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Signaling and Switching. Chapter 6. Objectives. In this chapter, you will learn to: Define modulation and explain its four basic versions Explain the different types of multiplexing techniques, their benefits, and hardware requirements

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Signaling and switching

Signaling and Switching

Chapter 6

Tamra Dean -- Modified by: Brierley


Objectives
Objectives

In this chapter, you will learn to:

  • Define modulation and explain its four basic versions

  • Explain the different types of multiplexing techniques, their

  • benefits, and hardware requirements

  • Discuss the fundamental types of switching used in voice and data communications

  • Identify the differences between local and tandem switching

  • Describe modern signaling techniques used to route calls to their destination

Tamra Dean -- Modified by: Brierley


Modulation
Modulation

  • A technique for processing signals in which two waves are combined to produce a wave that possesses characteristics of both and can be decoded to separate these characteristics.

  • Information wave - the wave containing the signal you want to transmit.

  • Carrier wave - the wave that is modulated, and whose properties are constant and known to both the sender and receiver.

  • Guided waves - waves that are bound to a carrier wave’s frequency.

Tamra Dean -- Modified by: Brierley


Modulation1
Modulation

  • Modulator - the device that imposes the information signal on the carrier signal at the transmission end.

  • Demodulator - separates the information from the carrier signal at the receiving end.

  • Modem - a device used to convert digital into analog signals and analog into digital signals.

Tamra Dean -- Modified by: Brierley


Modulation2
Modulation

Tamra Dean -- Modified by: Brierley


Amplitude modulation
Amplitude Modulation

Tamra Dean -- Modified by: Brierley


Amplitude modulation1
Amplitude Modulation

Tamra Dean -- Modified by: Brierley


Frequency modulation
Frequency Modulation

  • A method of modulation in which the frequency of the carrier signal is modified by the addition of the information signal.

  • Frequency shift keying (FSK) - when FM signals are converted into digital signals, the differing frequencies are conveyed as either 0s or 1s.

Tamra Dean -- Modified by: Brierley


Frequency modulation1
Frequency Modulation

Tamra Dean -- Modified by: Brierley


Frequency modulation2
Frequency Modulation

Tamra Dean -- Modified by: Brierley


Phase modulation
Phase Modulation

Tamra Dean -- Modified by: Brierley


Phase modulation1
Phase Modulation

Tamra Dean -- Modified by: Brierley


Phase modulation2
Phase Modulation

Tamra Dean -- Modified by: Brierley


Pulse code modulation pcm
Pulse Code Modulation (PCM)

  • The process of converting analog signals into digital signals

  • Sampling - the first step in converting analog signals to digital signals is to measure the amplitude of an analog signal at multiple instants.

    • The higher the sampling rate, the more closely the digital signal resembles the original analog signal.

Tamra Dean -- Modified by: Brierley


Pulse code modulation pcm1
Pulse Code Modulation (PCM)

Tamra Dean -- Modified by: Brierley


Quantizing
Quantizing

  • To create a replica of the audio wave in digital format, each sample is converted into its binary equivalent in a process called quantizing.

  • One problem with quantizing is that it introduces noise. This occurs because a signal composed of quantized values is not as precise as the original analog signal, which is made of one continuous wave.

  • Companding - This process of compressing and expanding a signal.

Tamra Dean -- Modified by: Brierley


Quantizing1
Quantizing

Tamra Dean -- Modified by: Brierley


Quantizing2
Quantizing

Tamra Dean -- Modified by: Brierley


Frequency division multiplexing fdm
Frequency Division Multiplexing (FDM)

  • Frequency division multiplexing (FDM) - a method of sending multiple analog signals simultaneously over one channel by separating the channel into subchannels, or bands.

  • Guardband - a narrow range of unused frequency between each band’s frequency. It ensures that signals do not interfere with each other.

