Nonsense or a sensible precaution?

[Spaghetti_Monster]

US navy returns to celestial navigation amid fears of computer hack - Telegraph (http://www.telegraph.co.uk/news/worldnews/northamerica/usa/11931403/US-navy-returns-to-celestial-navigation-amid-fears-of-computer-hack.html)

[Herod]

Makes sense really. At least the stars can't get hacked (yet)

[FlyPony]

Actually, USN has never stopped training its navigators in celestial navigation. That's always been the back up to Satnav and GPS. The only thing new is that they're bringing back celestial nav to the Naval Academy curriculum for the first time since the mid 2000s.

[Planet Basher]

Shirley if is ship based, an automatic autonomous tracking system could be used such as that on the SR71.

[Onceapilot]

Great. But decent stand-alone INS can be better!;)

OAP

[Cazalet33]

stand-alone INS

That belongs on the Oxymoron thread!

[Just This Once...]

The RAF already has one type in service with an exceptionally accurate astro tracker.

:ok:

[esa-aardvark]

I think there are also a few satellites hanging around up there with decent star tracking.
Have been for many years I think.
(yes I know it's easier up there, or is it?)

[Sandy Parts]

wonder if it will also see a return of the obligatory boot polish on the astro-sextant eyepiece? Kept many a kipper fleet crew sniggering through those long tedious transits..:p

[DaveUnwin]

Cazalet, do you understand how an INS works?

[4Greens]

Have been complaining for some time that Governments are too keen to remove ground based aids to save money.

[Herod]

Probably apocryphal, but the story goes of ATC asking a USAF aircraft what nav system he was using.

"We're using Charlie"
"Understand you're using Loran Charlie?"
"Negative. We've got a little fat navigator called Charlie, and he's shooting astro"

[Tankertrashnav]

When we took a Jaguar across the pond en route to Nellis, the four navs on the two tankers were happy to take INS updates from the pilot in the Jaguar, which got us to Goose with around a 1nm error - somewhat better than we could have achieved with astro which was all we had away from land.

On the other hand if somebody had been able to shoot astro on board Korean Airlines 007 on September 1st 1983, perhaps 269 people might have reached their destination instead of ending up in the sea off Sakhalin.

[KenV]

Shirley if is ship based, an automatic autonomous tracking system could be used such as that on the SR71. Funny that you mentioned that. The SR-71 was equipped with............wait for it............a "blue light" star tracker. Which is essentially what a human navigator with a sextant is.

Here's a discussion on the subject right here from a few years ago:

http://www.pprune.org/tech-log/104168-sr71-astral-navigation.html

[deptrai]

I have my sight reduction tables somewhere, and in a small yacht with a fickle electrical system and no engineers/electricians, I'd also bring a sextant, if only to help pass the time, but if I was the skipper of a major navy ship, I'd expect reasonably good dead reckoning, inertial navigation, clues from sonar, maybe even water temperature, as well as radar pilotage in coastal areas, would be quite enough to find my way around...

[beardy]

interestingly among others, shipborne radar, the internet, land line telephones, mobile telephones use GPS time signals. No GPS is a potential major crisis.

https://www.newscientist.com/article/dn20202-gps-chaos-how-a-30-box-can-jam-your-life/

http://rntfnd.org/wp-content/uploads/2013/09/GPS-Timing-Criticality-Volpe-Paper-2008.pdf

[tucumseh]

In 1996 it was discovered the original GPS spec was seriously wrong. Bit Timing Errors could cause significant errors during a single flight. If memory serves, anything GEM 1, 2 or 3 was affected. Compromised HaveQuick II, compounded by the US de-modifying thousands of radios just to make sure they wouldn't work. By 2003 the MoD corrected the former in one aircraft, the latter in two. (One had both problems. Now 19 years since its RLG/INS with embedded GPS was bought). An own goal that might be more of a problem than hackers. Maybe the penny's just dropped.

[deptrai]

the internet, land line telephones, mobile telephones

There's quite a few land-based atomic clocks that provide a public time signal, and most devices can easily be set to use specific time sources (eg no gps)

[beardy]

True, but not everyone is prepared nor will any changeover be swift and painless. Nor will corresponding units necessarily be on the same source.

Just saying it would not be smooth.

[MPN11]

In my minuscule navigational experience, I was pointing HMS Brierley in the right direction somewhere off the Isle of Wight [or somewhere nearby] using radar and cross-checking that with a Decca plot [YAY, Decometers!]. I was summoned to the bridge and told to start using visual bearings from assorted lighthouses, headlands and other such landmarks.

The answer was the same, but it was cold and wet up there on the bridge :eek:

[deptrai]

I'd argue that for critical infrastructure (on land), there is zero dependence on GPS. For anything that is connected to the internet, accurate time is usually provided by NTP (Network Time Protocol, invented in 1981). Very robust, distributed, and well thought out. A bit simplified, an NTP server without it's own time source queries a set amount of sources, and choses the most reliable one based on various criteria, and then propagates that signal. If one or two of many sources is a gps receiver, it will have no impact at all. GPS time signals are relatively novel, and any sensible system administrator running an NTP server would use mostly land-based atomic clocks, such as http://tycho.usno.navy.mil/what.html, they're still considered the gold standard ("The primary facility, in Washington, D.C. maintains 57 HP/Agilent/Symmetricom 5071A-001 high performance caesium atomic clocks and 24 hydrogen masers. The alternate master clock, at Schriever Air Force Base, maintains 12 cesium clocks and 3 masers. The observatory also operates four rubidium atomic fountain clocks, which have a stability reaching 7×10−16").

