Lab 1 By Mehran Mamonai

 A satellite is a radiofrequency repeater but New-generation satellites are regenerative.  Satellite amplify, conditions and reformat received (uplink) data and route (downlink) the data to specified locations.  Reformatting is done in Transponder.  Satellite moves in different orbits.  Satellite has vast number of Applications.  Limitation in Satellite.

 U.S.S.R.’s launch of the first artificial satellite called Sputnik (1957).  Worked only for 21 days as Telemetry services.  The first series of commercial geostationary satellites was inaugurated in 1965

 High Frequency Radio waves were used as carriers of information with a large bandwidth  Earth to Satellite Frequency is called Uplink  Satellite to Earth Frequency is called Downlink  Reception area called footprint (covering map)

 Transmitter and Responder = Transponder

 The satellites are characterized by the power they radiate in the beam axis  This corresponds to the power (expressed in dBW)

 Geostationary satellite (GEO)  High elliptical orbiting satellite (HEO)  Middle-earth orbiting satellite (MEO)  Low-earth-orbiting satellite (LEO)

 All satellite occupies an orbit around the ground located at about 36,000 km (35785) height  satellite speed coincides to the earth rotation speed.  Also called Geosyncronous.

 An HEO satellite is a specialized orbit  satellite continuously swings very close to the earth, loops out into space, and then repeats  It is an elliptical orbit approximately 18,000 to 35,000 km above the earth’s surface  Not necessarily above the equator

 Satellite orbiting approximately 8,000 to 18,000 km above the earth’s surface  Not necessarily above the equator  between the LEO and GEO

 Orbit between altitude of approximately 160km to 2,000 kilometers  Majority of artificial satellites, have been in LEO.  Satellite cannot orbit less than 300 km due to the larger atmospheric drag.  Lowest Delay then orbit MEO and GEO.

 C – band  Up-link: from about 5.7GHz to about 6.5GHz  Down-link: from 3.4GHz to 4.2GHz  Ku – band:  Up-link: from about 14GHz to about 14.5GHz  Down-link: from 10.95GHz to about 12.75GHz, with the following sub-division:  – 11.70GHz FSS band (Fixed Satellite Services) for TV communication  – 12.50GHz DBS band (Direct Broadcasting Satellite) for direct diffusion  – 12.75GHz SMS band (Satellite Mobile Services)

 More channels on the same band  Polarity formats  Linear ▪ Horizontal ▪ Vertical  Circular ▪ LHCP ▪ RHCP

 Frequency modulated by the Video + Audio composite signal  PAL  NTSC  SECAM  MAC  Superior clearness of the digital superior to the 50% in respect to PAL

 Employs the QPSK digital modulation