Italsat 1

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General

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

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End of life

Out of service	Jan 2001
Cause	deorbited?

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External resources

sat-index articles

Technical data

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EIRP coverage

Ka-band National
Ka-band Multibeam

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Specifications

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

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

Main transponders	3
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

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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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