When there is a relative motion between the source and the observer then there will be change in the frequency of the wave. This phenomenon is called Doppler effect.
For example,when the source and the observer are moving each other then the frequency increases in this case. When the source and the observer are moving away from other then the frequency decreases in this case.
Therefore, Doppler effect is the name of the perceived change in a sound wave's frequency due to motion between the observer and the sound source.
It doesn't on account of radio waves are longer than optical waves. Radio waves are a sort of electromagnetic radiation with wavelengths in the electromagnetic range longer than infrared light. These long waves are in the radio locale of the electromagnetic range.
