Millions of Android phones against the biggest enemy of GPS
Google is now using the large install base of its Android platform to get the biggest enemy of GPS location tracking under control: data from millions of devices should help deal with interference from the ionosphere.
Measuring disturbances in the ionosphere
Researchers at Google have developed a method to map the ionosphere in detail using GPS data from smartphones. This layer of Earth’s atmosphere at altitudes of 60 to 1000 kilometers can delay GPS signals, causing navigation errors. In a recently published study in the journal Nature The researchers showed how they could aggregate GPS signals from millions of Android devices and thus record the ionosphere with high accuracy.
Every modern smartphone has GPS receivers that process signals from satellites in medium Earth orbit. On their way to Earth, these signals pass through the ionosphere, where they are slowed down and deflected, which can lead to errors in location determination. Conventional correction models in smartphones often manage to at least partially compensate for these errors. The Google researchers therefore wanted to find out whether the measurements from Android devices as a whole could be used to map the ionosphere.
By aggregating anonymized data from millions of smartphones worldwide, a precise map of free electrons in the ionosphere was created. This was particularly successful in populated areas and on the respective dayside of the earth. Google says this method provides better coverage, especially in regions like India and Central Africa where high-tech monitoring stations are rare.
Strength of the many
The collective measuring power of smartphones showed astonishing results: in some areas, the model based on Android data exceeded the accuracy of existing monitoring stations. This enabled the researchers to precisely detect phenomena in the ionosphere such as plasma bubbles and the so-called equatorial anomaly over South Asia.
These events may have gone unnoticed without the new mapping network, as there are only a few stations in the region. Brian Williams, one of Google’s researchers, explained that the smartphone-based model not only improves the accuracy of GPS but also serves as a scientific tool. “By aggregating the measurements from smartphones, we create a detailed picture of the ionosphere that would not otherwise be possible,” said Williams.
