S. K. CHAUDHARY EDUCATIONAL TRUST’s

SHANKARA INSTITUTE OF TECHNOLOGY

KUKAS, JAIPURDEPARTMENT OF ELECTRONICS AND COMMUNICATION

  

 

SESSION-(2012-2013)

PRESENTATION ON-PRASAR BHARATI(AKASHVANI),JAIPUR

 

PRESENTED TO:- PRESENTED BY:-

Mr. RAJESH KANWADIA SACHIN KUMAR JHA

Ms. SHWETA AGARWAL B.TECH.VII SEM

(ASSISTANT PROFESSOR ) ROLL NO:-09ESIEC104

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ACKNOWLEDGEMENTI am very glad to present this presentation on various communication

method’s in prasar bharati “ akashvani”.

I express my special thanks to Mr.ATUL GUPTA for providing me the opportunity for internship in AKASHVANI Jaipur. I even express my gratitude towards Mr.HARISH PATSAARIYA my training coordinator and Mr. SUPRIYO BANARRJI(technical engineer).

I wish to express my thanks to Mr. ASHUTOSH MISHRA (H.O.D. of ECE Department), Mr. RAJESH KANWADIA (ASSISTANT PROFESSOR), Ms.SHWETA AGARWAL (ASSISTANT PROFESSOR) and all the faculty of SHANKARA INSTITUTE OF TECHNOLOGY who helped me providing us all the resources required for such a task .

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CONTENTSINTRODUCTION OF A.I.RSTUDIO ACOUSTICOUTSIDE BROADCASTRADIO NETWORKING TERMINALWAVE PROPAGATIONALLOCATION OF FREQUENCYSATELLITE COMMUNICATION

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INTRODUCTION The operations of All India Radio began formally in 1936,

as a government organization ,with clear objective to inform,educate and entertain the masses.

When India attained Independence in 1947,AIR had a network of 6 stations and a complement of 18 transmitters.The coverage was the 2.5% of the area and just 11% of the population

AIR today has network of 232 broadcasting centers with 149 medium frequency,54 high frequency and 171 FM transmitters.The coverage is 91.79% of the area.

AIR covers 24 languages and 146 dialects in home services.In external services It covers 27 languages;17 national and 10 foregion languages.

ALL INDIA RADIO is one of the largest radio networks in the world. The headquarters is at the Akashvani haven New Delhi.

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STUDIO ACOUSTIC Acoustic treatment is provided in studios, control rooms, and

other technical areas in order to achieve the acoustic conditions . Reflected waves can create echo effect in the room. To achieve

the desirable effects of the reflected sound, the dimensions and shape of the room are decided with due care and acoustic treatments are also provided on the various surfaces.

The ‘hanging-on’ of the sound in a room after the exciting signal has been removed, is called ‘reverberation’. So the reverberation time is the main cause ,it damages the causticity of room. Too much of reverberation may impair the quality of programmed.

Remedy: Acoustic absorbers are provided on the inner surfaces of the room to achieve optimum R/T characteristics

Porous Materials: Mineral wool, glass wool, etc. are members of this class. These materials are very good absorber and are most effective in mid and high frequencies.

 Design of room acoustic is calculated by eyeing's formula.

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OUTSIDE BROADCAST(OBs) Major events that occur at different parts of a country, such as

sports events, cultural and national events and other such programmed that originate from outside the broadcast studio are covered as Ob.

Live broadcast and spot recordings are example’s of Obs. Different types of equipments used in OBs is OB amplifier,

Microphones, tape recorders. OB amplifier is a portable mixing unit. Normally four low level

microphone inputs and one high level input from a PTR or UPTR, can be mixed and controlled by this unit.

A tone generator providing three spot frequencies (75 Hz, 750 Hz or 1 kHz, 7.5 kHz) is incorporated in this unit so that the frequency response of the telephone line on which the programmed is fed can be quickly checked at CR end and equalization done

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MicrophoneOmni

directional microphone

• Omni-directional microphones are sensitive to sound from all directions • preferred in studio

recordings.

Radio/wireless

microphone

• radio microphones are used in locations where long cable distances are involved or where it is not possible to lay the cable.

Use of wind shields

• When microphones are used out of doors, in windily conditions, wind shields are used

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Tape recorders Spot interview and glimpses of the various events

taking place in a particular city, are covered by spot recordings done with Ultra Portable Tape Recorders (UPTRs) and cassette tape recorders.

They are light weight battery operated recorders and are provided with only headphone monitoring facility in order to avoid the drain on the batteries.

Generally two sets of either dry cells or chargeable cells are taken for the OB recordings, so that at least 30 minutes of recorded programmed is made feasible

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RADIO NETWORKING TERMINAL The analog/digital radio networking receive terminal is used to receive

satellite radio signal to feed the relay transmitter or for monitoring purpose. The basic system consists of a parabolic dish antenna with feed, outdoor units (LNBC).

