Iridium (communication system)

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Iridium LLC logo

Iridium is a global satellite communication system operated by the US company of the same name, Iridium Communications Inc., based in McLean (Virginia) , comprising 66 active satellites in six orbits and one or more reserve satellites per orbit. Originally 77 satellites were planned for this satellite constellation ; the system is therefore named after the chemical element iridium with the atomic number 77.

The Iridium network has the area codes +8816 and +8817. The network identifier assigned by the ITU is 901-03.

development

Soldiers of the US Air Force check the functionality of an Iridium cell phone in Antarctica (2010).

Iridium Inc.

The idea for Iridium was born at Motorola in 1985 . It should enable global voice and data transmission via satellite telephones and PDAs . The concept for this was established by 1988. In 1991 the company Iridium Inc. was founded, which developed the system and put it into operation in September 1998. The call costs were initially very high at around eight US dollars / min, the end devices were expensive and much more unwieldy than planned. As a result, instead of the planned two million users, only around 55,000 customers could be acquired.

On August 23, 2000, Iridium Inc. had to file for bankruptcy. The satellites should be directed into the earth's atmosphere in order to let them burn up in a targeted manner. Expeditions would also have been affected by a planned shutdown . They had relied on accessibility in advance and did not have any other communication systems. These included Rune Gjeldnes and Torry Larsen on a Norwegian expedition to the North Pole , Prince Frederik of Denmark on a dogsled expedition in Greenland and the French adventurer Jo Le Guen , who crossed the Pacific alone in his 9 m long rowboat . They received a call from the company announcing the end of operations. Finally, the shutdown was partially postponed due to public pressure .

Iridium Satellite LLC

On January 1, 2001, the Iridium system was taken over by the newly founded Iridium Satellite LLC . The satellites are operated and maintained by Boeing . Commercial operations resumed on March 30, 2001. The biggest difference to the previous operation is that no roaming with GSM - SIM cards in the Iridium network as well as with Iridium SIM cards in the GSM network is possible.

Iridium had 1 million paying subscribers as of April 2018 . More than 50% of all Iridium subscriptions are for M2M data transmission applications ( SBD ), less than 50% for voice telephony and worldwide Internet access . The largest single customer with around 10% participation is the military, above all the US Department of Defense . Other users are shipping companies, airlines, scientists or companies involved in mineral extraction.

In 2005, device prices fell significantly, and a minute of phone calls to landline or mobile networks cost between $ 0.90 and $ 1.50, depending on the number of minutes ordered. Significantly lower are the fees for regionally limited SIM cards, such as in America or Africa. A new Iridium satellite phone costs around € 1300. The annual subscription to worldwide voice telephony with an Iridium satellite phone costs around $ 530. A globally valid pre-paid SIM card for an Iridium satellite phone with a validity period of 30 days is available from 160 €.

Network coverage

Communication with Iridium is basically possible from any location on the earth's surface with a clear view of the sky. Worldwide reception is possible via the Iridium satellite network, but the Iridium reception may temporarily fail. If the Iridium reception fails, an object is located in the first Fresnel zone and interferes with the line of sight from the satellite telephone to the Iridium satellite. There should be no shrubs, trees, rocks, house or hut walls in the first Fresnel zone. Iridium satellites are sometimes very low in the sky outside the polar region (small elevation angle ). As a result, satellite communications over the Iridium satellite network are very susceptible to line of sight interference.

With a clear view of the sky, there is no interruption in all directions from an elevation angle of 8.2 °. In order to ensure perfect, uninterrupted communication with Iridium, no object from an elevation angle of 8.2 ° must disturb the view of the sky. As a rule of thumb, hold a clenched fist with your arm stretched out horizontally. The height of the clenched fist corresponds approximately to an elevation angle of 8.2 °. No object may reach the sky higher than a clenched fist.

  • Network coverage by Iridium, elevation angle 8.2 °

  • Network coverage in deep gorges and mountain valleys, elevation angle 21 °

  • Rule of thumb for perfect Iridium reception

  • Animation of the orbit of a polar orbiting satellite

In a very deep gorge, in which there is only an unrestricted view of the sky at the zenith , in the worst case no communication is possible for 120 minutes, since no Iridium satellite comes into visual contact during this time. Due to the rotation of the earth and the movement of the satellites in their orbits , a satellite is again at its zenith after around 120 minutes.

