A Seminar

ONPractical training

Taken at

“ AKASHVANI, NEW DELHI ”Submitted in partial fulfillment for the award of the degree

BACHELOR OF TECHNOLOGYIN

Electronics & communication     ( 2009-2010)  SUBMITTED TO: SUBMITTED BY:Mr. YOGESH BHOMIA ASHISH PANDEY(HOD) ROLL NO: 10ECE, A.I.ET   DEPARTMENT OF ELECTRONICS & COMMUNICATION ARYA INSTITUTE OF ENGINEERING & TECHNOLOGY JAIPUR

AKASHVANI, A.I.R some facts

All India Radio is the first and the foremost radio broadcaster of the nation.

AIR today has a network of 232 broadcasting centers with 149 medium frequency(mw), 54 high frequency (SW) and 171 FM transmitters.

The coverage is 91.79% of the area , serving 99.14% of the people in the largest democracy of the world.

AIR covers 24 languages and 146 dialects in home services. In external services, it covers 27 languages; 17 national and 10 foreign languages

Causes to choose AIR as training provider are :

To get a practical knowledge about various communication related theory.

To get a practical domain view of what I studied till now. To gain an insight in topics like Sat. Comm. ,Broadcasting,

uplink chain, downlink chain……. A chance to know about practical implementations of A.M &

F.M signals. To analyze various modulation techniques. To get an overview of networking between different fields of

engineering.

IMPORTANT ELEMENTS OF A.I.R

The studio and related components, The server room, and The Satellite communication.

In a general view we can call that, the signals i.e. various programs are produced at the studios and then transmitted through the satellite communication medium ,in-between them server room provides the important operations.

The studio & its Interconnections

Typical diagram of a console

A Control booth controlling the studios and signals in digital format to next level.

Master Switching Room

Monitoring in MSR

Flow of information within the network

Studios

Control Booth

Master Switching Room

Satellite Transmitter

Link (STL)

Server Room If studios are the heart of New Broadcasting House then

Server room is the brain of New Broadcasting House. All the 150 computers in the entire building are

connected to the server room as clients. All the clients are not connected to the central switch

directly. Instead, many mini LAN rooms have been provided on various floors of the building to which these clients are connected.

These rooms in turn are connected to the central switch. There are 7 such mini LAN rooms. Central switch are connected to LAN room by OFC while clients are connected to LAN rooms by RJ-45 lines.

Special lease line provided by VSNL.

Satellite Communication

Satellite Communication is the outcome of the desire of man to achieve the concept of global village. Penetration of frequencies beyond 30 Mega Hertz through ionosphere force people to think that if an object (Reflector) could be placed in the space above ionosphere then it could be possible to use complete spectrum for communication purpose.

This is only means which can provide multi access two way communication. The cost of transmitting information through satellite is independent of distance involved. Satellites are capable of handling very high bandwidth. Normally any satellite can

accommodate about 500 MHz in C Band. For example the bandwidth of INSAT-I is 480 MHz in C Band and 80 MHz in S Band. INSAT-II has a bandwidth of 720 MHz in C Band and 80 MHz in S Band.

It is possible to provide large coverage using satellite. For example Geostationary satellite can cover about 42% of earth surface using global beam.

Satellite can provide signal to terrestrial uncovered pockets like valleys and mountainous regions.

Satellites can provide uniform signals for urban areas or rural areas unlike terrestrial service which will lay more signal to urban areas (where the transmitters are located) as compared to rural areas.

It is easy and quicker to establish new satellite link using SNG terminal or VSAT terminal from any point to any other point as compared to any other means.

 

STUDIO TRANSMITTER LINKS AT A.I.R

The high quality sound programs from AIR studio centers are normally transported to the AIR transmitting centers with the help of Department of Telecommunications land lines. These gave way to VHF-FM transmit/receive systems in some of the AIR centers.

Now, AIR has introduced the new generation microwave studio-transmitter link (STL) for better reliability and quality.

AIR is having three types of STL called STL-01, STL-02 and STL-05. The numbers 01, 02 and 05 describe the number of base band (50 Hz - 15 kHz) channels that could be transported

Block Diagram for STL Tx

The STL transmitter essentially consists of eight

section A single audio input transformer (LT 11) which splits the audio input into two

equal audio outputs for (1+1) system.  The base band unit (1+1) consisting of a music amplifier AT 01, and a base

band interface unit GT 01 which is a 15 kHz low pass filter.  The radio frequency unit (1+1) which generates the carrier, FM modulates

and generates microwave (RF) power. (L1 TR SR04 A/B). An antenna change over unit which selects one of the (1+1) RF outputs for

feeding to the antenna. (L1RF-Tx). A low loss cable connected to a microwave dish antenna at suitable height

above the ground. Two identical (1+1) dc-dc power supplies. (DC-11). Two identical (1+1) monitoring (CM-01) and Alarm inter-face units. (AI 01). One each of logic (LO 11) and parameter control card (PC 02) which

selects one of the RF outputs to be connected to the transmitting antenna.

RADIO NETWORKING TERMINAL (RNT)

The various All India Radio stations spread throughout the nation are required to relay certain programs which are originating from Delhi. Similarly there are certain programs which are originating from capital stations are relayed by the other stations in that region.

In order to link Delhi and capital stations with other AIR stations, Radio Networking through INSAT is not only cost effective but also provide the good technical quality as compared to DOT lines and SW linkage.

The Radio Networking terminal located at AIR stations receive S-Band or C Band transmissions.

The programs thus received after processing are fed to the transmitter for broadcast purposes in local area. Thus RNT acts as the ground terminal for satellite signal reception.

Block Diagram of S-Band Receive Terminal

Frequency ranges used

Down link frequencies :

S-Band=2.5 to 2.7 GHz

C-Band=3.7 to 4.2GHz

Ex-C Band=4.5 to 4.8 GHz

Uplink frequencies :

S-Band=Down link freq. + 3300 MHz

C-Band/=Down link freq. + 2225 MHz

Conclusion

In this way we got an idea about how different elements work together for radio broadcasting and reception.

We got a chance to learn about satellite communication.

To and get an implemented view of various electronic devices and principles.

Any queries ?

“Feel free to ask”