GpxFix Blog
Understanding GPS Spike Zones: Identifying and Analyzing Erroneous GPS Data
By Roy Lachica on . Last updated .
GpxFix has a powerful feature called GPS Spike Zones that helps you identify and analyze erroneous data in your GPX files. This guide explains what GPS Spike Zones are, how they work, and how you can use them to better understand your GPS data.
What Are GPS Spike Zones?
A GPS spike is a sudden, unrealistic jump in location, speed, or elevation data recorded by a GPS device. These anomalies often occur when the GPS signal is weak or obstructed, such as when you are indoors, in a dense urban environment (an "urban canyon"), or under thick tree cover. GPS Spike Zones are sections of your route where GpxFix has detected such erroneous data.
When you upload a GPX file, GpxFix automatically analyzes the data for spikes. If any are found, they are highlighted on the map and in the elevation profile as "Spike Zones". This allows you to quickly see which parts of your activity data might be inaccurate.
How Does It Work?
The detection algorithm in GpxFix analyzes the distance and time difference between consecutive GPS points to calculate speed. If the calculated speed between points is unrealistically high (e.g., faster than a world-record sprinter for a running activity) and with movement in random directions, it flags that segment as a gps spike zone.
For example, if you start your watch indoors before heading out for a run, the initial GPS points may be erratic as the device struggles to get a satellite fix. This can result in a large spike in the data at the beginning of your activity. GpxFix will identify this and mark it as a Spike Zone.
Why Is This Useful?
Identifying GPS spikes is crucial for several reasons:
- Accurate Statistics: GPS spikes can significantly inflate your total distance and average speed. By identifying them, you can understand why your stats might seem off.
- Data Cleaning: GpxFix allows you to crop or cut out these spike zones. For instance, you can remove the erroneous data from the start of an activity that was recorded while you were still indoors.
- Performance Analysis: By highlighting data that is clearly wrong, you can focus on the parts of your activity that are accurately recorded, leading to a better analysis of your performance.
- Device Assessment: Consistently seeing spikes can help you understand the limitations of your GPS device and the conditions under which it performs poorly.
Common Causes of GPS Spikes
- Starting or stopping a recording indoors.
- Tall buildings in cities reflecting GPS signals.
- Dense forest canopies or deep canyons blocking the signal.
- Device malfunction or low battery.
How to Use the GPS Spike Zones Feature
When you view a track in GpxFix, any detected GPS spike zones will be automatically highlighted with a triangle warning icon on the map. Click these warnings to get more details.
If you want to correct the data, you can use the 'Crop/cut' tool in GpxFix to remove the faulty sections.
Ready to Analyze Your Tracks?
Upload your GPX file or load one of your Strava activities and we will automatically show erratic GPS zones.
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