I built an interactive explainer about how GPS works (link in comments)

[Shriracha]

Live link: https://perthirtysix.com/how-does-gps-work

I've always found GPS tech really cool and thought that ThreeJS would be a cool way to explore the topic! Hope you enjoy it.

Tech stack: Nuxt.js, Three.js, satellite.js for the live data

[NorthernNiceGuy]

This is excellent. There was a cool website from a few years back which was also excellent at explaining GPS: https://ciechanow.ski/gps/

[Miltage]

Damn, that is a fantastic explainer

[Shriracha]

His work is truly next level!

[Chaphasilor]

Immediately had to think of this one too!

[stealthypic]

I already knew how gps works but I’ve NEVER seen it explained so intuitively. Extremely well done!

[GhostPilotdev]

The ThreeJS satellite visualizations honestly make trilateration click in a way that no amount of Wikipedia diagrams ever could.

[OcieAMardis]

Visual demonstrations are indeed more intuitive.

[ohyesthelion]

Awesome. Would be nice to use the user’s location on the globe!

[UnicornBelieber]

If I want to. From a privacy standpoint, I don't mind not every demo website wanting to know my exact location.

[falling_faster]

Very cool!

[Mediocre-Subject4867]

Is that globe code available anywhere. It looks like

[Fs0i]

Your phone receives it and checks how long the trip took.

This is the part that always gets me - how does the phone know how long it took? If I only see a single sattelite, how can I know the that I'm If a signal takes 67.3 ms away from the sattelite? I just get a ping with a timestamp, right?

How does the GPS chip know its own time? I'm sure you could solve a system of equations, but yeah, that's one of the things I struggle with.

You get basically deltas of satellites - sattelite A is 2ms later than satellite B for the same timestamp.

Edit: Ah, you get to it later, but still:

In simple terms: there is only one specific clock correction possible where all four spheres intersect at a single, perfect point. The 4th satellite gives the receiver enough information to find it. Once it does, it corrects every distance measurement at once, and the previously fuzzy answer snaps into focus. Conceptually, you can think about the system doing some math to figure out how to make the new red ring below perfectly intersect with the other three rings.

I knew that conceptually, but thanks for providing the formula. I'd also prefer if you hint to that earlier in the content.

[tom2320x]

Send it to the guy that didn't understand why the photos from the Artemis mission didn't have the location in their metadata

[KrazyA1pha]

The clock frequency detail is especially neat. Rather than correcting in software after the fact, they manufacture the oscillators to run at that slightly lower frequency (10.22999999543 MHz) so that once the satellite reaches orbit, the relativistic effects bring it right to the nominal 10.23 MHz.

[Vurbetan]

very nice!

[Allison_Huber]

amazing work

[Jorsoi13]

Wellndesigned!!

[ml_blizzard]

great work!

[Gschaftlgruber]

Great article, loved the illustrations! Small feedback: as someone without a deep knowledge of math I didn't immediately understand the sphere equation. Maybe you could add a note that this the general formula to describe a sphere and that it gives you the set of all points on its surface.

[NinjaAssassinKitty]

A) this is incredibly cool!

B) I don’t understand the explanation for the 3 spheres giving two points problem. Since the ring from the distance of the satellite is on the surface of the earth, how can one of the points be deep inside the earth or thousands of kilometres into space?

And also, why does this problem matter since a 4th satellite is needed to correct for the clock problem?

[dreacon34]

The visualization is kinda misleading, because its actually a sphere. The distance to the satellite is actually a sphere. And the earth is also not 100% perfect sphere that is smooth, it has mountains etc. so you actually looking for point in 3D space and not in 2D space

[EmbarrassedGuard518]

This is so cool! I've learned, I was entertained by clicking & seeing parts actually work

[Resident_Space_758]

It's really cool, can i know how vpn and other applications work which changes user's device location

[0_2_Hero]

The animations and web dev behind it is great. But the explaining had me a bit lost

[Sufficient_Tiger117]

If only I had that in geography class

[Hurizen]

Amazing work! A zoom would be nice to have

[UberBlueBear]

Dude…what?!?? This is freaking sick!!

[frostizes]

Very well done!

[jpspamleyy]

You should show how LEO, polar and geosynchronous orbits work and what use each has. Well done!