Iridium Satellite System SHOAIB AHMED

SIDDIQUI

INTRODUCTION TO SATELLITE SYSTEM

An artificial body placed in orbit round the earth or another planet in order to collect information or for communication.

Some satellite are natural , like the moon ,which is a natural satellite of the earth . Other satellite are made by scientists and technologists to go around the earth and do certain jobs.

Some satellites send and receive television signals.

The signal is sent from a station on the earth’s surface.

The satellite receives the signal and rebroadcasts it to other places on the earth

WHY SATELLITE???? To avoid number of repeaters on the earth

surface. Avoiding line of sight propagation . High coverage area i.e. a single satellite

covers 48% earth surface . For this we require 3 satellites to cover the total surface.

To avoid obstacles like building , tree , mountain etc.

Instant communication. To cover remote areas. Increase data transfer rates.

CLASSIFICATION OF ORBITS1)Geostationary (or Geosynchronous) Earth Orbit(GEO)2)Medium Earth Orbit(MEO)3)Low Earth Orbit(LEO)4)Highly elliptical orbit(HEO)

LEO: Low Earth Orbit satellites have a small area of coverage. They are positioned in an orbit approximately 3000km from the surface of the earth They complete one orbit every 90 minutes The large majority of satellites are in low earth

orbit The Iridium system utilizes LEO satellites The satellite in LEO orbit is visible to a point on

the earth for a very short time

MEO: Medium Earth Orbit satellites have orbital altitudes between 3,000 and 30,000 km. They are commonly used in navigation systems

such as GPS

GEO: Geosynchronous (Geostationary) Earth Orbit satellites are positioned over the equator. The orbital altitude is around 30,000-40,000 km They complete one orbit every 24 hours. This

causes the satellite to appear stationary with respect to a point on the earth, allowing one satellite to provide continual coverage to a given area on the earth's surface

One GEO satellite can cover approximately 1/3 of the world’s surface

They are commonly used in communication systems

Iridium Satellite System Initial proposal called for 77 satellites in

the constellation Iridium name was derived from the

element Iridium having atomic no. 77 Later studies indicated that only 66

satellites were adequate

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The only satellite system with true pole-to-pole

coverage

66 low earth orbiting (LEO) satellites with 14 spares

It has onboard satellite switching technology which

allows it to service large areas with fewer gateways

Since it was originally designed as a voice only system,

it provides a low data rate of 2.4Kbps

SKETCH OF IRIDIUM SATELLITE

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Background - Iridium

Satellite Type LEO

Satellite altitude 780 km

Angle of inclination  86.4

Average satellite view time 9-10 minutes

Access scheme FDMA and TDMA

Maximum number of located users 80 users in a radius of 318 km

Theoretical throughput 2.4 Kbps

Type of data services Iridium-to-Iridium, Iridium-to-PSTN(Public switch telephone network)

The vision of Iridium was conceived in 1985 after the wife of Motorola Chief Engineer, Bary Bertiger, complained that she was unable to use her cell phone while vacationing in the Caribbean.

Barry Bertiger envisioned a technology that would allow Effortless communication from and to any corner of the earth

History

Iridium communications service was launched on November 1, 1998 .

The first Iridium call was made by then-Vice President of the United States Al Gore

Motorola provided the technology and major financial backing.

IRIDIUM SYSTEM ARCHITECTURE

The iridium uses GSM-based telephony architecture to provide a digitally switched telephony architecture network and global roaming feature is assigned in to the system.Each subscriber is assigned a personal phone no.and will receive only one bill,no matter in what country or area they use the telephone.

The Iridium system comprises three principal components: the satellite network, the ground network and the Iridium subscriber products including phones and pagers

The 66 satellites are grouped in six orbitals planes,11 active satellites in each plane

The satellite has a circular orbit at an altitude of 783km from the earth surface

The distance between the co-rotating planes is 31.6° and counter-rotating plane is 22°

Arrangement of iridium satellites

WORKING OF IRIDIUM NETWORK

The 66-vehicle LEO intre linked satellite constellation can track the location of a subscriber’s telephone handset,determine the best routing through a network of ground based gateways and inter satellite links, establish the best path for the telephone call, initiate all the necessary connections, and terminate the call upon completion. The unique feature of iridiuim satellite system is its crosslinks.with this two way global communications is possible even when the destinstion subscriber location is unknown to the caller.

The iridium system is a satellite-based,wireless personal communications network to permit a wide range of mobile telephone services including voice, data, networking facsimile, and paging,virtualy any detination anywhere on the earth.

Allowing any destination anywhere on the earth. Allowing telecommunication anywhere,anytime and any place each satellite is crosslinked to four other satellite:two satellite in the same orbital plane and two in an adjacent plane to relay digital information around the globe.

The crosslinks antennas point towards the closest spacecraft orbiting in the same plane and two adjacent co-rotating planes.feeder link antennas relay information to the terrestrial gateways and the system control segment located at the earth station

The phones of the IRIDIUM system use L-Band frequencies, with Frequency Division Multiple Access and Time Division Multiple Access (FDMNTDMA) multiplexing to make the most efficient use of a limited spectrum.

Iridium Disaster Communications Applications

Earth quake and tsunami alert through ISS. Disaster Early Warning Damage assessment reporting

Mobility required Relief supply logistics support

Ordering relief supplies Supply movement tracking and redirection

Coordination of search and rescue efforts Injury/death reporting Request for medical team support Coordination of evacuations

Facilitating communications between first responders / relief workers and survivors and family members

Taiwan Earthquake (1999) South Pole rescue (2001) September 11 (2001) Asian Tsunami (2004) Hurricanes Katrina and Rita(2005) Pakistani Earthquake (2005) Hurricanes Gustav, Hanna and Ike (2008) Haiti and Chilean Earthquakes (2010) Gulf of Mexico Oil Spill (2010) Japanese Tsunami (2011)

Historical usage of Iridium for Disaster Recovery

Tsunami warning system

31 Iridium equipped ocean buoys

Detect and report tsunami conditions

Pacific Coast Tsunami Warning System

Proprietary and Confidential

Downfall Insufficient demand for the service,

coupled with a massive initial capital cost Because Iridium's technology depended on

line-of-sight between the phone antenna and the orbiting satellite, subscribers were unable to use the phone inside moving cars, inside buildings, and in many urban area.

The cost of service was also prohibitive for many users

The bulkiness and expense of the handheld devices

Mismanagement has also been cited as a major factor

Present status Iridium Satellite LLC claims to have 203,000

subscribers as of June 30, 2007 Revenue for the second quarter of 2007 was

$66.7 million with EBITDA of $20.2 million Used extensively by the

U.S. Department of Defense Total bandwidth is 28.8 kbit/s, making real

time e-mail conversations finally possible. Iridium operates at 2200 to 3800 baud Iridium claims data rates up to 10 kilobits

per seconds for their 'direct internet' service

Iridium NEXT Iridium is currently developing, and is expected to launch

during 2016 and 2017, Iridium NEXT, a second-generation worldwide network of telecommunications satellites, consisting of 66 satellites, with six in-orbit and nine on-ground spares. These satellites will incorporate features such as data transmission which were not emphasized in the original design. The original plan was to begin launching new satellites in 2014. Satellites will incorporate additional payload for Aireon, Inc. and perhaps cameras and sensors in collaboration with some customers and partners. Iridium can also be used to provide a data link to other satellites in space, enabling command and control of other space assets regardless of the position of ground stations and gateways The constellation will provide L-band data speeds of up to 1.5 Mbit/s and high-speed Ka-Band service of up to 8 Mbit/s