Railway Telecommunications Systems Quiz

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Questions and Answers

What is required to ensure the proper functionality of earth electrodes?

Install additional earth electrodes for redundancy

Verify the connectivity of ground wires to each equipment (correct)

Measure the voltage output of each equipment

Conduct software testing prior to hardware testing

Which document is NOT part of the required documentation for indoor equipment?

Installation manual for equipment

Subscriber wise Telephone Directory (correct)

Wiring diagram for power panel

Operation and maintenance manual

Which tool is essential for crimping connections in cabling?

Cable Fault Locator

Krone Extractor

Crimping tool (correct)

Screw driver

What type of measuring instrument is required to test line conditions?

Line tester Signup and view all the answers

What type of documentation provides the layout and connection details for each rack?

Rack layout plan Signup and view all the answers

Which types of phones are connected through the exchange?

DTMF phones Signup and view all the answers

What type of signaling is NOT mentioned as used in the exchange?

Digital signaling Signup and view all the answers

What is the capacity of the railway telephone number system?

8 digits long Signup and view all the answers

Which of the following statements is true regarding the architecture of the exchange?

Exchange with capacity higher than 128 ports can be designed. Signup and view all the answers

What is the primary benefit of the non-blocking type TDM exchange?

It allows multiple connections without interference. Signup and view all the answers

In the boss-secretary configuration, what happens if the secretary's phone is unanswered?

The call gets transferred to the boss. Signup and view all the answers

How many ports have been provided for high-speed connectivity between exchanges?

2 Mbps Signup and view all the answers

What feature is available in divisional/zonal IP exchanges?

Audio conferencing Signup and view all the answers

Where should the Main Distribution Frame be installed?

In a separate room Signup and view all the answers

What is the preferred material for the earth connection along the frame?

Copper strip Signup and view all the answers

What temperature range should be maintained in the exchange equipment room?

22-25 degree C Signup and view all the answers

What should be done with underground ducts for cable entry?

Fill with sand and plaster the top Signup and view all the answers

What is the primary language for the man machine communication (MML)?

Common English Signup and view all the answers

What should not happen when executing any command in the system?

Command should cause malfunction Signup and view all the answers

What should be ensured when commands contain errors?

It should not stop or unduly alter system configuration Signup and view all the answers

Why is continuous testing of the system important?

To allow system quality check and fault indication Signup and view all the answers

What is a requirement for railway exchange subscribers to join a video conference meeting?

They can join using only audio if required. Signup and view all the answers

Which component is NOT part of the exchange system?

Video conferencing hardware Signup and view all the answers

What type of power supply is required for IP exchanges?

Either 230V AC or -48V DC Signup and view all the answers

What should be available to ensure interaction with the Exchange?

A VDU, keyboard, and printer with a PC Signup and view all the answers

What feature must the IDF include for effective safety?

Disconnecting type connectors Signup and view all the answers

What type of charger must be provided for a -48V DC power supply?

SMPS (Switch Mode Power Supply) charger Signup and view all the answers

How should outdoor cables be managed within the exchange system?

They must be terminated on a rack forming the MDF. Signup and view all the answers

What must be ensured for the IDF to function effectively?

Testing should occur only from the MDF. Signup and view all the answers

What is the maximum traffic calculated for trunk lines in the railway exchange?

0.8 Erlang/Trunk line Signup and view all the answers

What is NOT a requirement for the All India Intercom for railway officers?

Boss-secretary configuration Signup and view all the answers

Which configuration is recommended for redundancy in IP exchange servers?

1+1, active-passive or active-active configuration Signup and view all the answers

What must be ensured in a closed numbering scheme for railway divisions?

Uniform 5-digit number across the zonal Railway network Signup and view all the answers

What type of server should the IP exchange be installed on?

Common off-the-shelf hardware Signup and view all the answers

What is the preferred method of securing the network?

Securing the network instead of using secure protocols Signup and view all the answers

What is the purpose of logging important events in the IP exchange?

Assist in failure analysis Signup and view all the answers

What facility should be provided for interconnection to the PSTN exchange?

Direct Inward Dialing (DID) and Direct Outward Dialing (DOD) Signup and view all the answers

What is required of the protective device in terms of voltage rating?

It should be only slightly above the exchange fed voltage levels. Signup and view all the answers

What kind of fault detection capability is required from the system?

It should monitor performance and detect, locate, and report faults. Signup and view all the answers

What is the primary purpose of the protective devices in the IDF?

