---
title: "Source coding vs channel coding"
subject: "Data Communication"
chapter: 8
key: "semester_5/data_communication:source-vs-channel-coding"
source: https://www.bctengineer.com/q/semester_5/data_communication/source-vs-channel-coding
site: BCT Engineering
---

# Source coding vs channel coding

Data Communication · Chapter 8: Information Theory and Coding

- Asked in: 2078 Kartik, 2 marks
- Video: [Difference between SOURCE CODING, CHANNEL CODING AND LINE CODING - HINDI](https://www.youtube.com/watch?v=tWIgj2lbik4) — Electronics Subjectified
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/source-vs-channel-coding
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-8

## Question

How is source coding different from channel coding?

## Short answer

Source coding removes redundancy for compression, reducing bandwidth. Channel coding adds controlled redundancy (parity bits) to detect/correct errors, improving reliability at the cost of extra bits.

## Answer

**Source coding** removes redundancy from the source data to represent it with the fewest bits (data compression), e.g. Huffman, Shannon-Fano, run-length coding. It improves efficiency and reduces bandwidth or storage.

**Channel coding** deliberately adds controlled redundancy (parity bits) to the data so that the receiver can detect and correct errors caused by noise, e.g. Hamming, CRC, convolutional codes. It improves reliability but increases the number of bits sent.

Source coding comes first at the transmitter, and channel coding is applied afterwards; the receiver reverses them in the opposite order.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does source coding do?
   A. Adds parity bits for error correction
   B. Removes redundancy to represent data with fewest bits
   C. Encrypts the data
   D. Increases bandwidth
   Answer: B. Source coding compresses data, for example Huffman or run-length coding. (Key point: Source coding purpose)

2. What does channel coding do?
   A. Removes redundancy to save storage
   B. Reduces the number of bits sent
   C. Deliberately adds controlled redundancy so errors can be detected or corrected
   D. Converts analog to digital
   Answer: C. It adds parity bits, which improves reliability at the cost of more transmitted bits. (Key point: Channel coding purpose)

3. In the transmitter, which comes first?
   A. Channel coding, then source coding
   B. Source coding, then channel coding
   C. Both happen at once
   D. Neither; the receiver does it
   Answer: B. Source coding is applied first, then channel coding; the receiver reverses them. (Key point: Order of operations)

## Related in Data Communication

- [Source coding; fixed vs variable length codes](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Asource-coding-fixed-variable) — Data Communication, chapter 8
- [Need for channel coding](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Achannel-coding-need) — Data Communication, chapter 8
- [Dataword vs codeword; error coding techniques](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Adataword-codeword-error-coding) — Data Communication, chapter 8

## Related in other subjects

- [Source vs channel coding; Huffman for five symbols](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Asource-channel-huffman-five) — Communication Systems, chapter 6
- [Importance of source coding; Shannon-Fano vs fixed length (seven symbols)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Asource-coding-sf-fixed-seven) — Communication Systems, chapter 6
- [Importance of source coding; fixed vs Shannon-Fano (five symbols)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Asource-coding-fixed-sf-five) — Communication Systems, chapter 6
- [Importance of source coding; Shannon-Fano vs BCD (four symbols)](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Asource-coding-sf-bcd-four) — Communication Systems, chapter 6