USNA bringing back celestial navigation

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Dinochrome One
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Re: USNA bringing back celestial navigation

Post by Dinochrome One »

Dinochrome One wrote:
My last ship, USS Quapaw (ATF-110), had three distinct electronic navigation systems; OMEGA, Loran C, and SATNAV (an early version of GPS). We set out from Port Hueneme bound for Pearl Harbor for fire-fighting training.
Loran C stopped working after we got out of sight of land ... After a week the SATNAV faulted
My experience with all those gadgets has often been that they (a) fail once out of sight of landmarks and/or (b) fail in fog. In addition, depth sounders invariably fail when negotiating shallows. Murphy's law.
I see that my post got a severe haircut and a comment that I didn't write,......
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blackeagle603
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Re: USNA bringing back celestial navigation

Post by blackeagle603 »

Let me know when the Navy brings back raw radar videos airborne search radars... :ugeek: That would put the Navy and the rest of the universe back on it's axis and all will be well again.

Love me some long pulse video and a point of land at the right angle of dangle on the sweep to paint a crisp edge for a Nav Fix. Gyroscopic precession be damned, we got a nav fix and a flight tech to keep it updated. We don' need no steenking CAINS.
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Denis
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Re: USNA bringing back celestial navigation

Post by Denis »

Dinochrome One wrote:I see that my post got a severe haircut and a comment that I didn't write,......
Dinochrome, a thousand apologies!! It seems I wanted to quote your post and ended up editing it instead - I'm obviously not used to my amazing moderator powers yet. I'm very sorry, but I don't think I know a way to restore what I lost of your post...

Sorry :(
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kapikui
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Re: USNA bringing back celestial navigation

Post by kapikui »

JustinR wrote:
Aesop wrote:Except that plan would probably have the same effect on the airliners of 110 nations (including our own) as would turning all the traffic signals in the country to green simultaneously.
Um, no.

All flight management systems (FMS) installed on airlines the last 20+ years are all multiple sensor systems that calculate a best computed position from all inputs. That includes GPS, WAAS if equipped, VOR, DME, INS (Inertial Navigation System), and AHRS (Attitude and Heading Reference System.) Most of the time, our FMS operates in DME/DME mode, with GPS as verification. We can have the two GPS systems in our aircraft deferred (inop) and our only limitations are being unable to go into certain airports with surrounding high terrain, but that's because of our FAA approved ops specs, not an aircraft limitation. The only thing that would happen if the GPS signal was suddenly turned off is that aircraft would have slightly higher position error. Most aircraft that go over the ponds have multiple redundant INS systems. You would get more drift until you got back within range of land based navaids, at which time the FMS would correct the computed position. Oceanic tracks have lateral buffers built into the airway structure for reasons such as this. It certainly wouldn't be disastrous.
I don't know a lot about the GPS system or ballistic missiles, or airplanes or navigation for that matter, but I'm thinking you wouldn't have to turn it off for long enough to be that much of a problem for most aircraft. An ICBM from Russia had a flight time of about 30 minutes according to Wikipedia. If we can detect launches, a 10-15 minute loss of signal in the vicinity of the missile would more than take care of it. If the missile is moving, it would only be a couple of minutes in any given area. That amounts to a GPS glitch. If the missile is going someplace close (Israel for example), the time could be short as well.

Of course always wanting do something nasty, it makes me wonder if it would be possible to use the GPS system to essentially take control of a missile and make it hit a target of OUR choosing by skillfully manipulating the data it is receiving and making it think it is elsewhere. Probably not possible, but would be fun to put into a movie or something.
Aesop
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Re: USNA bringing back celestial navigation

Post by Aesop »

Termite wrote:Aesop,

There were Victor airways(VOR), DME, and precision approaches(ILS) before GPS ever came online.
As for trans-oceanic, inertial nav works just fine. If that doesn't work/isn't available, you just fly the last magnetic heading until over land or in range of a VOR or two, then figure out your position using intersecting radials.......and a map.

