Scenarios for losing GPS/GLONASS/Galileo constallations: are they plausible?

[14murs14]

Originally Posted by Cpt Pat

The output power from the GPS satellites is, are you ready... 25.6 watts. A little more than your VHF radio on your boat.

The antenna gain is listed at 13 dBi. Thus, based on the frequency allocation filing, the effective radiated power would be about 500 Watts (27 dBW).

Now, the free space path loss from 21000 km is about 182 dB. Take the 500 Watts (27 dBW) and subtract the free space path loss (27 - 182) and you get -155 dBW.

-155 dBW at the surface. That's 0.0000000000000005 watt. Not exactly something that's hard to jam. To put that into perspective, that's much less than the kinetic power of a snowflake hitting the ground. eLORAN uses 100,000 (or more) watt transmitters that are a lot closer than 21000 km away - which is why that system is jam-resistant.

14murs14: please check my math. I did a bit of rounding.

The extent of my "prepper" activities have been making sure I have enough room in my on board microwave oven to hold my handheld devices in a thunderstorm. And having a sextant, which I consider normal boat equipment.

I'm not a worrier. The likelihood of GPS getting jammed worldwide is maybe only a little higher than WWIII. And the likelihood that the Titanic would sink on its first voyage was what? Well, almost zero, until it happened. I like to think that people aren't stupid. But sometimes I'm wrong. Do the people in charge in Washington make you feel warm and fuzzy? Only you can decide on that.

But the chances of it getting jammed over a much smaller area is 100%. It's Almost certainly happening right now, somewhere, mostly in the Black Sea. Thank Putin.

The OP question was: "Scenarios for losing GPS/GLONASS/Galileo constellations: are they plausible?" My answer is: "It's possible. Here are my facts. You decide on plausibility."

Not to hijack the thread into an engineering discussion, but it's definitely not as simple as "the signal at the surface is 0.0000000000000005 watt so it's super easy to jam". The power required to jam a signal is dependent on a number of things, not just my signal equals your signal so your signal is gone. It's a subject far more in-depth than we could cover here, but for an intuitive grasp of just one aspect consider that every GPS satellite transmits on the same 1575.42 L1 frequency but none of them "jam" each other. It's not as simple as transmitting a 25 watt carrier signal at 1574.42 and viola, GPS is gone! That's exacerbate by fact that while 4 satellites in a 20,000 km orbit can theoretically "see" all of the earth's surface, your receiver on the surface will generally be far close to several of the 31 GPS satellites than the jamming satellite. Nor would anyone compare a 100 KHz terrestrial Loran C signal strength with a 1575 MHz satellite based signal, complete apples to oranges. I'll leave off with the in the weeds details at this point, but again yes, technically a foreign power could launch a jamming constellation and deny GPS. Just like any number of other "really bad things" a foreign power could do that would lead to WWIII. All fall into the category of small probability and at that point daily reality has changed so much that talk of sextants would be quaint at best! Since most of us get on airplanes every day that rely on GPS and much of our infrastructure now uses it, we've effectively determined it falls into the possible but not plausible category. My point being if you really think it's plausible you'd change a lot more in your life than just carrying a sextant on your boat, and sailors getting lost and starving would be the least of the world's concerns.

[Cpt Pat]

I'd like to close out my posts on this topic with some links to resources.


The USCG recently made public its GPS trouble reports and investigation findings. You can see those reports here: https://navcen.uscg.gov/?Do=GPSReportStatus.


An account of an actual global GPS timing failure in 2016 (debunking the "it can't happen" hypothesis) : https://www.theatlantic.com/technolo...-fails/486824/ If you only read one link, I recommend this one!


An article describing eLORAN and why we need to have a backup to GPS/GNSS: Innovation: Enhanced Loran : GPS World


An interesting article on how the Russians are apparently spoofing GNSS around the Kremlin: https://rntfnd.org/2018/09/11/the-kr...-moscow-times/


A now-declassified report on GPS weaknesses and disruption consequences: https://rntfnd.org/wp-content/upload...isruptions.pdf


A US DOT report on GPS vulnerabilities posted by USCG (written prior to LORAN-C being shut down): https://www.navcen.uscg.gov/pdf/vuln...ssess_2001.pdf

[hellosailor]

While GPS, Galileo, Glosnas, and the proposed UK system are all one way systems, the Chinese (Baidu?) system that is about half-deployed right now, apparently is a two-way system basically equal to a Spot Messenger integration, with SMS-type upload abilities as well.

