{"angles":[{"duration_seconds":90,"hook":"Your phone does not know where you are. It knows what time it is.","name":"It is a clock, not a map"},{"duration_seconds":60,"hook":"Your maps app only works because Einstein was right.","name":"Einstein in your pocket"},{"duration_seconds":75,"hook":"Four imaginary spheres, crossing at exactly one point on Earth: you.","name":"Four spheres find one person"}],"audience":"Curious general viewers, no technical background assumed","budget_cap_usd":2.0,"facts":[{"rating":"secondary","source":"How GPS Works, World of Physics","text":"The GPS constellation keeps at least 24 operational satellites, currently about 31, in orbit about 20,200 km above Earth, each circling the planet twice a day."},{"rating":"secondary","source":"How GPS works: satellites, timing and location, ReadKernel","text":"Each GPS satellite carries precise atomic clocks and continuously broadcasts its position and the exact time the signal was sent."},{"rating":"secondary","source":"How GPS works: satellites, timing and location, ReadKernel","text":"Signals travel at the speed of light, about 300,000 km per second, so a timing error of one microsecond means roughly 300 metres of distance error."},{"rating":"secondary","source":"GPS and Atomic Time, TodaysDateAndTime, describing the gps.gov principle","text":"A receiver needs signals from at least four satellites: three for position by trilateration, and a fourth to correct the receiver's own clock error."},{"rating":"secondary","source":"How GPS Works, World of Physics","text":"Relativity makes satellite clocks gain about 38 microseconds per day in total; uncorrected, positions would drift by about 10 km per day."},{"rating":"secondary","source":"How GPS Works, World of Physics","text":"Standard civilian GPS accuracy is about 3 to 5 metres."}],"platform":"Web and YouTube, landscape 1280 by 720","sources":[{"name":"How GPS works: satellites, timing and location, ReadKernel","url":"https://readkernel.com/hardware/how-gps-works"},{"name":"How GPS Works: The Physics of Satellite Navigation, World of Physics","url":"https://world-of-physics.com/blog/how-gps-works-physics/"},{"name":"How GPS Uses Atomic Time, TodaysDateAndTime","url":"https://todaysdateandtime.com/learn/gps-and-atomic-time/"},{"name":"Global Positioning System Becomes Operational, EBSCO","url":"https://www.ebsco.com/research-starters/history/global-positioning-system-becomes-operational"}],"topic":"How GPS finds you"}