GPS accuracy is a common concern and a lesser-known facet of GPS technology. Accuracy when using GPS is variable and depends on several factors. Typically, we expect our trackers to be accurate down to 3-5 meters (10-16 feet). This means there is some difference between the reported location and the displayed location in the Hapn app. This difference is usually minor but can occur when the tracker is indoors or underground. For example, if the tracker is on a car and the vehicle parks in an underground garage, the tracker may display the last position it received, likely as it turned into the garage. Thus, it may display the location in the app as the garage entry or on the street, when the car is actually in the garage.
To understand why these minor variations happen, we first have to look at how GPS works. The tracker is a receiver that gets a signal from the GPS satellite network. This signal contains the atomic time calculated by the satellite and is compared to the time on the tracker. The difference between the two values allows the tracker to determine its location on the globe.
However, if the tracker loses line of sight with the satellites, such as when the car goes underground into a garage, the last known location is what will be displayed. This can lead to a discrepancy between the actual location and the displayed location. Understanding that this can happen is crucial. For instance, if the tracker appears as stopped in the driveway of a parking garage but cannot be seen there, it can be assumed the tracker is in the garage.
Similarly, if the tracker is in your home garage, but the application displays it in your driveway, it's not an indication of the tracker not working. This is expected behavior and not an issue with the device.
Other factors that might cause greater than expected inaccuracy include the "urban canyon" effect caused by high-rise buildings blocking the GPS line of sight until the satellite is directly overhead. This can result in spotty connection and less accuracy than expected.
If you are experiencing inaccurate tracking beyond a 10-16 feet deviation and are in an area with good satellite line of sight, it may be a placement issue with the tracker itself. Certain materials like metal and concrete can also block the GPS signal, so tracker placement is crucial for GPS accuracy. For a more detailed look at tracker placement, visit our GL300 placement guide.
Once the tracker has been placed properly, it will operate within the expected accuracy (10–16 feet) unless one of those above mitigating circumstances occurs. This is the normal and expected accuracy of GPS trackers.
Understanding what to expect from your GPS tracker, combined with knowledge of how the tracker works, can help you feel confident in your GPS deployment. This will enable you to react appropriately when there may be a legitimate issue with the device and prevent you from trying to solve a non-existent problem.
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