Radio and TV
Radio: coding electromagnetic waves with the useful information (sound), so they can be transmitted through space, intercepted and converted back into sound.
Sound waves are transformed in electrical signals (oscillating electric current)
This electrical signal is combined with a broadcast signal or carrying signal (much higher frequency), which is than is amplified and radiated through antennas as electromagnetic waves
Electromagnetic waves travel in vacuum and reaches the radio sets.
the frequency of this electromagnetic waves (carrier frequency), depends on the broadcasting station.
Combination of the useful signal with the carrying signal called: modulation!
Two types of modulation: amplitude modulation (AM) and frequency modulation (FM)
Radio set in order to receive the
modulated signal, is tuned so it only
resonates with on carrying frequency
The radio filters out the carrying
frequency and retain the electrical
version of the sound information
amplified and reconverted to sound