Telecommunications Equipment

80 Questions

What is the primary purpose of the push button marked 'G' in the Standard 16 key DTMF Key Pad?

General call for calling stations simultaneously

What type of telephone is used in the way station equipment?

2-Wire/4-Wire desk type control telephone

What is the power supply requirement for the CCEO system?

Standard telecom supply (-48 V DC) only

What is the function of the 'RT' push button in the Standard 16 key DTMF Key Pad?

Repeating last transmitted station code

What is the purpose of the 'RS' push button in the Standard 16 key DTMF Key Pad?

Resetting the system

What is the component of the CCEO system located in the OFC hut itself?

Main equipment

What is the type of amplifier used in the communication equipment?

Two Way Amplifier

What is the purpose of the 'DL' push button in the Standard 16 key DTMF Key Pad?

Cancellation of code

What is the maximum temporary period for overhead telecom alignment permission given by the local Railway administration?

3 months

What is the primary purpose of provisioning multiple protection paths with route and service provider diversities?

To ensure high reliability of control communication circuits

What is the benefit of having only one type of equipment in a control section?

Ease of maintenance and inventory management

What is the purpose of supervisory facilities in a manual board?

To ensure the telephone connected to the exchange is disconnected from the control circuit after conversation

What is the primary function of Dual Tone Multifrequency (DTMF) System?

To transmit two frequencies simultaneously for calling one or multiple stations

What is the reason for ensuring only important officials have access to control circuits?

To prevent unauthorized access to control circuits

What is the purpose of recording control communication with time stamps?

To keep a record of control communication for future reference

What is the benefit of interconnecting a local telephone exchange with important control circuits?

To allow important officials to access control circuits with or without an operator's assistance

What is the purpose of the adjustable bracket on the arm of the microphone?

To hold the microphone in place

What is the recommended material for cable tray/rack(s)?

Longitudinal strips iron or angle iron with horizontal cross pieces of light material

What should be checked during quarterly maintenance of DTMF signalling equipment?

The functioning of all station codes including special codes, and DTMF signalling code level

What is the recommended location for cable tray/rack(s)?

In an accessible location with the shortest practicable runs between units

What is the purpose of the volume control on the loudspeaker?

To control the loudspeaker's volume

What should be checked during monthly maintenance of way station equipment?

Not specified in the manual

What is the recommended load for testing DTMF signalling code level?

600 ohms

What is the acceptable range for DTMF signalling code level?

Between 0 dBm to -7 dBm

What is the primary function of the CCEO system?

To enable voice communication and signaling through quad cable

What is the purpose of the hybrid attachment in control office equipment?

To convert 4 Wire operation to 2 Wire operation in control office equipment

What is the advantage of using VoIP based train control communication system?

It enables use of common infrastructure for voice and data services

What is the function of the operating console with DTMF code generator in the control office equipment?

To provide voice frequency signaling using DTMF signals

What is the purpose of the intercommunication system in a control office?

To facilitate communication between controllers in a control office

What is the difference between 4 Wire and 2 Wire operation in way station equipment?

The way station equipment is different for 4 Wire and 2 Wire working

What is the advantage of using DTMF calling system?

It enables voice frequency signaling using DTMF signals

What is the primary function of the control office equipment?

To provide voice communication and signaling through an Optical Fibre Communication System

What is the primary function of Control Room Equipment (CRE)?

Selectively calling any way station or any local telephone

Where is Test Room Equipment (TRE) typically located?

In the test room

What is the maximum number of local telephones provided by Local Telephone Equipment (LTE)?

How many control telephones can be connected to a Multi Telephone Way Station Equipment (MTWE) unit?

What is the purpose of a Three Way Amplifier (TWA) unit?

To connect more than 4 control telephones at a way station

What is the maximum capacity of a Multi Telephone Way Station Equipment (MTWE) unit?

4 control telephones

What is the type of cable used to connect a Multi Telephone Way Station Equipment (MTWE) unit to the VF channel from the PD Mux on the OFC system?

4-wire cable

What is the type of telephone instrument connected to a Multi Telephone Way Station Equipment (MTWE) unit?

Standard telephone instrument with a handset and a numeric dial

Where should incoming line wires and underground cables be terminated?

In the test room

What should be ensured while planning the entrance of cables into the building?

Avoiding damage due to proximity to water pipes, steam pipes, etc.