Most consumer devices are set to use a "lower level" (stratum in NTP terminology) time server, eg an NTP server run by Microsoft, Apple etc. which again uses multiple sources. The worst thing that can happen in case of a GPS time issue, is that clueless people who use only GPS will have the wrong time until someone tells them what to do. I can't see how it would affect critical infrastructure though.

[salad-dodger]

http://www.northropgrumman.com/capabilities/ln120gstellarinertialnavigationsystem/documents/ln120g.pdf
One of those should do the job.

S-D

[beardy]

GPS error caused '12 hours of problems' for companies - BBC News (http://www.bbc.co.uk/news/technology-35491962)

I see that one of the satellites 13microsec error caused problems for several large companies.

[Courtney Mil]

stand-alone INS
That belongs on the Oxymoron thread!
Now, in a very obscure way, you might be right, but I suspect not. Maybe tautology, but please explain. In what way is INS not stand-alone?

[megan]

I can't see how it would affect critical infrastructure thoughCivil aviation is getting rid of ground based aids and placing more and more reliance on GPS, RNP approaches for example, where the aircraft typically must have at least dual GNSS sensors, dual flight management systems, dual air data systems, dual autopilots, and a single inertial reference unit. Be in a world of hurt if GPS is lost.

[beardy]

Now, in a very obscure way, you might be right, but I suspect not. Maybe tautology, but please explain. In what way is INS not stand-alone?

As you ellipticaly allude, INS is independent of external inputs. However most modern aircraft don't use it's raw output, rather it is used to modify position accuracy for RNAV, as is GPS/GNSS information. With the withdrawal of so many ground based aids only GPS/GNSS can produce an RNAV position of sufficient accuracy to conduct what used to be known as precision approaches where ILS/MWLS are not available and approaches to 'precision' minima where non - precision aids have been withdrawn.

The long term loss of satellite signals would be serious. INS is insufficiently accurate.

[ORAC]

UK military creates quantum compass that could be the successor to GPS (http://www.extremetech.com/extreme/182973-uk-military-creates-quantum-compass-that-could-be-the-successor-to-gps)

[Courtney Mil]

Beardy,

I elliptically eluded? Cool!:cool:

[Pontius Navigator]

Remember GPS can be jammed.

[CoffmanStarter]

Crikey ... a Quantum Compass ... where does one keep Schrödinger's cat ;)

[Courtney Mil]

Naa, Coff, you don't need one of them. You need the old Phantom FG1 Navigational Computer Set - ASN-39. You tell it exactly where you are, what the wind is and your inside leg measurement, feed the hamster which turns its wheel, which drives some cogs through "a suitable system of gears and linkages" and it works out all the places you are not. Subtract that from all the places there are and you end up with your exact position +/- one hemisphere.

This system is not compatible with the quantum compass because the cat eats the hamster.

Apparently it was installed instead of a good INAS because naval aviators couldn't cope with anything that complicated.

http://i1159.photobucket.com/albums/p633/Courtneyon/image_zpspoflamir.jpeg

[beardy]

CM,

Can you escape (elude) an allusion?

[Courtney Mil]

Oops. Auto correct gets you every time.

Sadly, I didn't do the Escape and Elusion Course.

[Courtney Mil]

In the later days of the F-3 we used to carry a hand held GPS to update the INs when on ops. Now, my drone has a great little miniature IN in it so maybe we now need to carry a hand held IN to back up the GPS.

[ORAC]

Crikey ... a Quantum Compass ... where does one keep Schrödinger's cat It varies - but now we're deviating.....

[CoffmanStarter]

Naughty Boy Coff ... Sorry ORAC :E

[CoffmanStarter]

Courtney ...

Is there any truth in the rumour that when RN Aviators used to 'slave' their Phantom INAS alignments from the main 'Floating Airfield' INAS ... said ship thingy became uncertain if its position :}

Must dash ... will pick-up later ... but must get a few beers in for the rugby tomorrow :ok:

[Dougie M]

At one stage the C130K had a wall mounted "Hand Held" GPS known as the PLGR which was for ground army use. In the manual it specifically said "Not to be used in aircraft". This kit was the cross check for the Litton INS. Fortunately the Herc never got you anywhere too quickly to lose you badly. Quantum compasses weren't even a dream then. As for Schrodinger's cat it wasn't there.


http://i1299.photobucket.com/albums/ag76/dougiemarsh/f5b88b7a-711b-4bac-89dd-9043ec566da3_zpsntskfzcy.jpg

[CoffmanStarter]

I once 'acquired' a Pencil Box like that ... until some nana sat on it :{

[Courtney Mil]

but must get a few beers in for the rugby tomorrow

Now you're talking, Coff. :ok:

[ShotOne]

Looking at North Korea's planned satellite launch, this may not always be a theoretical debate. Much as we scoff at their technological (in)ability, it's entirely possible they could get a satellite up for just long enough to blow itsself to smithereens ...which is all it would take to wipe out our GPS (and lots of other) satellite constellations. Time to dust off those sextants after all?