Physics - Data transmittion

Music and speech vary continuously in frequency and amplitude. In the same way, analogue signals can vary in frequency, amplitude, or both. You may have heard of FM and AM radio - Frequency Modulated radio and Amplitude Modulated radio.

Digital signals are a series of pulses consisting of just two states: ON (1) or OFF (0). There are no values in between. DAB radio is Digital Audio Broadcast radio - it is transmitted as digital signals.

All signals become weaker as they travel long distances, and they may also pick up random extra signals. This is called noise, and it is heard as crackles and hiss…