GPS: A FASCINATING TECHNOLOGY
The GPS system (and soon Galileo) enables pinpointing your location to within a few meters by using signals from satellites located 20,000 km above us. To determine your position, your phone or watch receives signals from at least four satellites, calculates the time delays, and deduces your geographic coordinates along with the exact time.
This data is then used to track your route, estimate the distance you've traveled, and measure your speed. However, several factors can influence the accuracy of these measurements.
DISTANCE: OBSTACLES THAT DISRUPT THE SIGNAL
The quality of GPS reception heavily depends on your surroundings. Here are some key points to keep in mind:
- Natural and urban obstacles: Trees, tunnels, or buildings can weaken the signal, making it appear as though you’re zigzagging or overestimating your distance. Under ideal conditions, GPS has an accuracy of about 10 meters, with a distance error margin of 2%.
- Indoor GPS: Walls block GPS signals, making it non-functional indoors. If you practice an indoor sport, ensure your app is not set to rely on GPS.
- Best practices before and during your session:
- Before starting, position yourself in an open area, away from trees and buildings. Turn on your device, wait for the GPS signal to be detected (this takes between 5 seconds and 2 minutes), and stay still during detection.
- During your activity, keep your phone in an optimal position (screen facing outward, avoid placing it at the bottom of a bag).
ELEVATION GAIN: WHY GPS ALONE ISN'T ENOUGH
While latitude and longitude measurements are fairly accurate, altitude readings via GPS are less reliable. To address this, mapping databases are used to recalculate elevation gain after your session. These databases match your GPS points with local topographic information, providing much more accurate results.
In Summary: Practical Tips
- Before starting: Turn on your device in an open area and wait for the GPS signal to be detected.
- Avoid dense areas (forests, tunnels, large cities) to maximize accuracy.
- During your session: Keep your phone or watch in an optimal position.
- For elevation gain, let Decathlon Coach recalculate your data for reliable results.
By following these tips, you can enjoy more accurate GPS tracking and better analyze your performance!