On the website "ASE Satfinder" (see Related links) or with a smartphone - App for satellite tracking , the current location, the Iridium satellites are calculated in the sky. For this, the satellite tracking app needs current satellite orbit data . With this TLE data, the app can determine the locations of all Iridium satellites for the next 2 hours. With the help of this data, a suitable time for an upcoming telephone call can then be selected. Ideally, a telephone call should be made via the Iridium satellite currently at the zenith .

Due to the polar satellite orbits, the supply density in the polar regions is particularly high. For uninterrupted iridium communication, you therefore need less clear view of the sky in the polar regions than at the equator.

Iridium communication possible if there is
an unrestricted view of the sky from the elevation angle
Geographic
width 		Location At any time
(
uninterrupted) 		Reception gaps
are only
to be expected in the area of ​​the opposing satellite orbits
(only occurs every 12 hours)
0 ° equator 8.2 ° 8.2 °
50 ° Frankfurt am Main 10 ° 12 °
56 ° Edinburgh 10 ° 13 °
60 ° Helsinki 10 ° 14 °
66 ° 34 ′ Polar circle 12 ° 18 °
71 ° North Cape , Point Barrow 20 ° 20 °

  • Visible Iridium satellites in Frankfurt on December 12, 2011 at 10:27 p.m.

  • Visible Iridium satellites in Thule on December 12, 2011 at 10:25 pm

During long phone calls, the Iridium satellite has to be changed every nine minutes on average, as the previously used satellite disappears behind the horizon. The satellite change happens fully automatically. The two interlocutors do not notice anything from the satellite change as long as the rule of thumb “no objects with an elevation angle of more than 8.2 °” is observed. If the rule of thumb is not adhered to (objects with an elevation angle of more than 8.2 °), the call connection can be broken if the old satellite disappears behind the horizon and the new satellite is not yet in sight.

and display information about the image
Network coverage animation

Although the network coverage of Iridium technically allows worldwide use, Iridium satellite phones may not be imported or used in some countries for legal reasons (e.g. in 2015: Cuba , North Korea ). Some countries only allow the import, export and operation of Iridium satellite telephones on their national territory if certain conditions are met. In some states there is a reporting requirement (eg in 2015.: For Iridium satellite phones Russia , India ). Before operating, importing or exporting satellite telephones, it must be clarified whether this is permitted and whether there is an obligation to report.

Applications

Iridium enables global voice and data communication. Iridium is the only reliable commercial two-way communication tool that enables uninterrupted communication with the outside world in the polar regions . In the polar regions above the 82nd degree of latitude, reliable signal reception from geostationary satellites is not possible. For example, iridium is used by several research stations in the Antarctic ( Amundsen-Scott South Pole Station , Neumayer Station III ) for uninterrupted communication with the outside world.

On ships or airplanes moving in the polar regions, there is no legal requirement today that Iridium means of communication must be carried on board. However, it is to be expected that in the polar regions it will be mandatory to carry iridium communication equipment in the near future. In a few application areas (e.g. LRIT ) in the polar regions, the use of iridium as a means of communication is already mandatory.

Voice telephony

Iridium mobile phone

Iridium enables worldwide telephony . Telephone calls are carried over the Iridium satellites using circuit switching (CS) . Iridium enables SMS to be sent and received . It is possible to send and receive SMS between the Iridium network and a terrestrial cellular network . The exchange of SMS between the Iridium and mobile network must be supported by the mobile network provider ( SMS interworking ).

Since the transmission rate of voice data is extremely low at 2400  baud , a highly compressive codec called " Advanced Multi-Band Excitation " (AMBE), which was developed by the North American company Digital Voice Systems, Inc., is used. This codec is used in all active commercial satellite telephones from Iridium, Inmarsat , Thuraya and Globalstar and is also often used for radios with digital transmission methods ( DMR , dPMR ). Due to the strong compression of the voice data, the voice quality corresponds to a MOS value of 3.3. The voice quality is therefore between “decent” and “good”. The voice and connection quality is significantly worse than the usual voice and connection quality of terrestrial mobile to mobile / Natel . For comparison: For telephone calls using terrestrial cellular technology GSM / 2G and UMTS / 3G , the Adaptive Multi-Rate Narrowband (AMR-NB) codec with 12.2 kbit / s is normally used. AMR-NB with 12.2 kbit / s achieves a MOS value of 4.2 (voice quality: “good” to “excellent”).

