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BUILDING SERVICES II (QSM 554) TELECOMMUNICATION SYSTEM

Telecommunication is a transmission of message, over significant distance for the purpose of communication. Telecommunication nowadays include the use of electrical devices such as telegraph, telephones and teletypes, the used of radio, microwave communication, as well as fiber optics and the other associated electronics, plus the used of the orbiting satellites and the internet. Telecommunication system is defines a systems that help to transmit message in a proper planning or setting. It has to be neatly, durable, durable, flexible and easier to maintain for the end user. The telephone is telecommunication devices that transmits and receive sound, most commonly the human voice. The telephone are a point-to-point communication system whose most basic function is to allow two people separated by large distance to talk to each other. It is one most comm common on appli applian ances ces in the the devel develop op world world,, and and has has long long be cons conside idered red indisp indispens ensab able le to business, households and government. There is three type of telephone classification required installing the phone: a) The number number of phone phone needed needed in the area, area, buildin building, g, or residen residential tial area area b) The size of incoming incoming underground underground cable into into the building, building, the the number of pair is needed needed c) Total Total floor floor area of of the buildi building ng or resid residenti ential al area area There also have three category of telephone requirement before installation: 

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Category 1:

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The building must have the height of four storey or more

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The floor area must be more than 520 m2

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The cable size must be more than 50 pairs (telephone)

Category 2:

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BUILDING SERVICES II (QSM 554)

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The building height must be less than four storey height

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The floor area must be less than 520 m2

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The cable size must be less than 50 pairs

Category 3:

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For the residential used

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The cable size is 1 or 2 pair mostly

Category 1 and 2 were mostly apply for the industrialize building or commercial building that used more than 1 phone. The 3 rd category was main suited for the residential usage. Centrex is an office communication system that has a function similar to the PABX system, which is widely used in the country. Besides functioning as a direct line and extension, Centrex has all the basic features features for office office and home communic communicatio ation n needs. needs. Centrex Centrex service can operate with or without operators to receive incoming calls.

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Our case study was held at ‘Dewan Bahasa dan Pustaka‘building. The telecommunication system used in this building is Centrex system not PABX system. In our report we would like to elaborate details about Centrex system in this building.

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Background of Centrex Centrex is a virtual PABX services offered by TM (in Malaysia) with added features designed specifically to provide home & business customers or any other organizations with efficient and

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BUILDING SERVICES II (QSM 554) useful home & office communication facilities. With Centrex, it will give your customers superior service by allowing them to directly reach your staff without having to go through any interconnectors. At the same time, Centrex always makes a line available to your employees to directly call out, which means more business opportunities for your company. . Centrex enables both the internal and external communications including the service features to be provided directly through TM (Telekom Malaysia). It does not require the purchase of any cumbersome equipment or high maintenance costs.

CASE STUDY 5


Telecommunication System At “Menara Dewan Bahasa Dan Pustaka”

The system used in this building is Centrex System. This system has been used from 2002 until now.

Advantages Generally, there is several advantage of using Centrex system in ‘Dewan Bahasa dan Pustaka’ building (DBP) i.

Each line can function as direct lines and extensions. This will reduce operator job in handling calls in and calls out.

ii.

This building using Direct Inward Dailing (DID) this can be called directly to each user without going through the operator.

iii.

It does not involve the purchase and maintenance cost of PABX system for all operating system in exchange

iv.

The service of Centrex system can connect to fax machine

v.

The Centrex service will be un interrupted in the event of power failure

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Type of Centrex services Centrex system has a function to control the use of a telephone line. The limits for making a phone call are in accordance with the following categories. Table below shows the categories of calls are provided at ‘Dewan Bahasa dan Pustaka” building.

ITEM

CATEGORY

LIMIT OF CALLS

1

A0

There is no limit of calls (including international)

2

A1

Domestic calls and national calls (calls within malaysia)

3 4 5

B0 B1 C

Domestic calls and calls to the same area code Domestic calls only Call between internal connection calls only

If the user in category C is to make national calls, the user category C must ask permission of any category A1 or A0 user prior to make calls. Therefore, a call out by the user category C can be known by someone who is powerful.

Factor why this building install Centrex system. i.

Each line is a direct connection to consumers.

ii.

Callers from outside can directly dial the phone number without having through the operator.

iii.

Minimize the cost of using operator

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Total line for each category Based on current estimate 1. A0 - 44 lines 2. A1- 340 line 3. B0 - 151 lines 4. B1 - none 5. C – 305 lines At ‘Dewan Bahasa dan Pustaka’ building there are 600 line used. Total common lines used are 8 lines. Total customer service officer assigned to a telephone system is 2 person only. If there is no operator handle this system the call out and in also can be made

Problems occur when using Centrex system in DBP Operator system i.

Connection of a telephone call to the customers is often broken

ii.

