LM01-CSCC0323-CP03-1

Introduction

• The course discusses signaling techniques used on modern networks.

• Covers coaxial cable, twisted pair cable, and fiber-optic cable.

• Describes the physical media characteristics: cost, materials, and connector types.

Pre-Assessment

• Differentiate various transmission media by:

  • Costs

  • Throughput

  • Noise immunity

  • Size and scalability

Transmission Basics

• Transmit: Issuing signals along a network medium (e.g., cable).

• NICs (Network Interface Cards) can transmit and receive signals (are transceivers).

Analog and Digital Signaling

• Signaling types in data networks:

  • Analog: Generated as variable voltage (continuous waves).

  • Digital: Signals as discrete pulses measured in volts.

Analog Signal Properties

• Characterized by four basic properties:

  • Amplitude: Height of the wave (strength).

  • Frequency: Cycles of amplitude over time.

  • Wavelength: Distance between peaks.

  • Phase: Progress of the wave over time.

Key Points

• Information transmission methods: Analog and Digital.

Definitions

• Analog: Continuous variable voltage signal, less accurate.

• Digital: Composed of discrete pulses (0 or 1).

• Volt: Measurement of electric current pressure on a conductor.

• Voltage: Intensity of electric current.

Benefits and Drawbacks of Signals

• Analog Signal: More variable and conveys subtleties with less energy, but is imprecise and prone to flaws.

• Digital Signal: More reliable, less affected by noise, requires more pulses (overhead).

Overhead Definition

• Non-data information needed for signal routing/interpretation (e.g., network addressing).

Data Modulation

• Essential for transmitting between digital and analog systems (modulation/demodulation).

• Modem: Device that modulates and demodulates signals.

Modulation Techniques

• Frequency Modulation (FM): Alters the carrier frequency with data.

• Amplitude Modulation (AM): Alters carrier amplitude with data.

Transmission Categories

• Simplex: One-way communication.

• Half-Duplex: Both ways, but one at a time.

• Full-Duplex: Both ways simultaneously (e.g., Ethernet).

Multiplexing

• Allows multiple signals over one medium.

• Multiplexer (mux): Combines channels at transmission.

• Demultiplexer (demux): Separates signals at receiving end.

Types of Multiplexing

• Time Division Multiplexing (TDM): Divides channel into time slots.

• Statistical Multiplexing: Assigns slots based on priority (more efficient).

• Frequency Division Multiplexing (FDM): Assigns unique frequency bands.

Wavelength Division Multiplexing (WDM)

• Used in fiber-optic connections to carry multiple signals.

• DWDM: Can carry 80-160 channels, used in high-bandwidth WAN links.

Relationships Between Nodes

• Point-to-Point: One transmitter to one receiver.

• Point-to-Multipoint: One transmitter to multiple receivers (broadcast and non-broadcast).

Broadcasting Example

• Radio stations disseminate signals to multiple antennas.

Throughput and Bandwidth

• Throughput: Data transmitted over a period.

• Bandwidth: Difference between highest/lowest frequencies medium can transmit.

Baseband vs. Broadband

• Baseband: Digital signals; one signal/channel at a time (e.g., Ethernet).

• Broadband: Radio frequency signals; multiple signals simultaneously (e.g., cable TV).

Transmission Flaws

• Analog and digital signals are susceptible to:

  • Noise: Distorts signals (e.g., EMI and cross talk).

Noise Types

• EMI: From electrical devices or cables.

• Cross Talk: Signal interference from adjacent wires.

Other Transmission Flaws

• Attenuation: Signal strength loss over distance. Signals can be boosted using amplifiers (analog) or repeaters (digital).

• Latency: Delay in signal transmission; measured as round trip time (RTT).

Common Media Characteristics

• Match networking needs with media characteristics:

  • Throughput: Limited by physics and technology.

  • Cost: Variable based on installation, infrastructure, maintenance.

  • Noise Immunity: Fiber-optic cables least susceptible to noise.

  • Size and Scalability: Maximum nodes and segment lengths depend on latency and attenuation.

Connectors and Media Converters

• Specific for particular media types, affect installation and maintenance cost.

• Media converters enable networks on different media to interconnect.

Coaxial Cable

• Consists of a central metal core with insulation and shielding.

• Higher noise resistance; suitable for longer distances than twisted pair cable.

Coaxial Specifications

• RG-6: 75 ohms; used in cable TV.

• RG-8: 80 ohms; used in Thick Ethernet.

• RG-58: 50 ohms; used in Thin Ethernet.

• RG-59: 75 ohms; used for video distribution.

Connectors for Coaxial Cables

• F-type and BNC connectors used to terminate coaxial cables.

Twisted Pair Cable

• Composed of color-coded insulated pairs of copper wire.

Properties of Twisted Pair Cabling

• More twists reduce cross talk; categorized into various types (e.g., CAT 3, CAT 5, CAT 6).

• STP: Shielded against electromagnetic interference.

• UTP: Less expensive, less noise resistance.

Fiber-Optic Cable

• Composed of glass/plastic fibers transmitting data as light pulses.

Characteristics of Fiber-Optic Cables

• Higher throughput, high noise resistance, longer distances, though more expensive.

• Single-Mode Fiber (SMF): Narrow core for long-distance transmission.

• Multimode Fiber (MMF): Larger core for shorter distances but with higher attenuation.

Fiber-Optic Converters

• Connect multimode and single-mode fiber networks.

Serial Cables

• Uses sequential data transmission.

• RS-232: Defines several connector standards.

References

• Dean, T. (n.d.). Network+ Guide to Networks (6th ed.). Course Technology, Cengage Learning.

Post-Assessment

• Differentiate transmission media by costs, throughput, noise immunity, size, and scalability.