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Iridium Communications

Iridium Communications Inc. (formerly Iridium Satellite LLC) is a publicly traded American company headquartered in McLean, Virginia. Iridium operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units. The Iridium network covers the entire Earth, including poles, oceans and airways, with 66 satellites, with the remaining 9 acting as active backups, for a total of 75 launched as part of their new constellation.[3] Six remain on the ground as spares for a total of 81 built.[citation needed]

Iridium Communications Inc.
Public company
Traded asNASDAQIRDM
S&P 600 Component
IndustrySatellite telecommunication
Founded2001
Headquarters,
United States
Area served
Worldwide
Key people
  • Matthew J. Desch (CEO) *Thomas J. Fitzpatrick (CFO) *Suzi McBride (COO)
ProductsSatellite communications equipment
ServicesSatellite voice and data services
RevenueIncrease US$523.0 million (2018)[1]
Decrease US$41.7 million (2018)[1]
Decrease –US$13.4 million (2018)[1]
Total assetsUS$4.01 billion (2018) [2]
Total equityUS$1.60 billion (2018)[2]
Number of employees
450+ (2019) [2]
Websitewww.iridium.com

Iridium manages several operations centers, including Tempe, Arizona and Leesburg, Virginia, United States. The company derives its name from the chemical element iridium which has an atomic number of 77, equalling the initial number of satellites which were planned to be deployed.[citation needed]

HistoryEdit

The Iridium communications service was launched on November 1, 1998 by what was then Iridium SSC. The first Iridium call was made by Vice President of the United States Al Gore to Gilbert Grosvenor, the great-grandson of Alexander Graham Bell and chairman of the National Geographic Society.[4] Motorola provided the technology and major financial backing.[5] The logo of the company represents the Big Dipper.[6]

The founding company went into Chapter 11 bankruptcy nine months later, on August 13, 1999.[7] The handsets could not operate as promoted until the entire constellation of satellites was in place, requiring a massive initial capital cost running into billions of dollars.[8] 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 phones discouraged adoption among potential users.[7]

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 website, and a "run-around" from the company's representatives.[9] After Iridium filed bankruptcy, it cited "difficulty gaining subscribers".[10]

The initial commercial failure of Iridium had a damping 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.[7]

In August 2000, Motorola announced that the Iridium satellites would have to be deorbited;[11] however, they remained in orbit and operational.[12][13] In December 2000, the US government stepped in to save Iridium by providing $72 million in exchange for a two-year contract and approving the fire-sale of the company from US bankruptcy court for $25 million,[11] in March 2001. This erased over $4 billion in debt.[14]

Iridium 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 around $6 billion, the investors bought the firm for about $35 million.[8]

On February 10, 2009, Iridium 33 collided with a defunct Russian satellite, Kosmos 2251, 800 kilometres (500 mi) over Siberia.[15] Two large debris clouds were created.[16]

Iridium NEXT launch campaignEdit

Iridium replaced its original constellation by sending 75 new Iridium satellites into space on SpaceX Falcon 9 rockets. The campaign also consisted of upgrades to Iridium ground infrastructure.

The Iridium NEXT launch campaign was announced in 2007. Within three years, Iridium completed financing and began work on launching new satellites. In June 2010, Iridium announced a fixed-price contract with Thales Alenia Space for the design and construction of the next-generation satellites for the upgraded constellation.[17] Two weeks later, Iridium announced a $492 million contract designated the Falcon 9 as a major provider of launch services for the Iridium NEXT campaign, becoming the largest single commercial launch deal ever signed (simultaneously representing a benchmark in cost-effective satellite delivery to space).[18]

On January 14, 2017, 10 years after the campaign was first announced, the first of eight Iridium NEXT launches took place with SpaceX from Vandenberg Air Force Base in California.[19] Over the next two years, Iridium sent an additional 65 satellites into low Earth orbit to completely replace the original satellite constellation. The final Iridium NEXT launch took place on January 11, 2019, less than 2 years after the first launch.[20]

Present statusEdit

Iridium Satellite LLC merged with a special purpose acquisition company (GHQ) created by the investment bank Greenhill & Co. in September 2009 to create Iridium Communications Inc. The public company trades on Nasdaq under the symbol "IRDM". The company surpassed one million subscribers in March 2018.[21] Revenue for the full year 2018 was US$523.0 million with operational EBITDA of US$302.0 million, a 14% increase from $265.6 million in the prior year.[22]

The system is being used by the U.S. Department of Defense.[23]

Matt Desch is the CEO of Iridium LLC.[24]

Hosted Payload AllianceEdit

Iridium is a founding member of the Hosted Payload Alliance (HPA), a satellite industry alliance program. Membership in the HPA is open to satellite operators, satellite manufacturers, system integrators, and other interested parties.[25]

