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Unit 1 :TELEPHONE SWITCHING AND SIGNALLING. Objectives :. Interprete and describe the basic principles and functions of exchange. Recognize switching network and the term "concentrator", "distributor", "EXPANDER", and "multiplex“. Draw and label a block diagram of SPC switching.
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Objectives : • Interprete and describe the basic principles and functions of exchange. • Recognize switching network and the term "concentrator", "distributor", "EXPANDER", and "multiplex“. • Draw and label a block diagram of SPC switching. • Identify and describe the signaling principles.i. the type of signaling.Ii. the type of signal in the signaling between exchanges with customers.Iii. the type of signaling between the exchanges with the exchange.
Introduction: Tele comes from the Greek word that is long distance,while Foni is defined as sound or speech.Telephony communication means the transmission of speechat long range, where in the wave transmittervoice changed to the form of electrical signals and thenthe signal is converted back to wavevoice.
Frequency bandwidth used for telephony services is 300 - 3400 Hz frequency which is a human voice.Therefore, all telephony equipment and line connections between the devices must be able to communicate in the bandwidth.
Exchange : • Is a center where all the phone lines can be connected to enable communication speech is achieved. • The equipment in exchange functions as a switch for easy connection process. • Now, most of the exchanges is the type GSC (Group Swicthing Centre)
PPU PPZ PPZ PPK PPK PPK PPK PPT PPT PPT PPT PPT PPT PPT PPT P P P P P P P P P P P P P P P P Rajah : HirakiKebangsaan PPU - Main Switching Centre (MSC) PPZ - Switching Centre Zone (SCZ) PPK – Switching Centre Areas PPT – Local Switching Center P – Customers- two wire cable
3 types of exchange International exchange Local exchange Tandem Exchange Available in a same area Exchanges and tandem exchanges connecting to the nation Connecting two or more local exchanges and its main features is not connected to the customer.
Record the customer’s meter reading (time, no.telefon called) Overseeing the process between the client and exchange switching Function of exchange Record customer demand- Provides no. telephone, cut meter for temporary condition Provide supervisory signals (dial tone, ringing, busy tone interference) Control the quality of conversations and recorded service quality of exchanges .
Switching Network. Some of the required switching are:- Macam mane naksambung?? Concentrator ( Penumpu) Distribution ( Pengagih ) Expander Multipleks ( Multiplexer ) The combination of these networks can create complete Public Switching Telephone Network (PSTN).
distributors Customers Concentrator (Penumpu) Concentrator ( Penumpu ) • Permanent circuit connections made in this network. • Concentrator unit is controlled by the local switching exchange directly. The concept of traffic in the PSTN network
Advantages of concentrator are:- ►Able to handle thousands of users at the same time.►Line can reduce the cost of repeated use, repeater and others.
Distributor ( Pengagih ) ►The distributor (distributor) is a device between the concentrator (concentrator) and expander. This device is connect thousands of users in the PSTN network in stages.► Where, about 1000 local line will enter the off-line and only produce 100 output. Next, each distributor can handle 100 online from the concentrator.► Then, the line from the distributor, will enter the EXPANDER.
input channels Output channel Local line 1 Local line 1 Expander concentrator distributors Local line 1000 Local line 1000 Switching network of PSTN
Expander • This returns the number of units of the original line into the concentrator. • From the distributor, all the 100 line will enter the EXPANDER and reissue of 1000 online consumers in the destination separately. • EXPANDER and off the switching process depends on number of lines that is activated simultaneously.
Multipleks ( multiplexer ) ►This device is a tool that can reduce the number of cabling to be used in a process of signal transmission and receiving information.►This may be achieved by combining several input signals and produces an output only.►This combination technique known as multiplexing (multiplexing).♣ Time Division Multiplexing (TDM)♣ Frequency Division Multiplexing (FDM). ►Demultiplexing - separating the information to the original signal.
Signal Information 1 Signal Information 1 MUX DEMUX Signal Information 2 Signal Information 2 Signal Information 10 Signal Information 10 MULTIPLEXING AND DEMULTIPLEXING TECHNIQUE
Switching It is a process of connecting customers from one location to another through the exchange as the medium of communication. Switching functions:►provide services in facilities known customers.►when more sophisticated switching system it serves to provide additional facilities that enable communication network to provide better service to consumers, and overseeing the operations and maintenance.
