1. CPMT 1449 Computer Networking Technology – Lesson 2
CPMT 1449 Computer Networking Technology – Lesson 2.1-Chapter 3 Transmission Basics and Networking Media

2. Learning Objectives
Explain basic data transmission concepts, including full-duplexing, attenuation, latency, and noise
Describe the physical characteristics of coaxial cable, STP, UTP, and fiber optic media
Compare the benefits and limitations of different networking media
Explain the principles behind and uses for serial connector cables
Identify wiring standards and best practices for cabling buildings and work areas

3. Transmission Basics Transmit – means to issue a signal
Transmission – means the process of transmitting or the progress of a signal after it has been transmitted
The picture below represents basic transmissions (very basic)

4. Analog Signaling Generated as voltage that varies continuously
Characterized by 4 fundamental properties
Amplitude -
Frequency – The number of times the wave’s amplitude cycles from start to highest and lowest amplitude and back to the starting position over a fixed period of time
Wavelength -
Phase

5. Analog Signaling - Amplitude
Amplitude - A measure of the signal’s strength at any given point in time

6. Analog Signaling – Frequency
The number of times a wave cycles in a fixed period of time
Start point
Highest amplitude
Lowest amplitude
Expressed in Hertz (Hz)
If the frequency is 1 cycle in 1 second 1 Hz, it is considered an extremely low frequency

7. Analog Signaling – Wavelength
The distance between corresponding points on a wave’s cycle
Expressed in meters or feet

8. Analog Signaling – Phase
Is the progress of a wave over time in relationship to a fixed point
Measured in degrees

9. Digital Signaling
Composed of precise pulses of positive and zero voltages
More reliable than analog signaling
Less susceptible to noise
Uses less overhead – Overhead is all the non-data information that must accompany the signal
A positive voltage represents a 1
A zero voltage represent a 0
The 1’s and 0’s are indicative of the Binary system

10. Binary System
Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1
In the digital world, to count in binary, we have to understand the term bit and byte
Bit – equals a single pulse and is represented by a 1 or a 0
Byte – equals 8 bits, this means that a byte contains 8 place holder as shown: , when these numbers are added together they equal 255
To count in binary, we place the eight bit values in their perspective place holder position
We add the entire place holder values that have a bit value of 1 and
ignore the bit holder values of 0….see the example.

11. Data Modulation Data relies on digital transmissions
For networks that can only send data using analog signals the signal must be converted from digital to analog and back to digital this is called modulation and demodulation this is accomplished using a modulator/demodulator or what is commonly referred to as a modem
Connecting to the internet is a good example of modulation/demodulation
In modulation a simple wave called a carrier wave is combined with the data wave (see next slide)
The carrier wave has preset properties (amplitude, frequency, wavelength, and phase)
Frequency Modulation (FM) and Amplitude Modulation (AM)
FM – the frequency of the carrier signal is modified by the application
AM – the amplitude of the carrier signal is modified by the application

12. Data Modulation

13. Simplex/Half-Duplex/Full-Duplex
Simplex is one-way communication
Half-Duplex is two-way communication but not simultaneously
Full-Duplex is two-way communication simultaneously
Modern networks use full-duplex communications when sending and receiving data
It is important to remember that if the network is using full-duplex all devices must use full-duplex

14. Multiplexing
Allows multiple signals to be sent through a single transmission medium
This requires the use of channels and sub-channels
Channel – a distinct communication path
Sub-channel the separation of a channel into multiple channels
The channels are separated logically using a multiplexer/demultiplexer (mux/demux)
The multiplexer takes all of the channels that are going to be multiplexed and combines them to be sent down a single medium. Once they arrive at the distant end, the channels are separated and sent to their separate destinations
There are several types of multiplexing
Time Division Multiplexing (TDM)
Statistical Multiplexing
Frequency Division Multiplexing (FDM)
Wavelength Division Multiplexing (WDM)
Dense Wavelength Division Multiplexing (DWMD)

15. Time Division Multiplexing and Statistical Multiplexing
Divides the channels into multiple time slots
A time slot is assigned to each node and in that time slot is that node’s data
If a node has no data the time slot is wasted
Statistical multiplexing eliminates the wasted time slots
Senses an empty time slot and assigns the empty time slot to another node
The arbitration for the unused time slot is factors such as use, priority, and other advanced factors

16. Time Division Multiplexing

17. Frequency Division Multiplexing
Assigns a unique frequency band to each sub- channel
The signals are modulated with different carrier frequencies
Then multiplexed to travel over a single channel simultaneously
Two common forms
Cellular phone transmissions
DSL internet access

18. Frequency Division Multiplexing

19. Wavelength Division Multiplexing
Enables one fiber-optic connection to carry multiple light signals simultaneously
One light beam is divided into 40 different carrier waves each with a different wavelength (color)
Each wavelength is a different separate channel capable of transmitting up to 10Gbps
Each carrier wave is modulated with a different data signal
Lasers issue the modulated waves to the multiplexer that works like a prism, the waves are combined into a beam of white light
It is then placed on a single strand of fiber by another laser and demuxed the same way at the distant end.

