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Italsat 1


Designation 21055 / 91003A
Launch date 15 Jan 1991
Country of origin Italy
Mission Telecommunications
Geostationary orbit 13.2°E
Launch vehicle Ariane V41

End of life

Out of service Jan 2001
Cause deorbited?

External resources

sat-index articles

Technical data

EIRP coverage

Ka-band National
Ka-band Multibeam


Prime contractor Alenia Aerospace (was Selenia Spazio)
Platform Italsat
Mass at launch 1850 kg
Mass in orbit 1122 kg
Payload mass 273.4 kg: transponders: 198 kg, antennas: 75.4 kg)
Dimension 3.5 x 2.7 x 2.3 m
Solar array 21.8 m span
Stabilization 3-axis
DC power EOL: equinox: 1760 W, solstice: 1633 W
Payload power 937 W
Design lifetime 6 years

Equipped with 1 (+1 backup) 1 W propagation beacon, EIRP 27 dBW at 20 GHz for telemetry

Also aboard: a 40 GHz beacon phase modulated by a 505 MHz coherent subcarrier, and a polarization-switched (but otherwise unmodulated) 50 GHz beacon

Ka-band - National beam (20/30 GHz)

Main transponders
Backup transponders  
Power 20 W (TWTA)
Bandwidth 36 MHz
Coverage Italy (1.55 x 1.06 deg)
EIRP max 46.2 dBW
G/T 5.5 dB/K
SFD -99.6 dBW/m²
Polarization linear V (both upload and download)

Those transponders are intended for TV feeds

Ka-band - Multi beam

Main transponders 6 in 20/60 GHz
Backup transponders 2 in 20/30 GHz
4 in 20/60 GHz
Power 20 W (TWTA)
Bandwidth 120 MHz
Coverage Italy (6 spots of 0.49°)
EIRP max 57 dBW
G/T 16.1 dB/K
Polarization linear V (both upload and download)

The spot beams carry domestic telephone traffic with a total capacity of about 12,000 voice channels. Each beam operates in the SS-TDMA mode with QPSK modulation at 147 Mbits/sec in a 100 MHz RF bandwidth. On-board regeneration (demodulation and remodulation) is provided, and the beams are fully interconnected by a space-division switching matrix. Satellite resources can be allocated on a call-by-call basis or left as assigned until changed by ground control. Reconfiguration is by ground command; the satellite is not autonomous.

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