GPS Guide: How GPS Works, Coordinates, Devices & Navigation

1. What Is GPS?

GPS stands for Global Positioning System. It is a satellite-based positioning, navigation and timing system operated by the United States.

The GPS system uses satellites orbiting Earth, a network of ground-based control facilities and receivers used by people and devices around the world. GPS was originally developed for military purposes but has become an essential utility for smartphones, cars, watches, hiking devices, marine equipment, and digital mapping apps.

2. How Does GPS Work?

GPS works by using signals transmitted from satellites orbiting Earth at an altitude of approximately 20,200 kilometres. Each satellite continuously broadcasts its location and a precise timestamp. Your GPS receiver compares the signal transmit time with arrival time to determine distance.

Understanding Trilateration

A single satellite indicates that you are located somewhere on a sphere surrounding that satellite. Adding a second satellite narrows your position down to an intersecting circle. A third satellite narrows it to two specific points in space—one of which is on Earth. A fourth satellite provides 3D positioning (latitude, longitude, and elevation) while correcting clock discrepancies in the receiver.

3. How Accurate Is GPS?

A smartphone or consumer GPS device can typically determine position to within 3 to 5 metres under clear sky conditions. However, positioning accuracy varies based on environmental factors.

Note: Consumer GPS is suitable for general navigation and hiking, but professional land surveying or property boundaries require specialized differential GNSS equipment.

4. What Are GPS Coordinates?

GPS coordinates are numerical values used to identify any geographical point on Earth. Coordinates are expressed as a pair of numbers: Latitude and Longitude.

5. GPS Coordinate Formats

The same location can be written in three primary coordinate notations. Understanding format differences ensures accuracy when sharing data or entering coordinates into GPS receivers.

6. How to Find & Use GPS Coordinates

Finding precise coordinates allows you to pinpoint locations without street addresses, such as trailheads, emergency assembly points, or remote field locations.

1. 1
   Use the Maps.ie Finder

   Open the Maps.ie GPS Coordinates tool, search an address, or drag the map marker to immediately retrieve latitude, longitude, and elevation.

2. 2
   Always put Latitude First

   When entering coordinates manually into software, ensure latitude is entered first and longitude second. Reversing them (-9.0568, 53.2707) will target an entirely different location on Earth.

7. Types of GPS Devices & Features

Choosing the right positioning receiver depends on your activity context and environmental conditions.

8. GPS for Hiking: Waypoints, Tracks & Elevation

GPS navigation is invaluable for outdoor safety. It allows hikers to track routes, measure ascent profiles, and pinpoint key landmarks in low visibility.

9. GPS, Coordinates & Maps.ie Tools

Once GPS locates your position and expresses it in coordinates, you can leverage Maps.ie mapping tools to plan journeys, measure distances, or build custom maps.