Tamra Dean -- Modified by: Brierley


Frequency division multiplexing fdm1
Frequency Division Multiplexing (FDM)

Tamra Dean -- Modified by: Brierley


Time division multiplexing tdm
Time Division Multiplexing (TDM)

Tamra Dean -- Modified by: Brierley


Time division multiplexing tdm1
Time Division Multiplexing (TDM)

Tamra Dean -- Modified by: Brierley


Statistical multiplexing
Statistical Multiplexing

Tamra Dean -- Modified by: Brierley


Wavelength division multiplexing
Wavelength Division Multiplexing

Tamra Dean -- Modified by: Brierley


Switching
Switching

  • A method of establishing connections and sending information between nodes on a network.

  • Circuit switching - establishing a connection between two devices on a network, before they begin transmitting data.

    • The advantage of circuit switching is that it guarantees two devices exclusive use of a communications channel.

Tamra Dean -- Modified by: Brierley


Switching1
Switching

Tamra Dean -- Modified by: Brierley


Message switching
Message Switching

Tamra Dean -- Modified by: Brierley


Packet switching
Packet Switching

Tamra Dean -- Modified by: Brierley


Switching systems
Switching Systems

  • The combined collection of hardware and software that establishes connections between lines and trunks in order to complete calls.

  • Although makes and models differ between manufacturers, all modern switches share four essential elements:

    • Switching matrix

    • Line or trunk circuits

    • Central control computer

    • Common equipment

Tamra Dean -- Modified by: Brierley


Local switching systems
Local Switching Systems

  • A local switch performs the following functions:

    • Provides dial tone to a local subscriber

    • Accepts and interprets signals (including off-hook notification, dial tones, and so on) from the local subscriber

    • Receives signals from the destination’s local switch about when to terminate the call

    • Records local subscriber billing information

    • Stores information about subscribers (such as what type of service they have chosen) in a subscriber database

    • Tests and maintains the subscriber’s local loop

Tamra Dean -- Modified by: Brierley


Switching an intra office call
Switching an Intra-Office Call

Tamra Dean -- Modified by: Brierley


Tandem switching
Tandem Switching

  • A tandem switch may perform the following functions:

    • Provide termination for trunks at Class 1, 2, 3, and 4 central offices

    • Gather and transmit information about telephone network traffic and congestion

    • Determine the fastest path over the PSTN for long-distance calls

    • Carry data and voice signals between central offices

    • Test and maintain trunks

    • Assist in trunk configuration

Tamra Dean -- Modified by: Brierley


Tandem switching1
Tandem Switching

Tamra Dean -- Modified by: Brierley


Lucent s ess switch
Lucent’s ESS Switch

Tamra Dean -- Modified by: Brierley


Nortel s dms switch
Nortel’s DMS Switch

Tamra Dean -- Modified by: Brierley


Nortel s dms switch1
Nortel’s DMS Switch

Tamra Dean -- Modified by: Brierley


Switch signaling
Switch Signaling

  • The exchange of information between the components of a telephone network or system for the purposes of establishing, monitoring, or releasing phone circuits as well as controlling system operations.

  • Switch-signaling functions include:

    • Transmitting Address Information

    • Supervising

    • Transmitting Information

Tamra Dean -- Modified by: Brierley


Subscriber loop signaling
Subscriber Loop Signaling

  • The exchange of information about a telephone circuit over the local loop.

  • The primary types of supervisory signals include:

    • Idle circuit

    • Busy circuit

    • Seizure

    • Disconnect

Tamra Dean -- Modified by: Brierley


Common channel signaling ccs
Common Channel Signaling (CCS)

Tamra Dean -- Modified by: Brierley


Signaling system no seven ss7
Signaling System No. Seven (SS7)

Tamra Dean -- Modified by: Brierley


Summary
Summary

  • Modulation is a signal-processing technique in which an information wave is imposed on (combined with) a carrier wave to create a unique wave pattern.

  • Common methods of multiplexing include frequency division multiplexing (FDM), time division multiplexing (TDM), statistical multiplexing, and wave division multiplexing (WDM).

  • Switching is a method of establishing connections and sending information between nodes on a network.

Tamra Dean -- Modified by: Brierley