--- title: "Line coding 1101010111 (polar NRZ, polar RZ, Manchester, AMI)" subject: "Communication Systems" chapter: 6 key: "semester_6/communication_systems:line-codes-1101010111-polar-ami" source: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-1101010111-polar-ami site: BCT Engineering --- # Line coding 1101010111 (polar NRZ, polar RZ, Manchester, AMI) Communication Systems · Chapter 6: Baseband Digital Data Transmission - Asked in: 2081 Baisakh (CS II), 4 marks - Video: [Line coding in digital communication- Polar, Unipolar, Bipolar, RZ ,NRZ in simple way | HINDI](https://www.youtube.com/watch?v=rHPa0VU27l0) — Electronics Subjectified - 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-1101010111-polar-ami - Whole chapter: https://www.bctengineer.com/md/semester_6/communication_systems/chapter-6 ## Question Given the binary sequence 1101010111 represent in polar NRZ, polar RZ, Manchester and AMI codes. ## Short answer For 1101010111: Polar NRZ: 1→+V, 0→-V full bit. Polar RZ: 1→+V half-bit then 0, 0→-V half-bit then 0. Manchester: 1→+V then -V, 0→-V then +V. AMI: 0→0 V, 1s alternate +V,-V starting +V. Each code format described. ## Answer Line codes convert the bit stream into electrical pulses. Conventions used (bit period $T_b$, amplitude $V$): - **Polar NRZ:** 1 → $+V$, 0 → $-V$ for the full bit. - **Polar RZ:** 1 → $+V$, 0 → $-V$ for the first half bit, then 0. - **Manchester:** 1 → $+V$ then $-V$ (high-to-low at mid-bit); 0 → $-V$ then $+V$. - **AMI:** 0 → 0 V; successive 1s alternate $+V$, $-V$ (first 1 taken as $+V$, full-width pulses). Bit sequence: **1 1 0 1 0 1 0 1 1 1** ```text bits 1 1 0 1 0 1 0 1 1 1 Polar NRZ: +V |‾‾‾‾‾‾‾‾ ‾‾‾‾ ‾‾‾‾ ‾‾‾‾‾‾‾‾‾‾‾‾ 0 | -V | ____ ____ ____ Polar RZ: +V |‾‾ ‾‾ ‾‾ ‾‾ ‾‾ ‾‾ ‾‾ 0 | -- -- -- -- -- -- -- -- -- -- -V | __ __ __ Manchester: +V |‾‾ ‾‾ ‾‾‾‾ ‾‾‾‾ ‾‾‾‾ ‾‾ ‾‾ 0 | -V | __ ____ ____ ____ __ __ __ AMI (bipolar NRZ): +V |‾‾‾‾ ‾‾‾‾ ‾‾‾‾ ‾‾‾‾ 0 | ---- ---- ---- -V | ____ ____ ____ ``` Level in each bit (a pair means first half, second half): | Code | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | |---|---|---|---|---|---|---|---|---|---|---| | Polar NRZ | +V | +V | −V | +V | −V | +V | −V | +V | +V | +V | | Polar RZ | +V,0 | +V,0 | −V,0 | +V,0 | −V,0 | +V,0 | −V,0 | +V,0 | +V,0 | +V,0 | | Manchester | +V,−V | +V,−V | −V,+V | +V,−V | −V,+V | +V,−V | −V,+V | +V,−V | +V,−V | +V,−V | | AMI (bipolar NRZ) | +V | −V | 0 | +V | 0 | −V | 0 | +V | −V | +V | Observations: polar NRZ has a DC component when 1s are more frequent (here seven 1s); Manchester has a transition in every bit, so it carries timing; AMI has zero average value because its marks alternate. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In polar NRZ, a 0 is sent as: A. +V B. -V for the full bit C. -V for half the bit D. 0 V Answer: B. Polar NRZ uses +V for 1 and -V for 0 for the full bit. (Key point: Polar NRZ) 2. For 1101010111 (seven 1s), the AMI polarities are: A. + - - + - + - B. + + + + + + + C. + + - + - + - D. + - + - + - + Answer: D. Alternating polarity on the 1s gives + - + - + - +. (Key point: AMI sequence) 3. Why does polar NRZ here have a DC component? A. It uses zero level B. Mid-bit transitions C. Alternating marks D. Seven 1s outnumber the 0s Answer: D. With more +V than -V the average is non-zero; AMI averages zero because marks alternate. (Key point: Polar NRZ DC) 4. Why does Manchester carry timing? A. It uses three levels B. It uses half-width pulses only C. It has no transitions D. A transition occurs in every bit Answer: D. Mid-bit transitions in every bit let the receiver recover the clock. (Key point: Manchester timing) ## Close variants set in other exams - [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 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× - [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 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 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× ## Related in Communication Systems - [Line coding 100111010 (Polar RZ, bipolar NRZ, AMI, Manchester)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-100111010) — Communication Systems, chapter 6 - [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× - [Definitions of unipolar, polar, bipolar, RZ, Manchester codes](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Adefine-line-codes) — Communication Systems, chapter 6, asked 2× - [Line coding 1101010111; communication impairments](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-1101010111-impairments) — Communication Systems, chapter 6 - [Line coding 110011000001 (unipolar RZ, Manchester, HDB3)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aline-codes-110011000001) — Communication Systems, chapter 6 ## 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 - [Encode 1101001 with polar NRZ, AMI, Manchester](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-1101001) — Data Communication, chapter 5, asked 3×