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Chapter 4
Transmission of Digital Data / Media & Service
Satellite dish
Satellite
Radio Tower
BY Dr.Sukchatri Prasomsuk
Contents :
• 4.1 Digital Data Transmission• 4.2 DTE-DCE Interface• 4.3 Modems • 4.4 Type of Transmission Media
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4.1 Digital Data Transmission
• Communication Mode :
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4.1 Digital Data Transmission
• Data Transmission
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Data Transmission
Parallel Serial
Synchronous Asynchronous
4.1 Digital Data Transmission
• Parallel vs Serial line
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4.1 Digital Data Transmission
• Parallel Transmission : Transmission in which bits in a group are sent simultaneously, each using a separate link.
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Sender ;Computer
LPT1,LPT2,LPT3,etc.
Receiver ;Printer,Plotter, Circuit,
etc,
8 bits
4.1 Digital Data Transmission
• Serial Transmission : Transmission of data one bit at a time using only one single link.
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Sender(RS232)
0 1
0 1
0 1
0 1
Receiver(RS232)
0 1
0 1
0 1
0 1
Parallel/Serial Converter
0 1 0 1 0 1 0 1
8 bits are sent
4.1 Digital Data Transmission
• Asynchronous Transmission : Transfer of data with start and stop bit(s) and a variable time interval between data units.
• We send one start bit (0) at the beginning and one or more stop bits (1s) at the end of each byte. There may be a gap between each byte.
• Asynchronous here means “asynchronous at the byte level” but the bits are still synchronized; their durations are the same.
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4.1 Digital Data Transmission
• Asynchronous Transmission : Clock independent
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Sender Receiver11010011101100011110 110011
Start bitStop bit
Gaps
Data
Direction of flow
4.1 Digital Data Transmission
• Asynchronous Transmission :
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4.1 Digital Data Transmission
• Synchronous Transmission : A transmission method that requires a constant timing relationship between the sender and the receiver.
• We send bits one after another without start/stop bits or gaps. It is the responsibility of the receiver to group the bits.
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4.1 Digital Data Transmission
• Synchronous Transmission : Clock dependent
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Sender Receiver10100111 10001111 11001101
Data
Direction of flow
4.1 Digital Data Transmission
• Bit Oriented synchronization :
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4.1 Digital Data Transmission
• Character Oriented synchronization : BiSync
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4.2 DTE-DCE Interface
• Data Terminal Equipment (DTE) : A device that is an information source or an information sink. It is connected to a network through a DCE.
• Data Circuit-Terminal Equipment (DCE) : A device used as an interface between a DTE and a network.
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4.2 DTE-DCE Interface
• Data Terminal Equipment (DTE) : is any device that is a source of or destination for binary digital data.
• Data Circuit-Terminal Equipment (DCE) : is any device that transmits or receives data in the from of an analog or digital signal through a network.
• Interface : the electrical specification of EIA-232 defines that signals other than data must be sent using OFF -> lessthan -3 Volts and ON -> greater than +3 Volts
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4.2 DTE-DCE Interface
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DTE DCE DTEDCEI nternet / Netw ork
Interface; ~ 15 m.EIA-232,EIA-442,EIA-449
InterfaceEIA-232,EIA-442,EIA-449
Data Terminal EquipmentEnd of the user’s deviceon the WAN link
Data Communications Equipment• End of the WAN provider’s
side of the communication facility• DCE is responsible for clocking
DCEDTE
ModemCSU/DSU
DTE DTEDCE DCE
4.2 DTE-DCE Interface Serial Implementation of DTE vs DCE
4.2 DTE-DCE Interface Serial Implementation of DTE vs DCE
Internet
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CSU/DSU
End user
device
Service Provider
DTE
DCE
4.2 DTE-DCE Interface Serial Point-to-Point Connections
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4.2 DTE-DCE Interface Fixed Interfaces4.2 DTE-DCE Interface Fixed Interfaces
Router—rear view
Serial WAN ports can be fixed
4.2 DTE-DCE Interface Modular Interfaces
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Console
Router—rear view
Ethernet AUIEthernet 10BaseT ISDN BRI S/T
Serial WAN ports can be modular
Module
WAN Interface
Card
4.3 Modems
• Modem stands for MOdulator/DEModulator. • Modem is a communication device that converts
binary signal into analog acoustics signal for transmission over telephone lines and converts these acoustics signals back into binary form at the receiving end.
