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© 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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