Presentation on DD1

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 1/13

PRESENTATION ONDOORDARSHAN

RELAY KENDER(LPT 100W)SIRSA

Kamesh verma

7-EC-136L

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 2/13

INTRODUCTION

y STUDIO

y EARTH STATION

y SATELLITE COMMUNICATION

y EARTH STATION (LPT 100W)

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 3/13

StudioAction Area

y Production Control Room

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 4/13

Earth Station

In this section thestudio output is

amplify &modulate threwdifferent stages.After theseoperation thesignal is transmit

(uplink) at aparticularfrequency threwparabolic dishantenna(PDA).

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 5/13

Satellite CommunicationSatellite

Rx

Earth station

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 6/13

Earth Station Receivery This Parabolic Dish Antenna

(PDA) is used to receive

signal from satellite.

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 7/13

Earth Station (LPT 100W)

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 8/13

About the Blocksy Integrated Receiver Decoder (IRD):-

The incoming signal

from LNBC contain 70MHz IF signal, then the tunersection of this IRD is tuned it & a processor is used to

process it, after process we will get both (audio & video)

signal as separately the video is 1V peak to peak & audio

is get from this section is +6dBm.

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 9/13

Exciter Unity Three RF modulated signal are

amplified to 100W levels beforethey are fed to the antenna.

y The output of the IRDto be connected to the exciter

unit. The audio input is fed to theaural modulator while video ispasses through a video processorunit to the respective modulator.The audio is frequency modulatedusing 33.4MHz IF. While the videois amplitude modulated using38.9MHz IF. The video outputpower level is 10mW sync. Peakwhile audio is 1mW. Exciter ALC(Automatic Level Control) input isavailable on the rear panel of theexciter which can be fed fromDriver unit. Exciter needs 28Voperation and is supplied fromPSU units connected in parallel.

Video

Proc

Audio MOD.

Video

MOD.

Video

IF

comb.IF

Comb.

IF

Channel

Cnvrtr

To DriverUnit

1 V

Peak to peak

+6dB

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 10/13

Driver Unity The up converted signal from the exciter is fed to an

attenuator which is placed at front panel for adjusting theinput level. The signal is amplified using driver stage. The

overall gain of the amplifier can be adjusted by the frontpanel attenuator control to be about 33dB, such that25W/30W sync. peak will be available at the output of driver unit.

yThe exhaust fan operating at 230V AC is provided for

air in the driver unit to control the temperature of driveramplifier. The output called ALC can be fed to the exciter(Feedback) to keep the driver output constant.

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 11/13

Divider/Combiner & PA Unity Divider/Combiner Unit:-

This unit is used to divide the powerfrom the driver unit and fed to the two final power amplifiers.

This unit is also used to combine the output from the 50Wpower amplifier to obtain 100W synchronous peak power.

y Power Amplifier Unit:-

The power amplifier unit comprises of two

similar 50W power amplifier modules. The RF power outputfrom the driver unit is divided in to two parts using thedivider/combiner unit and fed to each 50W power amplifier.Each power amplifier is amplifies the power up to 50W with again of approximately 10dB.

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 12/13

Use Of MAST (Antenna)y T.V. antenna system is a part of 

broadcasting network which

accepts RF energy fromtransmitter and launches EM

waves in space. Cross folded

dipole antenna is used in VH

frequency band3 and its

radiation is Omni-directional.

8/7/2019 Presentation on DD1

http://slidepdf.com/reader/full/presentation-on-dd1 13/13

THANKYOU

Kamesh Verma