GPS Spoofing.

[aviatoreb]

10 hours ago, M016576 said:

The 3-ring laser gyro INS’s that drive attitude and position in a modern fighter jet drift up to 1NM an hour (if not aided by gps) and are still “within spec.” More than accurate enough for area navigation... not accurate enough for a hard IMC approach.

fighters typically use an INS that is continuously updated by GPS.  The reason being that the GPS alone cannot keep up with the speed and attitudes of the maneuvers that we typically fly during a fight.... or even during bombing patterns, really.  So the INS is doing the quick calculation work (roll, yaw, pitch, position), then the inputs are updated via GPS to make sure the own ships position doesn’t go out to lunch.  I’d imagine that commercial airlines use a similar system (ins aided by gps), rather than our “pure” gps type systems we see in GA.... but I could be wrong there.

if that INS is backed up by a WAAS gps, it has the herz/verz that are only a few feet off at their worst.

 

Thanks Job.  That's very interesting.  Actually in my day job a work with the kind of algorithms that you mention - data fusion of noisy data from observation measurements from disparate sources can be "fused" to produce a single observation that is then higher quality than each original observation alone.  But I know nothing of the specifics you just said in this fighter jet application.  I just work with the theory side.

Do you know how much the 3-ring laser INS system weighs?  I bet its expensive too.  

If the GPS system went down, 1NM per hour MIGHT still be enough to bring your airplane to safe area where then some other system such ground radar (what is that system called - PAR?) could then take over?  And 1NM is fighter jet speeds.  That would be what, 1/4NM at Cessna speeds?

[aviatoreb]

9 hours ago, jetdriven said:

The old school 747-200s had Litton-72 iron gyros and were good for 3T+2.  The later Litton-92 were ring laser gyros and although certified to the same standard they were more accurate. But still a ten to 20 mile circle after 12 hours.  The -400 with its ADIRU’s we’re always 0.0 after a 16 hour flight. 

Thanks Byron - very interesting - I heard that the old 747's used old school spinning gyros.  Which are very very heavy.  Do you know how heavy?

The physics of spinning gyros is inherently favoring a heavy system.  You need a big heavy gyro, spinning and incredibly high speed which then requires an even bigger drive system around it to keep it spinning.  Does anyone know the accuracy of the old school spinning gyro systems they used in submarines in the past?  They needed to be capable of navigating a submarine to relatively high accuracy (comparable to flying IFR under the sea) for a several month dive for an attack sub, didn't they?  I am speaking with my Tom Clancy knowledge  mixed with my knowledge of physics - not actual knowledge of what they actually did.  Who here is a former submariner?  Actually come to think of it - if someone is an actual submariner - I know the answer - you are not allowed to tell me.

I bet the Litton 92 laser gyro's are too heavy to imagine the same in GA - for now - but a far as ring gyros I see nothing fundamental that would preventing such a system generally from becoming relatively quite small in the future.

I got lost in the acronyms of your last sentence.  Can you expand?

Edited May 25, 2018 by aviatoreb

[jetdriven]

the ADIRU combines some stuff, the air data computer and the inertial reference unit. They are all solid state now, no moving parts. Pressure sensors on several axes basically.  All of the modern units are all digital, and update via GPS,  so they have zero calculated error. The old Litton's used triple mix solution and VOR cross check updating, which introduced errors itself. And then its constantly correcting and updating from VOR's and as time goes on, the circle of probability gets bigger.  Some of those Litton planes got FMS's installed with GPS updating and it again had a calculated position error of 0.0nm, bit the pure inertial error was there, often a dozen miles or more.  But since the FMS is now driving the plane, the IRU's were really just a backup in case GPS was jammed or signal was lost, such as flying over Mecca in a US registered 747...on sept 11th..... Yes, that may have happened....

Edited May 25, 2018 by jetdriven

[Piloto]

Another less expensive option is the TACAN navigation stations used by the military and civilian FMS. They provide azimuth and distance (DME) data more accurate than VOR and the ground installation is much more compact. In fact there are portable TACAN stations for military use. The TACAN aircraft antenna is just a single blade antenna same as the DME antenna. A single scanning TACAN nav receiver provides a position solution to an FMS without an INS/GPS input. Many TACAN ground transmitters are collocated with a VOR stations designated VORTAC.

