.gif)
Iridium (satellite)
Encyclopedia
Iridium Communications Inc. (formerly Iridium Satellite LLC) is a company, based in McLean, VA, United States which operates the Iridium satellite constellation
, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phone
s and other transceiver units. The Iridium network is unique in that it covers the whole Earth
, including poles, oceans and airways.
The company derives its name from the chemical element
iridium
. The number of satellites projected in the early stages of planning was 77, the atomic number
of iridium, evoking the metaphor of 77 electrons orbiting the nucleus.
The satellites are frequently visible in the night sky as satellite flare
s, a phenomenon typically observed as short-lived bright flashes of light.
Al Gore
. Motorola
provided the technology and major financial backing. The logo of the company was designed by Landor Associates, and represents the Big Dipper
.
The founding company went into Chapter 11 bankruptcy nine months later, on August 13, 1999. The handsets could not operate as promoted until the entire constellation of satellites were in place, requiring a massive initial capital cost running into the billions of dollars. 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 prohibitive for many users, reception indoors was difficult and the bulkiness and expense of the hand held devices when compared to terrestrial cellular mobile phone
s discouraged adoption among potential users.
Mismanagement is another major factor cited in the original 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 Web site, and a "run-around" from the company's representatives. After Iridium filed bankruptcy, it cited "difficulty gaining subscribers".
The initial commercial failure of Iridium 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 other proposed schemes were never constructed.
At one stage there was a threat that the Iridium satellites would have to be de-orbited; however, they remained in orbit and operational. Their service was restarted in 2001 by the newly founded Iridium Satellite LLC, which was owned by a group of private investors. Although the satellites and other assets and technology behind Iridium were estimated to have cost on the order of US$6 billion, the investors bought the firm for about US$25 million.
On February 10, 2009, Iridium 33
collided
with a defunct Russian satellite, Kosmos 2251, 800 km over Siberia. A pair of large debris clouds was created.
(NYSE: GHL) in September, 2009 to create Iridium Communications, Inc. The public company trades on NASDAQ under the symbol "IRDM". The company has approximately 447,000 subscribers as of the end of March, 2011 (compared to 320,000 in December, 2008). Revenue for the full year 2010 was US $348.2 million with Operational EBITDA
of US $158.9 million.
The system is being used extensively by the U.S. Department of Defense
through the DoD gateway in Hawaii. The DoD made up 23% of Iridium's revenues in 2010. An investigation was begun into the DoD contract after a protest by Globalstar
, to the U.S. General Accounting Office that no tender was provided. The investigation was suspended at the request of the Department of Defense, who cited national security reasons.
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 satellites are now an essential component of communications with remote science camps, especially the Amundsen-Scott South Pole Station
. As of December 2006, an array of twelve Iridium modems was put online, providing continuous data services to the station for the first time. Total bandwidth is 28.8 kbit/s.
al planes at a height of approximately 485 miles (780.5 km). Satellites communicate with neighboring satellites via Ka band
intersatellite links to relay communications to and from ground stations. Most of these satellites were launched in the late 1990s before the company went through bankruptcy. Since the bankruptcy, only seven additional satellites have been launched but an updated constellation of 66 satellites is currently being developed and is planned for launch in 2015-2017 on SpaceX
Falcon 9
Launch Vehicles from Vandenberg AFB Space Launch Complex 3
in California.
and Motorola
. The Motorola 9500 phone is a design from the first commercial phase of Iridium, whereas the 9555 model is the current version of the handset and was released in October 2008. Until the release of the 9555 the 9505A was the sole handset sold by the company — a functionally identical clone of the Motorola 9505 with some slightly different components.
Kyocera phone models SS-66K and SD-66K are no longer in production but still available in the second-hand and surplus market. The SD-66K phone is a small 900 MHz GSM phone that fitted in a cradle (KI-G100) that included a large antenna and facilitated connection to the Iridium network. The SS-66K is a self contained phone, but featured a rather unusual ball antenna.
All handsets can receive SMS
, but only the 9505, 9505A, 9555 and those based on the 9522 can send them.
s, bag phones, car phone
s and equipment intended for installation on ships and aircraft. A handset made by NAL research combined with a 9522 transceiver is used for some of these products. The DPL handset provides a user interface
nearly identical to that of the 9505 series phones.
s, such as those used for the tsunami warning system
, use Iridium satellites to communicate with their base. The remote device is programmed to call or send SBD (Short burst data, see below) messages to the base at specified intervals, or it can be set to accept calls in order for it to offload its collected data. Most of these units can be connected to a handset and used as a fixed telephone.
The following transceivers have been released over the years:
s (SIMs) are used in Iridium phones, much like those used for GSM. Prepaid SIM cards are usually green while post-paid cards are red.
by first dialing a number in Arizona
; the call is charged to the receiver at the standard rate for satellite to landline calls, but the caller only pays for the call to Arizona.
