--- title: "Line coding 1101010111; communication impairments" subject: "Communication Systems" chapter: 6 key: "semester_6/communication_systems:line-codes-1101010111-impairments" source: https://www.bctengineer.com/q/semester_6/communication_systems/line-codes-1101010111-impairments site: BCT Engineering --- # Line coding 1101010111; communication impairments Communication Systems · Chapter 6: Baseband Digital Data Transmission - Asked in: 2079 Chaitra, 6+2 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-impairments - Whole chapter: https://www.bctengineer.com/md/semester_6/communication_systems/chapter-6 ## Question Given the binary sequence 1101010111 represent in Unipolar RZ, Bipolar NRZ, Polar NRZ and Manchester encoders. Explain communication impairments with examples. ## Short answer Unipolar RZ: +V half-bit for 1. Bipolar NRZ: 1 alternates +/-V full width, 0=0. Polar NRZ: 1=+V, 0=-V full width. Manchester: 1=+V/-V, 0=-V/+V. Impairments: attenuation (signal loss), distortion (pulse spreading causing ISI), and noise (thermal, crosstalk, impulse). ## Answer #### Line codes for 1101010111 Bit period $T_b$, levels $\pm V$. Bipolar NRZ is drawn as full-width pulses whose polarity alternates for each 1. Manchester uses 1 = +V then −V, and 0 = −V then +V. **Unipolar RZ** ```text 1 1 0 1 0 1 0 1 1 1 +V ──| |─| |─| |─| |─| |─| |─| 0 |─| |─────| |─────| |─────| |─| |─| |─ ``` **Bipolar NRZ (1s alternate +V/−V, 0 = 0)** ```text 1 1 0 1 0 1 0 1 1 1 +V ────| |───| |───| |─── 0 | |───| |───| |───| | | -V |───| |───| |───| ``` **Polar NRZ** ```text 1 1 0 1 0 1 0 1 1 1 +V ────────| |───| |───| |─────────── -V |───| |───| |───| ``` **Manchester** ```text 1 1 0 1 0 1 0 1 1 1 +V ──| |─| |───| |───| |───| |─| |─| -V |─| |───| |───| |───| |─| |─| |─ ``` #### Communication impairments Impairments are the effects of the channel that make the received signal differ from the transmitted one. - **Attenuation:** the signal loses energy with distance. Example: a voice signal on a long copper line becomes weak, so repeaters or amplifiers are needed. - **Distortion:** different frequency components are attenuated or delayed by different amounts, so the pulse shape changes. Example: pulses spread on a band-limited telephone line and cause ISI. - **Noise:** unwanted random signals add to the signal. Examples are thermal noise in receivers, crosstalk between adjacent pairs in a cable, and impulse noise from lightning or switching. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. In bipolar NRZ, how are the 1s and 0s represented? A. 1 is a mid-bit transition B. 1 is always +V, 0 is zero level C. 1s alternate +V/-V, 0 is zero level D. 1 is +V and 0 is -V Answer: C. Bipolar NRZ gives each successive 1 the opposite polarity with full-width pulses, and sends 0 as 0 V. (Key point: Bipolar NRZ rule) 2. What is attenuation? A. Loss of signal energy with distance B. Interference between adjacent pairs only C. Spreading of pulses over time D. Unwanted random signal added Answer: A. Attenuation is the signal losing strength as it travels, which is why repeaters or amplifiers are used. (Key point: Attenuation) 3. Which impairment is caused by different frequency components being attenuated or delayed by different amounts? A. Crosstalk B. Attenuation C. Distortion D. Thermal noise Answer: C. Distortion changes the pulse shape because frequencies are treated unequally, e.g. pulse spreading causing ISI. (Key point: Distortion) 4. Which of these is an example of crosstalk-type noise? A. Interference between adjacent pairs in a cable B. Signal weakening on long copper C. Pulse spreading on a band-limited line D. Lightning only Answer: A. Crosstalk is noise coupled from neighbouring pairs in a cable; thermal and impulse noise are other examples. (Key point: Noise types) ## Related in Communication Systems - [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 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 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 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× ## 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 - [Polar, unipolar, bipolar, Manchester; encode 101000111011](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-101000111011) — 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 1001101110 with unipolar, polar, bipolar codes](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-1001101110) — Data Communication, chapter 5, asked 3×