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Poor GPS Data - Why and How to prevent it

What is poor GPS data, what does it refer to?

Poor GPS data describes any circumstance where the GPS accuracy is dropping and the location data recorded by the Tracker is not accurately representing the actual position of your dog.

That means the track in the position history diverges from the actual path you took.
In those cases there can be extra tracked segments (or unexplained missing data) you actually never took, which show up on the map.

Why does poor GPS data happen?

There are multiple factors to be considered to explain why poor GPS data is generated.
Under perfect conditions current GPS devices of any kind have an accuracy of about 3m. Depending on certain environmental factors this accuracy can decrease.
That means even when your device is working at its best there's always a slight error that can happen. Unfortunately no GPS System can pinpoint a location with a zero meter offset to its original position.

Your GPS device is connected to a number of satellites. Every signal that is sent back and forth is measured in time for how long it takes to travel between Tracker and satellite. The location can then be calculated with the measured signal duration.

This explains why GPS works perfectly under clear sky and is lacking functionality in woods or in small alleys with buildings all around.

When updating the GPS position more often like we do during an active Live Mode session the data comes in very fast. Slight deviations in signal running time can cause dislocations or from the actual position.

Examples of poor GPS data

Below you can see a perfect example of high buildings and dense areas; We walked into that courtyard during a Live Track. The GPS data got inaccurate during that time due to the surrounding tall buildings.
This inaccuracies are often resulting in jumping GPS tracks.

vienna_2_inaccuracy.png

On the next screenshot you can see a Live Track through wooden areas. We can see the track perfectly accurate on the road, but getting less accurate in the forrest due to signal blocking.

woods_inaccuracy.png

Here you can see where we take a short break during our Live Track; In less accurate surroundings the GPS signal can bounce back and forth within a certain radius. This is resulting in knots like below.

stop_inaccuracy.png

Here is another example of tall buildings interfering with accuracy. We walked on the pedestrian area close to the building walls which can result in Live Tracks that are shown in the middle of the street. The track is getting more accurate once those areas are left.

vienna_inaccuracy.png

The next example is showing a Live Track in which we drove the car. Putting the Tracker on the backseat of a car you might experience poor GPS data because there's no clear view at the sky.

In addition there were tall buildings which made the track even more inaccurate. This example is showing that different influences can add up when using the tracker in many different environments.

car_driving_buildings_inaccuracy.png

How to fix poor GPS data?

We at Tractive are doing everything to prevent such poor GPS data from happening and appearing on your location history. We have implemented algorithms that filter out many inaccurate datasets. Unfortunately we are bound by technical limitations by the GPS technology.

When the GPS Tracker records poor/inaccurate data during Live Tracking we can ignore or remove those from the location history and wait for a more accurate signal. This procedure is only working in Live Mode because of the more frequent location fixes.

In Basic Mode these algorithms cannot be used anymore because the location is determined and sent only once within a certain timeframe.

Unfortunately there is currently no way to fix or change poor data once it has been recorded and saved to your location history. Rest assured that we are constantly improving our system and algorithms to reduce the appearance of poor GPS data.

How to prevent poor GPS data

If your app is reporting poor or inaccurate GPS data in your Tractive app (orange badge) during Basic Mode you can try to activate the Live Mode to get frequent location updates.

In addition there are a few things you can do on your own to reduce the risk of poor GPS data.

  • Make sure that the GPS Tracker is positioned correctly on your pet's collar
    It is best located at the back so that it's not covered by body parts.
  • Restart your GPS Tracker from time to time
    This action re-initializes the internal hardware components and can improve the overall accuracy.

Further information can be found on the official GPS website by the US government:

http://www.gps.gov/