An INS is useless unless the position is crosscheck periodically with GPS or ground based systems. During a GPS jamming event the GPS is declared useless and ground nav systems are used by the FMS for position cross check like before GPS came to be.  

José

 

 

Edited May 25, 2018 by Piloto

[Mooneymite]

4 minutes ago, Piloto said:

Another less expensive option is the TACAN navigation stations used by the military and civilian FMS.

In my experience Tacan azimuth was not as good as VOR azimuth...possibly because it was mounted on a ship.  

Civil FMS's uses DME/DME primary.  Rho/Theta is considered a degraded mode.   Usually VOR azimuth provides bearing data, not TACAN.

The best non-jammable back-up nav is a proficient navigator with a sextant.  Installation in a Mooney would require a large nav table, an astro-dome and a navigator older than dirt.

[Yetti]

As far as VOR spoofing, apparently a Raspberry PI can do it.  Have not tried it.  one of the GPIO pins is the transmitter and then you play the sound file for the radial you would like it to send.

[M016576]

2 hours ago, Piloto said:

Another less expensive option is the TACAN navigation stations used by the military and civilian FMS. They provide azimuth and distance (DME) data more accurate than VOR and the ground installation is much more compact. In fact there are portable TACAN stations for military use. The TACAN aircraft antenna is just a single blade antenna same as the DME antenna. A single scanning TACAN nav receiver provides a position solution to an FMS without an INS/GPS input. Many TACAN ground transmitters are collocated with a VOR stations designated VORTAC.

An INS is useless unless the position is crosscheck periodically with GPS or ground based systems. During a GPS jamming event the GPS is declared useless and ground nav systems are used by the FMS for position cross check like before GPS came to be.  

José

 

 

The major difference between a tacan and a VOR is that the TACAN (which stands for Tactical Air Navigation, btw), phases the signal every 60 degrees... whereas a VOR phases the signal at 360 degrees.  That leaves the potential out there for a “60 degree lock-off” or phase shift (you think you’re on the 010 radial, but you’re actually on the 070 radial).  Most modern tacan receivers have fault detection for this, though.

[M016576]

2 hours ago, Mooneymite said:

In my experience Tacan azimuth was not as good as VOR azimuth...possibly because it was mounted on a ship.  

Civil FMS's uses DME/DME primary.  Rho/Theta is considered a degraded mode.   Usually VOR azimuth provides bearing data, not TACAN.

The best non-jammable back-up nav is a proficient navigator with a sextant.  Installation in a Mooney would require a large nav table, an astro-dome and a navigator older than dirt.

Not many people left out there that can shoot a Nav solution... or have an hour to complete the calculations!  

Boy.. that takes me back to my Cellestial Navigation class at the Naval Academy!

[EricJ]

3 hours ago, Mooneymite said:

In my experience Tacan azimuth was not as good as VOR azimuth...possibly because it was mounted on a ship.  

Civil FMS's uses DME/DME primary.  Rho/Theta is considered a degraded mode.   Usually VOR azimuth provides bearing data, not TACAN.

The best non-jammable back-up nav is a proficient navigator with a sextant.  Installation in a Mooney would require a large nav table, an astro-dome and a navigator older than dirt.

A sextant app on a smart phone and a little sextant bubble in the ceiling should do it. 

One of them is even called GPS Anti-Spoof.  Edit:   Apparently that app just helps determine whether the gps is accurate or not given external sextant input.   

https://play.google.com/store/search?q=sextant&c=apps

Edited May 25, 2018 by EricJ

[Jerry 5TJ]

Even if you use a conventional sextant you don’t have to do the spherical trig and draw LOP (no, not lean of peak!) on the chart. SW or an AP will make short work of the calculation. 

