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GPS Drift and Environmental Factor Impact on GPS Accuracy
GPS drift and environmental factors can impact the accuracy of locations and activities recorded by your Garmin watch. The information in this article will help you understand and reduce the impacts of GPS drift and environmental factors.
GPS Drift and Environmental Factors
What is GPS Drift?
GPS drift, in the most practical sense, is the difference between your actual location and the location recorded by a GPS receiver. Consumer grade GPS receivers (such as the ones Garmin makes) are not 100% accurate, this will usually cause a difference between your actual location and your recorded location.
The GPS location accuracy of Garmin outdoor watches is around 3 meters (10 feet), 95% of the time. This means, at any given time, your watch will save your location within 3 meters of your actual location. If your watch is recording a GPS location every second and you do not pause an activity while standing still, your watch can record up to 180 meters (590 ft) in just 1 minute. When in an area with degraded GPS signal, your watch can record even more distance while stopped. The distance recorded while standing still is a representation of GPS Drift.
What are Environmental Factors?
Any outside influence on the accuracy of your Garmin watch is an environmental factor and can cause degraded GPS signal. Environmental factors can range from using GPS downtown in a major city to running in a big group of people to trying to record a hike under a dense tree canopy. Using your watch to record GPS in those types of environments blocks the watch's ability to directly receive GPS signal. You can think of environmental factors as things that interrupt the signal path of a GPS satellite to your watch.
Examples of GPS Drift and Environmental Factors
Select options below, such as Example 1: GPS Indoors, to learn more.
Example 1: GPS Indoors
The image below shows a track recorded by a GPS handheld device that was turned on and recording in a building. This illustrates what it would look like if you were to record GPS while standing still in a highly degraded GPS environment.
Example 2: Stopping Without Pausing During an Activity
This images shows a hiker that stopped for a short amount of time without pausing their activity. You can see that the watch continued to record GPS points while the person was stopped. This added some additional distance to their hiking activity.
Example 3: GPS Distortion Caused by Environmental Factors
In the example below, the watch was recording an activity in an area known as an "Urban Canyon". Urban Canyons cause degraded signal due to poor visibility of the horizon and GPS signal refraction caused by windows on taller buildings. When signal is very degraded, the GPS accuracy of your watch goes down and the track of your activity may not show anywhere near the actual path you took.
Troubleshooting GPS Distance and Accuracy
Now that you know what causes activity distance to be incorrect, you can take steps to prevent inaccuracies. The information below will help you record more accurate tracks. Be aware that environmental factors cannot be completely overcome, and GPS drift is a natural occurrence.
Reduce Environmental Factors
The first step to recording accurate GPS data is to reduce distortion and degradation caused by environmental factors. GPS works best when there are no obstructions above 15 degrees over the horizon. Avoid the following when recording activities:
- Tall buildings
- Dense forest or canopy
- Canyons
- Using GPS in a dense group of people
- Using GPS indoors
- Using GPS under water
Soak the GPS
When a watch initially displays that it is GPS ready, it means that the watch has picked up the minimum amount of satellites needed to get your location. Soaking GPS is practice of allowing your watch additional time to communicate with satellites before you start moving for your activity. This practice allows for your watch to communicate to additional satellites, creating a stronger bond and helping to reduce degradation of GPS signal.
Soaking GPS
- Select an activity
- Wait for the GPS Ready message or GPS Indicator to turn green
- Wait 2-5 minutes before you start the timer for your activity
Update Software
Out of date software can lead to irregularities in recorded GPS data.
Follow the steps in this article for updating your watch with Garmin Express - Updating Maps and Software with Garmin Express
Turn on Auto Pause
Recording GPS while stopped is one of the biggest contributors to inaccurate distance in an activity. Setting your watch to pause when you are stopped, can greatly reduce the amount of additional distance recorded.
Turning on Auto Pause
Fenix 3 Series1
- Press and hold Up/Menu to access the Main Menu
- Select Settings
- Select Apps
- Select an activity, such as Hike
- Select Auto Pause
- Select When Stopped
Fenix 5 Plus Series2
- Press and hold Up/Menu to access the Main Menu
- Select Settings
- Select Activities & Apps
- Select an activity, such as hike
- Select (Activity Name) Settings
- Select Auto Pause
- Select When Stopped
Your watch will now automatically pause the activity that you made the change for when you are stopped. Recording will resume automatically when you start moving again.
1 These steps will also work for the D2 Bravo, epix, fenix 3 series, fenix Chronos, quatix 3 and tactix Bravo
2 These steps will also work for the D2 Charlie, D2 Delta series, Descent Mk1, fenix 5 series, Instinct, quatix 5 and tactix Charlie
Distance and Speed Recording Accessories
Sometimes you may not be able to avoid degraded signal caused by environmental factors. For instance, you may live in Chicago and running outside of the city is not feasible, in this situation you should use a foot pod.
Foot Pod
When using a foot pod, GPS will still be recorded for your activity, but your distance will be based on the number of steps you took multiplied by your stride length.
Speed Sensor
A speed sensor works similarly to a foot pod. Speed sensors use the size of your bike's wheel and the number of rotations it makes during a cycling activity to determine your distance. The speed at which your wheel rotates will determine speed. Just like using a foot pod, GPS will still be recording when using a speed sensor.
The Garmin Bike Speed Sensor can be purchased here: Garmin Bike Speed Sensor
Note: Make sure to check compatibility with your Garmin watch before purchasing a distance and speed recording accessory.
For more information on troubleshooting GPS, see the Related Content below.