Sketch the waveforms for the binary sequence 10110000011 using the following methods: (i) Differential Manchester, (ii) Bipolar-AMI, (iii) B8ZS and (iv) HDB3.

$$Binary \ Sequence - 10110000011$$

1] Differential Manchester

• Differential Manchester combines the logic of RZ and NRZ-I encoding techniques.
• It is used by IEEE 802.5
• In this type of encoding, transition always occurs in the middle of the bit interval.
• In simple words, we can explain as

Bit – 0 represents either any of the one formats depending upon the sequence.

• Pattern 1 of bit – 0 represents the transition that starts at the POSITIVE side, makes the transition, and returns to the POSITIVE side.
• Pattern 2 of bit – 0 represents the transition that starts at the NEGATIVE side, makes the transition, and returns to the NEGATIVE side.

Bit – 1 represents either any of the one formats depending upon the sequence.

• Pattern 1 of bit – 1 represents the transition that starts at the POSITIVE side, makes the transition, and returns to the NEGATIVE side. (Z – Shape pattern)
• Pattern 2 of bit – 1 represents the transition that starts at the NEGATIVE side, makes the transition, and returns to the POSITIVE side. (Inverted Z – Shape pattern)

These patterns are represented in the below figure:

Waveform for the Binary Sequence 10110000011 using the Differential Manchester:

Step-by-Step explanation for the above Differential Manchester waveform for the 10110000011:

• BIT 1 - Here, we start from the positive side which means using the pattern 1 of Bit – 1 (Z – Shape pattern) to start the waveform.

• BIT 0 - Then, use pattern 2 of Bit – 0, because the previous pattern ended on the negative side. Hence, according to that pattern 2 of Bit – 0 is selected to represent 0.

• BIT 1 - Then, use pattern 2 of Bit – 1 (Inverted Z – Shape pattern), because the previous pattern ended on the negative side. Hence, according to that pattern 2 of Bit – 1 is selected to represent 1.

• BIT 1 - Then, use pattern 1 of Bit – 1 (Z – Shape pattern), because the previous pattern ended on the positive side. Hence, according to that pattern 1 of Bit – 1 is selected to represent 1.

• BIT 0 - Then, use pattern 2 of Bit – 0, because the previous pattern ended on the negative side. Hence, according to that pattern 2 of Bit – 0 is selected to represent 0.

• 4 Consecutive 0’s - The pattern 2 of Bit – 0 is selected further 4 times because the previous pattern ended on the negative sides. Hence, according to that pattern 2 of Bit – 0 is selected to represent 0.

• BIT 1 - Then, use pattern 2 of Bit – 1 (Inverted Z – Shape pattern), because the previous pattern ended on the negative side. Hence, according to that pattern 2 of Bit – 1 is selected to represent 1.

• BIT 1 - Finally, use pattern 1 of Bit – 1 (Z – Shape pattern), because the previous pattern ended at the positive side. Hence, according to that pattern 1 of Bit – 1 is selected to represent 1.

2] Bipolar-AMI

• It stands for Bipolar Alternate Mark Inversion (AMI).
• In this type of encoding, Bit – 0 is represented by 0 voltage line, and Bit – 1 is represented by alternate positive and negative voltages.

Waveform for the Binary Sequence 10110000011 using Bipolar-AMI:

3] B8ZS

• B8ZS stands for Bipolar 8-Zero Substitution.
• It is one type of Scrambling method.
• It is used to solve the problem of the long sequence of zeros in the Bipolar-AMI encoding method.
• It is used when the data stream consists of 8 consecutive zeros.
• This B8ZS work is based on the below scenarios:

Scenario 1 - If the data stream does not contain 8 consecutive zeros:

• Then B8ZS generates the same waveform as Bipolar-AMI.

Scenario 2 - If the data stream contains 8 consecutive zeros:

• Then it checks the previous voltage level.

  • Case 1 - If previous voltage level is POSITIVE then it substitute or generates the waveform in the sequence of 0 0 0 + – 0 – + voltage format.

  • Case 2 - If previous voltage level is NEGATIVE then it substitute or generates the waveform in the sequence of 0 0 0 – + 0 + – voltage format.

• This encoding method creates two violations in AMI type of waveforms.

The given Binary Sequence 10110000011 does not contain 8 consecutive zeros. Therefore B8ZS encoding technique generates the same waveform as Bipolar-AMI.

Waveform for the Binary Sequence 10110000011 using B8ZS:

Because of the absence of 8 consecutive 0's, there is no change in the waveform and generates the same waveform as Bipolar-AMI.

4] HDB3

• HDB3 stands for High-Density Bipolar 3.
• It is one type of Scrambling method.
• It is also used to solve the problem of the long sequence of zeros in the Bipolar-AMI encoding method.
• It is used when the data stream consists of 4 consecutive zeros.
• This HDB3 work is based on the below scenarios:

Scenario 1 - If the data stream does not contain 4 consecutive zeros:

• Then HDB3 generates the same waveform as Bipolar-AMI.

Scenario 2 - If the data stream consists of 4 consecutive zeros:

• Then it computes the previous non-zero voltages and then checks the last voltage level.

  • Case 1 - If the count of non-zero voltage level is EVEN and the last voltage level is POSITIVE then it substitutes or generates the waveform in the sequence of – 0 0 – voltage format.

  • Case 2 - If the count of non-zero voltage level is EVEN and the last voltage level is NEGATIVE then it substitutes or generates the waveform in the sequence of + 0 0 + voltage format.

  • Case 3 - If the count of non-zero voltage level is ODD and the last voltage level is POSITIVE then it substitutes or generates the waveform in the sequence of 0 0 0 + voltage format.

  • Case 4 - If the count of non-zero voltage level is ODD and the last voltage level is NEGATIVE then it substitutes or generates the waveform in the sequence of 0 0 0 – voltage format.

• This encoding method creates one violation in AMI type of waveforms.

• The given Binary Sequence 10110000011 contains 4 consecutive zeros.
• But, up to 1011 binary sequence HDB3 generate the same waveform as Bipolar-AMI because no consecutive 4 zeros were found.
• After finding 4 consecutive 0's checks for the non-zero voltages that are 3 that means ODD number and last voltage level is POSITIVE.
• Therefore, it is categorized under Case 3.
• Hence generate waveform according to Case 3 in the sequence 0 0 0 + voltage format.
• The remaining bits after the 4 consecutive 0's again represented according to the Bipolar-AMI.

Waveform for the Binary Sequence 10110000011 using HDB3I: