GPS Outage NOTAM Affects GLONASS?

[Boilermonkey]

12 hours ago, 0TreeLemur said:

Recently read an article (MS Thesis) comparing the different GNSSs.   GLONASS uses a different frequency for each satellite.  A test done by the Norwegian Navy showed that jamming GLONASS requires about 7dB more power than that required to jam GPS. 

The GPS system specs are ridiculous.  -150dBm power levels at our receiver!!  A low power transmitter is all it takes to overwhelm any GNSS system.   In another thread there was a good discussion of the need for a more powerful ground-based GPS system, especially around airports.

All of the GNSS systems have some vulnerability, GALILEO is probably the best system that is available for public use.   GPS remains the gold standard and there are improvements in block III that could address some of the vulnerabilities if the avionics are upgraded to use the newer functions.  Or simply support L1, L2, and L5 bands for GPS.    There are several new developments in GNSS that will improve accuracy and reliability....but it all requires upgrades to avionics.

VOR and ILS remain the backup and will remain that way for at least a decade because that's what's in aircraft today.  Adding a new solution like eLORAN would require new infrastructure and avionics..and lack the accuracy needed for precision approaches.   Many have talked about using 4G/5G, LEO, UWB, and other technologies.  The challenge is that it needs to be part of infrastructure, not a privately operated solution.

[larryb]

I experienced 50 miles of GPS jamming a few years ago. Others were discussing it with ATC so I knew it wasn’t just me. My expensive GTNs lost reception but my cheap iPad had no trouble.

[carusoam]

Anyone see any glonass issues with Russia visiting Ukraine this week?

PP thinking out loud…

-a-

[NotarPilot]

On 2/9/2022 at 7:41 PM, ilovecornfields said:

Trust, but verify. Just curious based on the differences people mentioned above if it's an alternative for when GPS is down. Obviously not as a primary source.

I grew up being told "it's the USSR, not Russia." I guess now it's Russia. Maybe in the future it will be the USSR again.

It’ll probably be called the PUSSR…. Putin’s Union of Soviet Socialist Republics, the way things are going.

[EricJ]

6 hours ago, FlyingDude said:

Maybe the iPads surviving GPS outage found their location triangulating cellular towers, and not glonass? Does it directly tell you that it's hooked up to glonass in the absence of gps?

A cell phone or pad doesn't have enough information from cell towers to know it's location.    The cellular system can locate a user terminal, roughly, but not the other way around.

 

[Boilermonkey]

Assisted GPS via 4G/5G is part of the cellular architecture.  It is already a part of almost every smartphone, but requires the phone and network to work together to derive.  Moreover it is privately owned/operated.  Therefor it will likely never be used for aviation.  It is however being used for enhanced 911 capabilities.

[EricJ]

10 minutes ago, Boilermonkey said:

Assisted GPS via 4G/5G is part of the cellular architecture.  It is already a part of almost every smartphone, but requires the phone and network to work together to derive.  Moreover it is privately owned/operated.  Therefor it will likely never be used for aviation.  It is however being used for enhanced 911 capabilities.

Exactly, it is not native in the phone/tablet, the phone does no triangulation.   Even when using the cellular system location capability fully, it is not very accurate.

[Boilermonkey]

The e911 GPS fused with 4G/5G is getting pretty good.   Within 15 even inside a building.   Which is primarily for first responders to know where to find you....a very different safety and reliability case than aviation. 

[EricJ]

3 minutes ago, Boilermonkey said:

The e911 GPS fused with 4G/5G is getting pretty good.   Within 15 even inside a building.   Which is primarily for first responders to know where to find you....a very different safety and reliability case than aviation. 

5G will be good due to the microcells where available, which may be typical in urban areas/large buildings.   We were doing research in item location (warehouses, etc.) using BT/WiFi fifteen years ago, but it is still quite challenging.   Multipath is not your friend in these cases, and can also impair GPS.

