06-12-2012, 04:01 PM
COMMUNICATION and IT IN NHPC
COMMUNICATION.pptx (Size: 511.08 KB / Downloads: 20)
Equipment in Comm.sat
1) Payload :
Transponder : Transmit, Receive antennas
other equipments
Receives signals, multiplex, demuliplex, amplify and transmit.
2)Support Subsystems : Power Supply, Altitude, orbit control eqpt.
Telemetry, Telecommand systems
Orbits and Systems
LEO: Low Earth Orbit:
-- 0-2000 Kms
-- Orbit Period : 90 min
-- Short Round Trip Time (RTT)
-- Used for MSS: Mobile Sat. Series
-- Life :5-7 Years
Orbits and Systems
MEO: Medium Earth Orbit
-- 2000-36000 Kms
-- Intermediate Circular Orbit
-- Use Low Power and Smaller antenna than GEO
--
Earth Station
Main Earth Station:
Delhi, Kolkata, Chennai, Mumbai and Shilong
Diameter of Antenna: 11 Mtr
Mounting: Azimuth
G/T Ratio (Figure of Merit) : 31.7 db/*k
LNA : Low Noise Amplifier in Central Hub
G/T Ratio used to describe the capability
Of an earth stn to receive a signal from satellite
G= Gain of Antenna at Receiving freq.
T= Effective noise temperature of the receiving system.