it will not be a problem in U.S.- maybe because of many more gro und stations.

From the wiki link: "The FAA responded to this criticism saying that they were aware of the iss ues and risks but were unable to disclose how they are mitigated as that is classified. A possible mitigation is multilateration to verify that the cl aimed position is close to the position from which the message was broadcas t. Here the timing of received messages is compared to establish distances from the antenna to the plane"

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satellite navigation and periodically broadcasts it, enabling it to be tra cked. The information can be received by air traffic control ground station s as a replacement for secondary surveillance radar, as no interrogation si gnal is needed from the ground. It can also be received by other aircraft t o provide situational awareness and allow self-separation.

e dinosaur, another technology being replaced by vastly improved performanc e of GPS.

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There is no such capability, it's all talk and concept development, to put it nicely. The main players have no intention of ever delivering a product. If they were even close, they would have found the MH370 long ago. The Nav y put a ton of money in that search.

That's very useful. An interesting capability enforcing international law h as come from that:

Very cool link. The articles I found say it's just approaching the mandatory deadline of Jan 2020. That must have been for small/ non-commercial aircraft.

All of that just goes to underline that there is no digital signature or authentication code in an ADS-B transmission. Look at the Defcon presentations - you can buy a HackRF for $200 that could emit a plausible ADS-B transmission, sufficient to convince some autopilots to take evasive action from a phantom plane flying to a nose-on collision.

Also:

It's simply incompetent to be fielding a new system with such a critical weakness in the 21st century.

Clifford Heath.

Yep. Putin allegedly carries a GPS spoofing transmitter everywhere he goes so that he can't be targeted by a GPS guided smart bomb.

Or, it might be simple screwups.

I maintain two ADS-B receivers the send position reports to FlightAware: (Click on the orange bar for the 2nd receiver).

Right now, both receivers are sitting on my desk at home (because I'm too busy to weatherproof package and install them on suitable mountain tops). Just a Raspberry Pi 3 Model B, an RTL-SDR receiver, a 1090MHz antenna, and internet access:

This is what one of my receivers actually hears: Be nice and don't trash or crash it.

In the "Site Information" section of the above "stats" URL is the Lat-Long location of my receivers. I supplied this position when I setup the account for each receiver. Normally, the location of the ground station isn't really important because the aircraft reports its position and altitude using its GPS and altimeter. However, not all aircraft beacon their position using ADS-B, and others have their position dropped from the internet feed. To supply the missing positions, a system of multilateration is used to located the aircraft. To do the necessary trigonometry, the location of the ground receiving station must be known accurately. Since that location is user supplied and not verified, it's quite possible to accidentally (or intentional) create problems. For example, I gave a demonstration of ADS-B using one of my receivers and forgot change my receiver location to the meeting room. I recognized my mistake during my presentation and quickly made the necessary change. When I returned home, I forgot to change my location back, and successfully repeated my mistake for about an hour. I later discovered that it was easier to just turn off multilateration. Plenty of other ways to cause problems.

What keeps the system from falling apart is that most dense metro areas have hundreds of ground based ADS-B receivers. If one of them is producing insane locations, it's a simple matter for the system to simply report the position reported by the majority of ground stations, and ignore the insane reports. This is being done in various ways. The most obvious is that before a ground station is allowed to report positions using multilateration, the system runs a sanity check on its reports. After about 10-15 minutes of consistent reports, the MLAT indicator lights up green on my control panel. If I report garbage, such as failing to locate my station properly, it stays red and my reports are discarded.

Drivel: This map is what ADSB reported for airplanes flying over central Oregon following the path of totality during the 2017 eclipse: Many of the pilots were using ADS-B reports to prevent collisions. It worked.

GPS is being spoofed.

The military, and related state organisations.

Never underestimate the power of screwups!

Often a system's success is determined not by how it worksbut by how it fails. Thinking about such things are a good way of distinguishing a professional engineer from a mundane :)

But in the case of Abersytwyth, advance notification via NOTAMs rules out cockups.

That's easy to get past. The first missle targets the spoofing transmitter and a second misslle, close on it's heels target the target using the now functional GPS signal. Lather, rinse, repeat as needed to get rid of the s poofing transmitters.

I'm not sure that is needed though. I seem to recall that military stuff h as it's own channel for GPS which gives much more accurate location and is coded to prevent spoofing. Supposedly there are also anti-jamming techniqu es, but I'm not sure how they would work if the jammer is strong. But jamm ing doesn't necessarily much with a missile so much. Towards the end of th eir trip they can switch to inertial guidance which will get them "close en ough".

That won't work. GPS jammers and spoofing devices are fairly simple and small devices. Putin probably would not put his trust in just one such device and would probably scatter multiple jammers and spoofers around his probable location. An incoming missile would need some way to decide which of the jammers or spoofers to target, which might prove difficult. I have some ideas, but that's as far as I want to discuss in a public forum.

For GPS, which is controlled by the US military, L2 frequencies are used for consumer devices and L1+L2 frequencies are used for military devices. L2 is scrambled with well known codes (which can be changed if necessary). L1 is scrambled using military grade coding. Encryption will somewhat prevent spoofing but not jamming.

I can't tell from the various articles on the topic if the US GPS system, Russian Glonass system, European Galileo system, or Chinese Beidou, or all of them, are being spoofed.

The received GPS signal is VERY weak. Typically about -125dBm at the receiver input. Most of the articles I've read about anti-jamming techniques are based on improved receivers. That's because it's unlikely that the US will tolerate major and revolutionary changes to the GPS satellite system which might render millions of receivers non-functional due to obsolescence.

You're correct about turning off the GPS as a missile approaches its target. Because GPS requires the receiver to decode data sent at a fabulous 50 bits/sec in order to obtain the necessary corrections and update the ephemeris, lock much be maintained for fairly long periods. Due to their high speed, GPS guided missiles don't have the luxury of continuous guidance and instead calculate a target solution at some unspecified altitude before turning off the GPS and flying a ballistic trajectory towards the target. At that altitude, it would picking up jamming signals from multiple sources.

I suspect Putin is more concerned about slow GPS guided drones, than about JTAM bombs, guided missiles, or other high speed guided weapons.

Spoofing in the Black Sea: What really happened?

Make your own GPS spoofer: Software-Defined GPS Signal Simulator Plenty more:

There's nothing hard about picking a single target from the herd. They ain 't zebras.

You just need N+1 missiles for N decoys.

That's why I pointed out that jamming would not be effective on the close a pproach since GPS isn't needed for the final mile or two.

Not relevant. Putin can't jam up GPS for an entire city constantly. The j amming has to have some fairly local limitation or the utility of GPS dies for an entire city. That's not acceptable anywhere.

Not sure what you are trying to say here. The type of missile that would b e used to attack an individual would not be observed at launch time and so no extraordinary measures can not be taken until it is close. You seem to be talking about ICBMs which carry nuclear weapons and can be targeted to t he source of the local GPS jamming and definitely be close enough. I serio usly doubt GPS is even used as a primary location means with ICBMs since th ey need to be used in the event of the GPS system being attacked directly. They can use the stars to obtain an exact orientation and use dead reckoni ng from the launch. I don't know what they actually do, but I seriously do ubt taking out GPS is a significant impact to them.

Bingo.