--- title: "Line coding 1011000010000000000111" subject: "Communication Systems" chapter: 6 key: "semester_6/communication_systems:line-codes-long-sequence" source: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-long-sequence site: BCT Engineering --- # Line coding 1011000010000000000111 Communication Systems · Chapter 6: Baseband Digital Data Transmission - Asked in: 2076 Asoj (CS II), 6 marks - Video: [Line Coding Techniques | RZ, NRZ, Unipolar, Polar, Bipolar & Manchester | Digital Communication](https://www.youtube.com/watch?v=daf9F9NC7zQ) — Engineering Funda - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-long-sequence - Whole chapter: https://www.bctengineer.com/md/semester_6/communication_systems/chapter-6 ## Question Draw the timing diagram of Polar NRZ, Polar RZ, Manchester and unipolar RZ for the following binary sequence 1011000010000000000111. ## Short answer Polar NRZ: +V for 1, -V for 0, no transitions in long zero run. Polar RZ: +V/-V for first half of bit then 0; self-clocking but double bandwidth. Manchester: +V then -V for 1, -V then +V for 0; always a mid-bit transition. Unipolar RZ: +V half-bit for 1, 0 for 0; loses timing during zeros. ## Answer Conventions (bit period $T_b$, amplitude $V$): | Code | Bit 1 | Bit 0 | |---|---|---| | Polar NRZ | $+V$ for full bit | $-V$ for full bit | | Polar RZ | $+V$ first half, then 0 | $-V$ first half, then 0 | | Manchester | $+V$ then $-V$ (high-to-low at mid-bit) | $-V$ then $+V$ (low-to-high) | | Unipolar RZ | $+V$ first half, then 0 | 0 for full bit | Bit sequence (22 bits): **1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 1** Each character below is half a bit period. ```text bits 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 1 Polar NRZ: +V |‾‾ ‾‾‾‾ ‾‾ ‾‾‾‾‾‾ 0 | -V | __ ________ ____________________ Polar RZ: +V |‾ ‾ ‾ ‾ ‾ ‾ ‾ 0 | - - - - - - - - - - - - - - - - - - - - - - -V | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Manchester: +V |‾ ‾‾ ‾ ‾ ‾ ‾ ‾‾ ‾ ‾ ‾ ‾ ‾ ‾ ‾ ‾ ‾ ‾‾ ‾ ‾ 0 | -V | __ _ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ Unipolar RZ: +V |‾ ‾ ‾ ‾ ‾ ‾ ‾ 0 | --- - --------- --------------------- - - - ``` Observations: - **Polar NRZ** stays at $-V$ for the long run of ten 0s (bits 10–19): no transitions, so the receiver can lose bit timing. - **Polar RZ** returns to zero in every bit, so every bit has an edge, but it needs twice the bandwidth of NRZ. - **Manchester** has a transition at the middle of every bit even in the long zero run, so it is self-clocking and has no DC component; its bandwidth is twice that of NRZ. - **Unipolar RZ** gives no pulse at all during the run of zeros, so timing is lost there, and it has a DC component. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In Polar RZ, a bit 0 is sent as: A. 0 for the full bit B. -V for the first half, then 0 C. +V for the first half, then 0 D. -V for the full bit Answer: B. Polar RZ uses +V (1) or -V (0) for the first half-bit and returns to zero. (Key point: Polar RZ definition) 2. In Manchester coding as used here, bit 0 is: A. +V then -V B. -V then +V C. 0 then +V D. -V for the full bit Answer: B. Bit 1 is high-to-low and bit 0 is low-to-high, so every bit has a mid-bit transition. (Key point: Manchester definition) 3. What problem does Polar NRZ have during the run of ten 0s? A. No transitions, so bit timing can be lost B. Too many transitions C. Amplitude doubles D. It becomes unipolar Answer: A. NRZ stays at -V throughout the run, giving the receiver no edges for clock recovery. (Key point: Long zero run in NRZ) 4. Why is Manchester good for a long zero run, and what is its cost? A. Mid-bit transitions give self-clocking and no DC, but need twice the NRZ bandwidth B. It needs half the bandwidth C. It has DC but is narrowband D. It uses three levels Answer: A. Every bit has a transition and the average is zero, at the cost of double bandwidth. (Key point: Manchester advantages) ## Close variants set in other exams - [Line coding 1011000010000000001 (polar NRZ, AMI, Manchester)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-polar-ami-manchester-long) — Communication Systems, chapter 6, asked 2× ## Related in Communication Systems - [Line coding 1001101101 (unipolar NRZ, polar RZ, AMI, Manchester)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1001101101) — Communication Systems, chapter 6, asked 8× - [Line coding 10110101 (polar NRZ, unipolar RZ, AMI, Manchester)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-10110101) — Communication Systems, chapter 6, asked 8× - [Line coding 1011001010 (polar NRZ, polar RZ, Manchester, AMI)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1011001010) — Communication Systems, chapter 6, asked 8× - [Line coding 1001001101 (polar NRZ, polar RZ, Manchester, AMI)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1001001101) — Communication Systems, chapter 6, asked 8× - [Line coding 1101010111 (polar NRZ, polar RZ, Manchester, AMI)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1101010111-polar-ami) — Communication Systems, chapter 6, asked 8× - [Line coding 1101010011 (polar NRZ, polar RZ, Manchester, AMI)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1101010011) — Communication Systems, chapter 6, asked 8× ## Related in other subjects - [Line coding and NRZ, RZ, AMI](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aline-coding-nrz-rz-ami) — Telecommunications, chapter 3 - [Line coding: polar RZ and bipolar AMI](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-polar-rz-ami) — Data Communication, chapter 5 - [Encode 10101111000011 with NRZ, RZ, AMI, Manchester](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-10101111000011) — Data Communication, chapter 5 - [Polar, unipolar, bipolar, Manchester; encode 101000111011](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-101000111011) — Data Communication, chapter 5