An Iridium phone (without the aerial)

The Iridium satellite constellation is a system of 66 active communication satellites and spares around the Earth. The system was originally to have 77 active satellites, and as such was named for the element iridium, which has atomic number 77. The original name was retained even though the number of active satellites is less than planned (the element with atomic number 66 is called dysprosium which in Greek means "hard to get at/hard to get in contact with" and so was not acceptable). Iridium allows worldwide voice and data communications using handheld devices. The service is interdicted for political reasons in North Korea, Hungary, Poland, and Northern Sri Lanka. Image File history File links Iridium_logo_web. ... Image File history File links 9505A_Iridium_phone. ... Image File history File links 9505A_Iridium_phone. ... A group of electronic satellites working in concert is known as a satellite constellation. ... MILSTAR:A Communciation Satellite A satellite is any object that orbits another object (which is known as its primary). ... Earth (IPA: , often referred to as the Earth, Terra, or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... General Name, Symbol, Number iridium, Ir, 77 Chemical series transition metals Group, Period, Block 9, 6, d Appearance silvery white Atomic mass 192. ... In chemistry and physics, the atomic number (Z) is the number of protons found in the nucleus of an atom. ... In chemistry and physics, the atomic number (Z) is the number of protons found in the nucleus of an atom. ... General Name, Symbol, Number dysprosium, Dy, 66 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white Atomic mass 162. ...

The satellites used are frequently visible in the night-sky as short-lived bright flashes, known as Iridium flares. Satellite flare is the phenomenon caused by the reflective surfaces many satellites have today. ...

History

Iridium communications service was launched on November 1, 1998 and went into Chapter 11 bankruptcy on August 13, 1999. The first Iridium call was made by then Vice President of the United States Al Gore. November 1 is the 305th day of the year (306th in leap years) in the Gregorian Calendar, with 60 days remaining. ... 1998 (MCMXCVIII) was a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... Chapter 11 of the Bankruptcy Code governs the process of reorganization under the bankruptcy laws of the United States. ... The examples and perspective in this article or section may not represent a worldwide view. ... August 13 is the 225th day of the year in the Gregorian Calendar (226th in leap years), with 140 days remaining. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... The Vice President of the United States is the second-highest executive official of the United States government. ... |- ! Born | March 31, 1948 Washington, D.C. |} Albert Arnold Gore, Jr. ...

Its financial failure was largely due to insufficient demand for the service. The increased coverage of terrestrial cellular networks (e.g. GSM) and the rise of roaming agreements between cellular providers proved to be fierce competition. The cost of service was also prohibitive for many users, despite the continuous world-wide coverage of the Iridium service. In addition, the bulkiness and expense of the handheld devices when compared to terrestrial cellular mobile phones discouraged adoption among users. Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ...

Mismanagement has also been cited as a major factor in the program's failure. In 1999, CNN writer David Rohde detailed how he applied for Iridium service and was sent information kits, but was never contacted by a sales representative. He encountered programming problems on Iridium's website and a "run-around" from the company's representatives. After Iridium filed bankruptcy it cited its "difficulty [in] gaining subscribers". 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... The Cable News Network, commonly known as CNN, is a major cable television network founded in 1980 by Ted Turner. ...

The initial commercial failure of Iridium has had a dampening effect on other proposed commercial satellite constellation projects, including Teledesic. Other schemes (Orbcomm, ICO Global Communications, and Globalstar) followed Iridium into bankruptcy protection, while a number of proposed schemes were never constructed. Teledesic was a 1990s proposal to build a commercial broadband satellite constellation for Internet services. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... ICO Satellite Management, LLC, formerly ICO Global Communications, plans to offer S-band mobile satellite services (MSS) via a satellite in geostationary orbit and auxilliary ground-based relays. ... Globalstar is a low Earth orbit satellite constellation for telephone and low-speed data communications, similar to (and competing with) the Iridium satellite system. ...

The Iridium satellites, however, remained in orbit, and their services were re-established in 2001 by the newly founded Iridium Satellite LLC, owned by a group of private investors. 2001: A Space Odyssey. ...

Present status

The system is being used extensively by the U.S. Department of Defense for its communication purposes through the DoD Gateway in Hawaii. The commercial Gateway in Tempe, Arizona provides voice, data and paging services for commercial customers on a global basis. Typical customers include maritime, aviation, government, the petroleum industry, scientists, and frequent world travelers. Iridium Satellite LLC claims to have approximately 142,000 subscribers as of December 31, 2005, a 24% increase from the total as of December 31, 2004. Revenue for the calendar year 2005 was up 55% over 2004. The United States Department of Defense, abbreviated as DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. ... This article is becoming very long. ... Downtown Tempe and Arizona State University Tempe (pronounced by local residents) is a city in Maricopa County, Arizona, USA, with a 2004 population estimate of 160,676. ...

