Why can my GPS coordinates be inaccurate?
Certificall records GPS coordinates at the time of each photo to certify the location of the intervention. Under certain conditions, these coordinates may be imprecise or incorrect. This page explains the possible causes and how to address them.
Possible causes of inaccurate location
Weather conditions
Weather can disrupt GPS signal reception:
- Heavy rain or storms: precipitation interferes with signal reception.
- Thick clouds: can weaken the signal, especially under dense cloud cover.
- Unstable atmospheric pressure: pressure variations slightly affect signal propagation.
- Heavy snow and thick fog: reduce reception quality, especially outdoors.
Physical environment
- Dense buildings and urban areas: GPS signals bounce off façades before reaching the phone, which can distort the calculated position.
- Basements, car parks or indoors: signals do not pass through concrete or metal.
- Rural or mountainous areas: network coverage is sometimes too weak to refine the location.
Location source used
Your phone combines several sources to determine its position:
| Source | Accuracy | Availability |
|---|---|---|
| GPS satellite | Very high | Outdoors only |
| Wi-Fi | High | Indoors |
| Mobile network (4G/5G) | Medium | Variable |
When the satellite signal is weak, the phone falls back on the mobile network, which is less precise.
Device state
- Power-saving mode: may disable or limit GPS to preserve battery life.
- GPS disabled: if location is turned off, Certificall falls back on the mobile network.
- Insufficient permissions: the app must have access to precise location (not approximate) in the phone settings.
- Frozen position: restarting the app or the phone can fix a stuck location.
How to improve accuracy
- Let the GPS calibrate before entering: if possible, wait a few seconds outside the building before starting the intervention. The phone will acquire an accurate position that it will retain for subsequent photos, even indoors.
- Check permissions: in the phone settings, make sure Certificall has access to precise location ("Always" or "While using the app").
- Enable Wi-Fi: even without a network connection, having Wi-Fi on helps the phone refine its position.
- Disable power-saving mode: this mode can limit GPS.
- Restart the app or phone: forces a fresh GPS acquisition before the next photo.