There is no call waiting, call transfer and call divert if the call is not answer.

iii.

Telephone system (console) used were obsolescence (no spare part support in the market)

Centrex system

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BUILDING SERVICES II (QSM 554) i.

Line of phone often broken such as no ringing tone, cannot call and receive call, line always in active and there is noise .

ii.

System fault especially hardware 10- PAIR KRONE in MDF room.

iii.

Damage of data card.

iv.

Fiber damage

Cost Estimated monthly rental rate is RM20 for each line (total does not include payment of usage). The cost for rental line is RM20 x 600 = RM 12, 000.00 per month.

Total fee for phone bills in last 3 month in 2011 i.

August 2011 – RM 29,652.65

ii.

September 2011 – RM36, 287.78

iii.

October 2011 – Rm 36,221.17

The management of DBP has proposed to change the telecommunication system from Centrex system to PABX System. There one main factor that they decide to use PABX system which is reduction of cost. An ISDN PRI (primary rate interface) in PABX line has 30 circuit (30 simultaneous can be made at the same time) and offers a total of 200 extension number. It mean that this building only need 3 line of ISDN PRI. Rental cost for 3 ISDN PRI line illustrate as follow:

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BUILDING SERVICES II (QSM 554) COMPARISON OF OCCUPANCY RATE OF CENTREX AND ISDN PRI FOR MONTHLY RENTAL

Monthly Rental

Centrex System (600

ISDN PRI

Reduction of cost

lines) RM 20 (for each line)

RM 900 (each PRI) x

RM 9,300.00 per

X 600 lines + RM

3 = RM 2,700.00

month

12,000.00

DBP can get saving of RM 111,600.00 per year by leasing PABX system. Charge for use between the two services is the same for all local calls and calls to other country.

COMPONENT IN TELECOMMUNICATION SYSTEM External components

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Telephone Cabinet

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The cabinet is a place to distribute lines to the distribution point box before reaching a customer’s building house as portrayed. Generally, the cabinet is the end for main cable where it start at the main distribution frame and passes through the cabinet. The connection from the cabinet to the main distributor normally uses the cable that in different size. The functions of cabinet’s are to save the usage of cable and replacing cable would be easier, to avoid the joint be opened and this would save cost and time. It also to act as a place to perform maintenance checking and for upgrade the arrangement of lines.

Internal components

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MDF Room

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BUILDING SERVICES II (QSM 554) The MDF room compliance the telecommunication wiring. In this room it also placed existing MDF. The system were put together in these room for maintained purposed. This is function the switch room for the better access and maintained purpose.

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Main distribution frame (MDF)

Main distribution frame (MDF or main frame) is a signal distribution frame for connecting equipment that is inside plant to cable and subscriber carrier equipment. The MDF is a

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BUILDING SERVICES II (QSM 554) termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires at the MDF. All cable copper pairs supplying services through user telephone lines are terminated at the MDF and distributed through MDF to equipment. Cables to intermediate distribution frames terminate at the MDF. Trunk cables may terminate on the same MDF or on separate trunk main distribution frame (MDF). In simple word, functions of MDF are to test the phone line, to execute the jumper process, to check the problem phone line, to check the problem phone line, to cut the phone line manually and to connect the phone line manually. Main distribution frame (MDF) is a distribution frame on one part of which the external trunk cable entering a facility terminate and also have another part which is internal user subscriber lines and trunk cabling to any intermediate distribution frames terminate. The MDF is used to cross-connect any outside line with any desired terminal of the multiple cabling or any other outside line. Usually, MDF holds central office protective devices and functions as a test point between a line and the office. The MDF in a private exchange performs functions similar with MDF in central office including heat coils and also as a test point between a line and the office.

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Cable Tray

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The cable tray functioned for the placing of electrical and telecommunication wiring. The purposed to place these wiring neatly. The telecommunication and electrical wiring can be place in similar tray but it will be separated in color or conduit. The reason is for identify the wire and its function of the wiring. The tray is metal box and it usually is steel because steel cannot be corroded or rust.

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Telecommunication riser

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The telecommunication riser is a compartment vertically aligned and usually beginning from the first-storey or basement and extending through to the topmost level of a multi-storey building. It is used to accommodate telecommunication cables from the MDF room to various floors of the building. For residential buildings, two cable trays/cable ladder or metal trunking area required in the telecommunication riser to facilitate the installation of cables. Telecommunication riser shafts must be installed in a direct vertical line throughout the building.

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Trunk line

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The trunk line is circuit connecting telephone switchboards as distinguished from local loop circuit which extend from telephone exchange switching equipment to individual telephone or information origination/termination equipment. When dealing, trunk lines are the phone lines coming from the telephone provider. This differentiates these incoming lines from extension lines that connect to individual phone sets. Trunking saves cost because there are usually fewer trunk lines than extension lines since it is unusual in most offices to have all extension lines in use for external calls at once.