Since Iridium will not sell prepaid cards or even its subscription call service directly, it is hard to obtain the exact price of making a call. There are numerous distributors that will activate Iridium phones and sell pre-paid vouchers and SIM cards.
s around the world. For a 500 minute annual plan the cost of the "basic rates" fluctuates around US$1.25 per minute, depending on the distributor. There are also regional plans that offer slightly cheaper rates than the normal, but these minutes can only be used in a specified geographic location (such as Africa
, North America
, Canada
or Alaska
).
Iridium and other satellite phones may be identifiable to the listener by the "clipping" effect of the data compression
and the latency
(time delay) due to the electronic equipment used and the distances the signal must travel. The voice codec
used is called Advanced Multi-Band Excitation
.
Iridium operates at only 2.2 to 3.8 kbit/s, which requires very aggressive voice compression
and decompression algorithm
s. Latency for data connections is around 1800 ms
round-trip, using small packets.
Despite the bandwidth limitations, transparent TCP/IP is supported. Iridium claims data rates up to 10 kilobit
s per second for their "direct Internet" service which utilizes v.42bis compression
over a PPP dialup connection to Iridium's Arizona gateway. Actual data rates remain at 2300 to 2400 bit/s for any compressed data such as a JPG image or ZIP
file, but plain text or HTML may transfer "up to" 10 kbit/s. Iridium 9500, 9505 and 9505A phones can be connected to computers using an RS-232
connection, as can the 9522A transceiver module. The 9555 phone connects to computers with a standard USB cable, using an internal USB to serial bridge chip and Windows drivers to emulate a serial COM port for compatibility with standard PPP clients.
. Their values range from 50 to 5,000 minutes; the 50 minute cards have no validity and the 75 minute vouchers are valid for only a month, but the 5,000 minute cards stay valid for two years. Since Iridium charges quite a bit for merely accessing their network without making calls it is possible to extend the validity of such an account by a month for around US$45. It is also possible to refill such an account without purchasing a new SIM card.
The 500 minute card is the most common one, which remains valid for one year and can usually be bought for US$600 to $750, while the 75 minute card can cost up to US$175 and the 5,000 minute card costs around US$4,000.
for the Global Mobile Satellite System
. Each subscriber is given an 8-digit number prefixed by one of these country codes. However many regional telephone service operators have no interconnect agreement
with Iridium or other satellite networks and users on these networks need to call reversed charge to a U.S.-based number.
Since spring 2007, postpaid
Iridium subscribers have an option to associate their Iridium numbers with a direct U.S.-based number (the so-called +1 Access service).
s no longer being in production for many years now. Messages are delivered to pre-selected "MDAs" which cover a certain geographic area. Three of these MDAs may be selected on a web-based portal or updated automatically if the paging service is bound to an Iridium phone. Each country has its own MDA based on its country code
; some of the larger countries are divided into several MDAs, while separate MDAs exist for sections of ocean and common aeronautic routes.
This service costs around US$70 per month with a limited number of messages allowed, or US$140 for an unlimited number of inbound messages.
Pagers are assigned with telephone numbers in area code 480
and can also be contacted using email, SMS and the web-based interface used to send messages to Iridium phones.
format or over HTTP to a preconfigured address; the mobile unit does not include a destination address when sending a SBD message. A crude positioning report is also included in each message sent. SBD messages take from 6 to 22 seconds to send or receive.
and FDMA
based system using L-band spectrum between 1616 and 1626.5 MHz. Iridium exclusively controls 7.775 MHz of this and shares a further 0.95 MHz. In 1999 Iridium agreed to timeshare a portion of spectrum, allowing radio astronomers to observe hydroxyl
emissions; the amount of shared spectrum was recently reduced from 2.625 MHz.
The type of modulation used is normally DE-QPSK, although DE-BPSK is used on the uplink (mobile to satellite) for acquisition and synchronization. Each time slot is 8.28 ms long and sits in a 90 ms frame. Within each FDMA channel there are four TDMA time slots in each direction. The TDMA frame starts off with a 20.32 ms period used for simplex messaging to devices such as pagers and to alert Iridium phones of an incoming call, followed by the four upstream slots and four downstream slots. This technique is known as time division multiplexing. Small guard periods are used between time slots. Regardless of the modulation method being used, communication between mobile units and satellites is performed at 25 kilobaud
.
Channels are spaced at 41.666 kHz and each channel occupies a bandwidth of 31.5 kHz; this allows space for Doppler shifts.
The satellites are also able to transfer mobile units to different channels and time slots within the same spot beam.
s which link to the network through the satellites visible to them. The space-based backhaul
routes outgoing phone call packets through space to one of the earth station downlinks ("feeder links"). Station-to-station calls from one satellite phone to another can be routed directly through space without going through an earth station. As satellites leave the area of an earth station, the routing tables are updated and packets headed for the earth station are forwarded to the next satellite just coming into view of the earth station. Communication between satellites and earth stations is at 20 and 30 GHz.
Gateways are located in
The pre-bankruptcy corporate incarnation of Iridium built eleven gateways, many of which have since been closed.
Gateways have also been built in Pune
(India
), Beijing
(People's Republic of China
), Moscow
(Russia
), Nagano (Japan
), Seoul
(South Korea
), Taipei
(Taiwan
), Jeddah
(Saudia Arabia) and Rio de Janeiro
(Brazil
). The company is seeking to reactivate gateways in Russia, and China to comply with national laws in those countries.
