--- title: "Line coding 1001001101 (polar NRZ, polar RZ, Manchester, AMI)" subject: "Communication Systems" chapter: 6 key: "semester_6/communication_systems:line-codes-1001001101" source: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-1001001101 site: BCT Engineering --- # Line coding 1001001101 (polar NRZ, polar RZ, Manchester, AMI) Communication Systems · Chapter 6: Baseband Digital Data Transmission - Asked in: 2072 Chaitra (CS II), 4 marks; 2071 Chaitra (CS II), 4 marks (asked 2 times) - 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-1001001101 - Whole chapter: https://www.bctengineer.com/md/semester_6/communication_systems/chapter-6 ## Question Represent binary sequence 1001001101 in polar NRZ, polar RZ, Manchester and AMI codes. ## Short answer Polar NRZ: 1=+V, 0=-V flat. Polar RZ: half-width +V for 1, -V for 0, return to zero. Manchester: 1=+V half then -V half, 0=-V then +V. AMI: 1s alternate between +V and -V half-width pulses, 0 no pulse. Sequence 1001001101 drawn accordingly. ## Answer Bit sequence: **1 0 0 1 0 0 1 1 0 1**, bit period $T_b$, levels $\pm V$. Conventions used: Manchester sends 1 as a +V half followed by a −V half, and 0 as −V then +V (Lathi/Haykin; the IEEE 802.3 convention is the opposite). AMI sends alternate 1s as half-width +V and −V pulses, starting with +V, and 0 as no pulse. **Polar NRZ (1 → +V, 0 → −V)** ```text 1 0 0 1 0 0 1 1 0 1 +V ────| |───| |───────| |─── -V |───────| |───────| |───| ``` **Polar RZ (half-width pulses)** ```text 1 0 0 1 0 0 1 1 0 1 +V ──| |─| |─| |─| |─| 0 |─| |─| |─| |─| |─| |─| |─| |─| |─| |─ -V |─| |─| |─| |─| |─| ``` **Manchester** ```text 1 0 0 1 0 0 1 1 0 1 +V ──| |─| |───| |─| |───| |─| |───| -V |───| |─| |───| |─| |─| |───| |─ ``` **AMI (bipolar RZ)** ```text 1 0 0 1 0 0 1 1 0 1 +V ──| |─| |─| 0 |─────────| |─────────| |─| |─────| |─ -V |─| |─| ``` AMI: the five 1s get polarities + − + − +. Polar RZ and Manchester give a transition in every bit, which helps clock recovery. AMI has no DC component. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. For the sequence 1001001101, which are the AMI polarities of its five 1s starting with +? A. + + - - + B. + - + - + C. - + - + - D. + 0 - 0 + Answer: B. The five 1s alternate in polarity: + - + - +. (Key point: AMI polarities) 2. Which of these codes give a transition in every bit helping clock recovery? A. Polar NRZ and AMI B. Polar RZ and Manchester C. Only AMI D. Unipolar NRZ Answer: B. Polar RZ returns to zero in every bit and Manchester has a mid-bit transition in every bit; AMI loses timing on runs of 0s. (Key point: Transitions for timing) 3. Which code in the question is described as having no DC component due to alternating pulses? A. AMI B. Polar NRZ with all 1s C. Unipolar NRZ D. Unipolar RZ Answer: A. Alternating the polarity of 1s cancels the DC component in AMI. (Key point: DC component) 4. In polar RZ, what is sent for a 0 bit? A. Nothing for the whole bit B. -V for half a bit then 0 C. +V for half a bit then 0 D. -V for the whole bit Answer: B. Polar RZ sends 0 as a half-width -V pulse, then returns to zero. (Key point: Polar RZ for a 0 bit) ## 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 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× - [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× ## 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 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×