The operation of telephone as communication

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BUILDING SERVICES II (QSM 554) Modern telephones operate on essentially the same principles that were developed than 100 years ago. They use a single pair of wires that connect the phones and a power source. When the phones are connected, the power source causes a current to flow in loop, which is modulated by the voice signal from the microphones in one headset and excites the earphone in the opposite headset. Dialing was originally done by a rotary dial that simply switched the current on and off in a number of pulses corresponding to the number dialed. Dialing is now mostly accomplished with tones. Telecommunications use various mediums to transport information and data. These include fiber optics, internet and radio waves. A telecommunication network is defined as the process of sending and receiving electrical signals over distances using an arrangement of resources. All telecommunication networks are run by computers. Telephone has gone through many changes. The older telephone was rather simpler in the theory. There is 48v of electricity on the phone line. When we pick up the telephone, the circuit is closed and the electrical current begins the flow. Inside the transmitter part of the telephone are little carbon granules that cause a resistance to the flow of electrical current. When we speak, the pressure from our voice causes a diaphragm to push down on the carbon granules, thereby changing the resistance according to the pressure in our voice. This is known as current modulation. The current then travels through the phone line, containing small variations that are proportional to the pressure from our voice. When they reach the receiver at the other end, the opposite procedure is done. The small variations in current cause a magnetic coil in the speaker to move and reproduce our voice.

Distribution

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The operation is starting from the main exchange. From the main exchange, it will distribute to the other main exchange which is branch exchange. From the branch exchange it will go through to the telephone cabinet and arrive to the residential area. At residential area, it have many distribution points which is allocate for the numbers of houses. The distance for the one distribution point to another is about 30 – 50 acres. Same goes with commercial area, the telephone cabinet distribute line to the distribution point. One distribution point present for the one line of the building. For the high rise building, the telephone cabinet will through to the joining chamber and arrive to the SDF room. From the SDF room, the line is distribute to the whole storey of building.

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Diagram show the system of telecommunication if a phone call was received

When we received the call, the signal of incoming call enters to the MDF (main distribution frame). In telecommunication, MDF is a distribution frame on one part of which the external trunk cables entering a facility terminate, and on another part of which the internal user subscriber lines and trunk cabling to any intermediate distribution frames terminate. MDF is a cable rack that interconnects and manages the telecommunication wiring between itself and any number of IDF (intermediate distribution frame), which connects internal lines to the MDF. After that the incoming call through the cable tray going to the telecommunication riser. The telecommunication riser is a compartment vertically aligned and usually beginning from the first storey or basement and extending through to the top most level of the building. the

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BUILDING SERVICES II (QSM 554) telecommunication riser continue with transfer the signals to the residential. The residential also known as a receiver. The receiver is the output or destination component. This responsible for receiving message in the form transmitted, decode it if applicable and render the original information.

Duct system The duct can be used to carry out both low-voltage electrical supplies and transmit calls for phones. These low voltage circuits must be segregated inside the duct. The duct of layout depends on the use of the building. There are three types of ducts layout which are: a) Grid system b) Branching system c) Perimeter system

a)

Grid system

This method provides adequate facility for telephone. It is used in open-plan offices. A suitable spacing of the ducts is 1.5 – 2.5 m, but other spacing may be used depending upon the degree

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BUILDING SERVICES II (QSM 554) of flexibility required. For Malaysia grid is 3.6m x 3.6m while British grid is 3.0m x 3.0m. The cable is located under floor through trucking. It is a flexible system which is easy to make any interior layout for the cabinets. b)

Branching layout

This method used a central feeder duct with branches to each window bay. The branches may either terminate just short of the wall outlets, or extend to wall outlets. The layout provides reasonable flexibility for open plan office but it is also use for portioned office with the central feeder duct in corridor. It is suitable because there is a fix partition and suitable for office rooms and individual shops lots in shopping complex, hotels and apartment. It is more economical because the cable can be taken directly to telephone unit without any diversion.

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BUILDING SERVICES II (QSM 554) c)

Perimeter layout

This method is the cheapest among others but does not provided the flexibility obtained by other two above layouts. A main feeder duct is located about 450mm from outside wall with short branches taken from junction boxes to the wall outlets for telephones and electrical supply. It is an alternative to the branching layout. This method normally located at the internal perimeter floor skirting. Other than that it is normally use as combination with the grid layout. This system is easy to maintain and suitable for the office building in circular shape.

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BUILDING SERVICES II (QSM 554) Conclusion As a conclusion, telecommunication system plays many roles in a building. It is make the work easy and faster. The chosen of system also important because it is effect to the cost occur. From the case study that we were held, the PABX system is more value for money compared to Centrex system which is need tp pay for each line. In Centrex system it is easier to communicate because it’s a direct call compared to PABX system. Each of these systems has have their own advantages.

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