Satellite Navigation - Computerphile

satelites travel at 22,000 km away ? lower than an airliner ?

bad explanation, disappointed

i looked this video up thinking he was steve wozniak

Cool video. I think that 5 years later this topic could definitely be revisited as there is enough content to easily fill a 10-15 minute video. The video did a decent job of illustrating how position is found through the intersecting of signals but time and it's dilation could definitely be covered in more depth.

I didn't know Steve Wozniak had a British accent...

Everything this guy said was a lie

yes i feel a 2nd part to this explaination could be helpful.

I think when you try to detect the position of something in Eve Online you use a very similar technique.

50Hz refresh rate?
I've never seen a GPS Receiver refreshing that fast

1 wrong they orbit at i believe mid orbit and that is exactly 2300 miles
2 the clocks are called stratum 1, 2 or 3.


if you have genuine questions about satellites shoot me a mssg, as long as i am allowed to give you the information you want i will tell you what your looking for

You didn't explain what is done with the timecodes that are received. How are they compared. What is the point of them. The way you explained it, just sounded like radio triangulation which ould be done with any signal.

1080@50 xD. 50?

This channel is just fantastic, please keep up the good work.

I presume there must be another video about sat nav errors, could you please share the link.

I came here to learn about celestial navigation of satellites but the talk is about terrestrial navigation with GPS :(

But the earth isn't flat? computerphile iluminati confirmed.

I thought I was watching this to learn something new but it was only explained in cliché laymen's terms.

Who else here live on a balloon ?

Need more context on what he's actually talking about. Would appreciate some equations or how exactly the time precisions produces a location

i think GPS is the best invention ever :)

Surprised you didn't expound on the affect of time dilation on the satellites. I always thought that was the most interesting part of the system.

I thought this was going to be about how satellites navegate

feeling slightly dissatisfied with this video - feel like it could have been explained clearer and in more depth :/

Must admit, I'm disappointed that the need to account for time dilation wasn't mentioned.

the guy doesnt explain nicely like others! :(

so how does one "connect" to a sattelite?

Incorrect explanation. The fourth satellite is not used to determine which of the two points in space you are at, it is used (as you said later in the vid) to determine the time. Selecting which of the two points is done by assuming that you are near the surface of the Earth. (The other point tends to be thousands of kilometers in space.)

There are also corrections for atmospheric refraction and such things of course.

I thought that this would be more detailed i.e. the specific way they code it to handle so many different orders at once (as in so many people using one satellite)

Please, more detail on this fascinating subject!

Certainly just obtaining the time from each satellite does not allow you to calculate your location. Doesn't each satellite also have to broadcast the longitude and latitude that it is currently orbiting over?

Those Balloons remind me of scanning in EvE Online arghhhhhhh

I actually didn't really understand that...

They dont realy know what they,re taking about

Is the 50Hz refresh (for location) the standard in Europe? It's 1Hz in most phones in the US.

Hang on a sec... so if you are on the intersection of 4 spheres, you know your point location. But didn't you create the spheres on distance? So how do you know the distance from each satellite not just four times if you don't know the time when you receive the data packets?

Wrong info on Computerphile is new thing. For position equation we need 4 sats because of 4 variables. (x,y,z,t)
Current algo check for earth answers, so we elemenate multiple dots by logic, not extra sat.
On video we was told about 4 sats for 3 vars and some magic for time solve. Just misleading info, guys.

To learn more ... Read GPS for Land Surveyors by Jan Van Sickle. Excellent book.

I would like another explanation, I am probably stupid but... Does the satellite send its position on orbit? How is time translated to position ? I did not actually get the surfaces intersections, I mean: the signal is always going to get to me, is it the intersection of the same time being read ?

I am really surprised that the very important role of relativity (both special and general) wasn't even mentioned! This is actually an amazing and remarkable fact about GPS navigation. If the algorithms would not take into account those corrections, the whole system becomes useless very quickly. Basically every GPS user experimentally tests SR and GR on a daily basis.

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This seems to be the least obvious way of breaking down GPS. Mr Fuller's explanation totally leaves aside the connection between time and position, in other words, why and how time is used to locate your device. Which is really the underlying principle of the whole thing. And without time dilation, it's barely scratching the surface. Could do much better.

666666 subscribers!

666,666 subscribers. Spooky

666,666 subscribers who is that dude ?

ooooh that's what triangulation is then?

666,666 subscribers

27th

you didn't go over time dilation!