There is a Web/e-mail to SMS gateway which enables messages to be sent from the Internet or an e-mail account to Iridium handsets for free. There is also a voice mail
service.
Iridium generally does not have roaming agreements with terrestrial/cellular operators. Telstra in Australia allows postpay GSM subscribers to use their SIM card. However, global roaming has to be activated and both incoming and outgoing calls are charged to this account, and the call rate is around US$4 per minute; the incoming calls are via the GSM phone number of the account, with country code, etc., prefixed. In order to use the network, it is necessary to have not only appropriate equipment, such as a handset or the optional cellular cassette for the Motorola 9505 phone, but also a pay-as-you-go or contract Iridium SIM card.
, receiver tracking is difficult, but not impossible, as the position of a mobile unit can be determined using a Doppler shift calculation from the satellite. These readings however can be inaccurate with errors in the tens of kilometers. Even without using Doppler shifts, a rough indication of a unit's position can be found by checking the location of the spot-beam being used and the mobile unit's timing advance
.
The position readings can be extracted from some transceiver units and the 9505A handset using the
In the past, Iridium has used this method of tracking to block service to U.S. embargo
ed countries, such as North Korea
and other politically unpopular regions, such as Northern Sri Lanka
. It is also used to stop geographically bounded plans from being used outside the designated area.
Iridium satellite constellation
The Iridium satellite constellation is a large group of satellites providing voice and data coverage to satellite phones, pagers and integrated transceivers over Earth's entire surface. Iridium Communications Inc...
, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phone
Satellite phone
A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites...
s and other transceiver units. The Iridium network is unique in that it covers the whole Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, including poles, oceans and airways.
The company derives its name from the chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
. The number of satellites projected in the early stages of planning was 77, the atomic number
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
of iridium, evoking the metaphor of 77 electrons orbiting the nucleus.
The satellites are frequently visible in the night sky as satellite flare
Satellite flare
Satellite flare is the phenomenon caused by the reflective surfaces on satellites reflecting sunlight directly onto the Earth below and appearing as a brief, bright "flare"....
s, a phenomenon typically observed as short-lived bright flashes of light.
History
Iridium SSC, Iridium communications service was launched on November 1, 1998. The first Iridium call was made by then-Vice President of the United StatesVice President of the United States
The Vice President of the United States is the holder of a public office created by the United States Constitution. The Vice President, together with the President of the United States, is indirectly elected by the people, through the Electoral College, to a four-year term...
Al Gore
Al Gore
Albert Arnold "Al" Gore, Jr. served as the 45th Vice President of the United States , under President Bill Clinton. He was the Democratic Party's nominee for President in the 2000 U.S. presidential election....
. Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
provided the technology and major financial backing. The logo of the company was designed by Landor Associates, and represents the Big Dipper
Big Dipper
The Plough, also known as the Big Dipper or the Saptarishi , is an asterism of seven stars that has been recognized as a distinct grouping in many cultures from time immemorial...
.
The founding company went into Chapter 11 bankruptcy nine months later, on August 13, 1999. The handsets could not operate as promoted until the entire constellation of satellites were in place, requiring a massive initial capital cost running into the billions of dollars. The increased coverage of terrestrial cellular networks, e.g., GSM, and the rise of roaming
Roaming
In wireless telecommunications, roaming is a general term referring to the extension of connectivity service in a location that is different from the home location where the service was registered. Roaming ensures that the wireless device is kept connected to the network, without losing the...
agreements between cellular providers proved to be fierce competition. The cost of service was prohibitive for many users, reception indoors was difficult and the bulkiness and expense of the hand held devices when compared to terrestrial cellular mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s discouraged adoption among potential users.
Mismanagement is another major factor cited in the original program's failure. In 1999, CNN
CNN
Cable News Network is a U.S. cable news channel founded in 1980 by Ted Turner. Upon its launch, CNN was the first channel to provide 24-hour television news coverage, and the first all-news television channel in the United States...
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 Web site, and a "run-around" from the company's representatives. After Iridium filed bankruptcy, it cited "difficulty gaining subscribers".
The initial commercial failure of Iridium had a dampening effect on other proposed commercial satellite constellation projects, including Teledesic
Teledesic
Teledesic was a company founded in the 1990s to build a commercial broadband satellite constellation for Internet services. Using low-earth orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/second and downlinks of up to 720 Mbit/second...
. Other schemes (Orbcomm
Orbcomm
ORBCOMM is a company that offers M2M global asset monitoring and messaging services from its constellation of 29 LEO communications satellites orbiting at 775 km. Like its voice-centric competitors Iridium and Globalstar, it filed for Chapter 11 protection, in September, 2000. ORBCOMM issued...
, ICO Global Communications, and Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
) followed Iridium into bankruptcy protection, while a number of other proposed schemes were never constructed.