Phone rates from land lines to Iridium phones are $3 to $14 per minute, from Iridium to land lines about $1.50 per minute and between Iridium phones less than $1 per minute. Iridium and other satellite phones may be identifiable to the listener because of the particular "clipping" effect of the data compression and the latency (experienced as a noticeable lag or time delay) due to the electronic equipment used. Iridium operates at a data rate of 2400 baud, which requires very aggressive voice compression and decompression algorithms. The voice codec used is called Advanced Multi-Band Excitation. In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use through use of specific encoding schemes. ... Latency is the time a message takes to traverse a system. ... In telecommunications and electronics, baud (pronounced , unit symbol Bd) is a measure of the symbol rate, that is the number of distinct symbolic changes (signalling event) made to the transmission medium per second in a digitally modulated signal. ... In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use through use of specific encoding schemes. ... Flowcharts are often used to represent algorithms. ... A Codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. ... AMBE is a speech coding standard developed by Digital Voice Systems, Inc. ...

The former Iridium provided phones from two vendors, Kyocera and Motorola. Neither still manufacture handsets. Kyocera phone models SS-66K and SD-66K are no longer in production, but still available in the second hand and surplus market. The Motorola phone 9500 is a design from the first commercial phase of Iridium, whereas the current 9505A model is the most current version of the handset and the 9522A is the most current version of the OEM L-Band Transceiver module designed for integration into specific applications. Kyocera Corporation (京セラ, Kyō-Sera, also known as Kyoto Ceramics) TYO: 6971, (NYSE: KYO) is a Japanese company based in Kyoto, Japan. ... Motorola (NYSE: MOT) is an American international communications company based in Schaumburg, Illinois, a Chicago suburb. ...

Iridium phone numbers all start with +8816 or +8817 (which is like the country code for a virtual country) and the 8-digit phone number.

Technical details

The constellation

The Iridium system requires 66 active satellites in orbit to complete its constellation, with spare satellites in orbit to fill in case of failure. Satellites are in low Earth orbit at a height of approximately 485 miles. Satellites communicate with neighbouring satellites via intersatellite links. Each satellite can have four intersatellite links: two to neighbors fore and aft in the same orbital plane, and two to satellites in neighboring planes to either side. The satellites orbit from pole to pole with an orbit of roughly 100 minutes. This design means that there is excellent satellite visibility and service coverage at the North and South poles, where there are few customers. Because satellites use an over-the-pole orbital constellation design there is a "seam" where satellites in counter-rotating planes next to one another are travelling in opposite directions. Cross-seam intersatellite-link handoffs would have to happen very rapidly and cope with large Doppler shifts; Iridium only supports intersatellite links between satellites orbiting in the same direction.

The cellular lookdown antenna has 48 spot beams arranged as 16 beams in three sectors. The four intersatellite cross links on each satellite operate at 10 Mbit/s. The cross links were originally envisioned to be optical.

The satellites

The satellite each contain seven Motorola/FreeScale PowerPC 603E processors running at roughly 200 MHz. Processors are connected by a custom backplane network. One processor is dedicated to each cross-link antenna ("HVARC"), and two processors ("SVARC"s) are dedicated to satellite control — one being a spare. Late in the project an extra processor ("SAC") was added to perform resource management and phone call processing. Motorola (NYSE: MOT) is an American international communications company based in Schaumburg, Illinois, a Chicago suburb. ... IBM PowerPC 601 Microprocessor PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ...

The original design envisioned a completely static 1960s "dumb satellite" with a set of control messages and time-triggers for an entire orbit that would be uploaded as the satellite passed over the poles. It was found that this design did not have enough bandwidth in the space-based backhaul to upload each satellite quickly and reliably over the poles. Therefore, the design was scrapped in favor of a design that performed dynamic control of routing and channel selection late in the project, resulting in a one year delay in system delivery. The 1960s decade refers to the years from 1960 to 1969, inclusive. ... (Note - this refers to present TV usage, mainly in the USA. In the UK backhaul often means the optical fibre connection from the DSL equipment (DSLAM etc) in a telephone exchange back to the core network). ...

Earth base-stations

Iridium routes phone calls through space. There are four earth stations and the space-based backhaul routes phone call packets through space to one of the downlinks ("feeder links"). Station-to-station calls can be routed directly through space with no downlink. As satellites leave the area of an Earth base station the routing tables change and frames are forwarded to the next satellite just coming into view of the Earth base station.

Patents

The main patents on the Iridium system are in the area of mass production of satellites. Iridium made a key hire of the engineer who set up the automated factory for Apple's Macintosh, and he created the technology necessary to mass-produce satellites in weeks (instead of months or years) on a gimbal, at a record low cost of only $5 million per satellite ($40M including launch costs, 1998 dollars.) Apple Computer, Inc. ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... A gimbal is a device using Euler angles to measure the rotation of an object in three dimensions and to control that rotation. ...

Quotes

"Iridium will succeed because every time we estimated the growth of cellular phones, we were LOW by a factor of four" - Bary Bertiger of Motorola, system inventor.

See also

• Globalstar
• Iridium flare
• Thuraya

Globalstar is a low Earth orbit satellite constellation for telephone and low-speed data communications, similar to (and competing with) the Iridium satellite system. ... Satellite flare is the phenomenon caused by the reflective surfaces many satellites have today. ... Thuraya is a regional satellite phone provider, mainly focused on the Europe, Middle East, and Africa area. ...

External links

• So how do you order Iridium satellite service? (CNN)
• Iridium Satellite Phones
• Details of the Iridium system'
• Technical success and economic failure (MIT)