--- title: "Line coding 100111010 (Polar RZ, bipolar NRZ, AMI, Manchester)" subject: "Communication Systems" chapter: 6 key: "semester_6/communication_systems:line-codes-100111010" source: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-100111010 site: BCT Engineering --- # Line coding 100111010 (Polar RZ, bipolar NRZ, AMI, Manchester) Communication Systems · Chapter 6: Baseband Digital Data Transmission - Asked in: 2078 Chaitra, 2+2+2+2 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-100111010 - Whole chapter: https://www.bctengineer.com/md/semester_6/communication_systems/chapter-6 ## Question Represent 100111010 using following encoders. a) Polar RZ b) Bipolar NRZ c) AMI d) Manchester ## Short answer Polar RZ sends +V half bit for 1, -V half bit for 0. Bipolar NRZ and AMI both alternate polarity on each 1, with full-width (NRZ) or half-width (RZ) pulses; 0 is no pulse. Manchester: 1=+V/-V, 0=-V/+V mid-bit transition. ## Answer Bit sequence: **1 0 0 1 1 1 0 1 0**, bit period $T_b$, levels $\pm V$. The first 1 is taken as positive for the bipolar codes. Bipolar NRZ uses full-width pulses whose polarity alternates for each 1. AMI uses the same alternation with half-width (RZ) pulses. #### a) Polar RZ 1 → +V for half the bit, 0 → −V for half the bit, then return to 0. **Polar RZ** ```text 1 0 0 1 1 1 0 1 0 +V ──| |─| |─| |─| |─| 0 |─| |─| |─| |─| |─| |─| |─| |─| |─ -V |─| |─| |─| |─| ``` #### b) Bipolar NRZ 0 → 0 V. Each 1 → full-width pulse with polarity alternating + − + − +. **Bipolar NRZ** ```text 1 0 0 1 1 1 0 1 0 +V ────| |───| |───| 0 |───────| | | |───| |─── -V |───| |───| ``` #### c) AMI 0 → 0 V. Each 1 → half-width pulse with polarity alternating + − + − +. **AMI (RZ)** ```text 1 0 0 1 1 1 0 1 0 +V ──| |─| |─| 0 |─────────| |─| |─| |─────| |───── -V |─| |─| ``` #### d) Manchester Transition at every mid-bit: 1 → +V then −V, 0 → −V then +V. **Manchester** ```text 1 0 0 1 1 1 0 1 0 +V ──| |─| |───| |─| |─| |───| |─ -V |───| |─| |─| |─| |───| |───| ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In polar RZ, what happens for a 0 bit? A. -V for half the bit then return to 0 B. +V then -V C. 0 V for the whole bit D. -V for the full bit Answer: A. Polar RZ sends +V for 1 and -V for 0 for half a bit, then returns to zero. (Key point: Polar RZ) 2. For 100111010, which polarities do the five 1s take in bipolar NRZ? A. - + - + - B. + + + + + C. + - + - + D. + - - + + Answer: C. Successive 1s alternate polarity: + - + - +, with the first 1 taken as positive. (Key point: Bipolar NRZ pulse polarity) 3. How does AMI differ from bipolar NRZ here? A. There is no difference in alternation B. AMI uses half-width (RZ) pulses; bipolar NRZ uses full-width C. AMI sends 0 as -V D. AMI uses non-alternating pulses Answer: B. Both alternate polarity on 1s and send 0 as 0 V; AMI uses half-width pulses while bipolar NRZ uses full-width. (Key point: AMI vs bipolar NRZ) 4. What is a defining feature of Manchester code? A. Three voltage levels B. Zero level for 0 C. Transitions only when the bit changes D. Transition at the middle of every bit Answer: D. Manchester has a mid-bit transition in every bit (1 = +V then -V, 0 = -V then +V), which carries timing. (Key point: Manchester) ## Related in Communication Systems - [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 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 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 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 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: 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 - [Line coding and NRZ, RZ, AMI](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aline-coding-nrz-rz-ami) — Telecommunications, chapter 3 - [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×