Monday, July 23, 2012

GSAT-7 [INSAT-4F] - India's military communication satellite [Indian Navy]

A brief overview of India's first dedicated military communication satellite being built for the Indian Navy.

UPDATE [2013.08.29]: Originally written in 2012, some changes have been made to the post, to reflecting subsequent developments & new information.

Recent articles, last month, reported of an Indian-built satellite, the GSAT-7 [INSAT-4F] being prepared for launch later this year on August 30, 2013. GSAT-series satellites being India's communication satellites, the first of which [GSAT-1] was launched in 2001, what made this news especially noteworthy was its end-user - the Indian Indian-Navy-FlagNavy 1. With the launch of this satellite, it would become the first branch of India's Armed Forces to have its own dedicated satellite. This development, when successfully executed, would mark a significant, step towards Indian military planners broad-based vision of leveraging the powers & benefits of space-based assets for military operations.

Original plans included its launch using the Indian Space Research Organisation's [ISRO] own, Geosynchronous Satellite Launch Vehicle [GSLV], currently under development. However, owing to slip-ups in GSLV's development schedule, the task would now be performed by Arianespace's launch service from Kourou in the French Guyana - a longstanding partner for launching ISRO's heavy communication satellites. This launch is tentatively scheduled for the end of this year, or the first month of the next.

Network-Centric Warfare [NCW]

Network-centricity has come to become the Holy Grail of military planning & operations worldwide, and justifiably so. Access to relevant information from various quarters of the battlefield, in real-time, in hands of the Commanders would make their job that much more effective, enabling them to take precise decisions that could turn or maintain course of the battle in ones own favour, thanks to superior situational awareness.

Towards implementation of such a communication network for seamless flow of information, the Indian Armed Forces have been at the job, in consort with their industry partners, for developing & putting in place software protocols & hardware for dedicated systems, isolated from the World Wide Web [WWW]. Through this, decision-makers can tap into the information infrastructure, to access data generated from multiple sources & assets such as reconnaissance satellites, Unmanned Aerial Vehicle [UAV], ones own soldiers carrying communication & surveillance equipment, radar networks [both, ground-based & AEW&CS], among others, linking every aspect of military operation to a single point of confluence, giving them a wide, accurate & holistic overview of the battlefield scenario.

In fact, one of the largest such test of the Indian Army's NCW doctrine & capability, at the level of a Brigade formation, was conducted during Exercise Sudarshan Shakti, held in December 2011, by the Indian Army's Southern Command with the 21 Corps [Sudarshan Chakra Corps] playing the lead2. Analysis of the results of this exercise would help in fine-tuning its evolving Standard Operating Procedures [SOPs] & implementation of its doctrine, addressing shortcomings & helping put in place a robust network that not only provides  timely information but is also able to sustain & recover from attacks - both of the physical kind [through redundancies & easily replaceable elements], as well as digital intrusions, and continue performing as designed.

As of today, however, major portions of the network relies primarily on wired [optical fibre, copper] & terrestrial troposcatter radio communication for voice & non-voice data transfer over longer ranges. Such an arrangement imposes a range limitation up to which these networks can operate [wired & non-wired] & Project-Mercury-Flash-Indian-Army-02amount of data transmitted [wireless]. With the use of satellite-based communication systems, this drawback can be satisfactorily addressed. Presently, however, the Indian military makes use of a limited amount of the satellite bandwidth, as allocated to it on ISRO's civilian communication satellites. Project 'Mercury Flash' 3 carried out by the Corps of Signals in 2005 on the Army Static Switched Communication Network [ASCON]4, as part of a strategic broadband satellite network, imparted limited amount of satellite-based communication capability to the system, whose utilisation has to be rationed & prioritised.

A similar communication network, linked using using hi-speed fibre optic cables, known as the AFNet, has been setup for the Indian Air Force, too. As part of the Network of Network structure, the Army, Navy & Air Force's individual network would be linked up to form the Defence Communication Network [DCN]5 architecture being worked on through public-private partnership in the country.

However, owing to the present limitation of satellite resource, the military is unable to explore the entire gamut of possibilities that can be exploited through satellite communication.

Naval Requirement

The Indian Navy is in a unique position as far as its communication requirements are concerned. In keeping with the Nation's policy, as followed presently, it is the only branch of the country's Armed Forces that regularly embarks on prolonged deployments that can be described as expeditionary in nature, while still being under Indian command. Activities carried out in accordance with this mandate, though not restricted to these, include,

  • visiting foreign ports
  • engaging with the host nation's Navy & taking part in joint Naval exercises, multinational in many cases
  • stationing itself in waters of foreign nations to protect the host nation's maritime interests. Carrying out Hydrographic surveys on their behalf.