At one stage there was a threat that the Iridium satellites would have to be de-orbited; however, they remained in orbit and operational. Their service was restarted in 2001 by the newly founded Iridium Satellite LLC, which was owned by a group of private investors. Although the satellites and other assets and technology behind Iridium were estimated to have cost on the order of US$6 billion, the investors bought the firm for about US$25 million.
On February 10, 2009, Iridium 33
Iridium 33
Iridium 33 was a U.S. Iridium communications satellite. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 GMT on 14 September 1997, by a Proton-K carrier rocket with a Block DM2 upper stage...
collided
2009 satellite collision
The 2009 satellite collision was the first accidental hypervelocity collision between two intact artificial satellites in Earth orbit. The collision occurred at 16:56 UTC on February 10, 2009, at above the Taymyr Peninsula in Siberia, when Iridium 33 and Kosmos-2251 collided...
with a defunct Russian satellite, Kosmos 2251, 800 km over Siberia. A pair of large debris clouds was created.
Present status
Iridium Satellite LLC merged with a special purpose acquisition company (GHQ) created by the investment bank Greenhill & Co.Greenhill & Co.
Greenhill & Co., Inc. is a leading independent investment bank focused on providing financial advice on significant mergers, acquisitions, restructurings, financings and capital raisings to corporations, partnerships, institutions and governments. The firm made $298.6m in sales in 2009, with a...
(NYSE: GHL) in September, 2009 to create Iridium Communications, Inc. The public company trades on NASDAQ under the symbol "IRDM". The company has approximately 447,000 subscribers as of the end of March, 2011 (compared to 320,000 in December, 2008). Revenue for the full year 2010 was US $348.2 million with Operational EBITDA
EBITDA
EBITDA is an acronym for earnings before interest, taxes, depreciation, and amortization. It is a non-GAAP metric that is measured exactly as stated. All interest, tax, depreciation and amortization entries in the income statement are reversed out from the bottom-line net income...
of US $158.9 million.
The system is being used extensively by the U.S. Department of Defense
United States Department of Defense
The United States Department of Defense is the U.S...
through the DoD gateway in Hawaii. The DoD made up 23% of Iridium's revenues in 2010. An investigation was begun into the DoD contract after a protest by Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
, to the U.S. General Accounting Office that no tender was provided. The investigation was suspended at the request of the Department of Defense, who cited national security reasons.
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 satellites are now an essential component of communications with remote science camps, especially the Amundsen-Scott South Pole Station
Amundsen-Scott South Pole Station
The Amundsen–Scott South Pole Station is the American scientific research station on the high plateau of Antarctica. This station is located at the southernmost place on the Earth, the Geographic South Pole, at an elevation of 2,835 meters above sea level.The original Amundsen-Scott Station was...
. As of December 2006, an array of twelve Iridium modems was put online, providing continuous data services to the station for the first time. Total bandwidth is 28.8 kbit/s.
Hosted Payload Alliance
Iridium is a founding member of the Hosted Payload Alliance (HPA). The HPA is a satellite industry alliance formed to increase awareness of the benefits of hosted government payloads on commercial satellites. Membership in the HPA is open to satellite operators, satellite manufacturers, system integrators and other interested parties.Iridium satellite constellation
The Iridium system requires 66 active satellites in orbit to complete its constellation and spare satellites are kept in-orbit to serve in case of failure. The satellites are in six polar low Earth orbitLow Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
al planes at a height of approximately 485 miles (780.5 km). Satellites communicate with neighboring satellites via Ka band
Ka band
The Ka band covers the frequencies of 26.5–40 GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" — in other words, the band directly above the K-band...
intersatellite links to relay communications to and from ground stations. Most of these satellites were launched in the late 1990s before the company went through bankruptcy. Since the bankruptcy, only seven additional satellites have been launched but an updated constellation of 66 satellites is currently being developed and is planned for launch in 2015-2017 on SpaceX
SpaceX
Space Exploration Technologies Corporation, or more popularly and informally known as SpaceX, is an American space transport company that operates out of Hawthorne, California...
Falcon 9
Falcon 9
Falcon 9 is a rocket-powered spaceflight launch system designed and manufactured by SpaceX. Both stages of its two-stage-to-orbit vehicle use liquid oxygen and rocket-grade kerosene propellants...
Launch Vehicles from Vandenberg AFB Space Launch Complex 3
Vandenberg AFB Space Launch Complex 3
Space Launch Complex 3 is a launch site at Vandenberg Air Force Base that has been used by Atlas and Thor rockets. It was built in the early 1960s and consists of two pads, SLC-3E and SLC-3W . The East-West coastline at Vandenberg allows SLC-3 to launch over-ocean polar trajectories that avoid...
in California.
Handsets
The former Iridium provided phones from two vendors, KyoceraKyocera
is a multinational manufacturer based in Kyoto, Japan. It was founded as in 1959 by Kazuo Inamori and renamed in 1982. The company has diversified its founding technology in ceramic materials through internal development as well as strategic mergers and acquisitions...
and Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
. The Motorola 9500 phone is a design from the first commercial phase of Iridium, whereas the 9555 model is the current version of the handset and was released in October 2008. Until the release of the 9555 the 9505A was the sole handset sold by the company — a functionally identical clone of the Motorola 9505 with some slightly different components.
