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Satellite Communication Iridium Satellite PART VII

Satellite Communication Iridium Satellite PART VII

The first Iridium launch failed in the year 2000. The new Iridium provides communication services to the Defense Department of the United States and was commercially made available in the month of March 2001. Iridium launched its internet services in the month of June 2001, with only 10Kb/sec, with data rate at 2.4Kb/sec soon afterwards. Iridium is ideally suited for industrial applications, such as, heavy construction, defense/military, emergency services, maritime, mining, forestry, oil and gas and aviation.

Iridium helps communication in the remote areas of this world, where communication infrastructure is completely absent. With 86% of the Earth and all the oceans without such communication facilities, Iridium provides coverage to those areas, including the air routes and the Poles. Many people live and work in those areas where cellular coverage and landline services are not present. Satellite communication has made a difference providing immediate help to those people when needed.

Iridium was initially a project headed by Motorola in the late 1990’s, and they developed the project which invited investments globally. The project failed in its very inception, since the Motorola management did not know how to evaluate the system in the market and its demand, related to its price. At this stage the cost of the system came to about $5.0 million and Motorola could attract no more than 50,000 subscribers. The system went into bankruptcy and was almost being scrapped, when a consortium of private investors pulled it out from the bankruptcy court in 2001. The system which exists today has become very cost effective, with its handsets and effective services, offering the most competitive prices in satellite communication.

The Iridium constellation is frequently visible in the night sky with brief flashes, which are known as Iridium flares. These flashes are usually from the shiny part of the satellite, such as, the polished three door-like antenna or the solar panels, which reflect sunlight directly on to the Earth below, appearing as brief flashes or bright “flare”. The flares are, at times, so bright that it can be seen in day time also, but they are very impressive at night. The Iridium system is a set of 66 low Earth orbit (LEO) satellites at an elevation of 485 miles above the Earth.


On November 1, 1998, Iridium service was launched and consequently went into bankruptcy on August 11, 1999. The first call using this service was made by the then Vice President of the United States, Mr. Al Gore. Insufficient demand for the service was largely responsible for its financial failure. With increased coverage of terrestrial and cellular telephony (GSM), and the rise in the roaming service agreements between the service providers, proved to be the failure of Motorola’s satellite project. The prohibitive cost of the service did not bring many subscribers, despite Iridium’s continuous worldwide coverage. Additionally, the high price and the bulk of the hand held system, when compared to a mobile handset, discouraged users to take up Iridium service.

There were major management lapses too in Iridium’s initial failure. It is said that sales enquiries were not followed up in the sense that it should have been and help-line activities were practically absent. This failure discouraged other satellite constellation projects, including Teledesic, while other such projects, such as, Orbcomm, ICO Global Communications, and Globalstar followed Iridium into bankruptcy protection. There were other such projects which never took off. The Iridium constellation remained in orbit, and the services were re-established in 2001 by the newly founded Iridium Satettlite LLC., who bought the Iridium system for $25 million.

The Iridium System

The Iridium system is a constellation of 66 satellites in low earth orbit (LEO) satellites, providing wireless personal communication, with voice features, covering virtually any destination on Earth. The system comprises of three main components: the satellite network, the ground network and the Iridium subscriber products, including phones and small handheld pagers. The pagers are only capable of receiving messages. The Iridium network enables voice and data to be routed to virtually any place on Earth, including the oceans, seas and air routes. The constellation of the Iridium relays this voice data information from one to the other and reaches them to the desired destination.

The constellation of Iridium is in polar orbit, situated at an altitude of 485 miles above the earth, circling the Earth once every 100 minutes at a speed of 16,832 miles per hour. Each satellite is cross-linked to four others, with two in the same orbital plane and the other two in the adjacent plane. The constellation comprises of 7 planes with 11 satellites in each plane. The combination travels in one direction and rotates in a group over the North Pole and after crossing over the pole it travels down towards the South Pole. The satellites move in phases in all the planes except the ones in planes 3, 5 and 7, where the satellites are halfway out of phase. A minimum tolerance of distance is maintained in the flights of all the satellites so that they do not collide while travelling over the poles.

The ground network is comprised of the control system and telephony gateways which are used for connecting the incoming links to the terrestrial telephone system. The system control segment manages the global operational support and control services for the satellite constellation. The satellite data tracking is done by this system control segment, which delivers the information to the gateways and performs the termination control function of messaging services. Gateways form the interconnection between the Iridium system and the terrestrial telephony, are a part of the terrestrial infrastructure that provides telephony services, messaging, and support to the network operations.

The Iridium system started to provide commercial global satellite communications services as from 28th March, 1991. It came out with enhanced voice quality feature and simplified pricing plans. Iridium extended its service to data services soon after its launch. The system is designed to provide a wide range of services to varied users, including –

* Voice calling

* Short Messaging Service (SMS)

* Roaming

* Positioning

* Facsimile

* Data transmission

Iridium provides its service to cellular phone users, who work outside the cellular coverage areas, to the people who live in such areas where the basic infrastructure of telephony does not exist, to the existing air routes and to the ships in the seas and oceans. The access of Iridium satellites is based upon line-of-site principle and the handset cannot be used in covered areas, like, inside a building, while the pagers are quite effective and, as a better means to receive messages, it can be used inside the buildings. This feature enables the user to leave a message if he is unable to get in touch with the person concerned from his handset.

Iridium allows connectivity virtually anywhere in the world and offers World telephony, World Paging and World Data Services. The ground switches of Iridium connects the satellite to the terrestrial public switched network which allows an Iridium phone to communicate to any cellular system anywhere in the world. The subscriber to the Iridium system has one phone number to make and receive calls, no matter where he is in the world.

The United States Government’s Department 0f Defense uses the Iridium system extensively for its communication purposes and utilises the DoD gateway at Hawaii. The commercial Gateway in Tempe, Arizona, provides commercial services for the public for voice, data and paging services. The services are on a global basis. Typical customers who are using the Iridium services include, maritime, aviation, government, the petroleum industry, scientists, and frequent world travelers. The company, Iridium Satellite LLC, claimed that, as of 8th November, 2004, there were already approximately 169,000 subscribers to the Iridium system. The revenue went up by 55% by the calendar year 2004 from that of 2003. New satellites have been planned to be launched by the year 2010 and these satellites are ready.

It costs $3 to $14 per minute to call an Iridium phone from a landline and about $1.50 per minute to call from Iridium phone to a landline. As for an Iridium phone to another, the cost is $1.00 per minute. Calls from Iridium phones can be easily recognised by the particular clipping effect which is introduced by the effect of data compression and the inherent delay in such satellite telephony. LOO satellites have lower transmission delay than the geostationary ones. For “direct internet” services, Iridium claims to have a data rate of 10Kb/second and it is possible to connect an Iridium phone to the PC through a RS-232 cable.

Iridium offers world class products and services, whether be it a satellite based mobile telephone or a fixed phone for remote on-site communication. It provides high quality voice, roaming and Short Messaging Service (SMS) and asynchronous dial-up fax and data services up to 9,600 bps. The Iridium phones, which are slightly larger than the cellular phones, are manufactured by world renowned companies, such as, Ericsson, Qualcomm and Telit. All of these phones work on multiple modes, being compatible with terrestrial AMPS, CDMA, or GSM networks, as well as their own Iridium satellite network.