With increasing Indian investments being made in countries far off from India, and its citizens moving there in economic pursuits, it would not be unforeseeable to envisage a situation whereupon the Navy is called in to act in a manner that would protect the well-being of its people & investment, during conditions of instability in the overseas country. A situation similar, to that just described arose during the 2011 military campaign to ouster Libyan dictator Muammar Gaddaffi, when around 18000 Indians6. who were working in that country had to be safely exfiltrated. Undertaking 'Operation Blossom', the Indian Navy played a stellar role in ensuring a smooth execution of the task7. In such situations, it is critical for an effective line of communication to be maintained between the overseas Naval deployment and leadership back home, least miscommunication lead to further worsening of the situation in an already hostile environment. With progressive growth of the country's economy, it is only natural for the scale & quantum of such overseas deployments to be commensurate with the growth. Correspondingly, the numerical strength of the country's Naval fleet, too, is expanding to keep up with requirements. This would call for a demand for requirement of an effective, uninterruptible, voice & non-voice line of communication, not only between the combatant fleets & mainland, but also amongst the numerous other combat vessels themselves, in order to co-ordinate & execute an effective plan of action.

Thus it is only natural that the Indian Navy be the first to have at its disposal, a dedicated communication satellite. Satellite-based communication has been carried out in the Indian Navy, in a somewhat patchy & piecemeal manner so far. Many of its warships, like the Rajput-class Destroyers, Brahmaputra-class Frigates, Sukanya-class Patrol Vessels, are known to carry INMARSAT-C 8 communication equipment on board, implementation for which was carried by the Tata Communications Ltd & Bharat Electronics Ltd. [BEL]9. However, slow data transfer speeds, foreign ownership of the satellite fleet, raising security concerns being major impediments, its use is restricted to specific narrow applications, like during anti-piracy patrols off the coast of Africa. Many of them also use Ku-band VSAT terminals, built by BEL & the Electronics Corporation of India Ltd. [ECIL], using which warships can communicate by bouncing the signals off ISRO's fleet of GSAT-series civilian satellites, a stop-gap practice, capability for which was put in place as part of the on-going 'Project Rukmani' 10. However, as mentioned earlier, owing to the primarily civilian nature of the end-use of these satellites,  transponder allocation to the Armed Forces is limited - shortage of required number of transponders being a problem faced in the civilian domain itself, in India.

Enter the GSAT-7 Satellite

GSAT-7-Military-Communication-Satellite-India-01 GSAT-7-Military-Communication-Satellite-India-02


Also Read: 1st Picture Of India's Military Communication Satellite - INSAT-4F

Therefore, to broaden the scope of the Navy's communication and data sharing capabilities, ISRO should soon be putting up in orbit the GSAT-7 Communication satellite, also identified as INSAT-4F. The satellite was originally planned to be launched in the year 2010 [GSLV-F05]. However, owing to delays arising out of the GSLV programme, and other possible challenges faced in building this satellite for as sensitive an application as this, it is only now said to be ready for launch. The satellite is tentatively scheduled to be launched aboard the Ariane-5 rocket  along with the ABS 2 [ST 3, Koreasat 8] Space Systems/Loral [SSL]-built EUTELSAT 25B/Es'hail 1 satellite in January 201311 on August 30, 2013.

Comprehensive-Assembly,-Test-and-Thermo-Vacuum-Chamber-[CATVAC]-ISROThe satellite was reported to be undergoing Thermal Vacuum testing in the Comprehensive Assembly, Test and Thermo-Vacuum Chamber [CATVAC] facility1 at ISRO Satellite Centre's [ISACs] ISRO Satellite Integration and Test Establishment [ISITE], situated in Bengaluru [formerly, Bangalore]. This test simulates extreme temperature conditions in the vacuums of Space beyond what the satellite would likely encounter during operation & evaluate the satellite's ability to sustain it and perform its designed operation12.

Built around ISRO'S INSAT-2000 bus [also known as I-2000 or I-2K]13, the satellite is said to have a mass of 2330 kgs. It would carry 4 transponders than can transmit in the Ku-band, along with transponders for transmitting in the S-Band [1 transponder], UHF & C-Band [3 transponders]14 of the electromagnetic spectrum. The GSAT-7 has been designed with a service life of 9 years. With the Indian Navy's present mandate being protection of Indian interests extending from the Strait of Hormuz to the Malacca Strait, where its warships are expected to spend most of their deployment time, the satellite would be positioned in the 74o East longitude Geostationary Earth Orbit [GEO]A. It is equipped with liquid thrust apogee kick motors capable of imparting a thrust of up to 4.4 kN, to move the satellite from the Geosynchronous Transfer orbit [GTO] where the Launch Vehicle would place it [apogee:35,929 km; perigee: 249 km at an angle of 3o w.r.t the Equator], to the Geosynchronous Equatorial Orbit [GEO], the process being called orbit raising operation. It is expected that the satellite would require three orbit raising operations to position it at its pre-determined orbit, at a distance of 36,000 km over the Equator24.Nickel-Hydrogen storage cell batteries capable of providing 2 kWe would provide power to the on-board systems15. The batteries would be recharged with the help of 2 solar panels, attached to the satellite. Though built specifically for the Navy, the GSAT-7's capability can be tapped into by the Army & Air force too, as required1. The IAF would, after the GSAT-7 launch, get its own dedicated communication satellite, the GSAT-7A 16.