Kyocera phone models SS-66K and SD-66K are no longer in production but still available in the second-hand and surplus market. The SD-66K phone is a small 900 MHz GSM phone that fitted in a cradle (KI-G100) that included a large antenna and facilitated connection to the Iridium network. The SS-66K is a self contained phone, but featured a rather unusual ball antenna.
All handsets can receive SMS
Short message service
Short Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
, but only the 9505, 9505A, 9555 and those based on the 9522 can send them.
Pagers
Two pagers were made for the Iridium network — the Motorola 9501 and Kyocera SP-66K. These are one-way devices that could receive messages delivered in the form of SMS.Other satellite phones
Several other Iridium-based telephones exist, such as payphonePayphone
A payphone or pay phone is a public telephone, often located in a phone booth or a privacy hood, with pre-payment by inserting money , a credit or debit card, or a telephone card....
s, bag phones, car phone
Car phone
A car phone is a mobile phone device specifically designed for and fitted into an automobile.In the late 1970s and 1980s, the car phone was more popular than the regular mobile phone...
s and equipment intended for installation on ships and aircraft. A handset made by NAL research combined with a 9522 transceiver is used for some of these products. The DPL handset provides a user interface
User interface
The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...
nearly identical to that of the 9505 series phones.
Standalone transceiver units
These can be used for data-logging applications in remote areas, now a common practical use for Iridium's services. Some types of buoyBuoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...
s, such as those used for the tsunami warning system
Tsunami warning system
A Tsunami warning system is used to detect tsunamis in advance and issue warnings to prevent loss of life and damage. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal...
, use Iridium satellites to communicate with their base. The remote device is programmed to call or send SBD (Short burst data, see below) messages to the base at specified intervals, or it can be set to accept calls in order for it to offload its collected data. Most of these units can be connected to a handset and used as a fixed telephone.
The following transceivers have been released over the years:
- Iridium 9575 — A Jet-water, shock and dust resistant (IP65), as well as GPS enabled handset, launched in September 2011.
- Iridium 9555 — The most recent satelite handset,with Integrated speakerphone and hands-free capability, launched in late 2008.
- Iridium 9522B — A transceiver released in late 2008, is smaller than the 9522A and has similar features.
- Iridium 9522A — Based on the 9522, some variants have built in GPS and autonomous reporting functions. Supports SBD.
- Motorola 9522 — Last Motorola transceiver, supports outgoing SMS but no SBD.
- Motorola 9520 — Original transceiver module, does not support outgoing SMS or SBD. Designed for use in vehicles with accompanying handset
SBD Modems
These devices support only SBD and do not use a SIM card.- Iridium 9601 — Supports only SBD, several tracking devices and other products have been built around this modem.
- Iridium 9602 — Smaller, cheaper version of 9601 (released in 2010).
SIM card
Removable Subscriber Identity ModuleSubscriber Identity Module
A subscriber identity module or subscriber identification module is an integrated circuit that securely stores the International Mobile Subscriber Identity and the related key used to identify and authenticate subscriber on mobile telephony devices .A SIM is held on a removable SIM card, which...
s (SIMs) are used in Iridium phones, much like those used for GSM. Prepaid SIM cards are usually green while post-paid cards are red.
Iridium OpenPort®
Iridium OpenPort® is a broadband satellite voice and data communications system for maritime vessels. The system is used for crew calling and e-mail services on sea vessels such as merchant fleets, government and navy vessels, fishing fleets and personal yachts. Iridium’s Global Service Program provides shipboard technical support to Iridium OpenPort customers.Services
Calls to Iridium phones are expensive, costing several dollars a minute. It is possible to call with charges reversedCollect call
A collect call in the USA and Canada or reverse charge call in the UK and other countries is a telephone call in which the calling party wants to place a call at the called party's expense...
by first dialing a number in Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
; the call is charged to the receiver at the standard rate for satellite to landline calls, but the caller only pays for the call to Arizona.
Since Iridium will not sell prepaid cards or even its subscription call service directly, it is hard to obtain the exact price of making a call. There are numerous distributors that will activate Iridium phones and sell pre-paid vouchers and SIM cards.
Voice and data calls
The Iridium system deals with "minutes", which are subdivided into several much smaller "units". These minutes are the "basic rate" to landlines and ordinary mobile phoneMobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s around the world. For a 500 minute annual plan the cost of the "basic rates" fluctuates around US$1.25 per minute, depending on the distributor. There are also regional plans that offer slightly cheaper rates than the normal, but these minutes can only be used in a specified geographic location (such as Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
or Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
).
- Calls to landlines worldwide: 1.00× basic rate
- Calls to other Iridium phones or voice mail: 0.50×
- Sending SMSShort message serviceShort Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
messages: 0.33× - Calls to other satellite phones: 5.00–13.50×
- Data calls: 1.00×
Iridium and other satellite phones may be identifiable to the listener by the "clipping" effect of the data compression
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
and the latency
Lag
Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
(time delay) due to the electronic equipment used and the distances the signal must travel. The voice codec
Codec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
used is called Advanced Multi-Band Excitation
Advanced Multi-Band Excitation
Advanced Multi-Band Excitation is a proprietary speech coding standard developed by Digital Voice Systems, Inc.- Overview :AMBE is a codebook-based vocoder that operates at bitrates of between 2 and 9.6 kbit/s, and at a sampling rate of 8 kHz in 20-ms frames...
