THE INDIAN NATIONAL SATELLITE SYSTEM (INSAT):

INSAT system is the result of previous experiments such as those of SITE (Satellite Institutional Television Experimental) program, STEP (Satellite Telecommunications Experiments project) and APPLE. It is a multipurpose and multi agency system. It transcends three vital national services such as long distance communications, TV and radio broadcasting and meteorology. It is a joint venture of Department Of Space (DOS), the Department Of Telecommunication (DOT), the Indian Meteorological department (IMD), All India Radio (AIR) and Doordharsan. The overall coordination and management of INSAT system rests with the secretaries level INSAT coordination committee (ICC). The secretariat of this committee resides in the DOS. The DOS has the direct responsibility for establishment and operation of the INSAT space – segment facilities.

The INSAT system uniquely provides geostationary platforms for simultaneous domestic communications and earth observations functions. The first four generation INSAT series, (INSAT -1A-1B-1C and 1D) were all US based and launched by either US or European space launch vehicles.

The satellites are handled from the INSAT Master Control Facility (MCF) at Hassan in Karnataka. They can also be controlled through two satellite control earth stations (one with a 14 metre fully steer able antenna and the other with a 7.5 metre limited stearability dish), one additional 14 metre fully steer able antenna and an

INSAT-1 Satellite Control center (SCC) with Telemetry Tracking and Control (TTC) equipment, on-orbit checkout equipment, computer facilities and auxiliary power services. The INSAT MCF was upgraded with addition of the INSAT-2 SCC and two associated 11metre satellite control earth stations.

INSAT -1A:

The INSAT – 1A system was envisaged with a space segment comprising two multipurpose satellites, each providing two higher powers TV broadcast and twelve telecommunication national coverage transponders, in addition to also providing meteorological services. The INSAT –1A was launched by US Delta in April 1982 but was abandoned in September 1983 when its attitude propellant was exhausted.

INSAT- 1B:

Launched on 30 August 1983 from Canaveral, it almost suffered the same fate as INSAT – 1A. Video recordings suggested that it might have been struck by orbiter debris during release, though this could not be confirmed. It was not until mid-September that Ford and Indian controllers at Hassan’s MCF succeeded in deploying its solar array. By then it had been stationed at 74 deg E in place of INSAT – 1A.

Full operational capability was achieved in October 1983. It continued to operate into 1990 with all its 4375 two way voice or equivalent circuits in use. Around 36,000 earth images were returned. Eleven of its 12 c-band transponder and its 2 S-band transponders provide direct national wide TV and communication to thousands of remote villages, plus a detailed weather and disaster – warning service. Around 35,000 Indian built 3-to 3.6 metres in diameter. Earth receives only terminals were in place to supply rural communities with social and educational programs.

INSAT – 1C:

The INSAT-1C satellite was launched on 21 July 1988 from Kourou for location at 93.5 deg E to bring the INSAT system up to full capacity. Half of the 12 – C band transponders and its two S-band transponders were lost when a power system failure knocked out one of the two buses, but the meteorological earth images and its data collection systems were both fully operational. Earth lock was lost 22 November 1989

And the satellite was abandoned.

INSAT – 1D:

The specification for the INSAT – 1D is the same as the INSAT – 1B but with expanded battery and propellant capacities. It is launched on 12 June 1990, from Canaveral, to conclude the first generation of INSAT series. Launching was planned for 29 June 1989 but 10 days before it was seriously damaged following installation on the Delta when a

34 kg crane hook fell 10m directly on to it. The fully insured satellite was repaired by Ford Aerospace. It assumed prime role from INSAT – 1B on 17 July 1990. Its design life is 7 years.

Applications:

The great advantage of INSAT is its flexibility. It permits any kind of size of network based around a central hub and remote locations. This makes hem particularly patient for corporate networks or for e.g. communication among educational, government or health care institutions.

• Local area network interconnection
• Voice and fax transmissions
• Data broadcasting
• Video conferencing
• In-house training
• Business TV or radio

• Written by T ARUNKUMAR.
• In category Engineering.
• 15 years ago.

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