Automatic Level Control [ALC] Driver Amplifier for the Ku-Band being used in the GSAT-7 has been designed & developed at ISRO'S Space Applications Centre [SAC] in Ahmedabad17. According to a paper published some years back, the antilog mesh-processor for the satellite is being specially developed for the satellite,

"This paper describes the design and development of surface acoustic wave (SAW) filters proposed to be used in the analog mesh-processor payload of GSAT-7 satellite. Four high performance SAW filters with center frequencies in the range of 176 MHz to 183 MHz and band widths in the range of 0.78 MHz to 2.28 MHz are being developed for the payload. Delta-function Model is used in the first order design of these filters followed by the rigorous estimation and compensation of various important second-order effects, namely, Diffraction, Bulk waves and electromagnetic feed through. Further, the effect of inter-electrode capacitance of the filterspsila IDT (Inter Digital Transducer) which contributes to a tilt in the pass band frequency response of the filterspsila has also been explained by using Crossed-field Model. Simulated and measured results at various stages of development of the 176.57 MHz filter are presented. The paper also discusses the qualification plan for these devices, for space use."


India's private sector industry participation in building this satellite, too, has been noted. A long time supplier for the country's Defence-Aerospace programmes, Astra Microwave Products Limited [AMPL] has reported to have supplied UHF-VHF Payload Subsystems to be carried by the satellite. They have also reported to be working on Ku-Band receivers & outdoor unit for ISRO's GSAT program, the band at which the GSAT-7 would be communicating in18. Coaxial resonators used in the GSAT-7's receivers are reported to have been procured from Haryana-based SM Creative Electronics Limited19.


The process of upgrading the communication equipment on-board the entire fleet of the Indian Navy's warship, to get them ready for satellite communication, has already begun. Israel-based Orbit Communication Systems Ltd. is reported to be providing the transceiver system to be used.  Equipped with an 1.15m double-offset Orsat AL-7103 Mk II antennae20, satellite link-up would occur over the Ku-band. 2011 was the year by which all IN ships would be equipped with these antennas. The awarded contract was in the vicinity of around $296 million USD21.

Once the satellite is operational, it would be possible to link-up every Indian naval submarine, aircraft, & warships to each other along with their shore-based command, as long as they remain under the shadow of the satellite's footprint. This satellite link-up, built on an IT-powered communication system, would be enabled with the help of a secure Data Link - II 22, developed by BEL. This would make possible end-to-end seamless shore-to-ship and vice-versa connectivity. It would result in higher-speed, secure transmission of data, SITREP, intelligence, GIS in real-time, in most cases. This would help the leadership generate an accurate battle space overview of the fleet formation, building up a maritime domain awareness, as accurate to the one on the ground. Such, on-the-fly communication becomes even more critical when one takes in to account the fact that a Naval platform is considered to be the most credible of practical Nuclear deterrence available so far. With India working towards developing its own sea-based Nuclear deterrence, it is, therefore, critical to have a secure, non disruptive line of uninterruptible communication with the country's strategic command authority, to ensure prevention of catastrophe due to lack of clear communication.

Such a datalink would make it possible to interlink sea-based strategic missile with radars & sensors. This synergy of sensor-weapon fusion would, thereafter, make it possible to engage the enemy target in manners earlier not feasible, exploiting the individual capabilities of the platforms to the optimal level. From a platform-centric force ['I shoot what I see'], the Indian Navy would have the opportunity to transition to becoming a network-centric force ['I can shoot what you can see'], leading to a significant jump in the quality of missions that can be undertaken.

This footprint of India's satellite-based communication can be increased by placing a constellation of communication satellites in orbit, then bouncing the signal off them to reach its destination further off. In fact, SAC is reported to be working on developing such Intersatellite links as part of its Technology Development initiatives [TDI]23, in all likelihood, for this purpose.

In conclusion, it can be said that the Indian Armed Forces stands on the threshold of entering a new phase of warfare capability, in which access to knowledge & information is as lethal a weapon as possession of deliverable Nuclear warheads. Concerted efforts to strengthen this communication network would provide the military with a distinct & tangible advantage in their efforts to keep the nation secure from external military challenges.


Related: India's Space Shuttle [Reusable Launch Vehicle (RLV)] program - some information


Note: Owing to the military application of the satellite, as being reported, there is insufficient information about the GSAT-7 in the public domain. A fair amount of what has been said involves some amount of informed speculation. Therefore, this post must be considered to be a work in progress, that will be periodically revised & updated as and when newer information is made available in the public domain.

A - As per the International Telecommunication Union's Radiocommunication Bureau's [BR] 2008 Annual Space Report on the use of the geostationary-satellite orbit [GSO], ISRO had seemed to notify the position of the GSAT-7 & [possibly] GSAT-7A as 86o & 89o East longitudes.

1st image source