Advantages of MLT-3 encoding | Disadvantages of MLT-3 encoding
This page covers advantages and disadvantages of MLT-3 encoding multiline transmission. It mentions benefits or advantages of MLT-3 encoding and drawbacks or disadvantages of MLT-3 encoding.
What is MLT-3 encoding multiline transmission ?
MLT-3 encoding uses three levels (+V, 0, -V) and three transition rules to move between levels. It is similar to NRZ-I. Following rules are applied to encode bit pattern in the example below.
• If the next bit is zero ('0'), there is no transition.
• If the next bit is one ('1) and current level is not zero '0', the next level is 0.
• If the next bit is one ('1) and current level is zero ('0'), the next level is the opposite of the last nonzero level.
The encoding as per above rules is shown in the figure.
Though it is simular to NRZ-I, its encoding provide such shape of signal which reduces required bandwidth. Let us understand this with following example of long sequence of ones ('1s').
In this example, signal pattern (i.e. +V 0 -V 0) repeats every 4 bits. From the example, it is imperative that MLT-3 converts non-periodic signal to periodic signal with period equals four times of bit duration.
MLT-3 is useful to transmit 100 Mbps on copper wire which can not support greater than 32 MHz.
Benefits or advantages of MLT-3 encoding
Following are the benefits or advantages of MLT-3 encoding:
➨It has signal rate which is (1/4)th of the bit rate.
➨Due to its signal shape, it reduces required bandwidth.
Drawbacks or disadvantages of MLT-3 encoding
Following are the drawbacks or disadvantages of MLT-3 encoding:
➨It does not support self-synchronization for long string of zeros ('0').
➨It is more complex than NRZ-I due to use of three levels and complex transition rules.
Line coding techniques
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