Built with Claude Opus 5.5: an interactive 3D explainer of how GPS finds you, on the real satellites overhead

Your phone never sends anything to GPS satellites. It only listens. So how does it know where you are? I built Pinpoint to show it in 3D, using the real GPS satellites above you right now. There's a narrated story of about four minutes, then modes to play with: \- Fire four signals and watch them meet at your position \- Break the fix: bad clock, bunched satellites, no relativity, drag a satellite around \- Ride a satellite with time warp \- A game where you find a hidden phone by tuning the clock \- A time machine back to 1994, when accuracy was blurred on purpose Nothing is faked. The satellite positions come from real orbit data, and every number is worked out live in your browser. Stack: TypeScript, three.js, Vite, plain DOM, Web Audio. The GPS maths is written from scratch. Inspired by this video: [https://www.youtube.com/watch?v=K-pgPNFcAj4](https://www.youtube.com/watch?v=K-pgPNFcAj4) Live:…