0

I "play" with google/glm/mmap in order to find the coordinates of a cell. I note that the returned values can changed (queries on several days).
Any explanation ?

Bertaud
  • 2,888
  • 5
  • 35
  • 48

1 Answers1

0

It appears that the coordinates returned are a weighted average of locations where cell phones reported connecting to that base station. That is, they are not the coordinate of the base station antenna. This is actually better for geolocation purposes since you want to know where the cell phone is, not where the base station is. One of the parameters returned with the coordinates is a measure of the "spread" of the reports --- which gives one some idea of how accurate the geo-location is likely to be. It appears that as reports continue to come in to mmap, the data base is updated and so changes are possible over time, usually rather minor.

Note that, in the case of CDMA at least, the true location of the base station antenna can be obtained using getBaseStationLatitude() and getBaseStationLongitude() methods on cellLocation in e.g. onCellLocationChanged() callback. This is not supported by all carriers. U.S. Cellular does provide this information, Verizon Wireless sadly does not. Femtocells do provide the information using their built in GPS. Again, depending on your application, knowing the base station location may not be what is required.

Berthold
  • 21
  • 1