posted by Michael Jones .
In __, the amplitude of the carrier wave is changed to transmit information; the frequency is not changed.
In __, the frequency of the carrier wave is changed
__ phones and __ phones use radio waves to transmit signals.
__ use electromagnetic signals from a base station
Communication __ enable radio signals to be sent from one part of Earth to another
The __ consists of satellites, ground-based stations, and portable units with receivers used to help locate objects on Earth.
AM; FM; cell phones; cordless phones; radio and television; satellites; GPS system