Saturday, March 24, 2018

Does GPS require clear view of sky to lock satellites?


I have been reading conflicting information about the GPS signal lock in the XDA Developers Forums.


Certain users say they have to be outdoor to get any lock in to satellites, others say they could lock in their home basement.


Which one is it?



Answer



GPS uses radio frequencies between 1 and 2 GHz (L1 signal at 1.57542 GHz and L2 signal at 1.2276 GHz). These have to get through for GPS to work, which is not the same as visibility.


For example, my GPS (Garmin Etrex Legend HCx) gets a fix on the top floor of the house, below the roof made of tiles, insulation and drywall. It doesn't get a fix on lower floors, where there's too much concrete and steel in between.


BTW, I had a Motorola Defy for a while, if I remember correctly it also worked, but had a much lower precision, sometimes it was hundreds of meters off.



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