To promptly isolate equipment in cases of voltage or current overload. Signup and view all the answers

Which of the following is a requirement for the current/voltage rating of the protective device?

It should not produce noticeable heat in the main components. Signup and view all the answers

What type of maintenance is required on a daily basis?

Checking the battery set voltage and UPS/charger output. Signup and view all the answers

What is the benefit of having self-restoring protective devices?

They automatically recover from operational faults. Signup and view all the answers

What must be avoided in the operation of protective devices?

Decreased efficiency in speech or signaling circuits. Signup and view all the answers

How often should individual cell voltage and load tests be performed on batteries?

Fortnightly. Signup and view all the answers

Study Notes

Railway Exchanges

Railway exchanges use automatic, electronic, and digital technologies, including IP technology. New exchanges must use IP technology.
Session Initiation Protocol (SIP) is used for IP telephony. Exchange software runs on standard servers.
Open-source VoIP software is typically used for integration and cost-effectiveness.
IP exchanges used in railway telecommunications must adhere to open standards to ensure interoperability. They should support third-party phones and include licensing if necessary.
Video telephony is supported by the system.
IP telephony integrates with existing LAN infrastructure, using a separate voice VLAN for prioritized voice traffic over general data.

Intercom Systems

Intercom facilities can be independent exchanges or use features of main exchanges. Optimizing intercom systems is a goal.

Gateways

FXS gateways interface with FAX machines, analog phones, and other analog telephony equipment, either centralized or distributed.
IP phones use PoE (Power over Ethernet) for power and have two Gigabit Ethernet ports. This provides direct LAN connectivity to the PC and eliminates the need for a separate LAN connection in each room.

Connectivity

SIP trunks/PRI (Primary Rate Interface) gateways connect to NGN (Next Generation Network) or PSTN (Public Switched Telephone Network). FXO (Front Exchange Office) devices are used if PSTN PRI connectivity is unavailable.
VoIP phones used in exchanges must meet open standards. These phones will work with third-party exchanges and SIP servers.

###Telephone Sets

Subscriber telephone sets can be analog or IP (including softphones and video phones); IP phones should support SIP.
Analog phones should have CLI (Command Line Interface) functionality

Divisional and HQ Exchanges

Divisional and headquarters exchanges connect to NGN using either PRI(Primary Rate Interface) or SIP trunks. Subdivisional exchanges can also connect to NGN if feasible. Multiple paths and media gateways in the NGN network improve reliability.
Sub-divisional exchanges connect to divisional exchanges using PRI or SIP Trunks in a mesh or ring configuration. Divisional IP exchanges can be used where possible.
NGN networks handle STD (subscriber trunk dialing) calls. Each headquarters and divisional exchange gets a unique railway STD code.

Numbering Scheme

Railways establish a closed numbering scheme of 5 digits, making exchanges nationally accessible via their designated division STD codes.

Intercom, Maintenance and System Requirements

A Railway-wide intercom is available for senior officers.
An IP exchange server, with redundant power supplies, offers active-active or active-passive redundancy.
Remote maintenance centers support remote management of the exchange.
The system can function as a local, tandem, transit, or combined exchange.
The system supports video telephony.
Railway telephone numbers are five digits plus an allocated STD code (Three digits including the leading zero).

Protective Devices

Surge protection devices (on IDF, Intermediate Distribution Frames) prevent damage from excess voltage or current. Their voltage rating is slightly above the exchange's voltage levels. These devices should isolate the equipment. The devices must be self-restoring type
Protection arrangement on IDF and MDF (Main Distribution Frame) are required to ensure that the service is not affected.

Maintenance Procedures

Daily, monthly, quarterly, and six-monthly routine maintenance tasks include testing of batteries, cables, and other components.
Yearly, comprehensive wiring and insulation checks are recommended.
Detailed documentation is required to assist in service and maintenance.

Exchange Components and Cabling

The system consists of hardware (e.g., racks, cables, and termination boxes), software, gateways and cables, and a power supply.
The system integrates test and measuring equipment.
Telecom equipment is to be provided with appropriate surge and lightning protection.
External cables and connectors must be appropriate for the environment and meet electrical safety regulations.
The system design includes protective arrangements to prevent against damages from faults or unexpected events.
An adequate number of tools and materials is recommended for maintaining and troubleshooting communication links.

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Description

Test your knowledge on railway exchanges, intercom systems, and gateways in telecommunications. This quiz covers key technologies such as IP telephony and the use of open-source software. Explore how these systems work together to enhance communication in railway operations.