Tracking
Bad GPS data
Introduction to GPS
GPS data is generally very reliable. But it's not 100% reliable. When you're tracking a trip with SeaPeople we rely on the quality of the GPS data that is collected by your phone. There are cases when the phone gets bad GPS data and it varies a lot by phone manufacturer and your environment (cliffs, sky view, etc…)
GPS works by connecting a device to a number of overhead satellites and precisely measuring the time it takes for a signal to travel between your device and the satellites. It is a digital copy of celestial navigation. The speed of the signal travels is known and the amount of time the signal is in transit allows your device to calculate the distance to each satellite. Since the geo-position of each satellite is known, as well as the distance between those satellites and your GPS device, your position can be triangulated.
Bad GPS data examples
Lost GPS signal
When the GPS signal is lost the pre and post lost signal positions will be connected by a straight line as shown below. Make sure your phone has a decent view of the sky and some carbon fiber structures can block or absorb GPS signals, especially with thick layers, but it is not a complete signal jammer and the impact varies by application. You can use free GPS signal testing apps in the app stores to test your signal quality.
It's also important to keep the app running when tracking. If you force close the app while tracking it will resume tracking automatically when it's restarted but your track will look like it lost GPS signal because the locations collected while the app was closed will not be know to the SeaPeople app.
GPS Bounce
Tall cliffs or buildings can cause GPS signals to bounce between the satellites and a device. There's also a more common bounce which is caused by modern phones using cell towers and wifi to improve GPS positions. These GPS bounces cause jumps in your track. As the phone receives a single position that's far off your track. We have algorithms to reduce the impact of bounces and we filter out as much as we can, but there are still cases where your track can have them.
Steps to take on Android device to improve tracking
There's a very wide range of Android devices and manufacturers and they have different quality GPS receivers and typically have more tracking issues.
Here are a few tips to help improve tracking quality on Android:
Disable any battery saver settings including Power Saving Mode, Battery Management, Optimization, or any third-party apps.
Look at the battery optimization settings for your device and turn off all optimizations for the SeaPeople app.
Turn off location accuracy from Location Services > Location Accuracy. To improve device location, Android devices with Google Play services have a Location Accuracy service that uses information from wireless signals, such as Wi-Fi access points, cellular network towers, and GPS, along with device sensor data. This has shown to cause a lot of GPS track bounces and bad tracks.
If you're having a lot of reccuring tracking issues with bad GPS data it's useful to use another application to compare GPS data. AllTrails or Strava are good examples of apps that are similar to SeaPeople in how they track. If your GPS data is bad, so will your tracks in all these apps.
Fixing bad GPS data
SeaPeople optimizes the location data provided to it by the phone and removes very obvious bad GPS data. But we can only make the most out of the data that is provided. It's a hard problem to completely solve and all tracking apps have similar issues.
However, we've provided tool in the app that help fix up tracks after they have been recorded.
Below is a demo of how you can find the track editing tools for a trip that's been saved. You can remove or move points on the track. Open the track editor and select the part of the track that you want to see the individual points. By default the track editor doesn't show all points on the track as that would be too expensive. But when in Move or Delete mode, select a section of the track and points around that section will be shown. Zoom in to see more detail.