Analog and Digital Signals
There are two different methods of sending an electronic signal from A to B.
ANALOG signals are continuous, and can take any value. DIGITAL signals encode
values into binary numbers. As a binary number is made up entirely from 0’s and 1’s,
it may be transmitted in the form of electronic on/off pulses (on =1, off =0). When
these pulses are received, they are processed. A digital signal is made up of discretely
variable physical quantities.
Whilst these two types of signal both transmit information in electrical voltages, they
each have their advantages and disadvantages. In recording audio signals, analog
systems are useful, because they can give a faithful electronic representation of a
complex waveform. However, because of the need for amplification of the electronic
signal, ‘noise’ can be added along the signal path. This noise is due to unavoidable
electron activity in the circuitry. Unfortunately, there is no easy way to get rid of
noise from the original signal. Consequently, the noise (audible as a ‘hiss’) is added to
the signal with each stage of transmission.
A digital equivalent to this system would sample the sound wave at selected intervals
and transmit the values that correspond to the sound wave in binary code. The digital
representation of the sound wave could then be moved around or processed within the
system without picking up any additional noise. Although the electron (noise) activity
is still taking place, whenever the digital signal is repeated, during each stage of the
transmission, the noise can be omitted.
Analog Signal Digital Signal
Accurate reproduction of signal needs
extra work
Very immune from noise
Suffers from noise and distortion Output is accurate but can have errors
from the sampling process
Simple technique Complicated but can operate at long
distance
