Analogue and digital signals

Analogue and digital signals

1. Analogue

   • An analogue sound may have any value within a continuous range - this can be converted into an electrical signal
   • This graph shows how the voltage of an analogue signal vary with time. The voltage has an infinite number of different values
   • Why do they lose quality
     • All types of signals lose strength as they travel. This is called attenuation and means that signals often have to be amplified so they can be used. Signals can also pick up noise
       • Amplifying an analogue sound also amplifies the noise. It is difficult to distinguish the noise from the signal because an analogue signal can have any value. This means that the analogue sound is of lower quality by the time it is received

2. Digital

   • A digital signal only contains two values.'0'-off, '1'-on
     • They are used to encode analogue information
   • Unlike analogue, a digital signal does not vary smoothly, and so is described as being a discrete signal
   • Advantages
     • No loss of signal quality - analogue signals lose quality during transmission but digital signals are received unchanged
     • More information - digital signals can carry more information than analogue signals

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