Restructure: USD fix + updated descendants

# [TECH] GPS (Global Positioning System)

**GPS** is a satellite-based navigation system providing global positioning and timing to any receiver, accurate to ~3 m commercially and ~30 cm with augmentation, requiring corrections from both special and general relativity.

## Overview

The US DoD GPS constellation (24 satellites, first launch 1978, fully operational 1995) uses time-of-flight measurements from 4+ satellites to triangulate position. Each satellite carries an atomic clock; without relativistic corrections (SR: −7 μs/day; GR: +45 μs/day), position errors would accumulate at 10 km/day. GPS is used in navigation, precision agriculture, surveying, finance (timestamping), and now autonomous vehicles.

## Key Actors

- **Companies**: Rockwell International (GPS satellites), Trimble (1978), Garmin (1989), Qualcomm (chipsets), u-blox
- **Inventors**: Ivan Getting (1912–2003), Bradford Parkinson (1935–), Roger Easton (1921–2014)

## Key Patents

- Easton, R. US Patent 3,789,409 (1974) — navigation signal processing

## Economic Value

GPS contributes approximately **\$USD 1.4 trillion/year** to the US economy alone (RTI International for CGSIC, 2019). Global estimate: ~\$USD 2–3T/year. Precision agriculture GPS savings: \$USD 25B/year. Autonomous vehicles will add \$USD 500B+/year.

## Notes

RTI International *Economic Benefits of GPS* (2019). Global value extrapolated from US figure using GDP ratio. The system's construction cost (~\$USD 12B) is dwarfed by its economic return.

## What This Enables

- **[TECH] Mobile Phones & Smartphones** — GPS chips in smartphones enable navigation, location services, ride-hailing, and geotaggingasset tracking used by billions daily.
- **[TECH] Electric Vehicles (EVs)** — GPS enables route planning, charging station navigation, fleet telematics, and autonomous vehicle positioning.⏎
# Parents

* [TECH] Rocket & Space Launch
* [SCI] General Relativity
* [TECH] Radar
* [TECH] Rocket & Space Launch
* [SCI] Special Relativity