20. Dense Wavelength Division Multiplexing
Most common for fiber networks
Can carry between 80 and 160 channels
Provides less separation between carrier waves
Used on high-bandwidth or extremely long WAN links

21. Transmission Between Nodes
Point-to-Point
Involves one transmitter and one receiver
Transmits data intended only for one receiver
Typically these are WAN links
Point-to-Multipoint
One transmitter to 2 or more receivers
Uses Broadcast or Non-broadcast transmissions
Broadcast – sent to all nodes on that network
Non-broadcast – sent to only specific nodes on that network

22. Throughput and Bandwidth
Throughput - capacity
See the throughput chart below
Is the measure of data transmitted during a given time period
Measured in bits per second (bps)
Bandwidth – this term is normally used interchangeably with throughput
Is actually the measure of the highest and lowest frequencies that a medium can transmit
Measured in hertz (Hz)

23. Baseband and Broadband
transmission form where digital signals are sent through the medium by direct current (DC) pulses
Requires exclusive use of the wire’s capacity
When a node transmits all other nodes must wait until that transmission ends
Ethernet is an example of baseband communications
Broadband
Signal is modulated as radio Frequency (RF) analog waves
Each wave uses different frequency ranges
Does not encode information as digital signals
Has two meanings in networking terms
Meaning 1 – carries RF signal across multiple channels on coaxial cable
Meaning 2 – several different network types that use digital signaling to transmit at extremely high transmission rates

24. Transmission Flaws
Transmissions-analog or digital- are susceptible to degradation between the time they are sent until they are received
Three major types
Noise
Attenuation
Latency

25. Noise
Any undesirable influence that is capable of distorting or degrading a signal
Three major types
Electromagnetic Interference (EMI)
Radiofrequency Interface (RFI)
Cross Talk – interference from a wire medium that is in close proximity of another wire medium
The use of amplifiers and repeater help combat these three transmission flaws (Layer 1 devices)

26. Amplifiers and Repeaters
Used to amplify analog signal
Does not “clean” the noise out of the signal, but rather amplifies the signal and the noise
Repeaters
Used to regenerate digital signals
Since the signal is regenerated the noise is not repeated

27. Attenuation and Latency
The loss of the signal’s strength as it travels away from its source
Attenuation is commonly seen at the wire medium that carries the signal to the transmission system’s antenna when using radios as the transmission systems
Latency
The delay of the signal or the time it takes to travel from sender to receiver.
Commonly measured on networks via the round trip timer (RTT) and is measured in milliseconds (ms)

28. Connectors RJ45 Connectors BNC Connector
Connectors connect the cable to the device
Different cabling types use different connectors
F-Type Connector
RJ11 Connectors

29. Fiber Optic Connectors
There are 10 different connectors used with fiber-optic cables. Listed are the most common
ST Connector SC
Connector
LC Connector
MT-RJ Connector

30. Unshielded Twisted Pair
Networking Cables
Shielded Twisted Pair
(STP)
Coaxial
(coax)
Fiber Optic
(fiber)
Unshielded Twisted Pair
(UTP)
There are several types of cabling that can be used concerning networks. Listed is the most common found in today’s modern networks

31. Terminating Twisted Pair
Two standards

32. Twisted Pair Cable types
3 Types of Twisted Pair Cable
Straight-through
Crossover
Rollover

33. Fiber Optic Cable Contains one or more fiber strands at its core
Data is transmitted using pulsing light sent via lasers
Each fiber is surrounded by cladding
All is wrapped in Kevlar strands to protect the fiber core and then wrapped in a plastic sheath
Has 2 types of fiber cable
Single Mode Fiber (SMF)
Multimode Fiber (MMF)

34. Single-Mode and Multi-Mode Fiber
Single Mode Fiber
Has a narrow core (>10 microns in diameter)
Has very little reflection
Has the highest bandwidth and can travel the longest distances
Very expensive
Multimode Fiber (create a graphic)
Core has larger diameter (between microns in diameter – normally 62.5 microns)
Because of the core diameter, several pulses of light can be sent at different angles
Extremely high through put
Resistant to noise
Good security
Industry standard for high-speed networking

35. Fiber Optic Cable

36. Data Terminal Equipment (DTE)/Data Circuit Terminating Equipment (DCE)
DTE refers to the user side of the cable – connects to equipment that is the responsibility of the user
DCE side connects to a multiplexer or modem – required to provide timing to the DTE side of the cable
TIA/EIA standard RS 232 (Recommended Standard 232)
Uses DB-9 or DB-25 (most common)

37. End of Presentation
For more information on this lesson, See Chapter 3 in the text book or the Professor
**All Slides and graphics were produced by Professor Patrick Hughes**