The Global Positioning System (GPS) is a US satellite navigation system that lets a receiver calculate its position, speed and exact time anywhere on Earth.
How GPS works
GPS is operated by the US Space Force and uses a constellation of about 31 active satellites. Each satellite continuously broadcasts its position and a very precise time signal from atomic clocks. A receiver measures how long the signals take to arrive and calculates its location by trilateration; at least four satellites are needed for latitude, longitude, altitude and time. GPS is one of several global navigation satellite systems (GNSS), together with Europe’s Galileo, Russia’s GLONASS and China’s BeiDou; modern phones use all of them.
Why GPS matters for security
GPS is critical infrastructure: besides navigation, mobile networks, power grids and financial systems use it for time synchronisation. Civilian GPS signals are very weak and not authenticated, which enables two attacks:
- Jamming – blocking reception with noise. Large-scale jamming around the Baltic Sea and in the Middle East has affected thousands of flights.
- Spoofing – broadcasting fake signals so a receiver shows a wrong position or time. Ships and aircraft have reported being “moved” to airports far away.
Location data is also a privacy risk: apps, photos and fitness services can reveal where people live and work. Galileo has started signing its navigation messages (OSNMA) to make spoofing harder.
Best practices
- Limit app access to precise location and remove location metadata from photos you share.
- Critical systems should cross-check GNSS time and position with other sources and detect jamming.
- Check your devices for unknown trackers if you suspect stalking.
