Data Communication Networks Lecture Slides based largely on the book Electronic Communication Systems by Wayne Tomasi and covering topics on Data Communication Codes, Error coding, Bit and Character Synchronization, Data Communication Hardware, UART, and USRT.

1. Module 4
Fundamental Concepts of
Data Communications
Chapter 22
Electronic Communications Sytems , Fifth Editon
By: Wayne Tomasi
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Prepared by: Engr. Jeffrey Des B. Binwag

2. Data Communication Codes
• Baudot Code
• ASCII (American Standard Code for
Information Interchange)
• EBCDIC (Extended Binary Coded Decimal
Interchange Code)
• Bar Codes
– Code 39
– UPC (Universal Product Code)
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3. Data Communication Codes
• Categories:
–Alphanumeric Characters
–Graphic Control Characters
–Data Link Control Characters
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4. Error Coding
• Error Detection. Involves monitoring data transmission
and determining when errors have occurred.
– Redundancy Checking: VRC and/or LRC, CRC,
Checksum
– Hamming Code
• Error Correction. Involves the correction of messages
that have been determined by error detection codes to
contain errors at the receiver.
– Retransmission
– Forward Error Correction: VRC/LRC, Hamming Code
– Symbol Substitution
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5. Character Synchronization
• Character Synchronization. Involves identifying the
beginning and end of a character within a message or an
extended bit sequence.
– Asynchronous Serial Data. Also known as start-stop
transmission because each data character is framed between
start and stop bits so that time gaps in between characters do
not present a problem.
– Synchronous Serial Data. Generally involves transporting
serial data at relatively high speeds in group of characters
called blocks or frames with no lapses in between characters.
A unique synchronization character is transmitted at the
beginning of each message block as opposed to providing start
and stop bits per character.
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6. Bit Synchronization
• Bit Synchronization. A process that ensures the
transmission and reception of the same number of
bits without errors and in the correct order without
considering the relation of each bit to adjacent bits
as part of a character or message. Such procedures
include correct sampling as well as proper start-bit
verification.
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7. Data Communications Hardware
All endpoints in a data communication network have
three fundamental components namely:
• Data Terminal Equipment (DTE). Any binary digital
device that generates, transmits, receives, and/or
interprets data messages. (i.e.: LCU, STACO, ACIA, UART,
USRT)
• Data Communication Equipment (DCE). These are
equipment that interfaces data terminal equipment to
the transmission channel. (i.e.: MODEM)
• Serial Interface. A communication line that ensures the
orderly flow of data between a DTE and DCE. (i.e.: USB,
RS 232)
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8. Two-point Datacom Circuit
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9. DataCommunications
Hardware
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10. Universal Asynchronous Rx/Tx
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11. UART FUNCTIONS
• Parallel-to-serial at the Tx and Serial-
to-parallel conversion at the Rx
• Error detection
• Framing
• Formatting
• Status monitoring
• Voltage level conversion/matching
• Bit and character synchronization
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12. UART Control Word
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13. UART Transmitter
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14. UART Receiver
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15. UART Receiver Start-bit Verification
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16. USRT Sampling Error
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17. USRT FUNCTIONS
• Parallel-to-serial at the Tx and Serial-
to-parallel conversion at the Rx
• Error detection
• Synchronization
• Formatting
• Status monitoring
• Voltage level conversion/matching
• Bit and character synchronization
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18. QUIZ 2 COVERAGE
All Discussions in the book by Tomasi covering the following topics:
• Datacom Circuits
• Serial and Parallel Data Transmission
• Datacom Circuit Arrangements
• Datacom Networks
– Components, Functions, and Features
– Models
– Topologies
– Classifications
• Datacom Codes
• Error Coding
• Character and Bit Synchronization
• Datacom Hardware
• Datacom Circuits
• UART and USRT
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