Encoding and Decoding analog and digital signals

1. Encoding and decoding
analog and digital
signals

2. Encoding involves converting data
from its original form into another
form for transmission. Decoding is
the reverse process.

3. Analog data is represented by
using continuous variable physical
quantities, such as voltages.

4. For example, a watch that displays
the time by hands moving
smoothly around the clock face is
an analog device.

5. Most natural events in the real
world, such as temperature, light
and pressure, are in analog form.

6. For example, a digital clock shows
the time as a certain number of
hours and minutes.
Digital data is represented in the
form of digits or numbers.

7. Information technology works
with data in a digital form.

8. Digital signals are represented as a
series of 0s and 1s.

9. The form of the data (either
analog or digital) and the
transmission signal (either analog
or digital signal) affects the quality
of the data received and the cost
of transmission.

10. The quality of analog data
depends on maintaining the exact
wave as it moves through a wire
or space. If it is corrupted in any
way, there is no way of
regenerating the wave.

11. However, digital data is
transmitted as a series of 0s and
1s, and it is possible to regenerate
data that has been corrupted.
That is, to reconstruct the data, it
is only necessary to distinguish
between a 0 and a 1.

12. There are four encoding and
decoding possibilities in
transmission:
• Analog data to analog signal.
• Digital data to analog signal.
• Digital data to digital signal.
• Analog data to digital signal.

13. Information technology works
with data in a digital form.

14. Analog data to analog signal. The
wave shape of the data is encoded
into the signal. A telephone
encodes analog data in the form
of sounds into analog signals
suitable for the telephone line. If
the signal is corrupted, there is no
way of restoring the original
analog data.

15. Digital data to analog signal. A
series of 0s and 1s is encoded into
a continuous wave. A modem
encodes (or modulates) digital
data from a computer into
analog signals for the telephone
line. When the analog signal is
received by another modem, it
decodes (or demodulates) the
analog signal into digital data.

16. A modem encodes digital data to
analog signals and decodes analog
signals to digital data.

17. Analog data to digital signal—the
wave shape of the data is encoded
into a series of 0s and 1s. This
process of generating digits or
numbers is called digitising.

18. Images are digitised using such
devices as scanners, and sounds
are digitised using a process called
sampling.