What is Unipolar Encoding?

Digital transmission system manages by sending voltage pulses and a medium link, usually a wire or cable. The most encoding one voltage stands for binary '0' and other voltage as binary '1'.

The polarity of pulse defines either +ve or – ve unipolar encoding because it works with only one polarity. This polarity is authorized to one of the two binary states, generally '1'. The other state frequently '0' described by zero voltage. The figure explains the idea of unipolar encoding. The binary '1's treated as the +ve voltage and '0' are encoded as zero voltage. Unipolar encoding is simple and inexpensive.

Disadvantages of Unipolar

There are two disadvantages of Unipolar as follows −

DC Component

A unipolar encoded signal’s average amplitude is non-zero, creating a direct current component (means a component without –ve voltage or zero frequency). When a signal includes the DC component, it cannot traverse through media that don’t manage the DC component.


When a signal is unvarying, the recover cannot decide the starting and end of each bit. Therefore, a synchronization issue in unipolar encoding can appear whenever the data stream contains a huge stream of 1’s or 0’s.

Digital encoding scheme use change in voltage level to medicate changes in bit type. A signal change also indicates that one bit has ended and another bit has begun. So a series of one kind of a bit, say several 1’s, occurs with no voltage change, indicate the start of the next bit in a sequence.

An expected bit rate of 1000 bps and receiver detects +ve voltage lasting 0.006 seconds. It reads one bit per 0.01 second. The shortage of synchronization between sender and receiver clock distort the timing of the signal. If six 1’s is stretched to 0.007 seconds will cause a study of an extra 1 bit and decode everything erroneously.