Project Report on

Industrial and Field Exposure Training

June 2012 to 26 July 2012)

At

ALL INDIA RADIO, ALMORA

ALL INDIA RADIO, ALMORA

The motto of All India Radio is educating entertaining and informing people of this region.

A radio station with type one station facilities & 1KW MW transmitter was made on 15/6/1986 by Shri V.N.Gadgil.

This Radio station has a Control room, Receiving Room and other associated technical facilities.

Operative frequency of this station is 999 KHZ and coverage area of this station is 23 Km to 42 Km.

Introduction to AIR

Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible light.

Radio is based on wireless communication or satellite communication.

PRINCIPLE OF AIR

1. TRANSMITTING:

Step1. A Radio wave carries information signal.Step2. Signals are converted into electrical signals.Step3. A carrier wave is then produced from

the modulation.Step4. The wave is then amplified , and sent to the antenna.Step5. The antenna then converts signal into

an EM wave.

2. RECEIVING:

Step1. An antenna on receiving the signal send it to the receiver.

Step2. The receiver then converts the electrical signal and sends it to the

amplifier.

Step3. With the help of speaker/headphones jack

this is converted into a sound wave.

BASIC ELEMENTS USED IN AIR

1. MICROPHONES 2. COMPACT DISC AND PLAYERS3. AUDIO PROCESSOR4. CONSOLE TAPE RECODER (CTR)5. AUDIO AMPLIFIERS6. TRANSMITTER7. CAPTIVE EARTH STATION(CES)8. TRAVELING WAVE TUBE AMPLIFIER

(TWTA)

1.MICROPHONES :

It converts sound waves into electrical signal

When sound waves strike a microphone’s diaphragm, they cause it to move within an electro-magnetic field

This electro-magnetic field in turn creates a variance in an electrical current.

This signal is then transmitted to output device which reproduce the original sound waves and reinforce it.

Special Microphones:

Combined Microphones. Lip Ribbon Microphones. Lapel Microphones. Contact Microphones. Gun Microphones. Cordless Microphones.

2. COMPACT DISC AND PLAYERS

It is a digital audio storage medium. It stores 0 & 1 as a digital medium. 1 is stored at the pits and 0 is stored at

‘FLATS’ or ‘no-pits’. In the disc medium optical methods are used

for writing out recoding process.

3.AUDIO PROCESSOR :

Analog audio signal is converted into digital signal by ADCS with 16 linear quantization at a sampling frequency rate of 44.1 KHz.

FUNCTIONS OF AUDIO PROCESSORS Prevent over modulation as much possible and

minimize it when it occurs.

Compensate for non-linear transmitter, more

common with medium wave and short wave

broadcasting.

Adjust overall loudness to desired level.

Correct errors in audio levels.

4.CONSOLE TAPE RECODER(CTR):

Console tape recorder is an audio storage device.

5.Audio Amplifiers

An audio amplifier is an electronic

amplifier that amplifies low-power

audio signals.

It performs tasks like pre-

amplification, equalization, tone control,

mixing effects.

AUDIO AMPLIFIERS used in AIR Pre-Amplifier:

It is the first amplifier in the

broadcast chain.

The output from a microphone or

a pickup which is at very low level

is fed to its input

Programme Amplifier:

Programme amplifier provides second

stage of amplification.

The output obtained from the fader box

or mixing console is fed to the input of

this amplifier.

This amplifier gives a maximum output.

Monitoring Amplifier:

These Amplifiers are used as a boosting module for the signals.

Output from programme amplifier is not enough to drive the loudspeaker.

Therefore these amplifiers are provided to boost these signals further.

6.TRANSMITTER

Transmitter provides a power output of 1000 W on carrier. A medium wave antenna is used as a

transmitter. Almora station is provided with a 1KW

Medium Wave Transmitter operating on the frequency of 999 kHz.

7.CAPTIVE EARTH STATION(CES) CES are used to uplink its programme for

distribution in its Network through

satellite.

