17-11-2012, 12:08 PM
REPORT ON SIGNAL & TELECOMMUNICATION
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INTRODUCTION
HISTORY
The first railway on Indian sub-continent ran over a stretch of 21 miles from Bombay to Thane.
The idea of a railway to connect Bombay with Thane, Kalyan and with the Thal and Bhore Ghats inclines first occurred to Mr. George Clark, the Chief Engineer of the Bombay Government, during a visit to Bhandup in 1843.
The formal inauguration ceremony was performed on 16th April 1853, when 14 railway carriages carrying about 400 guests left Bori Bunder at 3.30 pm "amidst the loud applause of a vast multitude and to the salute of 21 guns."
The first passenger train steamed out of Howrah station destined for Hooghly, a
Distance of 24 miles, on 15th August, 1854. Thus the first section of the East Indian Railway was opened to public traffic, inaugurating the beginning of railway transport on the Eastern side of the sub-continent.
In south the first line was opened on Ist July, 1856 by the Madras Railway Company. It ran between Veyasarpandy and Walajah Road (Arcot), a distance of 63 miles. In the North a length of 119 miles of line was laid from Allahabad to Kanpur on 3rd March 1859. The first section from Hathras Road to Mathura Cantonment was opened to traffic on 19th October, 1875.
These were the small beginnings which is due course developed into a network of railway lines all over the country. By 1880 the Indian Railway system had a route mileage of about 9000 miles.
STRUCTURE
Indian Railways has one of the largest and busiest rail networks in the world, transporting over 18 million passengers and more than 2 million tones of freight daily. It is the world's largest commercial or utility employer, with more than 1.4 million employees. The railways traverse the length and breadth of the country, covering 6,909 stations over a total route length of more than 63,327 kilometers (39,350 mi). As to rolling stock, IR owns over 200,000 (freight) wagons, 50,000 coaches and 8,000 locomotives. Indian Railways operates about 9,000 passenger trains and transports 18 million passengers daily across twenty-eight states and one union territory.
Sikkim, Arunachal Pradesh and Meghalaya are the only states not connected by rail. The passenger division is the most preferred form of long distance transport in most of the country.
Indian Railways is divided into zones, which are further sub-divided into divisions. The number of zones in Indian Railways increased from six to eight in 1951, nine in 1952, and finally 16 in 2003. Each zonal railway is made up of a certain number of divisions, each having a divisional headquarters. There are a total of sixty-seven divisions.
Each of the sixteen zones, as well as the Kolkata Metro, is headed by a General Manager (GM) who reports directly to the Railway Board. The zones are further divided into divisions under the control of Divisional Railway Managers (DRM). The divisional officers of engineering, mechanical, electrical, signal & telecommunication, accounts, personnel, operating, commercial and safety branches report to the respective Divisional Manager and are in charge of operation and maintenance of assets. Further down the hierarchy tree are the Station Masters who control individual stations and the train movement through the track territory under their stations' administration. (see fig.)
COMMUNICATION
Today, it would be difficult for us to imagine life without the telephone. World-wide, there are some 750 million telephone connections in use and the number of Internet users has exploded in the last few years. By the year 2010, according to a forecast from Nortel, there will be almost 475 million Internet users and the number of services provided will also grow rapidly.
To control the working of employers and to ensure the proper running of trains, we need fast and reliable means of communication. To ensure this we have “SIGNAL & TELECOMMUNICATION” department. They provide path and sources (Equipments) to communicate. Their work is to provide the line and maintain it.
Railway communication provides uninterrupted motion of trains. Due to faster means of communication there is increase in the efficiency and greater control. To communicate we require some media, which carry our signal. In past, railway use iron wires, copper wires or aluminum wires for signal propagation. Now, a day we railway use Microwave, Quad cable, Optical Fiber cable & satellite communication.
The explosion in demand for network bandwidth is largely due to the growth in data traffic, specifically Internet Protocol (IP). Leading service providers report bandwidths doubling on their backbones about every six to nine months. This is largely in response to the 300 percent growth per year in Internet traffic, while traditional voice traffic grows at a compound annual rate of only about 13 percent.
ROUTER:
A router is a device that interconnects two or more computer networks, and selectively interchanges packets of data between them. Each data packet contains address information that a router can use to determine if the source and destination are on the same network, or if the data packet must be transferred from one network to another. Where multiple routers are used in a large collection of interconnected networks, the routers exchange information about target system addresses, so that each router can build up a table showing the preferred paths between any two systems on the interconnected networks.
A router is a networking device whose software and hardware are customized to the tasks of routing and forwarding information. A router has two or more network interfaces, which may be to different physical types of network (such as copper cables, fiber, or wireless) or different network standards. Each network interface is a small computer specialized to convert electric signals from one form to another.
SWITCH:
In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.[1][2] The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts. Each set of contacts can be in one of two states: either 'closed' meaning the contacts are touching and electricity can flow between them, or 'open', meaning the contacts are separated and nonconducting.
A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically-operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece. Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in a process and used to automatically control a system. For example, a thermostat is an automatically-operated switch used to control a heating process. A switch that is operated by another electrical circuit is called a relay. Large switches may be remotely operated by a motor drive mechanism. Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be pad-locked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock.
Very small Aperture terminal: (V.S.A.T.)
Very small aperture terminal. It is small satellite terminal used for digital communications. VSAT is a new technology recently introduced in Indian Railway. It is already in by television news channels for live news telecast. A hi-tech satellite based VSAT hub system aimed at strengthening communication facilities across railways network was launched by the Indian Railways firslty in New delhi. The system will provide vast number of voice, data and video applications and data connectivity to remote locations of Railways freight operating information system.
GENERAL DEFINITION:
A small earth station, usually less than 2.4 meters, used for satellite communications. . Term describes a ground unit to receive (or send) data via satellite. Generally consists of an ODU (Outdoor Unit) and IDU (Indoor Unit). A Very Small Aperture Terminal (VSAT), is a two-way satellite ground station with a dish antenna that is smaller than 3 meters. Most VSAT antennas range from 75 cm to 1.2 m. Data rates typically range from 56 Kbit/s up to 4 Mbit/s. A Very Small Aperture Terminal (VSAT), is a two-way satellite ground station or a stabilized maritime Vsat antenna with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m.