[Piloto]

With the upcoming of nuclear submarines able to navigate underwater for months (limited by crew food) an underwater accurate navigation systems was developed by the US Navy called Omega. Because of the low frequency operation VLF (10KHz) the signal was able to reach submarines down to 200ft. Omega was also in use by civilian surface ships and airplanes. Unlike current computerized systems today the first Omega nav receivers only provided lanes of position (phase differences) and you correlated these lanes on an Omega chart to find your position, similar to Loran A TDs. After the development of "compact" computers the navigators were able to display Lat/Long readings, initially on a teletype TTY printer. The same printer also read VLF messages on submarines. The same printer sound used by the Star Trek Enterprise ship computer. 

José

Edited May 25, 2018 by Piloto

[Mooneymite]

12 minutes ago, Piloto said:

With the upcoming of nuclear submarines able to navigate underwater for months (limited by crew food) an underwater accurate navigation systems was developed by the US Navy called Omega. Because of the low frequency operation VLF (10KHz) the signal was able to reach submarines down to 200ft. 

True..., but the Boomers needed even better accuracy than Omega could provide.  You'll notice that Omega never came close to providing even CAT I accuracy in aircraft.

But at least Omega didn't have the hazards associated with ELF.

I'm sure the submariners on Mooneyspace are well aware of the present nav solutions, but they may not offer it as a Mooney option.  

[Piloto]

On my first oceanic crossing to LECU the only thing I had was a Bendix variable tuning T12C ADF to find first Flores and then Santa Maria island for refueling. One uncertainty in my mind was my ground speed, distance and fuel available. One of the problems with variable tuning ADF is that you needed to identify the station Morse code to insure you were tuned to the right station. Being a ham radio operator that was not a problem. Wish I had an Omega navigator. Back in the 80s weather reports at Santa Maria came by an old FAX machine in which the ink faded away the moment you touched the paper.. 

José

Edited May 25, 2018 by Piloto

[ShuRugal]

On 5/23/2018 at 3:53 PM, aviatoreb said:

If someone wanted to - can't a VOR be spoofed as well?

yes, and much more easily.  All you need to do to spoof a VOR is broadcast a CW beacon and and omni antenna spamming the phase-shifted beacon for the radial you wish to spoof.

[Piloto]

23 hours ago, Mooneymite said:

In my experience Tacan azimuth was not as good as VOR azimuth...possibly because it was mounted on a ship.  

Civil FMS's uses DME/DME primary.  Rho/Theta is considered a degraded mode.   Usually VOR azimuth provides bearing data, not TACAN.

The best non-jammable back-up nav is a proficient navigator with a sextant.  Installation in a Mooney would require a large nav table, an astro-dome and a navigator older than dirt.

Theoretically a TACAN should provide a 9-fold increase in accuracy compared to a VOR, but operational use has shown only an approximate 3-fold increase. TACAN operates on UHF vs VOR on VHF. UHF is less prone to atmospheric signal bending than VHF, specially under heavy weather conditions. VOR is most accurate at low elevation angles while TACAN is accurate at high and low elevation angles.

https://en.wikipedia.org/wiki/Tactical_air_navigation_system

José

 

Edited May 26, 2018 by Piloto

[thinwing]

On 5/25/2018 at 7:33 AM, M016576 said:

Not many people left out there that can shoot a Nav solution... or have an hour to complete the calculations!  

Boy.. that takes me back to my Cellestial Navigation class at the Naval Academy!

Dang.me too ..taking sun shots,sun semi diameter and those nav tables based on star shots...my goofs were enormous,not 1/2 nm but hemispherical errors!!My nav training was at Moss Landing Marine Labs,summer of 74

[Mooneymite]

We were in Corpus Christi.  Every night we had to go to the "outhouse" and do starshots.  When we first started that outhouse was located all over the globe.  Gradually, very gradually, the triangles got smaller and smaller....

Then they put us in the back of a bouncing T-29.  The triangles got big again.  

[0TreeLemur]

On 5/25/2018 at 10:02 AM, Mooneymite said:

The best non-jammable back-up nav is a proficient navigator with a sextant.  Installation in a Mooney would require a large nav table, an astro-dome and a navigator older than dirt.

They're cranky and can be unreliable too.

[N201MKTurbo]

Nobody on the news is saying anything about it, but...