During telephone calls, speech distortions and short interruptions are to be expected for technical reasons, even with perfect network reception. The use of rules of speech (e.g. "understood" / "answer") is recommended.

Data transfer and internet access

Iridium enables worldwide data communication with circuit switching ( CS) or packet switching (PS). Iridium enables global internet access via satellite . The average round- trip packet time (RTT) of the Internet access realized via Iridium satellites is 700 to 1800 milliseconds (ms) .

Iridium Certus

The Iridium satellites from the second generation (Iridium NEXT) enable the new Iridium Certus service. Iridium Certus enables IP -based data transmission and direct internet access.

Overview of the IP -based data transmissions offered by Iridium Certus
Receiving device Frequency band Maximum possible data transfer rate
Permanent installation on land L-band 1.4 Mbit / s download / 528 Kbit / s upload
Fixed installation on the vehicle L-band 704 Kbit / s download / 352 Kbit / s upload
Permanent installation on a ship L-band 1.4 Mbit / s download / 528 Kbit / s upload
Fixed installation in an aircraft L-band 1.4 Mbit / s download / 528 Kbit / s upload

Data transmission for M2M applications

With “Iridium Short Burst Data” (SBD), Iridium enables global data communication for M2M applications using the datagram method with very small amounts of data and data transmission rates .

GMDSS

Iridium ship antenna on the deck of the Lyubov Orlova in Antarctica

It is likely that in the near future in the sea area A4 the distress communication (GMDSS) on iridium in the carriage requirement. Iridium has received approval for GMDSS application from the IMO . The GMDSS applications via Iridium satellites are not expected to go into operation until 2020 at the earliest.

In order for Iridium to meet the very high availability requirements for GMDSS, the technical equipment must:

be completely geo - redundant . Geo- redundancy is achieved if the redundancy is set up at a location that is far away ( straight line distance> 100 kilometers). A major natural disaster (e.g. earthquake ) could seriously damage the Iridium facilities in Tempe or Leesburg, with a massive impact on the availability of the Iridium satellite network. This is why the geo-redundant construction of the Iridium installations at a distant location is essential for GMDSS.

LRIT

Ships must announce their current position using LRIT . In the polar waters (sea area A4) the current position of the ship must be communicated via iridium.

FANS

Today, aircraft can use Iridium Air Traffic Control ( FANS ) communications equipment to fly over remote regions . FANS over Iridium will likely become mandatory equipment for flights over the 82nd parallel in the near future .

Technical

The main advantage of a satellite-based communication system is that large areas can be covered without terrestrial stations. The end devices ( terminals ) communicate directly with the satellites. The satellite network is connected to the existing earth-based telephone and data networks (e.g. Internet ) via several earth stations . Earth stations for the Iridium satellite network are located in:

Earth stations for the Iridium satellite network
Location country Remarks
Tempe in Arizona United StatesUnited States United States Earth station and main gateway for civil use
Izhevsk RussiaRussia Russia Earth station and gateway for civil use in Russia
Wahiawa in Hawaii United StatesUnited States United States Earth station and gateway for military use by the authorities and armed forces of the USA and their allied forces
Chandler in Arizona United StatesUnited States United States Earth station (exact area of ​​operation not publicly known)
Fairbanks in Alaska United StatesUnited States United States Earth station for civil use via the main gateway in Tempe
Yellowknife in the Northwest Territories CanadaCanada Canada Earth station (exact area of ​​operation not publicly known)
Iqaluit in Nunavut CanadaCanada Canada Earth station (exact area of ​​operation not publicly known)
Longyearbyen on Spitsbergen ( SvalSat ) NorwayNorway Norway Earth station for civil use via the main gateway in Tempe
Punta Arenas in Southern Patagonia ( KSAT ) ChileChile Chile Earth station for civil use via the main gateway in Tempe

In the case of Iridium, the individual satellites are also connected to one another by inter-satellite links (ISLs). If a satellite itself has no contact with an earth station, telephone calls and other useful signals are forwarded via other iridium satellites. An active connection is switched from satellite to satellite until one of these satellites is within range of an earth station. The connection is passed on from the earth station to the Iridium gateway. The call then finds its way into conventional telephone networks via the Iridium gateway. The data transmission from the satellite to the handheld devices takes place in the L-band and between the satellites and from the satellites to the earth station in the Ka-band . Calls that run between Iridium users are switched directly between the satellites without an intervening earth station.

