keep in touch (phr): to maintain contact
sophisticated (adj): advanced: complex
frequency (n): number of times a sound wave vibrates within a specified time
base station (n): antenna on top of a building, mountain, etc. that relays telephone calls
antenna (n): device for sending and receiving electronic signals
cell (n): geographical area covered by a base station
transmit (v): to send (a message, picture, etc)
The GPS communicates with satellites by means of radio waves. This gives it precise information as to its location. If the radio waves are blocked, when the GPS is in a tunnel.
for example, then the GPS may not recognize where it is.
Having established its location by satellite, the GPS reports it to the driver, using measurements of latitude and longitude. These measurements enable the GPS to plot a map on the GPS screen.
There are at present 30GPS satellites owned by the USA and Russia, but other countries around the globe are developing their own GPS satellites too.