Iridium satellite constellationEdit

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 orbital planes at a height of approximately 485 miles (780 km). Satellites communicate with neighboring satellites via Ka band intersatellite links to relay communications to and from ground stations. The original constellation was launched in the late 1990s before the company went through bankruptcy. In January 2017, Iridium began launch next-generation satellites through its $3 billion launch campaign, Iridium NEXT. The new satellites were sent into space on SpaceX Falcon 9 launch vehicles from Vandenberg AFB Space Launch Complex 4 in California over the course of eight launches between January 2017 and January 2019.[26][27] On January 14, 2017, SpaceX launched 10 of the new Iridium satellites into orbit.[28] The second launch of Iridium NEXT satellites took place on June 25, 2017 on a SpaceX Falcon 9 rocket out of Vandenberg Air Force Base. This was the second of eight scheduled launches.[29] The third launch of 10 NEXT satellites took place on October 9, 2017. On December 22, 2017, ten additional satellites were deployed after a successful launch on a SpaceX Falcon 9 rocket. On May 22, SpaceX successfully launched an additional five Iridium NEXT satellites from Vandenberg Air Force Base.[30]

On January 11, 2019, the final ten satellites were placed in orbit by SpaceX.[31]

Subscriber equipmentEdit

HandsetsEdit

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PagersEdit

Two pagers were made for the Iridium network – the Motorola 9501 and Kyocera SP-66K.[36] These are one-way devices that could receive messages sent in the form of SMS.

Other satellite phonesEdit

Several other Iridium-based telephones exist, such as payphones,[37] and equipment intended for installation on ships and aircraft. The DPL handset made by NAL Research combined with a 9522 transceiver is used for some of these products. This handset provides a user interface nearly identical to that of the 9505 series phones.[38]

Standalone transceiver unitsEdit

These can be used for data-logging applications in remote areas. Some types of buoys, 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 short burst data (SBD) messages to the base at specified intervals, or it can be set to accept calls in order for it to offload its collected data.

The following transceivers have been released over the years:

  • Iridium Core 9523 – Similar to the 9522B, a modular transceiver released in 2012, designed to be an embedded solution.[buzzword]
  • Iridium 9522B – A transceiver released in late 2008, is smaller than the 9522A and has similar features. It also supports Circuit-Switched Data (CSD), not just SBD.
  • 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[39]

Short burst data modemsEdit

These devices support only SBD for Internet of things (IoT) services and do not use a SIM card.

  • Iridium 9601 – Supports only SBD, several tracking devices and other products have been built around this modem. It was an Iridium manufactured product designed as an OEM module for integration into applications that only use the Iridium Short Burst Data Service. Short Burst Data applications are supported through an RS-232 interface. Examples of these applications include maritime vessel tracking or automatic vehicle tracking.[40]
  • Iridium 9602 – Smaller, cheaper version of 9601 (released in 2010).[41]
  • Iridium 9603 – One-fourth the volume and half the footprint of 9602[42]

Iridium OpenPortEdit

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.[43]

Iridium operates at only 2.2 to 3.8 kbit/s, which requires very aggressive voice compression[44] and decompression algorithms.[45] (By comparison, AMR used in 3G phones requires a minimum of 4.75 kbit/s, G.729 requires 6.4 kbit/s, and iLBC requires 13.33 kbit/s.) Latency for data connections averages 1800 ms round-trip, with a mode of 1300 to 1400 ms and a minimum around 980 ms.[46] Latency is highly variable depending on the path data takes through the satellite constellation as well the need for retransmissions due to errors, which may be around 2 to 3% for mobile originated packets under good conditions.

Paging ServiceEdit

The one-way paging service is still operational, despite the pagers not being in production for many years now[citation needed][when?]. 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.

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.[47]

Air safety communicationsEdit

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 for aircraft flying in the FANS environment, including areas not served by Inmarsat (above or below 70 degrees latitude) which includes polar routes.[48]

Technical detailsEdit

Air interfaceEdit

Communication between satellites and handsets is done using a TDMA and FDMA based system using L-band spectrum between 1616 and 1626.5 MHz.[49] 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.[50][51]

External "hockey puck" type antennas used with Iridium handheld phones, data modems and SBD terminals are usually defined as 3dBi gain, 50 ohm impedance with RHCP (right hand circular polarization) and 1.5:1 VSWR.[52] As Iridium antennas function in frequencies very close to that of GPS, a single antenna may be utilized through a pass-through for both Iridium and GPS reception.

The type of modulation used is normally DE-QPSK, although DE-BPSK is used on the uplink (mobile to satellite) for acquisition and synchronization.[53] 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.[54] 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.[49]

HandoffEdit

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.[55] 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.[54]

The satellites are also able to transfer mobile units to different channels and time slots within the same spot beam.

Ground StationsEdit

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 several earth stations 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.[56]

Gateways are located in

  • Tempe, Arizona (USA)
  • Fairbanks, Alaska (USA)
  • Svalbard, Norway (Europe)
  • Punta Arenas, Chile (South America) [57]

The pre-bankruptcy corporate incarnation of Iridium built eleven gateways, most of which have since been closed.[58]

See alsoEdit

ReferencesEdit

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External linksEdit