Why does GPS work when underground and under big buildings but radio signals, Wi-Fi, and cell phone signals struggle?
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GPS requires a clear view of the sky, and actually changes in how well it works over the course of the day (when more or fewer satellites are overhead).
The location tracking on your phone uses GPS, but also triangulates off of cell towers.
If you’re in a place where cell antennas / boosters have been installed (like in some building basements) or in a tunnel, the location info displayed on your phone is coming from triangulation, not from GPS.
If there is actually no cell service or WiFi service in a location, then your phone has no idea where you are.
Also your phone used a standard ping from cell towers to triangulate position. It’s not using GPS. My understanding is there is a standard frequency that allows all phones to Ping every carriers towers so all carriers benefit from enhanced positioning data for their users
What do you mean? They absolutely struggle underground, in carparks etc
Because it doesn’t need constant satellite communication to estimate your position. As other’s have said, it uses a wide range of tools, other than a GPS signal, to figure out where you’re located.
From a physics view point, GPS signal bands are not far from the bands your phone uses, so they penetrate matter in similar capacities. What blocks phone signals will also block GPS signals.
What kind of GPS are you using? Mine instantly fails when I go even one floor under in my garage
GPS are dependent on line of sight to three or more satellites.
When I start my rental car in the :ogan AP garage, there is no connectt til exiting.
It doesn’t actually work, it just guesses your movement and fills in the blank until you’re back in the real world.
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.
GPS doesnt actually work any better than wifi or cellphone signals, the only reason you can keep on the road is because the GPS probably has at least the local map saved somewhere on your device so it can refer to it in case of signal drop and the device also has an accelerometer in order to tell how fast youre going. theres also a basic compass to tell the direction too. all in all GPS just has a lot more ability to store data locally than wifi and gps does.
Somewhat related: why does my Sirius satellite radio lose signal under heavy tree cover, but keeps on playing when I drive through tunnels?
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