Radio broadcasting in India began in 1922 when the first license was granted. The government established the India State Broadcasting Service (ISBS) which later became All India Radio (AIR) in 1936. AIR today has a network of over 400 stations across the country. In the 1990s, private FM radio was introduced and has increased listenership. The document discusses the working of an FM transmitter which involves modulating a carrier wave with left and right audio signals using a stereo coder and VHF oscillator. It also describes some of the studios used for different types of radio programming at AIR Jodhpur such as drama, talk, music, and commercial broadcasting studios.

1. ON
Poata C-Road, Jodhpur (Rajasthan)
Presented to :
Ms. Laxmi Chaudhary
Presented By :
Moinudeen Tak
7th
sem, ECE

2. • 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.

3.  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

4. Transmitting
A 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.
Receiving
An 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.

5.  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.

6. 6
THREE-TIER BROADCASTING SYSTEM

7. Working Of an FM Transmitter
L
R
Stereo
coder
VHF
oscillator
&
modulator
Wide Band
Power
Amplifier
Frequency
crystal
oscillator
10Mhz
Frequenc
y divider
1/1000
Phase
detector
Rectifie
r and
filter
Programm
able divider
1/N
antenna

8. 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.

9. 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

10. 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.

11. 11
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

12. 12
CONSOLE

13. 13
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.

14. 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

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