The transmission power of cell phones is limited for technical reasons. In order to enable a connection to be established with low transmission power, the Iridium satellites were placed in a low, non- geosynchronous orbit with a high inclination . The Iridium satellites orbit the earth at an altitude of about 780 km in six nearly polar orbits (orbit inclination = 86.4 degrees) with eleven satellites in active use and one reserve satellite per orbit. A satellite needs about 100 minutes to orbit the earth. When a satellite is no longer functional, it is brought into an orbit around 500 km above sea level, from which it is finally directed into the earth's atmosphere and burns up.

In the dense forest with tall trees, the connection reserve of the Iridium satellite phones is not sufficient for voice communication.

Satellite fleet

Second generation Iridium satellites (Iridium Next)

From January 2017 to January 2019, the first generation of Iridium satellites was replaced by new second generation satellites (Iridium Next). The old satellites were replaced by new satellites gradually. For several months the Iridium satellite network consisted of both old Iridium satellites and new satellites. The new satellites are fully compatible with the old satellites. On February 5, 2019, the last first generation Iridium satellite was decommissioned and replaced by a second generation Iridium satellite.

The cost of next-satellite fleet to 2.9 billion US dollars estimated. Each Iridium NEXT satellite is equipped with an ADS-B receiver. Satellite-based ADS-B enables air traffic control in regions that are not covered by air traffic control radar today. 65 Iridium Next satellites will be equipped with an AIS receiver. Satellite-based AIS allows coastal states to monitor the waterways in regions that today do not by land-based VHF - Marine Radio to be covered.

Iridium bought 81 satellites of its second generation of satellites "Iridium Next" from Thales Alenia Space for 2.1 billion US dollars. Another 800 million dollars were spent on starting them. The company SpaceX was awarded eight starts with Falcon 9 rockets . During the first 7 Falcon 9 launches , 10 Iridium Next satellites were brought into space per rocket launch. During the 8th Falcon 9 launch, 5 Iridium Next satellites were launched. As of January 2019, 75 satellites have been in orbit, 9 of which are reserve satellites. The remaining 6 satellites are waiting on the ground as a reserve for their eventual deployment.

Overview of missile launches with Iridium Next payload
mission Satellite numbers Missile type begin
Iridium-1 102, 103, 104, 105, 106, 108, 109, 111, 112, 114 Falcon 9 v1.2 Block 3 Success January 14, 2017
Iridium-2 113, 115, 117, 118, 120, 121, 123, 124, 126, 128 Falcon 9 v1.2 Block 3 Success June 25, 2017
Iridium-3 107, 119, 122, 125, 127, 129, 132, 133, 136, 139 Falcon 9 v1.2 Block 4 Success October 9, 2017
Iridium-4 116, 130, 131, 134, 135, 137, 138, 141, 151, 153 Falcon 9 v1.2 Block 3 Success December 23, 2017
Iridium-5 140, 142, 143, 144, 145, 146, 148, 149, 150, 157 Falcon 9 v1.2 Block 4 Success March 30, 2018
Iridium-6 110, 147, 152, 161, 162 Falcon 9 v1.2 Block 4 Success May 22, 2018
Iridium-7 154, 155, 156, 158, 159, 160, 163, 164, 165, 166 Falcon 9 v1.2 Block 5 Success July 25, 2018
Iridium-8 167, 168, 169, 170, 171, 172, 173, 175, 176, 180 Falcon 9 v1.2 Block 5 Success January 11, 2019

The first new satellite went into operation on February 23, 2017 and integrated into the existing Iridium satellite network.

The new satellites of the 2nd generation should be fully compatible with all known Iridium devices.

  • Start gallery of the Iridium Next series

  • Start of Iridium-1

  • Start of Iridium-2

  • Start of Iridium-3

  • Launch of Iridium-4

  • Start of Iridium-5

First generation Iridium satellites

The total cost of the first generation of Iridium satellite fleet amounted to 5 billion US dollars . The satellites weigh 689 kg and are around four meters high and 1.3 meters in diameter. They are based on Lockheed Martin's LM700A satellite bus and are vertical in orbit. They each have two solar cell brackets at the upper end aligned parallel to the horizon, three inclined antennas measuring 1.86 m by 0.88 m and further antennas at the lower end. The three-axis stabilized satellites were launched between May 1997 and June 2002 in several groups with different launchers (five each with the launch with Delta-2 , seven each with the launch with the Proton and two each with the launch with the Langer Marsch 2 or Rokot KM).

