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Troubleshooting: location accuracy

Benchmrk uses your device's built-in GPS/GNSS receiver to determine your position. Understanding the factors that affect accuracy helps you get the best results in the field.

GPS/GNSS accuracy on iOS​

Consumer-grade iOS devices typically achieve horizontal accuracy of:

  • 3–5 metres in open sky conditions with good satellite visibility
  • 5–15 metres in urban areas with buildings causing signal reflection (multipath)
  • 15–30+ metres in dense tree canopy, indoors, or deep urban canyons
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The location shown in Benchmrk is your device's GPS position, not a survey-grade measurement. It is suitable for navigating to the general area of a mark, but not for precise coordinate determination.

Factors affecting precision​

Satellite visibility​

GPS accuracy depends on the number and geometry of visible satellites. Open sky with a clear view of the horizon provides the best accuracy.

Multipath interference​

In urban areas, GPS signals can bounce off buildings and structures, causing position errors. This is known as multipath interference.

Atmospheric conditions​

Ionospheric and tropospheric delays can affect signal timing. These effects are generally small but can contribute to position uncertainty.

Device hardware​

Newer iPhones include dual-frequency GPS (L1 + L5) receivers, which provide better accuracy than older single-frequency devices.

Indoor or covered locations​

GPS signals are significantly degraded indoors, under dense tree canopy, or in covered areas.

Steps to improve accuracy in the field​

  1. Move to open sky — step away from buildings, trees, and overhead structures.
  2. Wait for convergence — after launching the app, wait 30–60 seconds for the GPS to settle on an accurate position.
  3. Enable Wi-Fi — even if not connected to a network, having Wi-Fi enabled helps iOS use Wi-Fi positioning to supplement GPS.
  4. Check the blue dot — the blue circle around your location dot indicates the estimated accuracy. A smaller circle means better accuracy.
  5. Use a newer device — iPhone 12 and later models support dual-frequency GPS for improved accuracy.

Accuracy and survey marks​

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The GPS position shown in Benchmrk is for navigation purposes only. It should not be used as a survey-grade coordinate. Always use the published coordinates from the mark details panel for survey work.

When navigating to a mark:

  • Use GPS to get within the general area (typically within 5–10 metres).
  • Use visual identification and the mark description to locate the physical mark.
  • The AR view can help with the final approach by showing the mark's position relative to your camera view.
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