There are 108 88 MHz frequency range – only send a signal wave; Communicate using sound waves, mixed with carrier wave by wave frequency carrier wave signal will sound according to the changes.
Frequency range 88 - 108 MHz signal only wave ground. Communicate using sound waves combined with a carrier wave. The frequency of the carrier wave is altered by sound waves.
Frequency 88 - 108 MHz. The ground wave signal Communicate using sound waves mixed with carrier wave. The frequency of the carrier wave signal is changed according to sound waves.