• A Modulator converts a digital signal into an analog signal using ASK, FSK, PSK or QAM.
(Digital-to-Analog)• A Demodulator converts an analog signal into a
digital signal. (Analog-to-Digital)
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4.3 Modems
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4.3 Modems
• Modem Type :• 1. Asynchronous : for Low speed
communication• 2. Synchronous : for High speed
communication• 3. Half-Duplex : must alternately send
and received signals. • 4. Full-Duplex : can simultaneously
handle two signals using two carriers to transmit and receive data.
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4.3 Modems
• Signal Constellation
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4.3 Modems
• Constellation Samples :
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4.3 Modems
• Some Standard :• V29 : -Transmission rate up to 9600 bps• V.32bis : -2-dimensional TCM with 128
points -Transmission rate up to 14,400
bps• V.32ter : -2-dimensional TCM with 512
points -Transmission rate up to 19,200
bps• V.34 : -2-dimensional TCM with 768
points -Transmission rate up to 28,800
bps
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4.3 Modems
• Error Correcting :• LAPD (Link Access Protocol D) : based on
HDLC synchronous protocol.• MNP (Microcom Networking Protocol) : trademark
of Microcom• TCM : modulation with error detecting code• V.42 : CRC error correcting standard
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4.3 Modems
• Fallback :
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4.3 Modems
• Intelligent Modems : contain software to support a number of additional functions, such automatic answering and dialing.
• The AT command format is : AT command [parameter] command
[parameter] command [parameter] ...
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4.3 Modems
• Hayes Commands set :
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4.3 Modems
• Hayes Response Code :
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4.4 Type of Transmission Media
• Transmission media can be divided into two broad categories:
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Transmission Media
Guided UnGuided
Twisted-paircable
Coaxialcable
F/Ocable
Microwave Satellite Cellular
- Radio wave (Wireless)
4.4 Type of Transmission Media
• Twisted-pair cable: UTP (100 Hz - 5 MHz)
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4.4 Type of Transmission Media
• Twisted-pair cable : STP (100 Hz - 5 MHz)
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4.4 Type of Transmission Media
• UTP Category (CAT):• Category 1 : for telephone systems, low speed.• Category 2 : for voice and data transmission of
up to 4 Mbps.• Category 3 : transmission of up to 10 Mbps.
(Standard cable for telephone system)• Category 4 : transmission of up to 16 Mbps.
Category 5 : transmission of up to 100 Mbps. • Category 6 : transmission of up to 250 Mbps.
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Differentiating between Connections
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AUI connectors are DB15
ISO 8877 (RJ-45) connectors and jacks are slightly larger than RJ-11 phone connectors and
jacks
Fiber Connector Port
UTP Device
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The RJ-45 Connector
1
8
8 Pair 4 R4
1234567
Wire PairT is TipR is RingPair 2 T2Pair 2 R2Pair 3 T3Pair 1 R1Pair 1 T1Pair 3 R3Pair 4 T4
Pin
UTP Implementation Straight-through
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Wires on cable ends are in same order
Pin Label1 RD+2 RD-3 TD+4 NC5 NC6 TD-7 NC8 NC
Cable 10BaseT/100BaseT Straight-through
Pin Label1 TD+2 TD-3 RD+4 NC5 NC6 RD-7 NC8 NC
Server/Router
8 1
1
8
Straight-through Cable
81Hub/Switch
8 1
o
UTP Implementation Crossover
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Some wires on cable ends are crossed
8 1
og
Cable 10BaseT/100BaseT Crossover
Pin Label1 RD+2 RD-3 TD+4 NC5 NC6 TD-7 NC8 NC
Pin Label1 RD+2 RD-3 TD+4 NC5 NC6 TD-7 NC8 NC
Crossover Cable
18 1
8
8 1
br
Hub/Switch Hub/Switch
4.4 Type of Transmission Media
• Coaxial Cable : (100 KHz - 500 MHz)• RG-8, RG-9, RG-11 used in thick Ethernet, Radio• RG-58 used in thick Ethernet, Radio Transmitter• RG-59 used for TV
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4.4 Type of Transmission Media
• Fiber Optic Cable : Typical
