Nonsense or a sensible precaution?
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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.
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.
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Originally Posted by Cazalet33
stand-alone INS
I can't see how it would affect critical infrastructure though
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?
The long term loss of satellite signals would be serious. INS is insufficiently accurate.
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.
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.
Last edited by Courtney Mil; 5th Feb 2016 at 11:00.
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.
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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
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
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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.
