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Difference Between Manchester and Differential Manchester Encoding

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  • Difficulty Level : Basic
  • Last Updated : 29 Oct, 2022
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Bi-Phase encoding is the best solution for synchronization. A transition occurs in the middle of each bit period that serves the synchronization and encoding of the data

There are two types of bi-phase signal encoding techniques:

Manchester Encoding:

  • In  Manchester encoding, a low-to-high transition represents a 1, and a high-to-low represents a 0.
  • The duration of the bit is divided into two levels.
  • Voltage remains at one level in one half and moves to another level in the second half. 

NOTE :

+ve voltage = 1

-ve voltage = 0

There are two types of conventions in Manchester encoding:

1. Dr. Thomas: In this manchester encoding 0 is represented as low-to-high and 1 is represented as high-to-low.

Dr. Thomas Manchester Encoding

Dr. Thomas Manchester Encoding

2. IEEE802.3: In this manchester encoding, 0 is represented as high-to-low and 1 is represented as low-to-high.

IEEE 802.3 Manchester Encoding

IEEE 802.3 Manchester Encoding

Application of Manchester Encoding:

  • It is used for IR protocols, RFID, and NFC system.
  • Manchester Encoding is transparent.
  • There is no signal-dropping issue.

 Differential Manchester Encoding:

  • It is also known as the Biphase mark code, etc.
  • The presence and absence of the transition indicate the value.
  • In  Differential Manchester Encoding 0 should contain an edge but 1 should not contain any edge it should be continuous.
 Differential Manchester Encoding

 Differential Manchester Encoding

Application on Differential Manchester Encoding:

  • For every bit, there is a transition guaranteed
  • Used in 802.5 with Twisted Pair. 

Difference Between Manchester and Differential Manchester Encoding:

S. No Manchester Encoding  Differential Manchester Encoding
1. Manchester encoding s a synchronous clock-encoding technique used by the physical layer to encode the clock and data of a synchronous bit stream. Differential Manchester encoding is a line code in which data and clock signals are combined to form a single 2-level self-synchronizing data stream
2. Low to High represents 1 and High to Low represents 0. No transition at the start of a bit period represents 1 and transition at the start of a bit period represents 0.
3. It provides better signal synchronization.  It provides less signal synchronization as compared to manchester encoding.
4. Signal rate is the drawback of manchester encoding as there is always one transition at the middle of the bit and maybe one transition at the end of each bit.  It maps at least one transition per bit time and possibly two bits. Its modulation or signal rate is two times that of NRZ. Hence it requires more bandwidth.
5. Used by IEEE 802.3 specification for Ethernet LAN   Used by IEEE 802.5 specification for Token Ring LAN 
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