https://www.popsci.com/technology/google-gps-map/
"If you’ve ever followed a navigation app only to have it drift off course, the
culprit responsible for the mix-up may be hovering 50-200 miles overhead. That
region of the Earth’s atmosphere called the ionosphere can contain varying
levels of free electrons that, when highly concentrated, can slow down GPS
signals traveling between satellites and device receivers. That delay, similar
to someone running late to work after frantically bobbing and weaving through a
crowded city street, is one of the leading contributors to errors in navigation
systems.
In a paper published this week in
Nature, Google researchers demonstrated
they were able to use GPS signal measurements pulled from millions of anonymous
Android mobile devices to map the ionosphere. Though a signal from any single
mobile device is too “noisy” to tell researchers much about the ionosphere,
that noise gets corrected when there are many other devices to compare against.
In the end, the researchers were able to use the vast web of Android phones to
map out the ionosphere with a level of accuracy that matches monitoring
stations. In areas like India and Central Africa, the Android technique
actually far surpassed the accuracy of monitoring stations alone.
Scientists around the world can measure this ionospheric traffic (officially
called total electron content (TEC) through a network of high-quality
ground-based monitoring stations. These detection tools are effective but they
are also relatively expensive to build and maintain, which makes them less
common in developing regions of the world. That unequal access to monitoring
stations leads to disparities in the global ionospheric mapping accuracy.
Researchers from Google tried to address this mismatch by leaning on something
already owned by a majority of the world’s population: mobile phones.
Google researcher and paper co-author Brian Williams told
Popular Science he
had previously seen firsthand how changes to the ionosphere could hinder GPS
capabilities while working on Android products. He says he saw this project as
an opportunity to simultaneously contribute scientific advancements and improve
accuracy for everyday mobile device users.
“Instead of thinking of the ionosphere as interfering with GPS positioning, we
can flip this on its head and think of the GPS receiver as an instrument to
measure the ionosphere,” Williams said. “By combining the sensor measurements
from millions of phones, we create a detailed view of the ionosphere that
wouldn’t otherwise be possible.”"
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
