As with all GPS systems, GRETA also believes tracking works better the more GPS satellites are available. Since GPS satellites are not geostationary, accessibility can fluctuate even in the open air. In general, visibility is already limited as soon as a GPS tracker is hidden – either by being in a bag or by the tracker being in a building. Depending on the location, the shield is different, and sometimes has more, sometimes less influence on the position determination.

And what does that mean exactly for the position?

As the number of visible GPS satellites decreases, the accuracy of positioning is reduced. Due to the fact that insufficient data is available for an exact position, the position is estimated as accurately as possible. As a result, successive positions may look like the tracker is jumping.

However, this jumping usually only occurs when the tracker is not moving, as in that case no significant change in position can be detected.