by PatPend
My cellphone has a built-in GPS receiver. I thought it might be fun to use it to find out the speed & bearing of the trains I'm on. However I can't get a signal inside any train (C3/M1/M3/M7), despite holding the phone up to the window. The phone's instruction manual states that certain glass coatings will block the GPS signal. Are the train windows coated or treated in some fashion? Has anyone else had any luck using a GPS receiver inside the train?