Is it possible that the Iranian missiles missed their targets because our military made them miss?

There has to be something to all that GPS testing going on around here.

[tigers2007]

Were these missiles supposed to be Iranian made? They seem to come up with some ridiculous flops like their alleged “US fighter jet killer” flying thing that looked like a cross between a Hasbro toy and a miniature Stealth fighter.


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[Gagarin]

1 hour ago, N201MKTurbo said:

Nobody on the news is saying anything about it, but...

Is it possible that the Iranian missiles missed their targets because our military made them miss?

There has to be something to all that GPS testing going on around here.

Your assumption is very reasonable. The first thing the Air Force would do is GPS spoofing. 

Edited January 8, 2020 by Gagarin

[EricJ]

4 hours ago, N201MKTurbo said:

Nobody on the news is saying anything about it, but...

Is it possible that the Iranian missiles missed their targets because our military made them miss?

There has to be something to all that GPS testing going on around here.

Many armaments like that use IMUs rather than sat nav for jamming/spoofing immunity. 

3 hours ago, tigers2007 said:

Were these missiles supposed to be Iranian made? They seem to come up with some ridiculous flops like their alleged “US fighter jet killer” flying thing that looked like a cross between a Hasbro toy and a miniature Stealth fighter.

It may have been intentional.   Remember that these are the same guys that spoofed a very high-end US drone and took control of it.   They know how to do things like navigate missiles.  

https://en.wikipedia.org/wiki/Iran–U.S._RQ-170_incident

 

[PJClark]

7 hours ago, N201MKTurbo said:

Nobody on the news is saying anything about it, but...

Is it possible that the Iranian missiles missed their targets because our military made them miss?

There has to be something to all that GPS testing going on around here.

exceedingly unlikely.  look at the post strike sattelite pics here, and look at the circles added to the photo:

https://www.sfgate.com/news/article/Sattelite-photos-Ain-al-Asad-base-Iran-attack-14959198.php

In the Ground Attack world the aim point is called a "DMPI" ("dimpey", Desired Mean Point of Impact).  The most obvious one here is right in the center of mass of the center of the 5 soft shelters at the lower left. Right in the center of the center building. They hit exactly what they were aiming for.

But that's important to the narrative for many reasons.  1.  It shows they chose very, very carefully to make sure they didn't hurt anyone.  2.  the frag is very small--a B-1 WSO (bombardier) friend says that looks like a max 100 lb warhead. Peanuts...but very interesting. 3.  they sent 12 missiles.  5 broke up in flight.  In any case, not enough to overwhelm US Patriot batteries if they'd been there.  All very deliberate, carefully chosen so that nobody got hurt but face was saved.

I've been asked about this almost constantly since last Friday morning and I will summarize my assessment this way:

The droning of Suleimani was a message to the Iranian leadership.  The missile attack response was also a message, and it said "message received and understood".

[tigers2007]

“Reverify our range to target. One ping only”




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[0TreeLemur]

1 hour ago, PJClark said:

exceedingly unlikely.  look at the post strike sattelite pics here, and look at the circles added to the photo:

https://www.sfgate.com/news/article/Sattelite-photos-Ain-al-Asad-base-Iran-attack-14959198.php

In the Ground Attack world the aim point is called a "DMPI" ("dimpey", Desired Mean Point of Impact).  The most obvious one here is right in the center of mass of the center of the 5 soft shelters at the lower left. Right in the center of the center building. They hit exactly what they were aiming for.

 5 broke up in flight.  In any case, not enough to overwhelm US Patriot batteries if they'd been there.  All very deliberate, carefully chosen so that nobody got hurt but face was saved.

I've been asked about this almost constantly since last Friday morning and I will summarize my assessment this way:

The droning of Suleimani was a message to the Iranian leadership.  The missile attack response was also a message, and it said "message received and understood".

Thanks for the link.   I agree with your assessment- small warheads, high accuracy.  Scary.

The videos I've seen online look like some kind of interceptors in the boost phase.  I just assumed they were Patriots.   Wouldn't the US position Patriots near potential targets?  Were the 5 that broke up in flight failed propulsion systems or intercepts?