Siksha Sarovar

Siksha Sarovar (sikshasarovar.com) is a free educational web application that helps students in India learn programming and prepare for academic and competitive exams. The platform offers structured coding courses (C, C++, Python, Java, HTML, CSS, PHP, Power BI, AI, Machine Learning, Data Science), complete university curriculum notes for BCA/MCA students with previous year question papers, Class 10 and Class 12 CBSE/HBSE school notes, and dedicated preparation material for SSC, UPSC, Banking, Railway and other government exams. Browsing the site is completely free and requires no account. Users may optionally sign in with Google solely to save their learning progress, quiz scores and personal preferences across devices.

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Unit 4: Communication System & Data Transmission

Lesson 30 of 34 in the free Fundamentals of IT & Computers notes on Siksha Sarovar, written by Rohit Jangra.

Unit IV — Communication System & Data Transmission

A data communication system transfers data from one device to another. Understanding the components, modes, speeds, and media of data transmission is fundamental to networking.

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Basic Elements of a Communication System

Every communication system has five essential components:

ComponentDescription
MessageThe information (data, voice, video) to be communicated
SenderThe device that transmits the message (computer, phone)
ReceiverThe device that receives the message
Transmission MediumThe physical path through which the message travels (wire, air)
ProtocolSet of rules governing data transmission (TCP/IP, HTTP)

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Data Transmission Modes

Transmission mode describes the direction of data flow between two devices.

ModeDirectionExample
SimplexOne direction onlyKeyboard→CPU, TV broadcast, Radio
Half-DuplexBoth directions, but not simultaneouslyWalkie-talkie, CB radio
Full-DuplexBoth directions simultaneouslyTelephone, Video call, Internet

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Data Transmission Speed

UnitDescription
bpsbits per second — base unit
KbpsKilobits per second = 1,000 bps
MbpsMegabits per second = 1,000 Kbps
GbpsGigabits per second = 1,000 Mbps
BandwidthMaximum data transmission capacity of a channel
ThroughputActual data transfer rate achieved in practice
LatencyDelay between sending and receiving data

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Analog vs Digital Transmission

FeatureAnalogDigital
Signal typeContinuous wave (sine wave)Discrete binary pulses (0/1)
Noise sensitivityHigh (noise degrades signal)Low (can regenerate cleanly)
AttenuationAmplified (noise amplified too)Regenerated (noise-free)
Bandwidth efficiencyLowerHigher
ExamplesAM/FM radio, telephone linesEthernet, fiber optics, Wi-Fi

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Transmission Media

Guided (Wired) Media:

MediumSpeedDescription
Twisted Pair (UTP/STP)Up to 1 GbpsPairs of copper wires twisted together; most common (Ethernet)
Coaxial CableUp to 10 GbpsCentral conductor with shielding; used in cable TV
Fiber Optic CableUp to TbpsUses light through glass fibers; immune to EMI; long distances

Unguided (Wireless) Media:

MediumDescription
Radio WavesLong-range; used in AM/FM radio, Wi-Fi (2.4/5 GHz)
MicrowavesLine-of-sight; satellite and terrestrial links
InfraredShort-range, line-of-sight; TV remotes, IrDA
SatelliteVery long-range; GPS, satellite TV, global internet

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Serial vs Parallel Transmission

TypeDescriptionUse
SerialBits sent one by one over a single channelLong-distance (USB, Ethernet)
ParallelMultiple bits sent simultaneouslyShort-distance (older printer ports)
Key Takeaway: A communication system consists of sender, message, medium, receiver, and protocol. The three transmission modes (simplex, half-duplex, full-duplex) and the distinction between analog and digital transmission are standard exam questions. Fiber optic cables offer the highest bandwidth and lowest signal loss.