PHYS-P 150 Lecture 35: Lecture 35: Cellphone Tech Part 2
PHYS-P 150 verified notes
35/48View all
Document Summary
Phys-p150 lecture 35 cellphone tech part 2. Phones usually have multiple speakers and multiple microphones: remarkably small devices. Almost all mobile devices use these devices that rely on electric force. Thin conducting membranes deflect when acted upon by sound waves: this changes the capacitance and results in an oscillating current. Barometers can operate similarly-good for determining your phone"s altitude: can sense changes in pressure using the membrane, again using capacitance for effect. Compasses merge an accelerometer and gyroscope to tell which way you are oriented. By contrast, gps can show you your location but cannot tell you which way you are facing. Many mem devices that can detect its orientation compared to the magnetic field of the. Earth: hall sensor, lorentz force sensor, fluxgate sensor, anistotropic magnetoresistive materials. Fcc requires phones to be able to track their location to the nearest 100 feet for 911 emergency calls. Gps was originally intended for the military.
