Navigation system Independent of any artificial satellites, using solar lunar and star positions in conjunction with video image correction, utilizing Google Earth or a similar source-- theircompetitor, Jan 02 2017 Automatic Celestial Navigation for PC [xaviergisz, Jan 03 2017] Automatic Celestial navigation https://en.wikipedi...l_Navigation_System [bs0u0155, Jan 04 2017] i-sextant-- FlyingToaster, Jan 02 2017 What if it's cloudy?-- MaxwellBuchanan, Jan 02 2017 gyroscopes-- FlyingToaster, Jan 02 2017 Just as the vikings used a sunstone, presumably modern phone or drone cameras could have multi-spectral sensors.
The notion of using imagery versus an image database (plus gyroscopic inertia) does address clouds to some extent.
A truly hybrid navigation system (one that for instance seamlessly uses cell tower triangulation, wifi routers with known addresses, etc), would be quite resilient-- theircompetitor, Jan 02 2017 Along with accelerometers, could we not build a GPS using magnetoreception to navigate the way that migrating birds do?-- 2 fries shy of a happy meal, Jan 02 2017 So, sort of "compass" type of thing?-- MaxwellBuchanan, Jan 02 2017 Not a 'pole' detector, a field line proximity detector.-- 2 fries shy of a happy meal, Jan 02 2017 Why not just stay where you are ?-- 8th of 7, Jan 02 2017 How do you get to Google Earth in the middle of the ocean without a satellite?-- pashute, Jan 02 2017 1. Inflate airbed on beach.
2. Walk into sea carrying airbed.
3. Climb onto airbed.
4. Wait.-- 8th of 7, Jan 02 2017 well, you could have it on CD, simple enough, [pashute] :)
I was discussing GPS satellites, not all satellites.-- theircompetitor, Jan 02 2017 //Not a 'pole' detector, a field line proximity detector.//
Sounds a lot like a dip compass, which aligns with the local field and tells you the local magnetic dip angle.-- MaxwellBuchanan, Jan 02 2017 Fascinating. Never heard of a dip compass before.I had assumed that the Earth's magnetic field lines were more uniform, after all the migrating wedges of Canadian Geese zig-zag as they migrate as though feeling individual lines, so I had also assumed that it would be possible to tell when crossing one latitudinally.
Bit of a snarled mess though isn't it?-- 2 fries shy of a happy meal, Jan 02 2017 Yes. And they're dynamic; the drift is rapid enough to make them useless as a navigational tool, primarily because it's not accurately predictable.
The chaotic* nature of the field means that aliasing is commonplace - not what's needed. If a navigational method yields, for example, three possible solutions, then this can often be resolved by reference to other factors, but where there are a dozen or more scattered in the same general area, it's useless.
*In the strict mathematical sense.-- 8th of 7, Jan 02 2017 North star?-- RayfordSteele, Jan 02 2017 // I had also assumed that it would be possible to tell when crossing one latitudinally.// Uh, you do know that a field line is not actually a line?
But anyway, the general trend is for the field to align northish-southish, and to be horizontal at the equator whilst dipping down into the poles. But locally it's much more chaotic - basically a mess.
You can navigate pretty precisely if you have a good compass and dip-compass, and an up-to-date magnetic map.
Sturton (and this is, of course, completely irrelevant) navigates using alcomancy. Basically, he can tell how far he is from a pub in any given direction; triangulation and a comprehensive internal map of pubs allow him to pinpoint himself to within about 20 metres across most of the UK.-- MaxwellBuchanan, Jan 03 2017 Of course, finding a pub that he hasn't been barred from for life is a little more of a challenge.-- 8th of 7, Jan 03 2017 //Uh, you do know that a field line is not actually a line?//
I did not know that for myself no.When looking at a magnetic field through a ferrocell or in home experiments, (my daughter got me a ferrous sand hourglass with a magnetic base and I've been playing with it), the filed lines seem well defined while turning a magnet.Linear peaks and troughs at least.-- 2 fries shy of a happy meal, Jan 03 2017 If you put iron filings on or near a magnet (which I'm guessing is similar to your setup), they tend to form discrete chains or lines. But that is because of the way the individual filings distort and respond to the field.
The first filing to stick to the magnet acts as a little spike, concentrating the field around its tip. That, in turn, causes another filing to join it, which does the same thing again, and so on. So, the filings naturally "crystallize" into chains. Conversely, there's a weak repulsive force induced between adjacent chains, so they space themselves out. It's not the case that the magnet produces discrete "field lines".
