GPS accuracy tips

Collection of some tips I got from elsewhere on this board and externally - please edit/add!

  • GPS soaking: even after your interface tells you you have “good” GPS, let your device sit collecting extra satellites
  • Calibrate a phone compass (not sure if this works for other devices?) by holding the phone flat in front of you and moving it in a figure 8. In a map interface you should see the beam narrow and/or the dot jump closer to your actual location.
  • In Runkeeper, you can correct a bad trace by editing the activity. You can manually move points or use “Snap to Roads” (but it may take a long time to complete).

Below are a few more.

For GPS soaking, 5 minutes is the ideal time to wait (if possible/practical). This allows the GPS chipset to download the ephemeris data from all of the GPS satellites in view, which allows for more accurate GPS points. When you start moving as soon as the GPS is “Ready” (i.e. has computed a fix), the GPS chipset has only synchronized time with the satellites used for the fix. This requires the GPS chipset to use its server generated ephemeris data, which your device previously downloaded. That data could be from minutes to days old (depending on when it was last updated) and the older that it is the less accurate it is, as it is a projection of each GPS satellite’s position in the sky. Getting the latest data directly from the satellite insures that the data is most accurate. With the bitrate of the transmission of this data, it takes the GPS chipset about 30 seconds per satellite to download the ephemeris data from the satellite.

  • If you are using a watch, make sure that its settings for the GPS are set to the most accurate mode (many watches have settings for this and default to less accurate modes for power efficiency). Preferred settings are multi-band (if supported), All supported constellations enabled (GPS+GLONASS+Galileo+etc.), Most frequent data logging mode (every second). If you are using an Apple Watch Ultra, make sure “precision start” is enabled for the workout app.

  • If you are using a watch, sync it with its mobile phone app prior to heading out for your workout (to insure latest server generated ephemeris data is loaded on the watch).

  • Wear the watch on your left wrist. Most watch GPS antenna designs are optimized for left wrist performance.

  • If you are in the market for a watch purchase one that supports multi-band (AKA dual frequency) GPS. Multi-band supports both the L1 and L5 frequencies. When both bands are enabled on a GPS device its point accuracy will be far better in environments where multipathing is prevalent (bouncing of GPS signals between objects (glass surfaces, rock faces, bodies of water, etc.) Watches that currently have multi-band capability include Apple Watch Series 8 and Ultra, Garmin 255, 265, 655, 955, 965, Fenix 7 Sapphire and Solar, Coros Vertix 2, Apex Pro 2.