GPS uses signals from an orbital constellation to determine position through 3-D trilateration. Today's navigation mixes GNSS positioning with digital maps, crowd-sourced traffic, and smartphone apps. Accuracy ranges from single-digit meters for basic civilian use to centimeter-level with RTK; signal blockage, outdated maps, and device settings still limit what GPS can do.
What GPS is and who runs it
GPS stands for Global Positioning System. It's a satellite-based navigation service originally developed for the military and now available to everyone. The U.S. government operates the GPS constellation and provides free civilian signals used by smartphones, car infotainment systems, dedicated navigation units, and many industry applications.How satellites give you a position
A network of satellites orbits Earth and continuously sends timing signals. A receiver measures the travel time from several satellites and uses 3-D trilateration to compute latitude, longitude, and altitude. Modern receivers typically use signals from multiple satellite systems (GPS plus other GNSS networks like GLONASS, Galileo, and BeiDou) to improve coverage and accuracy.The constellation is designed so multiple satellites are visible from any location. Current satellite counts and exact constellation status change over time, so verify the latest operational number for the U.S. GPS constellation before citing a specific figure.
Devices, maps, and live traffic
Today most people navigate with smartphones and map apps. These combine GNSS position fixes with digital maps, routing algorithms, and live data sources. Traffic delay estimates come from cellular and vehicle crowd-sourced reporting (for example, location/telemetry shared by app users) and from traffic feeds provided to mapping services. Many in-car systems also connect to those same services via cellular networks.Some receivers can broadcast a device's location (for fleet tracking, location sharing, or emergency services). But a typical consumer GPS receiver only receives satellite signals; it does not send your position unless you enable an app or service that transmits it.
Accuracy and enhancements
Basic civilian GNSS positioning commonly achieves single-digit meter accuracy. Augmentation systems improve that: satellite-based augmentation (like WAAS in the U.S.) can reduce error to 1-2 meters for many uses, while differential techniques and RTK (real-time kinematic) can reach centimeter-level accuracy for surveying and precision agriculture.Accuracy still depends on antenna quality, signal obstruction (trees, buildings, tunnels), and multipath errors. Urban canyons and dense foliage can reduce performance or cause intermittent fixes.
Practical limits and common misconceptions
- Government tracking: Most GPS receivers only receive signals. However, smartphones and tracking devices can transmit location if an app, carrier service, or device feature shares it.
- Weather concerns: GPS needs a clear view of the sky to see satellites; clouds themselves don't stop signals, but dense cover and obstructions can degrade reception.
- Getting lost: GPS tells you where you are. You still need context - maps, planning, and judgment - to navigate unfamiliar terrain safely.
- Restricted areas: GPS will not prevent entry to restricted zones. Navigation depends on current map databases and user awareness; always follow legal and safety signs and rules.
Bottom line
Modern auto navigation combines satellite positioning, digital maps, and live data to guide drivers and mobile users. It's powerful and convenient, but it has technical limits and depends on the devices and services you choose to use.- Confirm the current number of operational U.S. GPS satellites and update the satellite-count statement (as of 2025-08-24).