Heck, even in my "almost an airplane", I have a VFR sectional to back up my Garmin GPS-V and Galaxy S3 phone.
Quite so. How quaint.
There are also flight computers and actual slide rules, also handily pre-dating GPS by half a century.
What say I give you a dollar for each occasion either one of those is used to navigate any commercial air transport flight, and you give me a nickel for each time they aren't.
I can send a truck by for my winnings, or just forward you an account number for the EFT...

Last I looked, about 20 minutes after GPS became available for cars (which have been around at least a decade or two longer than airplanes) it was all of about 15 minutes before jackasses who'd never had GPS before managed to drive their cars off of cliffs and into swamps onto roads that didn't exist in the real world, because the GPS said it was there.

We won't even go into how many dingbats with a GPS and new set of hiking boots trigger a 200-man search-and-rescue operation in Hogwallow State Forest when their AA batteries fail.

Unilaterally turning GPS off deliberately would be seen worldwide as the national equivalent of throwing acid in everyone's face.
It isn't happening unless it's the result of a force majeure beyond anyone's actual control.
But ain't nobody turning off the stars, which is why the Navy should be teaching their people how to navigate by them.

They might have to drop a couple of GLBTQWERTY and makeup makeover classes for the cadidiots to shoehorn celestial navigation back into the curriculum, but shit happens.

It could even catch on, and they might find a reason to go back to focusing on teaching military leadership and warfighting at the service academies, just for a change of pace. Stranger things have happened.
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Netpackrat
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Re: USNA bringing back celestial navigation

Post by Netpackrat »

I just wanna say, eff you guys and your rabbit holes of arcane knowledge to go chasing down. I didn't spend enough time reading reading about celestial navigation to actually understand how to do any of it, but another item has been tentatively added to the list of things I'd like to learn to do.
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JustinR
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Re: USNA bringing back celestial navigation

Post by JustinR »

kapikui wrote:Of course always wanting do something nasty, it makes me wonder if it would be possible to use the GPS system to essentially take control of a missile and make it hit a target of OUR choosing by skillfully manipulating the data it is receiving and making it think it is elsewhere. Probably not possible, but would be fun to put into a movie or something.
Basically what Carver did with the ship in Tomorrow Never Dies. :)
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Rustyv
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Re: USNA bringing back celestial navigation

Post by Rustyv »

JustinR wrote:
kapikui wrote:Of course always wanting do something nasty, it makes me wonder if it would be possible to use the GPS system to essentially take control of a missile and make it hit a target of OUR choosing by skillfully manipulating the data it is receiving and making it think it is elsewhere. Probably not possible, but would be fun to put into a movie or something.
Basically what Carver did with the ship in Tomorrow Never Dies. :)
A proof of concept has already been done, by the University of Texas I believe.

Instead of turning off the satellites, you overpower the signal (GPS is weak by the time it hits your receiver) and feed the device modified timing data. End result, they were "flying" the drone by moving the planet from the autopilot's point of view.

I'll have to see if I can find the article. Interesting read.
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Rustyv
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Re: USNA bringing back celestial navigation

Post by Rustyv »

Never mind, the concept is interesting, but the article was from the BBC.

http://www.bbc.com/news/technology-18643134
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Termite
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Re: USNA bringing back celestial navigation

Post by Termite »

kapikui wrote: An ICBM from Russia had a flight time of about 30 minutes according to Wikipedia. If we can detect launches, a 10-15 minute loss of signal in the vicinity of the missile would more than take care of it. If the missile is moving, it would only be a couple of minutes in any given area. That amounts to a GPS glitch. If the missile is going someplace close (Israel for example), the time could be short as well.
Simply turning off the American GPS system would likely not make much difference. There's also the Russian GLONASS system(which, BTW, most Android OP system cell phones use), and the European Galileo system is coming online shortly. The Chinese, Indians, and Japanese have their own GPS systems planned for the near future.
Additionally, I suspect most ballistic missiles use internal gyros and programming for inertial navigation, so once the missile is launched, it probably doesn't need a GPS signal. And as Aesop pointed out, with a fair sized nuke, off target by a mile doesn't mean much if you're busting cities, not concrete bunkers.
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