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Electromagnetic Waves - Transmission.
Digital Signals have a higher quality than Analogue Signals.
The
quality of a signal is a measure
of how much the signal has changed
during transmission.
A high quality
signal has changed very little.
A low quality
signal has other information in it
which was not there in the
original.
The additional unwanted information
is called noise.
Any
noise which is present in an
analogue signal
reaches the receiver and is
processed by the electrical
equipment
as if it were part of the original
signal.
All signals become weaker
as they travel
and some frequencies in an analogue
signal
may weaken more
quickly than others.
If the signal is amplified during transmission,
then the noise is also amplified in the same
way.
A
digital signal has only two states called on and off.
Since noise is usually of low intensity compared to the signal,
noise is interpreted by the decoder as an
off state
and is not included in the
signal processing.
A digital signal ignores the
noise
and therefore has a higher
quality than an analogue signal.
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