Why does GPS work when underground and under big buildings but radio signals, Wi-Fi, and cell phone signals struggle?

Question

Why does GPS work when underground and under big buildings but radio signals, Wi-Fi, and cell phone signals struggle?

In: 4773

Answer 1

Everyone is explaining how GPS doesn’t really work underground. One thing I haven’t seen anyone talk about is magnetometer based location determination. Companies like AstraNav can get extremely precise locations using nothing but magnetic field patterns.

Phones and other devices can use these sensors to augment GPS when it’s not available or a high DOP.