ASANSOL ENGINEERING College

MANCHESTER ENCODING & DECODING TECHNIQUE

Title: Study of Manchester Encoding and decoding Technique.

Objective: To know about the implementation of Manchester Encoding

and decoding technique.

Equipment Required: 1.Manchester Coding Kit

2.Power Supply

3.CRO

4.Connecting wires

Theory:

In telecommunication and data storage ,Manchester Coding (also known as Phase Coding) is a line code in which the encoding of each data bit is either low then high or high then low, of equal time. It therefore has no DC component and is self-clocking, which means that it may be inductively or capacitively coupled ,and that a clock signal can be recovered from the encoded data.

It has the following characteristics:

Each bit is transmitted in fixed time. A ‘1’ is noted when high to low transition occurs , ‘0’ is expressed when a

low to high transition is made. The transition that is used to note ‘1’ or ‘0’ accurately occurs at the mid

point of a period.

Manchester Coding:

Manchester Coding symbol ‘1’ is represented by a positive pulse followed by a negative pulse and symbol ‘0’ is represented by a negative pulse followed by a positive pulse.

Mathematical Expression:

If symbol ‘1’ is transmitted ,then

x(t)= A/2 for 0≤t<Tb/2

-A/2 for Tb/2≤t<tb

And if symbol ‘0’ is transmitted then

x(t)= -A/2 for 0≤t<Tb/2

A/2 for Tb/2<t<Tb

Observation Table:

Application:

Manchester encoding is a form of binary phase keying (BPSK) that has gained wide acceptance as the modulation scheme for low cost radio frequency transmission of digital data.

Advantages:

1.The best advantage of Manchester Coding is that the clock is embedded in the signal ,hence the synchronization made easier.

2.Recovery of the transmitter clock easy.

Disadvantages:

1.The double bandwidth compared with RZ or other coding schemes.

2.It requires absolute sense of polarity at the receiver end.

Waveform:

Clock frequency Data Input (Information)

Precaution:

Check the connection properly. Take the observation carefully. Supply correct amount of voltage.

Conclusion:

After performing the above experiment we are now familiar with the Manchester coding format and its connection and circuit operation .