What affects the accuracy of speed and distance measurements with connected GPS on iOS?

Your Suunto 3 utilizes the GPS of your mobile phone and includes your phone’s GPS data in your exercise logs. The accuracy of the GPS data may be influenced by various factors like your phone model and the GPS chip integrated into your phone. Trees, buildings, mountains or any other kind of obstruction that blocks the sky may impact the accuracy of GPS. The way how you hold or carry your phone may also impact the GPS signal quality.

The following tips may help to improve the accuracy of speed and distance measurements with connected GPS:

• Ensure you have the latest app version installed on your phone
• Ensure that your phone has a working GPS chip. To check, activate location services, open a map application and check how accurate your position is.
• We will continue developing the software of your watch and will bring improvements to your watch with future software updates. Ensure you have the latest watch firmware version installed on your watch. To verify, install SuuntoLink on your computer and connect your watch with the supplied USB cable. Download SuuntoLink here. 
• Go outside for starting an exercise (GPS does not work in-doors).
• Wait until your watch gets location data from your Suunto app before starting an exercise. The GPS icon on your watch blinks grey while searching and turns green when the connection to your phone's GPS is established.
• Ensure you have a clear view of the sky. The view should not be blocked by any kind of obstructions (trees, buildings, mountains, etc.) as the signal strength may be affected.
• Be aware that carrying your phone in a pocket or backpack may affect the signal strength. We recommend carrying your phone in an outer chest pocket or preferably in your hand or in an armband close to your watch.

Troubleshooting steps
Verify after each step if the connection issue was resolved. If not proceed with the subsequent tips:

1. Ensure you approved location services for Suunto app in your phone’s privacy settings.
   Note: It may take several minutes to acquire a GPS signal.
2. Reset location services on your phone: Open Settings > Privacy > Location Services. Toggle Location services off and then on again.
3. Restart your phone.
4. Reset network settings on your phone. Open Settings > General > Reset > Reset Location & Privacy.
   Note: You will need to reconnect to all Wi-Fi networks and re-configure any custom network settings you might have had.

Note: The GPS signal strength depends on the quality and age of the GPS receiver in your phone and the number of GPS satellites currently in range. This and changes in the Earth’s outer atmosphere as well as changing weather patterns influence the GPS signal strength. Therefore, even when you exercise at the same place and with the same settings, the GPS accuracy may vary.

Note: Mobile GPS usage may add to roaming costs depending on your service package. We recommend checking this with your provider.

RELATED ARTICLES:
Connected GPS - User guide article
How are speed and distance measured when I don’t use connected GPS?
Why do I need to calibrate speed and distance measurement in my Suunto 3?