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4.4 Type of Transmission Media
• Fiber Optic Cable : Cable Structures
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4.4 Type of Transmission Media
• Fiber Optic Cable : Optical Comparison
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4.4 Type of Transmission Media
• Fiber Optic Cable : Light Source
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4.4 Type of Transmission Media
• Fiber Optic Cable : Transmission Mode
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4.4 Type of Transmission Media
• Telephone system :
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Exchange
Subscriber line
ConnectorHole
Pipe
TRUNK
Central Office
Exchange
Exchange
CitySatellite dish
4.4 Type of Transmission Media
• Intra-Office cable :
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Radio Tower
Exchange
CitySubscriber line
Termimal Box
SD wire Drop wire
ConnectorHole
ConnectorHole
Pipe
TRUNK
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Comparing Ethernet Media Requirements
Comparing Ethernet Media Requirements
10Base5 100BaseTX
10BaseT 100BaseFX
Media
Maximum Segment Length
Topology
Connector
50-ohm coax (thick)
500 meters
Bus
100 meters
Star Star Point-to-Point
EIA/TIA Cat3, 4, 5 UTP
2 pair
EIA/TIA Cat5 UTP2 pair
62.5/125 micron multi-
modeF/O
AUIISO 8877 (RJ-45)
Duplex media-interface connector (MIC) ST
ISO 8877 (RJ-45)
400 meters100 meters
4.4 Type of Transmission Media
• UnGuided Media :• Unguided media or wireless communication,
transport electromagnetic waves without using a physical conductor. Instead, signals are broadcast through air.
• VLF : Very low frequency (3KHz-30KHz)--Suface• LF : Low frequency (30KHz-300KHz)--Suface • MF : Middle frequency (300KHz-3MHz)--
Tropospheric• HF : High frequency (3MHz-30MHz) --Ionospheric• VHF:Very high frequency (30MHz-300MHz)-Space & line of
sight• UHF : Ultra high frequency (300MHz-3GHz) --Space• SHF : Super high frequency (3GHz-30GHz) --Space• EHF : Extremely high frequency (30GHz-300GHz) --Space50/63
4.4 Type of Transmission Media
• Wireless Communication :
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4.4 Type of Transmission Media
• UnGuided Media : Microwave
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4.4 Type of Transmission Media Diagram of a microwave repeater
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AMPLIFIER CONVERTERPOWER
AMPLIFIER
RECEIVING ANTENNA TRANSMITTING ANTENNA
4.4 Type of Transmission Media
Typical repeaters required of a 20 GHz System
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TRANSMITTER REPEATER 1
Repeater Unit
REPEATER 2
Repeater Unit
RECEIVER
25 Miles
4.4 Type of Transmission Media
• UnGuided Media : Satellite
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4.4 Type of Transmission Media
• UnGuided Media : Satellite Band
C-Band : 4-6 GHz ; 5.925-6.425 GHz Uplink, 3.7 - 4.2 HGz Downlink
X-Band : 7-8 GHz
Ku-Band : 11-14 GHz ; 14 - 14.5 GHz Uplink, 11.7 - 12.2 GHz
Downlink
K-Band : 20-30 GHz
Ka-Band : 20-44 GHz
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4.4 Type of Transmission Media
• UnGuided Media : Geostationary Satellite
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4.4 Type of Transmission Media
• UnGuided Media : Cellular Telephony
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4.4 Type of Transmission Media
• UnGuided Media : Frequency band 900 MHz
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Base Station
Uplink890-915 MHz999 Channels
Downlink935-960 MHz999 Channels
Dulplex distance 45 MHz
4.4 Type of Transmission Media
• Comparison of Media :
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4.4 Type of Transmission Media
• Ex. VSAT design for bank system
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Microwave towerMain Computer
Head Office(Bangkok)
Microwave towerHub Station Satellite dish
PC Terminal PC Terminal PC Terminal
PC Terminal PC Terminal PC Terminal
PC Terminal PC Terminal PC Terminal
Satellite
Branch OfficeDPU / Controller
Branch OfficeDPU / Controller
Branch OfficeDPU / Controller
SAMART TELCOMS
4.4 Type of Transmission Media
• Factor to select media :
• Cost• Data rate and Bandwidth• Distance
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Q/A
• Thank you
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