.
Iridium operates at only 2.2 to 3.8 kbit/s, which requires very aggressive voice compression
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
and decompression algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
s. Latency for data connections is around 1800 ms
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
round-trip, using small packets.
Despite the bandwidth limitations, transparent TCP/IP is supported. Iridium claims data rates up to 10 kilobit
Kilobit
The kilobit is a multiple of the unit bit for digital information or computer storage. The prefix kilo is defined in the International System of Units as a multiplier of 103 , and therefore,...
s per second for their "direct Internet" service which utilizes v.42bis compression
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
over a PPP dialup connection to Iridium's Arizona gateway. Actual data rates remain at 2300 to 2400 bit/s for any compressed data such as a JPG image or ZIP
Zip
Zip or ZIP most commonly refers to:*Zipper or zip, a device for temporarily joining two edges of fabric together*ZIP code, the USPS Zone Improvement Plan used in postal addresses in the USA*Zip drive, a removable data storage format...
file, but plain text or HTML may transfer "up to" 10 kbit/s. Iridium 9500, 9505 and 9505A phones can be connected to computers using an RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
connection, as can the 9522A transceiver module. The 9555 phone connects to computers with a standard USB cable, using an internal USB to serial bridge chip and Windows drivers to emulate a serial COM port for compatibility with standard PPP clients.
Prepaid service
Prepaid SIM cards are available from a variety of different outlets and sometimes appear on auction sites such as eBayEBay
eBay Inc. is an American internet consumer-to-consumer corporation that manages eBay.com, an online auction and shopping website in which people and businesses buy and sell a broad variety of goods and services worldwide...
. Their values range from 50 to 5,000 minutes; the 50 minute cards have no validity and the 75 minute vouchers are valid for only a month, but the 5,000 minute cards stay valid for two years. Since Iridium charges quite a bit for merely accessing their network without making calls it is possible to extend the validity of such an account by a month for around US$45. It is also possible to refill such an account without purchasing a new SIM card.
The 500 minute card is the most common one, which remains valid for one year and can usually be bought for US$600 to $750, while the 75 minute card can cost up to US$175 and the 5,000 minute card costs around US$4,000.
Post-paid service
There is a basic "Emergency" plan for around US$30 to US$40 per month that offers no minutes at all with calls charged at around US$1.39 per minute, and also numerous plans with included minutes. For the more expensive plans (around US$250 per month) the per-minute price dips slightly below US$1.Phone numbers
Iridium controls the virtual country codes +8816 and +8817, part of the 881 range designated by the ITUItu
Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...
for the Global Mobile Satellite System
Global Mobile Satellite System
The Global Mobile Satellite System is a general term referring to the selection of satellite phone providers available to private customers...
. Each subscriber is given an 8-digit number prefixed by one of these country codes. However many regional telephone service operators have no interconnect agreement
Interconnect agreement
An interconnect agreement is a business contract between telecommunications organizations for the purpose of interconnecting their networks and exchanging telecommunications traffic...
with Iridium or other satellite networks and users on these networks need to call reversed charge to a U.S.-based number.
Since spring 2007, postpaid
Postpaid
Post Paid: A model of cellular service whereby the customer is charged for usage in the prior month , and hence does not feature any limitations on volume of service used...
Iridium subscribers have an option to associate their Iridium numbers with a direct U.S.-based number (the so-called +1 Access service).
Paging service
The one-way paging service is still operational, despite the pagerPager
A pager is a simple personal telecommunications device for short messages. A one-way numeric pager can only receive a message consisting of a few digits, typically a phone number that the user is then requested to call...
s no longer being in production for many years now. Messages are delivered to pre-selected "MDAs" which cover a certain geographic area. Three of these MDAs may be selected on a web-based portal or updated automatically if the paging service is bound to an Iridium phone. Each country has its own MDA based on its country code
Country code
Country codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
; some of the larger countries are divided into several MDAs, while separate MDAs exist for sections of ocean and common aeronautic routes.
This service costs around US$70 per month with a limited number of messages allowed, or US$140 for an unlimited number of inbound messages.
Pagers are assigned with telephone numbers in area code 480
Area code 480
Image:Area_code_AZ.png|right|Map of Arizona area codes in blue poly 0 0 73 58 14 59 14 100 0 90 Area code 775poly 73 58 68 92 64 92 58 88 48 88 51 125 49 135 13 98 10 58 Area code 702poly 74 49 250 49 250 1 73 1 Area code 435...
and can also be contacted using email, SMS and the web-based interface used to send messages to Iridium phones.