And, yeah, it doesn't necessarily translate to air navigation very well.    A far more practical system will be triangulating off the VORs in the MON network, and this is possible today using the same platform as a Stratux.  Not as accurate as GPS, but as good as VOR nav.   Given how slowly technology changes in GA or aviation in general, I don't expect this to make it into anybody's panel in less than a decade or two, although the technology exists today, the antennas are already on the airplane, and usually already connected to the GPS box.  If/when the software becomes available in an RPi, lat/lon estimates using VOR triangulation could be pushed through the existing interface to an EFB.   I'm a little puzzled why somebody hasn't done this already.   I started working on it, found somebody else had already done it, and then got diverted onto other stuff, anyway.

 

[ilovecornfields]

So instead of calling FSS and doing a DF steer you’ll just be able to call them on the phone and ask them where you are?

[Boilermonkey]

On 3/1/2022 at 9:40 PM, ilovecornfields said:

So instead of calling FSS and doing a DF steer you’ll just be able to call them on the phone and ask them where you are?

Reminds me of several accidents where professional crews asked ATC what their altitude is when they have had failures.  Neither the pilot or the controller knew that the altitude was coming from. The airplane, not the radar, and has the same errant data.  DF is different, but calling ATC and asking for that kind of information request both sides to understand where the data is coming from.  I can imagine someone having a GPS failure/degradation and calling ATC....it they done switch to primary radar they would read back what the ADSB GPS information is.

[Hank]

I haven't read the entire thread, but I would suspect right now that GLONASS has its own unique set of issues, beginning last week . . . . .

[PT20J]

On 3/1/2022 at 6:40 PM, ilovecornfields said:

So instead of calling FSS and doing a DF steer you’ll just be able to call them on the phone and ask them where you are?

NO, they won't know. Call the CIA. They know where you are. 

[PT20J]

Interesting tidbit from the GFC 500 AFMS

 

It doesn’t say explicitly one way or the other if loss of GPS before beginning an approach precludes coupled VOR, LOC, BC, or ILS approaches.

[MikeOH]

On 3/3/2022 at 4:59 PM, PT20J said:

NO, they won't know. Call the CIA. They know where you are. 

Nah, call Google; they know where you are, AND what you are doing!

[0TreeLemur]

On 2/24/2022 at 10:43 PM, carusoam said:

Anyone see any glonass issues with Russia visiting Ukraine this week?

PP thinking out loud…

-a-

I read an article last week saying that all GNSS services in and around Ukraine are unreliable, and that includes territory as far west as Germany.

[kortopates]

14 hours ago, 0TreeLemur said:

I read an article last week saying that all GNSS services in and around Ukraine are unreliable, and that includes territory as far west as Germany.

Because of jamming or the like?

[0TreeLemur]

27 minutes ago, kortopates said:

Because of jamming or the like?

I assume so.   Looking at flightradar24, there are always NATO or US assets orbiting over Poland near the Ukrainian border.   Last night there was a Globalhawk flying a pattern at FL560.  This morning there were NATO and UK AWACS aircraft flying orbits.   I'd expect that they are ready to flip the switch and jam all GNSS systems within range if needed.  From FL 350 where the AWACS fly, the sea-leval horizon is 230 miles, from Globalhawk at FL 560 it is 290 miles.

[EricJ]

2 hours ago, 0TreeLemur said:

I assume so.   Looking at flightradar24, there are always NATO or US assets orbiting over Poland near the Ukrainian border.   Last night there was a Globalhawk flying a pattern at FL560.  This morning there were NATO and UK AWACS aircraft flying orbits.   I'd expect that they are ready to flip the switch and jam all GNSS systems within range if needed.  From FL 350 where the AWACS fly, the sea-leval horizon is 230 miles, from Globalhawk at FL 560 it is 290 miles.

There were a ton of US assets patrolling the border from within Ukraine until the invasion, since then they've been just outside the available borders as you mention.   Early on after the invasion a US Rep said that we were providing surveillance intelligence to the Ukrainians.  

I suspect GPS is either being turned off over Ukraine or altered, and I suspect the Russians are doing the same with GLONASS.   The Europeans may even be denying Galileo to the Russians, who knows?

So, yeah, it's probably not a good idea to rely on any of those around there.