The Basic Facts About Radio Signals Radio waves travel at 186,000 miles per second through air. If a modulation is made of the radio wave that exactly reproduces the amplitude and frequency characteristics of the original sound wave, then sound can be transmitted rapidly over long distances. This leads to a very interesting phenomena. During a live broadcast in New York, the music will reach listeners in California a fraction of a second before it can be heard by the New York audience sitting in the back of the concert hall.
All waves have a wavelength, an amplitude and a frequency as shown in the figure.
These properties of the wave allow it to be modified to carry sound information. AM radio is subject to problems with static interference. There is considerable background noise that changes the amplitude of the radio wave signal adding random crackling noises called static. For example, higher frequency is associated with the peak amplitude in the audio wave. FM waves do not have a problem with interference because the noise background does not modify the radio wave frequency.