Short burst data
Special modems such as the 9522A and Quake Q9612 can be used for sending and receiving short data bursts, less than 2 kilobytes at a time. This service is often used for asset tracking and remote monitoring. Messages are converted to be delivered in emailEmail
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
format or over HTTP to a preconfigured address; the mobile unit does not include a destination address when sending a SBD message. A crude positioning report is also included in each message sent. SBD messages take from 6 to 22 seconds to send or receive.
Air Safety Communications
In July 2011 The Federal Aviation Administration (FAA) issued a ruling that approves the use of Iridium for Future Air Navigation System (FANS) data links, enabling satellite data links with air traffic control (ATC) for aircraft flying in the FANS environment including areas not served by Inmarsat (above or below 70 Degrees Latitude) which includes Polar routes.Air interface
Communication between satellites and handsets is done using a TDMATime division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...
and FDMA
Frequency-division multiple access
Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access protocols as a channelization protocol. FDMA gives users an individual allocation of one or several frequency bands, or channels. It is particularly commonplace in satellite communication. FDMA, like...
based system using L-band spectrum between 1616 and 1626.5 MHz. Iridium exclusively controls 7.775 MHz of this and shares a further 0.95 MHz. In 1999 Iridium agreed to timeshare a portion of spectrum, allowing radio astronomers to observe hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
emissions; the amount of shared spectrum was recently reduced from 2.625 MHz.
The type of modulation used is normally DE-QPSK, although DE-BPSK is used on the uplink (mobile to satellite) for acquisition and synchronization. Each time slot is 8.28 ms long and sits in a 90 ms frame. Within each FDMA channel there are four TDMA time slots in each direction. The TDMA frame starts off with a 20.32 ms period used for simplex messaging to devices such as pagers and to alert Iridium phones of an incoming call, followed by the four upstream slots and four downstream slots. This technique is known as time division multiplexing. Small guard periods are used between time slots. Regardless of the modulation method being used, communication between mobile units and satellites is performed at 25 kilobaud
Baud
In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...
.
Channels are spaced at 41.666 kHz and each channel occupies a bandwidth of 31.5 kHz; this allows space for Doppler shifts.
Handoff
The Iridium system uses three different handoff types. As a satellite travels over the horizon, calls are handed to adjacent spot-beams; this occurs approximately every fifty seconds. A satellite only stays in view for seven minutes at the equator. When the satellite disappears from view, an attempt is made to hand the call to another satellite. If no other satellite is in view, the connection is dropped. This may occur when the signal from either satellite is blocked by an obstacle. When successful, the inter-satellite handoff may be noticeable by a quarter-second interruption.The satellites are also able to transfer mobile units to different channels and time slots within the same spot beam.
Earth base-stations
Iridium routes phone calls through space. In addition to communicating with the satellite phones in its footprint, each satellite in the constellation also maintains contact with two to four adjacent satellites, and routes data between them, to effectively create a large mesh network. There are four earth stationEarth station
A ground station, earth station, or earth terminal is a terrestrial terminal station designed for extraplanetary telecommunication with spacecraft, and/or reception of radio waves from an astronomical radio source. Ground stations are located either on the surface of the Earth, or within Earth's...
s which link to the network through the satellites visible to them. The space-based backhaul
Backhaul (telecommunications)
In a hierarchical telecommunications network the backhaul portion of the network comprises the intermediate links between the core network, or backbone, of the network and the small subnetworks at the "edge" of the entire hierarchical network...
routes outgoing phone call packets through space to one of the earth station downlinks ("feeder links"). Station-to-station calls from one satellite phone to another can be routed directly through space without going through an earth station. As satellites leave the area of an earth station, the routing tables are updated and packets headed for the earth station are forwarded to the next satellite just coming into view of the earth station. Communication between satellites and earth stations is at 20 and 30 GHz.
Gateways are located in
- TempeTempe, ArizonaTempe is a city in Maricopa County, Arizona, USA, with the Census Bureau reporting a 2010 population of 161,719. The city is named after the Vale of Tempe in Greece. Tempe is located in the East Valley section of metropolitan Phoenix; it is bordered by Phoenix and Guadalupe on the west, Scottsdale...
, ArizonaArizonaArizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix... - Wahiawa, HawaiiHawaiiHawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
— owned by Defense Information Systems AgencyDefense Information Systems AgencyThe Defense Information Systems Agency is a United States Department of Defense agency that provides information technology and communications support to the President, Vice President, Secretary of Defense, the military Services, and the Combatant Commands.As part of the Base Realignment and...
(DISADisaDisa is the heroine of a Swedish legendary saga, which was documented by Olaus Magnus, in 1555. It is believed to be from the Middle Ages, but includes Old Norse themes....
) - AvezzanoAvezzanoAvezzano is a town and comune in the Abruzzo region, province of L'Aquila. It is the main commercial, industrial and agricultural centre of the Marsica area, with high-tech industries such as a Micron Technology semi-conductor plant, and a large Telespazio satellite farm.-History:There are two...
, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
The pre-bankruptcy corporate incarnation of Iridium built eleven gateways, many of which have since been closed.
