Next time you’re on a flight, download a GPS speedometer app and launch it right before takeoff. You’ll notice that it’ll accurately measure the plane’s speed up to around 500 MPH, before it suddenly stops giving you a speed readout.
Like the other person said, this is to prevent your average dude building a guided missile using an old phone they have lying around.
Probably would just use an IMU exactly as the plane itself already does for its own navigation.
They get a lock on the ground, synchronize the IMU with the Earth’s orbit, and they keep track of where they’ve moved from the origin, supplemented by GPS.
What? Every smartphone I can remember owning has gotten a GPS signal if I hold it up to the window. Plenty of planes have GPS on board too. If there is a speed lockout, a 737 isn’t enough to break that threshold.
Last time I flew, there was no signal at all while flying.
There’s a number of factors that lead to that.
The cell base station antennas have a relatively narrow vertical beamwidth and are typically aimed a few degrees below horizontal. (Aircraft tend not to operate at that altitude)
usable range of each cell base stations is typically <50 km.
Cell base stations are optimized for communicating with mobiles moving less than 90km/h.
Given all that, if you happen to get a signal, you’ll be handing off between towers far too fast and too frequently for the network to reliably deal with.
Last time I flew, there was no signal at all while flying. not even GPS!
deleted by creator
That makes sense! Thanks
Next time you’re on a flight, download a GPS speedometer app and launch it right before takeoff. You’ll notice that it’ll accurately measure the plane’s speed up to around 500 MPH, before it suddenly stops giving you a speed readout.
Like the other person said, this is to prevent your average dude building a guided missile using an old phone they have lying around.
deleted by creator
Probably would just use an IMU exactly as the plane itself already does for its own navigation.
They get a lock on the ground, synchronize the IMU with the Earth’s orbit, and they keep track of where they’ve moved from the origin, supplemented by GPS.
deleted by creator
Thus draining the phone’s battery much faster.
Same thing happens if you are camping in a remote location with weak or non-existent coverage.
deleted by creator
What? Every smartphone I can remember owning has gotten a GPS signal if I hold it up to the window. Plenty of planes have GPS on board too. If there is a speed lockout, a 737 isn’t enough to break that threshold.
deleted by creator
There’s a number of factors that lead to that.
The cell base station antennas have a relatively narrow vertical beamwidth and are typically aimed a few degrees below horizontal. (Aircraft tend not to operate at that altitude)
usable range of each cell base stations is typically <50 km.
Cell base stations are optimized for communicating with mobiles moving less than 90km/h.
Given all that, if you happen to get a signal, you’ll be handing off between towers far too fast and too frequently for the network to reliably deal with.
There’s no way there was no GPS, maybe your phone was trying to base your location with antennas and not GPS