LOW POWER(100w) LOW POWER(100w) TRANSMITTER MAKE-GCEL TRANSMITTER MAKE-GCEL

MODEL 121-2 VHF CHANNEL 7MODEL 121-2 VHF CHANNEL 7

PRESENTED BY-PRESENTED BY-

T. MADHAN MOHAN REDDYT. MADHAN MOHAN REDDY

S. PRATHYUSHAS. PRATHYUSHA

T. PRATHIMAT. PRATHIMA

T. GANESHT. GANESH

INTRODUCTION

Doordarshan and AIR functions under the Ministry Doordarshan and AIR functions under the Ministry of information and broadcast unit in Government of of information and broadcast unit in Government of India. India.

Both works as an electronic media, for the activities Both works as an electronic media, for the activities of public in both culturally and literally to the noock of public in both culturally and literally to the noock and corner of the India.and corner of the India.

This spreads widely to cater the needs of viewers and This spreads widely to cater the needs of viewers and listeners of public in india and around the world.listeners of public in india and around the world.

It functions during the natural calamities and critical It functions during the natural calamities and critical times like war by giving messages to the concern, times like war by giving messages to the concern, radiating through the Antenna from the transmitter. radiating through the Antenna from the transmitter.

Programs are recorded at the studios located at Delhi and Programs are recorded at the studios located at Delhi and other state Capitals including small towns by organizing other state Capitals including small towns by organizing with local artists, eminent personalities and public. with local artists, eminent personalities and public.

The transmitters are divided into two categories based on The transmitters are divided into two categories based on channel operations i.e., UHF and VHF transmitters.channel operations i.e., UHF and VHF transmitters.

Similarly depending on power is classified as VLPT, Similarly depending on power is classified as VLPT, LPT and HPT.LPT and HPT.

Uplink Station

DOWN LINKUPLINK

Satellite CommunicationSatellite Communication

Receive Centre

Television Broadcasting System

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TV Transmitters

High Power TV Transmitters

both the signals (video and audio) modulate the carrier waves whose frequencies and types of modulations are as per established standards. These modulated carriers are further amplified and then diplexed for transmission on the same line and antenna.

Low Power TV Transmitters

both the signals (video and audio) are modulated separately but amplified jointly using common vision and aural amplifier.

SIGNAL INPUT PROCESS FOR TRANSMITTER

TYPES OF TRANSMITTER BASED ON POWER

In this 50w is considered as VLPT, 100w, 300w & 500w are called LPT’s and 1kw and 10kw are called HPT’s.

This transmitters are established based on the population, area to be covered and geographical conditions.

The transmitter at Madanapalli in Chittoor district of AP is low transmitter (LPT). It is GCL made 121-2 model and radiating 100w power.

LPT MAKE GCEL MODEL 121-2

The transmitter GCEL make 121-2 model contains the following blocks in the transmitter.

1. 230v Power Supply unit with RF bypass condancer.

2. DC Power Supply 28v- 2 no’s

3. Exciter unit – 2 no’s (one is spare)

4. Driver Amplifier- 2 no’s (one is spare)

5. Power Amplifier 50w – 2 no’s (one is spare)

6. Divider & Combiner unit – 1 no’s

PRINCIPLE OF EXCITER

Basic principle of the exciter is to produce intermediate frequencies as carrier for the vision and sound signals.

These intermediate frequencies are identical in the various T.V bands. It pass through several band limiting filters and pre-correction circuits before getting converted into the channel frequency and amplified.

The individual modules and their associated functions are listed below.

EXITER BLOCKS

1. Video Processor

2. Vision Modulator

3. Aural Modulator

4. IF Corrector

5. IF Combiner

6. IF Channel Converter

7. AC-DC Converter

Standards

The characteristics of the TV signal refer to CCIR B/G standards.

Vision/sound carrier spacing channel width

Frequency Range

Vision sound carrier spacing

5.5 MHz

Channel width 7 MHz (B) VHF8 MHz (G) UHF

Sound Modulation FM

FM deviation (maximum) + 50 kHz

APPLICATIONS

These are used in doordarshan relay centre & defence.

Its functions during the natural calamites & critical times like war by giving messages to the concern, radiating through the antenna.

It is used in communications purpose.

THANK YOUTHANK YOU