What is a necessary provision in test rooms?

Fire-proof walls

Why is it necessary to make test rooms dry and clear?

To prevent flooding in the basement

What is necessary to protect vital telecom equipment in the test room and control office?

Fire detection and suppression systems

Where should all line wires and communication cables be terminated?

In the test room

What should be made available in the Test room and Control office?

All of the above

Why should test rooms be free from overhead piping?

To prevent accidents and fires

What should be done with equipment producing noise during operation in the control office?

It should be located in a different room outside the control office.

Where should batteries, especially secondary cells, be located?

In a separate room outside the control office

Why should the test room be located close to the control office?

To enable the test room staff to attend to any fault promptly

What should be considered when planning a control office?

Space required for future additions and alterations

Why should wire runs to the controller's table be terminated on a terminal strip?

To provide a suitable place for termination

Why should separate conduits or runways be provided for communication and high voltage electric wires?

To provide mechanical protection for cables and wires

What should be included in the building specifications when constructing a control office?

Distributing systems for communication wires

Why should facilities for provision of communication wire be made during construction of the building?

To enable concealment of cables and wires

What is the primary function of the Local Telephone Equipment (LTE)?

To provide 20 local telephones at Head Quarter.

Where is the Control Room Equipment (CRE) typically located?

At the controller's desk.

What is the purpose of the Test Room Equipment (TRE)?

To carry out maintenance and testing functions on way station equipment.

What is the maximum capacity of a Multi Telephone Way Station Equipment (MTWE) unit?

4 control telephones.

What is the purpose of the Three Way Amplifier (TWA) unit?

To enable more than 4 control telephones at a way station.

What type of cable is used to connect a Multi Telephone Way Station Equipment (MTWE) unit to the VF channel from the PD Mux on the OFC system?

4-wire cable.

What is the type of telephone instrument connected to a Multi Telephone Way Station Equipment (MTWE) unit?

Two-wire Dialing Control Telephone (TDCT) with a numeric dial.

What is the typical location of the Multi Telephone Way Station Equipment (MTWE) unit?

At every way station.

How often should the line loop resistance be measured?

Once every year

What is the acceptable disparity between each limb of the loop resistance?

5% of normal calculated value

What is the purpose of using a test set with an audio oscillator in periodic tests?

To give a variable output from -10 dB to +10 dB with reference to 1 milliwatt across 600 ohms

What is the purpose of the test panel in the control office?

To facilitate independent testing of control circuits with way station equipment or control office equipment

What is the purpose of the megger in the control office?

To carry out insulation tests on internal wiring and external lines

How often should the protection path for Control Circuits of BSNL/RAILTEL be checked?

Daily

What is the function of the test oscillator in the control office?

To carry out measurement of line transmission loss and equipment insertion loss

What should be done to defects noticed during periodic tests?

Rectify them on the spot and retest

Where should the results of periodic tests be recorded?

In all of the above

Why is proper decoding of the set code of the equipment important?

To ensure correct actuation of buzzer/loudspeaker ring back and LED on the control telephone

What is the purpose of cleaning and proper termination of wires on the terminals on the rosette and CT box?

To prevent equipment failure due to poor connections

How often should joint testing of Long Haul network protection path with NOC (Railtel) be done?

Once every three months

Why should circuits be periodically tested by the inspector incharge?

To check the condition of inside wiring in control offices and way-stations

What is the benefit of having NMS along with associated equipment in the telecom control room?

To ease of operation, testing, and management

What should be checked during maintenance of control office equipment?

All of the above

What is the purpose of the test oscillator with a dB meter?

To carry out measurement of line transmission loss and equipment insertion loss

Study Notes

Local Telephone Equipment (LTE)

Provides 20 local telephones at Head Quarter

Multi Telephone Way Station Equipment (MTWE)

Provided at every way station
Connected to VF channel from PD Mux on OFC system by a 4-wire cable
Allows maximum 4 control telephones at a way station

Three Way Amplifier (TWA)

Used when the number of telephones required at a way station is more than four
Allows one more MTWE to be provided at a way station

Two-Wire Dialing Control Telephone (TDCT)