Composition of radio networking terminal 3.66m PDA LNBC LNBC change over Coaxial cable Cable assembly-3 core Digital Audio Receiver with L Band input Analog SCPCreceiver with L Band input Cable assembly N (M) to F (M)  

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Technical specification

Specification

Of

antenna

Specification

Of

L.N.B.C

Specification

Of

Analog receiver

Specification of

digital receiver

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Specification of antenna Type and Size :PDA (Perforated aluminum alloy)3.66m Receive Band : S - Band Frequency Band : 2.5-2.7 GHz Type of Mount : Elevation over Azimuth V.S.W.R : 1.3 Max. Wind Speed Operational : 75 Kmph Survival : 160 Kmph Feed Impedance : 50 0

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Specification of LNBC

Input Frequency : S-Band (2.5-2.7 GHz)

Output Frequency : L-Band (950-1150 MHz)

Noise Temperature : < 45 K Conversion Gain : >50 dB Gain Flatness : < 2 dB p-p in

any 40 MHz Band

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Specification of Analog receiver

Input Frequency : 950-1450 MHz Input Impedance : 75 Transponder Tuning : 1-24 I.F Frequency Tuning : 50-90 MHz Tuning Steps : 10 KHz Demodulation : FM De- Emphasis : 75 sec Audio Expanding : 1:2 Audio Distortion : < 1% Audio Frequency Response : 30 Hz-15 KHz S/N : 65 dB Audio Output Impedance : 600

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Specification of digital receiver

Input Frequency : 950-1450 MHz Input Level : -30 to –70 dBm Input Impedance : 75 De-modulation : QPSK Mode : Mono, dual Mono, Joint Stereo Receiver Eb/No (10-5 BER) : 6.5dBHz (Threshold) Audio Coding/Compression : ISO MPEG-1 Layer II Audio Program Channel Rate : 128, 192, 256 Kbps Audio Output Level : +9 dBm (max) adjustable Audio Distortion : < 0.5 % ( at +9dBm O/P) Frequency Response : +/- 1.0 dB (20 Hz – 20 KHz) S/N : Better than 75 dB Cross talk : Better than 75 dB Audio Output Channel : L, R, L+R [8]  

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BLOCK SCHEMATIC OF S-BAND ANALOG/DIGITAL R N TERMINAL

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Ground wave Practical importance at broadcast and lower frequencies,

guided along the surface of the earth. This mode of propagations exist when the transmitting and

receiving antennas are close to the surface of the earth. It is produce by the vertical antennas. It is used upto 2MHz frequency. It is also called medium wave propagation. Surface wave depends not only on frequency but power also. Transmission can be increase by increasing the power also.

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SKY WAVE OR IONOSPHERIC PROPAGATION

The range of sky wave propagation is 2to 30MHz. It is also known as short wave & point to point

communication. In this comm.E.M wave reflects from the ionosphere layer Global communication is also possible with the multiple

reflections of sky waves.I O N O S P H E R E

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SPACE WAVE PROPAGATION It is used at VHF,UHF and microwave frequencies. Frequency used is 30MHz to 300MHz. E.M waves from the transmitting antenna reach the receiving

antenna either directly or after reflections from ground in the earth troposphere.

Troposphere layer extends 16 km from the earth surface It is also known as LOS propagation,in LOS transmitting and

receiving antenna can see each other. The curvature of earth and the height of the transmitting and

receiving antennas determines max. range of communication.

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TROPOSPHERIC SCATTER PROPAGATION

In this wave propagate much beyond the line of sight propagation through the forward scattering.

It is also known as troposcatter The communication range is 160km to 1600 km

by using high power transmitter. Range of frequency is 100MHz to 10GHz. In this two antennas are so pointed that their

beams intersect midway between them above the horizon.

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VIRTUAL HEIGHT As the electromagnetic wave is refracted, it is bent

down gradually, rather than sharply. However, below the ionised layer, the path of the incident and reflected rays is exactly same as if reflection has taken place from a surface located at a greater height called the Virtual Height of this layer. Once the Virtual Height is known, the angle of incidence required for the wave to return to the ground at a selected spot can be calculated easily.

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FADING Fading is the fluctuation in signal strength at a

receiver, and may be rapid or slow, general or frequency selective. Fading is due to interference between two waves which left the same source but arrived at the destination by different paths. Because the signal received at any instant is the vector sum of all the waves received, alternate cancellation and reinforcement will result, if there is a path difference as large as a half wave length. Fluctuation is more likely with smaller wavelengths, i.e., at higher frequencies.

Fading can be due to the occurrence of interference between the lower and the upper rays of a sky wave

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SATELLITE COMMUNICATION

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.

Advantages: Satellite can be used for two way communication or broadcast purpose with the covered area.

Satellites are capable of handling very high bandwidth. Normally any satellite can accommodate about 500 MHz in C Band

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

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Satellite Earth Station Uplink / Downlink Chain

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CONCLUSION Broadcasting in India is being a nation service constitute the most

powerful medium of mass comm..It play significant role as a medium of info & education. In the developing country of India through it’s broadcasting AIR seek to promote education, national integration & also develop various aspect of India culture. It also give timely assistance to public & gov. department by quick dissemination of info. During natural dimities.

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

I got chance to learn about satellite communication and got an implemented view of various device n principle.

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REFERENCE http://en.wikipedia.org/wiki/All_India_Radio http://en.wikipedia.org/wiki/Reverberation http://en.wikipedia.org/wiki/Microphone K.d prasad,Antenna and wave propagation,third

edition2010-2011,page n.1102 topic 11.4,11.6,11.7,11.12,11.16.5

K.d prasad, Antenna and wave propagation,third edition2010-2011,page n.685 topic n.8.1

http://www.cs.wustl.edu/~jain/cis788-97/ftp/satellite_nets.pdf

Satellite communication, chapter 13,STI(T) publication,page n. 169,002/IC(G)2006.

ANYQUERY