Gateways have also been built in Pune
Pune
Pune , is the eighth largest metropolis in India, the second largest in the state of Maharashtra after Mumbai, and the largest city in the Western Ghats. Once the centre of power of the Maratha Empire, it is situated 560 metres above sea level on the Deccan plateau at the confluence of the Mula ...
(India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
), Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...
(People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
), Moscow
Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...
(Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
), Nagano (Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
), Seoul
Seoul
Seoul , officially the Seoul Special City, is the capital and largest metropolis of South Korea. A megacity with a population of over 10 million, it is the largest city proper in the OECD developed world...
(South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
), Taipei
Taipei
Taipei City is the capital of the Republic of China and the central city of the largest metropolitan area of Taiwan. Situated at the northern tip of the island, Taipei is located on the Tamsui River, and is about 25 km southwest of Keelung, its port on the Pacific Ocean...
(Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
), Jeddah
Jeddah
Jeddah, Jiddah, Jidda, or Jedda is a city located on the coast of the Red Sea and is the major urban center of western Saudi Arabia. It is the largest city in Makkah Province, the largest sea port on the Red Sea, and the second largest city in Saudi Arabia after the capital city, Riyadh. The...
(Saudia Arabia) and Rio de Janeiro
Rio de Janeiro
Rio de Janeiro , commonly referred to simply as Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America, boasting approximately 6.3 million people within the city proper, making it the 6th...
(Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
). The company is seeking to reactivate gateways in Russia, and China to comply with national laws in those countries.
Other technical information
Like other satellite networks, Iridium terminals need open line-of-sight to open sky in order to function. For instance, units will not work consistently indoors, or under forest cover. Iridium does have a very powerful paging channel that can ring the phone indoors, but the customer may have to walk outdoors to take the call.There is a Web/e-mail to SMS gateway which enables messages to be sent from the Internet or an e-mail account to Iridium handsets for free. There is also a voice mail
Voicemail
Voicemail is a computer based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to individuals, organizations, products and services, using an ordinary telephone...
service.
Iridium generally does not have roaming agreements with terrestrial/cellular operators. Telstra in Australia allows postpay GSM subscribers to use their SIM card. However, global roaming has to be activated and both incoming and outgoing calls are charged to this account, and the call rate is around US$4 per minute; the incoming calls are via the GSM phone number of the account, with country code, etc., prefixed. In order to use the network, it is necessary to have not only appropriate equipment, such as a handset or the optional cellular cassette for the Motorola 9505 phone, but also a pay-as-you-go or contract Iridium SIM card.
Tracking transceiver units
Without an extra Global navigation satellite systemGlobal Navigation Satellite System
A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...
, receiver tracking is difficult, but not impossible, as the position of a mobile unit can be determined using a Doppler shift calculation from the satellite. These readings however can be inaccurate with errors in the tens of kilometers. Even without using Doppler shifts, a rough indication of a unit's position can be found by checking the location of the spot-beam being used and the mobile unit's timing advance
Timing advance
In the GSM cellular mobile phone standard, timing advance value corresponds to the length of time a signal takes to reach the base station from a mobile phone. GSM uses TDMA technology in the radio interface to share a single frequency between several users, assigning sequential timeslots to the...
.
The position readings can be extracted from some transceiver units and the 9505A handset using the
-MSGEO AT command.In the past, Iridium has used this method of tracking to block service to U.S. embargo
Embargo
An embargo is the partial or complete prohibition of commerce and trade with a particular country, in order to isolate it. Embargoes are considered strong diplomatic measures imposed in an effort, by the imposing country, to elicit a given national-interest result from the country on which it is...
ed countries, such as North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...
and other politically unpopular regions, such as Northern Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
. It is also used to stop geographically bounded plans from being used outside the designated area.
See also
- 2009 satellite collision2009 satellite collisionThe 2009 satellite collision was the first accidental hypervelocity collision between two intact artificial satellites in Earth orbit. The collision occurred at 16:56 UTC on February 10, 2009, at above the Taymyr Peninsula in Siberia, when Iridium 33 and Kosmos-2251 collided...
- Broadband Global Area Network
- GlobalstarGlobalstarGlobalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
- InmarsatInmarsatInmarsat plc is a British satellite telecommunications company, offering global, mobile services. It provides telephony and data services to users worldwide, via portable or mobile terminals which communicate to ground stations through eleven geostationary telecommunications satellites...
- Iridium flare
- O3b
- OrbcommOrbcommORBCOMM is a company that offers M2M global asset monitoring and messaging services from its constellation of 29 LEO communications satellites orbiting at 775 km. Like its voice-centric competitors Iridium and Globalstar, it filed for Chapter 11 protection, in September, 2000. ORBCOMM issued...
- SkyWave Mobile CommunicationsSkyWave Mobile CommunicationsSkyWave Mobile Communications is a satellite telematics company that provides satellite transceivers, dual-mode satellite/GPRS terminals and satellite network services for global tracking, monitoring, and control of mobile and stationary assets...
- ThurayaThurayaThuraya , the Arabic name of the Pleiades, is a regional satellite phone provider. Its coverage area is most of Europe, the Middle East, North, Central and East Africa, Asia and Australia....