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