Small scale jamming has been dealt with, as when the FCC busted the idiot trucker passing Newark [Liberty] International regularly. Large scale jamming, by a combatant or other hostile actor, is addressed by the quiet use of military anti-radiation missiles, the same job as when they take out SAM radar sites. That was discussed 20 years ago. One can assume there has been continued attention paid to these things--and quite properly not discussed in public.

True wide area jamming, i.e. satellites from aggressors, are why the EU is proposing active military space capabilities, and why our own dear sweet Donny Boy has a jones for a Space Force.

Bear in mind, if someone actively jammed a military satellite communications system (GPS) that could be seen as an overt act or war--and might be quickly remedied. Similarly, if a half dozen military satellites were crippled? Don't be surprised if someone also thought of that twenty years ago, and "payback" is already quietly orbiting up there.

A loss of GPS would be what the Brits call a damned inconvenience. But we've got bigger things to worry about, like the hundreds of *documented* attacks on telephone longlines, cable infrastructure, internet backbone, and power utilities happening every year.

The recent natural gas pipeline overpressure incident, resulting in 80-odd home fires and explosions outside of Boston? Notice that *no*one* has even suggested how easily that could be attributed to one cyberattack, that overrode the pressure controls and shut down the pressure alarms on that pipeline? Yes, the CIA and FBI and CERT and all sorts of national people who get paid to worry about this stuff, have been predicting that for twenty years too.

If the power grids go down, that's gonna hurt a lot more than GPS going down. And it is done just as easily.

[Cpt Pat]

Originally Posted by hellosailor

[...] If the power grids go down, that's gonna hurt a lot more than GPS going down. And it is done just as easily.

If GPS goes down, it can take the power grid down with it (along with cell service, fire/police/emergency medical service radio trunking, and a lot more). Since it so wonderfully cheap and convenient, the engineering geniuses (who believe GPS is indestructible) have been creating a dependency on GPS timing into all sorts of critical infrastructure.

Please read: https://www.theatlantic.com/technolo...-fails/486824/

And nation-state GPS jamming is already occurring: https://www.reuters.com/article/us-n...-idUSKCN0X81SN


https://thebarentsobserver.com/en/se...ing-borderland


https://www.nbcnews.com/news/militar...-syria-n863931


Just keep repeating: "it can't happen here..."

[hellosailor]

"If GPS goes down,"
Good point, Pat. Keeping our fingers crossed about "Mutually Assured Destruction" really doesn't give me a warm fuzzy feeling, no matter how long that's worked for.

[Cpt Pat]

Originally Posted by hellosailor

"If GPS goes down,"
Good point, Pat. Keeping our fingers crossed about "Mutually Assured Destruction" really doesn't give me a warm fuzzy feeling, no matter how long that's worked for.

Yup. These days it's: "mutually assured DISRUPTION," which is a much lower threshold to cross. If someone launches an ICBM, there's little doubt about where it came from and what the consequences will be. That's what's kept the peace. Today, a technological attack can be carried out cheaply, anonymously, and deniably. For poor nations, it's a great way to assert geopolitical power. And anyone who thinks North Korea couldn't pull off a sophisticated technological/cyber attack should ask Sony Pictures. Their cyber warriors (Unit 112) started training the China in 1996.

If we retaliate in-kind against North Korea, the effect will be practically nil. Their civilians are still using typewriters and abacus calculators. The Russians are also proud of using the lowest level of technology to get the job done. Actually, that doesn't sound like a bad idea to me. That's why I like eLORAN as a "navigation Plan B": it's just 1950s tech dressed up to be more accurate. Plus it works indoors and under water.

[RaymondR]

Originally Posted by boat_alexandra

unless the pilot is completely incompetent, you should still survive even if gps fails.

In either case, you can just use celestial navigation. It is very easy today using the celestial navigation plugin for opencpn. You simply enter your sextant readings.

You can do running fixes, and use any star or planet, even the moon. Azimuth (compass based) which was never used in historical times because of the very complex computations as well as not having an accurate magnetic model for the earth is now possible. So a single sight can give you a fix.

The plugin also supports lunar sights in case you lose track of time. Who knows, maybe soon, it can automatically take sights with a camera and work similarly to a gps. Theoretically in this mode the accuracy could be within few hundred meters using cheap digital cameras, and gyros, and great software if enough celestial bodies can be observed.

That's very interesting, I did not know that particular plugin existed. Thanks.

I still have my good quality sextant aboard stored with a 30 odd year old programmable calculator (probably lost it's programming by now) which did what you describe as the capabilities of the the plugin. I'll download the plugin and rate the RTC in the computer using the HF time signals and have a newly effective backup for the GPS. Good work BA.