Standard telephone instrument with a handset and a numeric dial
Connected to MTWE with a twisted pair having a loop resistance of less than 1200 Ohm
Has a 16-key DTMF keypad for calling 99 stations with two push-button operation
Additional buttons for special functions:
- Push button 'G' for general call for calling stations simultaneously
- Push button LR for extending long ring at way stations
- Push button 'RT' for repeating last transmitted station code
- Push button 'RS' to reset the system
- Push button 'RC' for row/column frequency check
- Push button 'DL' for cancellation of code
Visual indications for "System O.K", "Display of station code", and "power ON" indication

Control Room Equipment (CRE)

Provided on the controller's desk
Allows the controller to selectively call any way station or any local telephone, TDCT of any way station and speak to it

Test Room Equipment (TRE)

Provided in the test room for carrying out maintenance and testing functions on way station equipment

CCEO System

Advanced equipment connected to traditional control communication system on OFC
Main equipment kept in OFC hut itself
Works only on standard telecom supply (-48V DC)

Way Station Equipment

Consists of DTMF decoder, voice communication equipment, and 2-wire/4-wire desk type control telephone
DTMF decoder can be assigned any DTMF station code/group code selectable with DIP switches

Intercommunication Between Local Telephone and Control Circuit

Allows important officials served by the local telephone exchange to gain access to control circuits with or without the assistance of an operator
Interconnection shall not affect the performance of the control circuits from the point of view of signaling or speech

Maintenance Instructions

DUAL TONE MULTI FREQUENCY CALLING SYSTEM:
- CONTROL OFFICE EQUIPMENT:
  - Check proper functioning of group codes A, B, C, and D
  - Check long ring - LR, general call, and special purpose keys
  - Check all visual indications provided on equipment
- WAY STATION EQUIPMENT:
  - Check proper functioning of all station codes including special codes
  - Check DTMF signaling code level between 0 dBm to -7 dBm across a load of 600 ohms
  - Check row/column DTMF frequency by pressing the 'RC' button and shall be within specified limits

Local Telephone Equipment (LTE)

LTE provides 20 local telephones at Head Quarter.

Multi Telephone Way station Equipment (MTWE)

MTWE is provided at every way station and connected to the VF channel from the PD Mux on OFC system by a 4-wire cable.
It allows connection of up to 4 control telephones at a way station.

Three Way Amplifier (TWA)

TWA is used when more than 4 telephones are required at a way station, exceeding MTWE's capacity.
It enables connection of an additional MTWE at a way station.

Two-Wire Dialing Control Telephone (TDCT)

TDCT is a standard telephone instrument with a handset and numeric dial.
Each TDCT is connected to MTWE with a twisted pair having a loop resistance of less than 1200 Ohm.

Control Room Equipment (CRE)

CRE is provided on the controller's desk.
It enables the controller to selectively call any way station or local telephone, TDCT, of any way station and speak to it.

Test Room Equipment (TRE)

TRE is provided in the test room for maintenance and testing functions on way station equipment.

Control Office Layout

Equipment producing noise during operation should be located in a different room outside the control office.
Batteries, especially secondary cells, should be located in a separate room outside the control office.
The test room should be located close to the control office to enable prompt attention to faults.
The test room should have enough floor area to accommodate the test panel, maintenance spares, tables, and chairs for the maintenance staff.

Inside Wiring in Control Office

Wire runs to the controller's table should be terminated on a terminal strip of approved type.
Separate conduits or runways should be provided for communication and high-voltage electric wires.
Mechanical protection should be provided for cables and wires to achieve trouble-free service.

Testing of Control Circuits

Test panel should be installed in all control offices for the use of maintenance staff.
Test panel should facilitate disconnection of control office equipment, patching facilities, monitoring of circuits, and provision for a universal calling device.
Test oscillator with a dB meter should be provided to carry out measurement of line transmission loss and equipment insertion loss.
100-volt megger should be provided to carry out insulation tests on internal wiring and external lines.

Periodic Tests

Control circuits should be periodically tested to check the condition of inside wiring, external lines, and equipment.
Circuits transmission loss should be measured once every year.
Line loop resistance should also be measured once every year.
Results of tests should be entered in a register maintained at each sectional inspector's headquarters and in the office of DSTE/Sr.DSTE.
Any defects noticed during tests should be rectified on the spot and the circuit retested before proceeding with further tests.

This quiz covers various types of equipment used in telecommunications, including Local Telephone Equipment, Multi Telephone Way Station Equipment, and Three Way Amplifier.

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