Types of switching Step by step • The main process through the development of telephone calls made through a tone switching step of dialed digits. • The problem of switching step by step:►Power : requires a lot of power to move the switch for call processing • component.►Space : The components of the main switch is made from brass, • copper, and magnetic pressure is very heavy and require steel • in the floor where they are fitted.►Maintenance: a lot of moving parts in a switch requires cleaning dirt and • oil to facilitate the communication is made in the switch.►Noise: communication through physical path be adjusted via the switch for call processing.
Crossbar ► Crossbar switching is an improvement from switching the step-by-step (switching strowger) ► Switching process performed by the relay (pet clothing). ► Consists of vertical and horizontal line. ► Require connection to a combination of two lines. ► This system has a horizontal switch used to select vertical switch. Horizontal switch function to hold the vertical switch. ► Other names called switchingmatrix.
Stored Program Control • Merupakankaedahpensuisanibusawattelefoni • Iamenggunakankawalankomputeruntukmemprosespanggilandaripadapenggunasecaraautomatik. • Operasikomputerberpandukanaturcara yang telahditetapkan. • Sistemdalambentuk modular iaituterdiridaripadasubsistem • Sistemmenggunakan ‘common channel signalling’ (CCS) • Sistemmenggunakan ‘time switch’
SPC switching block function • memory♣ Keep status of activities of users in software form. • Director of the control (control director)♣ Programs that control and direct the entire system. • File ♣ Store information of user charges.♣ Provide special schedules for special services or other services. • DTMF (decodic)- Decoding signals produced during the process of dialing
Scanner♣ Track the status of algae line telephone and cellular signaling. • Drivers ♣ Connect and disconnect the circuit.♣ Provide access to the dial tone signal and the signal. • CPU (central processing unit)♣ Control and programmed to execute the program. • Tone generator ♣ Generate a notification signal or a call sign.
SPC operating process • A caller picked up the telephone handle, A-line caller is activated and can be detected by the scanner. • CPU will detect and obtain location information, time and so when the caller A pick up the phone handle. • Information send to memory for storage. • Thereafter, the CPU will connect the caller A with switching path 'X' through the drive. • Dial tone is sent to the caller A from dial tone generator. • A caller entered digits dialed numbers, a dial tone generated by the DTMF stopped. • CPU identifying type of call and destination of the call.
Drivers will drive the switching devices 'X' to provide access to the for caller A with caller B. • CPU provides instruction on tone generator to send ringing tone for caller B and caller A. • Once the handle of caller B is lifted up, the scanner will detect the phone picked up and sent to the CPU. • After that, the CPU directs tone generator to stop ringing and start recording the time and location of the call. • After the conversation ended, whether the caller A or B put handle, the scanner will detect the emission signal and sent to the CPU. • CPU will provide the bill (payment) and the records are stored in files.
Advantages of SPC • Maintenance and monitoring is easy because the method of exchange operations may be varied by changing the stored program control at any time. • Signaling from the exchange can be handled easily and effectively. • Increase in line do not need additional signaling device. • Low maintenance costs. • The process is much faster than manual methods.
Disadvantages of SPC • Minor damage can lead the exchange operations to stop. • Ensure that employees trained on new techniques and methods of handling. • Maintenance of over-reliance on suppliers. • Service requires additional building equipment such as air-conditioned room and the program.
Signaling is defined as a transfer or change of address or information between different parts found in a telecommunications system. • Division involved in the signaling: ►Callers to the exchange►Exchange with an exchange►Exchanges with the so-called
Signaling method between the caller or the called exchange • Among the callers to exchange
Among the exchange to the caller • Among recipient to the exchange
The signal from the exchange to the caller or the receiver(standard service tones)
Exchange C ExchangeD traffic circuit Signaling line Transmitter or Receiver Signaling Exchange A Exchange B traffic circuit Transmitter or Receiver Signaling Method of signaling between exchange to exchange