[Cpt Pat]

Originally Posted by RaymondR

[...] download the plugin and rate the RTC in the computer using the HF time signals and have a newly effective backup for the GPS. Good work BA.

Yes, thank you boat_alexandra. I'm going to try that too.

Raymond, just an FYI: The HF time signals from WWV and WWVH are scheduled to be permanently decommissioned in 2019 -- to save $6 million: more cost savings madness. In a further move toward a colossal single-point-of-failure, the geniuses decided that we no longer need WWV because we have GPS time. You will also no longer be able to hear the GPS status reports from WWV, so you won't know if a GPS failure is only local or global. RIP WWV: 1922 - 2019.

I've been practicing with Canada's CHU time station on 3330, 7850, and 14 670 kHz. Not as strong a signal as WWV here in California.

[Jammer]

Originally Posted by 14murs14

Not to hijack the thread into an engineering discussion, but it's definitely not as simple as "the signal at the surface is 0.0000000000000005 watt so it's super easy to jam". The power required to jam a signal is dependent on a number of things, not just my signal equals your signal so your signal is gone. It's a subject far more in-depth than we could cover here

The main things are that the jamming equipment has to deal with path loss also, and has to overcome the process gain of the modulation.

Just like any number of other "really bad things" a foreign power could do that would lead to WWIII. All fall into the category of small probability and at that point daily reality has changed so much that talk of sextants would be quaint at best! Since most of us get on airplanes every day that rely on GPS and much of our infrastructure now uses it, we've effectively determined it falls into the possible but not plausible category. My point being if you really think it's plausible you'd change a lot more in your life than just carrying a sextant on your boat, and sailors getting lost and starving would be the least of the world's concerns.

I think that the thing to realize is that these other GPS users, in many cases, have contingency plans of their own. The FAA's continued operation of the VOR ground stations has been mentioned, upthread, for example. Users that depend on GPS for synchronization typically have precision clocks available as backup.

[RaymondR]

Originally Posted by Cpt Pat

Yes, thank you boat_alexandra. I'm going to try that too.

Raymond, just an FYI: The HF time signals from WWV and WWVH are scheduled to be permanently decommissioned in 2019 -- to save $6 million: more cost savings madness. In a further move toward a colossal single-point-of-failure, the geniuses decided that we no longer need WWV because we have GPS time. You will also no longer be able to hear the GPS status reports from WWV, so you won't know if a GPS failure is only local or global. RIP WWV: 1922 - 2019.

I've been practicing with Canada's CHU time station on 3330, 7850, and 14 670 kHz. Not as strong a signal as WWV here in California.

Thanks for the FYI. I occasionally tune to the time signals to check signal strength and propagation characteristics so now it won't be a mystery when I can no longer detect any of them.

We have a problem in Australia with the HF weather and sea safety broadcasts which our meteorological bureau occasionally threatens to discontinue. It is a good service used by a broad range of seafarers although there are not that many of us overall. So far we have seen them off with storms of protest but how effective this will be in the future I don't know.

[Cpt Pat]

Originally Posted by Jammer

The main things are that the jamming equipment has to deal with path loss also, and has to overcome the process gain of the modulation.





I think that the thing to realize is that these other GPS users, in many cases, have contingency plans of their own. The FAA's continued operation of the VOR ground stations has been mentioned, upthread, for example. Users that depend on GPS for synchronization typically have precision clocks available as backup.

I completely agree that's it's more than just a matter of overriding signal strength. My point is that a signal from a 100,000 watt transmitter 800 miles away (eLORAN) is proportionally much harder to jam than a 500 watt transmitter that is never closer than 12,000 miles away. That ratio is about 1 trillion to one. North Korea and Russia are overcoming the difficulties right now to jam GPS over wide swaths of territory. It's a done deal. Already accomplished.

https://www.reuters.com/article/us-n...-idUSKCN0X81SN
https://thebarentsobserver.com/en/se...ing-borderland
https://www.nbcnews.com/news/militar...-syria-n863931


(Note: I can only cite unclassified "open" sources in this forum.)

Regarding disruptions caused by degrading GPS for timing: many of the internal clocks used on cell towers and industrial systems are about the quality of a cheap quartz watch. The clocks use crystal oscillators, but depend on the accuracy of much more expensive rubidium clocks. Why incorporate an expensive rubidium time source when "GPS will never die?" (Answer: Engineering hubris.) In "free run" unsynchronized mode, those crystal clocks will drift out of useable spec in about a day. The last time a partial GPS timing failure of only 12 hours duration occurred, it created havoc. I rest my case.

https://www.theatlantic.com/technolo...-fails/486824/

The risk of GPS denial of service attack isn't hypothetical - it's a proven fact that has already been demonstrated by North Korea, Russia, Iran, and Air Force satellite self-inflicted administrative failure. We are arguing over whether the Sun will rise tomorrow in the east.