If you take a single piece of iron (or a magnetometer or any other instrument that responds to a magnetic field), and move it around near a magnet, you will find that the field changes continuously, not discretely.-- MaxwellBuchanan, Jan 03 2017 GPS is an acronym. Who knew-- theircompetitor, Jan 04 2017 If you precisely arrange a phone so that it casts a shadow on a pre-marked piece of paper, the phone could use the camera, time and internal compass to work out longitude and latitude. Of course, if it is dark, the camera cannot see the shadow.The built in LED flash-light solves this problem.-- Ling, Jan 04 2017 It's that sort of genius thinking that's made Belgium what it is today ...-- 8th of 7, Jan 04 2017 Baked: celestial navigation systems on satellites themselves as well as aircraft astro-inertial nav systems, ala SR-71.-- DIYMatt, Jan 04 2017 I think what you have invented is automatic celestial navigation <link>. The SR71 had it, because it was high enough to have untroubled access to star light, and fast enough that they went 'round and 'round relatively quickly. I've heard mention by exRAF V bomber pilots that there was supposed to be an equivalent device that "never worked". Probably cloud.-- bs0u0155, Jan 04 2017 matt, you beat me to it! any idea how they worked? I'm at a total loss as to how this could be done without digital imaging and computing.-- bs0u0155, Jan 04 2017 ICBM's use celestial navigation at apogee for course correction because it's independent of the vulnerable GPS networks. Must be pretty good too - Trident D5 has a CEP of ~90m and uses celestial navigation correction at separation. It must be extremely accurate to do that.
...But I'm pretty sure ICBM and SR71 celestial systems are only suited to operation above most of the atmosphere. Not sure how well you'd go down here amongst the dirt and smog.
I reckon you could do a lot however. A very accurate true (Rotational) south (within a couple seconds of arc, accurate enough to set up a telescope for timelapse photos) can be found anywhere in the southern hemisphere where the southern cross and the pointers are in view, although that's only 50% of the time of course. I'm sure there are other bright stars that can be reliably seen through light cloud, etc - of course you'll need to know the time to within a good accuracy. It would be fun to work on the algorithm...
I wonder if you could win one or more of the possibly now expired longitude awards/prizes?-- Custardguts, Jan 04 2017 Wonder if frequencies other than visible reliably make it through cloud cover.-- FlyingToaster, Jan 04 2017 // could we not build a GPS using magnetoreception to navigate the way that migrating birds do?
It's probably just me, but that seems a bit ambiguous? I don't think avian tool-use is quite up to it.-- not_morrison_rm, Jan 04 2017 Yes, the bubble I've lived in is popping very slowly... and by degrees.
We have been experiencing technical difficulties and apologise for any current or future inconvenience this may cause as internal systems are recalibrated/ upgraded for optimal efficiency.Fry-Co thanks you in advance for your patience.Normal operations will resume as soon as public safety issues are resolved.
Please stand by.-- 2 fries shy of a happy meal, Jan 05 2017 hmm, it turns out DIY radioastronomy is a thing. It also turns out that its fairly easy to spot the galactic plane. Depending on the frequency used, cloud shouldn't be a problem and using a couple of well chosen reference frequencies you should be able to to pull out a signature of the galactic plane and kind of overlay them for certainty. Then, as it's well mapped and its movement known you should be able to derive a couple of points at either end of the night sky. Should be useful enough to navigate by. Big- ish antenna though.-- bs0u0155, Jan 05 2017 Everything now seems to be 'cloud'-based so maybe this should be a system based on looking up at the sky and comparing the shapes of clouds seen from your location with their shapes seen from other people's locations and determining your location based on this comparison.-- hippo, Jan 05 2017 //looking up at the sky and comparing the shapes of clouds seen from your location with their shapes seen from other people's locations and determining your location based on this comparison//
While I think I am in Philadelphia, the clouds appear uniform and grey horizon to horizon. So I deduce that the city I am in is actually Manchester, UK. Good to know, might get a curry later.-- bs0u0155, Jan 05 2017 // Everything now seems to be 'cloud'-based //
Sp: Cloud sourced.-- Ling, Jan 05 2017 //It also turns out that its fairly easy to spot the galactic plane.// You can generally hear them going over.-- MaxwellBuchanan, Jan 05 2017 random, halfbakery