The programme up linked by the CES is

received by other AIR stations with their

radio networking terminals

8.TRAVELING WAVE TUBE AMPLIFIER

TWTA is an electronic device used to amplify radio frequency signals to high power.

Its operating frequencies range from 300 MHz to 50 GHz.

STUDIO CHAIN IN AIR STATION

1.BROADCAST STUDIO: It is an acoustically treated room

to give minimum noise level. Microphones, Turn Table, Tape

Disk, CD & are some equipments used in Broadcast Studio

2.STUDIO CENTER

Studio Center comprises of one and more studios

Recording Room: Equipment provided in recording room are

console tape recorded console tape decks, recording, dubbing panel having switches, Jacks and Keys.

Dubbing Room : Arrangement similar to recording room except

that as additional tape deck and mixer unit has been provided.

 Loudspeakers : Opposite function to microphone it converts

electrical signal into sound wave.

CONTROL ROOM:

 

Control room consists of control console. Control console is also known as

switching console.

MODULATION PROCESS

Modulation is a process of superimposing information on a carrier by varying one of its parameters (amplitude, frequency or phase).

Need for Modulation Antenna size can be reduced by modulating

the signal over higher frequency. To differentiate among transmissions (stations) Maximum to minimum frequency ratio can be

reduced to minimum by modulating the signal on a high frequency.

TYPES OF MODULATION

There are basically 3 types of modulation process.

Amplitude Modulation. Angle Modulation. Pulse Modulation.

SATELLITE

What is Satellite

NATURAL OR ARTIFICIAL OBJECT THAT REVOLVES AROUND A LARGER ASTRONOMICAL OBJECT, USUALLY A PLANET. THE MOON IS THE MOST OBVIOUS EXAMPLE.

SATELLITE SERVICES

FIXED SATELLITE SERVICE (FSS). Example: Point to Point Communication. MOBILE SATELLITE SERVICE (MSS).

• Example: Satellite Television/Radio• Also called Direct Broadcast Service (DBS).

BROADCASTING SATELLITE SERVICE (BSS).Example: Satellite Phones.

Types of Satellites

Satellite Orbits GEO LEO MEO Molniya Orbit HAPs

Geostationary Earth Orbit (GEO)

These satellites are in orbit 35,863 km above the earth’s surface along the equator.

Objects in Geostationary orbit revolve around the earth at the same speed as the earth rotates. This means GEO satellites remain in the same position relative to the surface of earth.

Low Earth Orbit (LEO)

LEO satellites are much closer to the earth than GEO satellites, ranging from 500 to 1,500 km above the surface.

LEO satellites don’t stay in fixed position relative to the surface, and are only visible for 15 to 20 minutes each pass.

A network of LEO satellites is necessary for LEO satellites to be useful.

Medium Earth Orbit (MEO)

A MEO satellite is in orbit somewhere between 8,000 km and 18,000 km above the earth’s surface.

MEO satellites are similar to LEO satellites in functionality.

MEO satellites are visible for much longer periods of time than LEO satellites, usually between 2 to 8 hours.

MEO satellites have a larger coverage area than LEO satellites.

Molniya Orbit Satellites

Used by Russia for decades. Molniya Orbit is an elliptical orbit. The

satellite remains in a nearly fixed position relative to earth for eight hours.

A series of three Molniya satellites can act like a GEO satellite.

Useful in near polar regions.

High Altitude Platform (HAP)

One of the newest ideas in satellite communication.

A blimp or plane around 20 km above the earth’s surface is used as a satellite.

HAPs would have very small coverage area, but would have a comparatively strong signal.

Cheaper to put in position, but would require a lot of them in a network.

OBJECTIVE OF AIR STATION

To upload the unity and integrity of the country

and the values enshrined in the constitution.

To promote national integration.

To provide adequate coverage to the diverse

culture, sports, game and current affairs.

To safe guard citizen’s right to be informed on

all matters of public interest and presenting a

fair & balance flow of information.

THANK YOU