© N. Ganesan, Ph.D. , All rights reserved.

Top School in Faridabad

By:School.edhole.com

© N. Ganesan, Ph.D. , All rights reserved.

Chapter

Asynchronous and Synchronous Transmission

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Chapter Objectives

• Explain the features of asynchronous and synchronous transmission and possible areas of application for each transmission type

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Chapter Modules

• Asynchronous Transmission• Synchronous Transmission

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© N. Ganesan, Ph.D. , All rights reserved.

Module

Asynchronous Transmission

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Questions

• What is the characterizing feature of asynchronous transmission?

• Give some examples of asynchronous transmission

• Can asynchronous transmission be conducted at high and low speeds? Give examples in each case School.edhole.co

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Asynchronous Transmission

• Burst mode transmission• Sender and receiver are not

synchronized with respect to the flow of the information

• However, the sender and receiver are synchronized with respect to the timing of the characters that are transmittedSchool.edhole.co

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A Note on Asynchronous Transmission

• In the past, asynchronous transmission referred only to character by character transmission where each character contained information about timing etc.– Note the use of start and stop bits

• At present, the concept of asynchronous transmission can be extended to cover packet transmissions as well

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The Use of the Word Asynchronous

• Asynchronous Transmission– Generally refers to the transmission

of characters with each character carrying information about timing

• Asynchronous Communication – Refers to overall communication

between two points • An example in this case would be ATM School.edhole.co

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Asynchronous Transmission Applied to Characters

Stop Bit Start Bit

Each character is individually timed.

Character FrameSchool.edhole.com

Asynchronous Transmission Applied to

Packets

Packets of data Packets of data

Burst of Data

A B

Intermittent transmission of packets of dataSchool.edhole.com

Analogy

Host expecting thearrival of guests

Intermittent of burst arrivalof guests

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Asynchronous Transmission/Communication

Application

• Character by character transmission

• Data packet transmission at present

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Speed Variations In Asynchronous Transmission

• Low and high-speed transmissions are possible

• Low speed– Almost all modem based communications

fall into this category

• High speed– Asynchronous Transfer Mode (ATM)

• Internet is a good example where asynchronous communication is used predominantly to carry the informationSchool.edhole.co

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Questions

• What is the characterizing feature of asynchronous transmission?

• Give some examples of asynchronous transmission

• Can asynchronous transmission be conducted at high and low speeds? Give examples in each case School.edhole.co

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End of Module End of Module

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© N. Ganesan, Ph.D. , All rights reserved.

Module

Synchronous Transmission

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Questions

• How does synchronous transmission differ from asynchronous transmission?

• Where is synchronous transmission used in practice?

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Synchronous Transmission• Sender and receiver are synchronized

with respect to the sending and receiving of information

• Each character need not have a start-bit and a stop-bit as the sender and the receiver are both synchronized

• Requires more hardware and software resources

• High speed communication is the norm

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A Note on Synchronous Transmission

• The definition of synchronous transmission refers to the transmission of characters

• However, the use of the word synchronous can be extended to cover packet transmission as well

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Usage in Practice

• Which one of the two transmissions is used widely in the real world? Explain.

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Examples of Synchronous Transmission

• High-speed communication links established using synchronous modems– It is now possible to establish high speed

links based on asynchronous transmission

• Used in a number of mainframe installations– Collective exchange of information between

the mainframe and the peripheral devices is based on synchronous transmission School.edhole.co

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In Summary

• Synchronous transmission plays a smaller role compared to asynchronous transmission in practice

• Implementation of synchronous transmission requires more resources

• Asynchronous technology has advanced– It is no more necessary to rely on

synchronous communication to establish a high speed communication link

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End of Module End of Module

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End of ChapterEnd of Chapter

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