ON

Poata C-Road, Jodhpur (Rajasthan)

Presented to :Ms. Laxmi Chaudhary

Presented By :Moinudeen Tak

7th sem, ECE

• 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 setellite communication.

• In this era of technology due to need of wireless communication, A national service was planned and developed by the Prasar Bharati Broadcasting Corporation of India.

The first license granted for transmitting a broadcast was given on February 23, 1922. The Radio Club of Calcutta was the first radio club to start functioning in Nov-1924

The Government run broadcasting set up was called the India State Broadcasting Service (ISBS) which is then turned into AIR (All India Radio) in June 1936.

The introduction of the commercial channel ‘Vividh Bharti’ in October 1957 increased the interest and popularity of radio.

AIR today has a network of 232 broadcasting centres 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.C

TransmittingA radio wave carries information signal; Signals are converted into electrical signals. A carrier wave is then produced from the modulation. The wave is then amplified, and sent to the antenna that then converts signal into an E.M. wave.

ReceivingAn antenna on receiving the signal send it to the receiver this then converts the electrical signal sends it to the amplifier either a speaker/headphones jack this is

then converted into a sound wave.

FM broadcasts were introduced in Madras in 1977 and later at Jalandhar in 1992, but it was only in 1993 when slots came to be leased to private companies.

On August 15, 1993 a Frequency Modulation (FM) Channel was launched in Bombay, with nine hours of radio which sloats was leased to private producers like Times FM, radiostar and Radio Midday.

In FM Phase II some 338 frequencies were offered of which about 237 were sold.

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THREE-TIER BROADCASTING SYSTEM

Working Of an FM Transmitter

L

RStereo coder

VHF oscillator & modulator

Wide Band Power Amplifier

Frequency crystal oscillator 10Mhz

Frequency divider 1/1000

Phase detector

Rectifier and filter

Programmable divider 1/N

antenna

Phase 1 of its working

• The L and R audio signals are converted into the stereo signal by a stereo coder. The stereo signal, also called the MULTIPLEXED (MPX) signal, then frequency modulates the VHF oscillator which is a voltage controlled oscillator (VCO) of the phase locked loop (PLL). The PLL is an automatic frequency control (AFC) system in the FM transmitter. In this arrangement, the phase of the VHF oscillator is compared with that of a reference crystal oscillator operating at 10 MHz the frequency of the reference oscillator is divided by 1/1000 with the help of three decade counters in cascade to bring it down to the audio range (10 kHz). The VHF oscillator frequency is also divided by a factor N to scale it down to 10 kHz.

Phase 2 of its working

• The phases of the outputs from the two frequency dividers are then compared in a phase comparator and the resultant error voltage is amplified, rectified and filtered to get a DC error voltage of positive or negative polarity which corrects and drift in the VHF oscillator frequency. The operating frequency and the variable factor N are synthesized with the help of digital frequency synthesis techniques. The FM signal obtained at the output of VHF oscillator is then amplified in a VHF Power Amplifier with an output power of 1.5 kW. This amplifier is the basic building block in the series of FM Transmitters. It is a wideband amplifier so that no tuning is required when the operating frequency is changed

Here is an example of both FM modulation and AM modulation you can see from the image that AM is much looser than the FM signal meaning that less data can be sent at one time as it isn’t compressed. The reason for the difference in sound quality as a lower bitrate must be sent across the wave.

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 There are following studio in AIR JODHPUR: --_ 1. DRAMA STUDIO: Recording of Drama, discussion, chat, phone in Program. 2 TALK STUDIO: For live program like talk and rural programs. 3. MUSIC STUDIO: Recording of musical programs and concerts. 4. CBS: Purely dedicated to commercial broadcasting service of Vividh Bharti 5. PLAYBACK STUDIO: For announcing and playback of songs and records. 6. DUBBTNG STUDIO: dubbing and editing of tapes.

STUDIO

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CONSOLE

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 PHONE IN PROGRAM CONSOLE

THIS CONSOLE IS GEENRALLY USED FOR THE PRODUCTION OF LISTENER INTERACTTVE RADTO/TV PROG RAM.

This is used to interface telephone line with the broadcast mixing console which is turn interfaces with the experts sitting in the studio.

This unit has provision for receiving 3 telephone line at a time. This system gives a new dimension and proves to be valuable medium to disseminate listener's information oriented live interactive program.

91.1 - Radio City

92.7 - Big FM

93.5 - S FM

94.3 - Radio One

98.3 - Radio Mirchi

101.3 - FM Rainbow

102.9 - Vivdh Bharati

104 - Fever FM

105.6 - Gyaan Vaani

Queries…If any…