---
title: "Data representation; analog vs digital system"
subject: "Data Communication"
chapter: 1
key: "semester_5/data_communication:data-representation-analog-digital"
source: https://www.bctengineer.com/q/semester_5/data_communication/data-representation-analog-digital
site: BCT Engineering
---

# Data representation; analog vs digital system

Data Communication · Chapter 1: Introduction

- Asked in: 2070 Asar, 2 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/data-representation-analog-digital
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-1

## Question

Define data representation. How can data be represented?

## Short answer

Data representation is how information is expressed for processing and transmission. Data can be text (ASCII, Unicode), numbers (binary), images (pixel encoding), audio (PCM sampling), or video (compressed frames); it may be analog (continuous) or digital (discrete).

## Answer

**Data representation** is the way information (text, numbers, images, audio, video) is expressed in a form that a computer or communication system can store, process and transmit.

#### How data can be represented
- **Text**: using codes such as ASCII (7/8 bit), EBCDIC or Unicode, each character mapped to a bit pattern. Example: 'A' = 01000001.
- **Numbers**: converted directly to binary (including 2's complement, floating point).
- **Images**: divided into pixels, each pixel coded in bits (1 bit for black/white, 8 bits for grey, 24 bits for RGB colour).
- **Audio**: continuous sound sampled, quantized and coded (PCM).
- **Video**: a sequence of images (frames) combined with audio, usually compressed.

Data may be **analog** (continuous values, e.g. voice) or **digital** (discrete values, e.g. text). Both can be sent as analog or digital signals.

## Check yourself

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

1. Text is represented by
   A. pixels
   B. sampling
   C. frames
   D. codes like ASCII or Unicode mapping characters to bit patterns
   Answer: D. 'A' = 01000001. (Key point: Text)

2. An RGB colour pixel uses
   A. 24 bits
   B. 1 bit
   C. 8 bits
   D. 7 bits
   Answer: A. 1 bit B/W, 8 bits grey. (Key point: Images)

3. Audio is represented by
   A. pixels
   B. sampling, quantizing and coding (PCM)
   C. ASCII
   D. frame sequences
   Answer: B. Continuous sound is digitised. (Key point: Audio)

## Related in Data Communication

- [Short note: Analog vs digital mux hierarchy](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aanalog-vs-digital-mux-hierarchy) — Data Communication, chapter 6
- [Digital vs analog spread spectrum](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aspread-spectrum-digital-vs-analog) — Data Communication, chapter 6
- [Advantages of digital over analog systems](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Adigital-vs-analog-advantages) — Data Communication, chapter 1, asked 5×
- [Compare analog and digital communication](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Adigital-vs-analog-comparison) — Data Communication, chapter 1, asked 4×
- [PCM and analog-to-digital conversion](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Apcm-working) — Data Communication, chapter 5, asked 4×
- [Define analog and digital signals](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aanalog-digital-signal-define) — Data Communication, chapter 1

## Related in other subjects

- [Digital transmission system; analog vs digital](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aanalog-digital-transmission-compare) — Instrumentation II, chapter 5
- [Analog vs digital multiplexing; 24-channel system](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aanalog-digital-mux-24-channel) — Telecommunications, chapter 3
- [Duplex digital communication system vs analog](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Adigital-comm-duplex-vs-analog) — Communication Systems, chapter 1
- [Analog and digital system block diagrams; linear and non-linear distortion](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aanalog-digital-block-linear-nonlinear-distortion) — Communication Systems, chapter 1