The whole crux of my argument is: we need a backup, and it's important to understand that, at sea, the only current backup is a sextant. That's sad. We will get eLORAN someday, it's been languishing in Federal agency agendas for 15 years, and hopefully it won't get pried loose from the governmental quagmire through - what we pilots call - graveyard progress. Denial of the problem through engineering rationalizations is what got us trapped in this corner. It's too late to say it can't happen. It already has.

[NorthCoastJoe]

It has been fun reading. But the sun comes up in the west every morning ... Oh or is it the east... Some dude sailed around the world with a tin clock for time. People depend too much on electronic gear and never learn to use the old simple methods. If all fails go simple DR.

[Jammer]

I brought this up on Navlist and thought I'd summarize that discussion here.


1) There was wide (but not unanimous) consensus that I'm a kook for thinking that loss of the GNSS constellations is likely enough to be worth preparing for.


2) There was a thorough and convincing rebuttal of my concern about collision risk, because the GPS satellites are in a lightly populated orbit that does not have a debris problem.


3) There is greater concern about spoofing. Some navlist-ians advocate taking a daily celestial site to cross check the GPS and confirm that it isn't being spoofed.


4) There was some convincing argument that the widely-held idea of running down a latitude to reach a coast, then identifying coastal features, is untenable because throughout the world there are many coastlines that are uniform and featureless and that have submerged hazards near shore.


5) There was an example cited of a boat where all GPS capability onboard was lost due to lightning, including a portable GPS that was wrapped in aluminum foil.

[mikecambrai]

In Europe we are developing eLoran precisely because of the ease in which GPS can be blocked. The signals are so weak and I think that you can buy quite cheaply on Amazon devices to block GPS. Around the ports, GPS is jammed by criminals who want to hide their stolen Mercs with tracking systems and this happens quite frequently.
In the Eastern Med recently GPS was blocked out between Cyprus and Egypt for at least a day.
Ships nowadays do not have to carry paper charts and this cuts out a considerable amount of work in updating charts, planning routes, navigating the ship etc. BUT the rider is that even with ECDIS you must always fix the ship using all means available like DR, EP, Lighthouses, Contours, headlands etc. This is a mandatory requirement. On ECDIS there is provision for all the normal fixing to be carried out which unfortunately is not always available on yacht navigators the size of a Kindle reader.
Read the enquiry into the grounding of the USS Guardian on the reefs in the Philippines if you want to see how easy it is to just believe the TV in front of you, and not look out of the window!

[Capt. Ray]

The last two or three decades of GPS navigation has proven that the satellite-based system is FAR more reliable than celestial navigation which is dependent on the weather - cloudy and misty days = no fixes. Having said that, I still carry two sextants! You never know and a skipper uses all navigation data one can get. But keeping up to date and having the almanac and sight reduction tables are a real pain so in all practicality one is stuck with an App.

DR plotting remains reliable within limits if you keep a written plot and log though loses accuracy over time. A Ded Reckoning plot (note spelling!) in my opinion is vital to give more information than instruments provide concerning currents, set, leeway etc.

Originally Posted by Jammer

Various threads on celestial navigation, emergencies, etc., have touched on GPS outages. While the usual focus is on failure of the equipment on board, there is some possibility, however remote, that the GPS and GLONASS constallations on which these devices depend could fail.


Possible failure causes could include:
* Electromagnetic interference due to space weather, making it difficult or impossible for receivers to receive the signal from satellites (https://www.bc.edu/research/isr/spac...ereffects.html).
* Loss of satellites due to debris. There is some concern that a single particularly serious collision could produce a debris cloud large enough to damage other satellites leading to a chain reaction that could render the all geosynchronous orbits unusable. https://physicsworld.com/a/space-deb...nderestimated/
* Deliberate shutdown or degradation of service by the nations responsible for operating these systems.
* Physical loss of satellites due to hostile action.
* Loss of control of satellites due to hostile compromise (hacking) of command and control systems or the satellites themselves.


It is my view that these scenarios are unlikely but possible, and that the prudent mariner may wish to maintain the ability to carry on with a voyage without reliance on these external systems, through use of dead reckoning, pilotage, celestial navigation, and an accurate on-board source of time.