  • Underside of a satellite: antennas

  • General view of an iridium satellite: solar cell paddles on the left, antennas on the right

Air interface

The data transmission from the satellite to the handheld devices takes place in the L-band . It is technically possible to use the frequency range from 1616 to 1626.5 MHz. However, this frequency range must be shared with Globalstar worldwide. In addition, the frequency range from 1610.6 to 1613.8 MHz is a very important and very sensitive frequency range for radio astronomy . The frequency range from 1618.25 to 1626.5 MHz is currently reserved for Iridium worldwide.

The digital data is transmitted with a mixture of frequency and time division multiplexing . The Iridium frequency range is divided into several channels using frequency division multiplexing (FDMA), which are separated by 41.666 kHz. Each channel is divided into 8 time slots using time division multiplexing (TDMA) . All channels up to 1626.0 MHz are duplex channels. In the duplex channel, four time slots are used for the downlink and four time slots for the uplink . The twelve channels in the frequency range from 1626.0 to 1626.5 MHz are simplex channels. The time slots of the simplex channels are used for the transmission of messages ( SMS ) and the signaling (ringing) of telephone calls.

With a duplex channel, a data transmission rate of 9.6 kbit / s in the downlink and 9.6 kbit / s in the uplink can be achieved. Permanently installed satellite antennas such as Iridium OpenPort or Iridium Pilot can transmit and receive simultaneously over several time slots and thus achieve significantly higher data transmission rates. Iridium OpenPort and Iridium Pilot allow the simultaneous use of 64 channels, which allows data transfer rates of up to 128 or 134 kbit / s. Satellite systems compatible with the new Iridium Certus service can transmit and receive simultaneously over even more time slots, which enables faster data transmission rates.

Currently, 186 duplex channels can be used for Iridium.

If two time slots are used simultaneously for the transmission of a telephone call, a better voice quality can be achieved ( AMBE with 4800 baud instead of 2400 baud).

Satellite collision 2009

On February 10, 2009, the Iridium satellite 33 collided with the discarded Russian military communications satellite Kosmos 2251 at a relative speed of 11.6 km / s . Both satellites were destroyed.

Iridium flare

Iridium flare

The first-generation satellites can be observed with the naked eye as so-called iridium flares for several seconds from the earth with the appropriate geometry sun-satellite observer . These are reflections of the sunlight on the antenna surfaces, which lead to the brightest luminous phenomena caused by artificial celestial bodies. They are up to around a thousand times brighter (at −9 mag) than Sirius , the brightest star in the night sky, and are visually comparable to a passing flare, whose light emission increases enormously for a short time. The angular velocity is well above that of aircraft, but below that of meteors . Acoustic phenomena do not occur. In photos with exposure times of a few seconds, the satellite appears as a bright strip of light with foothills tapering on both sides in the direction of flight.

The exact times for iridium flares can be calculated online using the orbital data for any place on earth (see web links). Since the new generation of Iridium satellites, which no longer cause such luminous phenomena, will completely replace the previous satellites, fewer and fewer flares have been seen since 2017.

See also

Web links

Individual evidence

  1. ^ ITU Operational Bulletin. (PDF; 600 kB) In: www.itu.int. May 18, 2012, accessed May 10, 2015 .
  2. ↑ Handelsblatt: Iridium Satellite resumes telecommunications services
  3. ↑ Forbes: The Return Of Iridium
  4. ↑ investor.iridium.com ( Memento from April 1, 2018 in the Internet Archive ) Iridium - Press release (English) - Fifth Successful Iridium® NEXT Launch Completed as Iridium Surpasses 1 Million Subscribers
  5. ↑ investor.iridium.com ( Memento from April 1, 2018 in the Internet Archive ) Iridium - Press release (English) - Iridium Announces Fourth-Quarter and Full-Year 2017 Results; Company Issues 2018 Outlook
  6. ↑ a b c SR Pratt et al: An operational and performance overview of the IRIDIUM low earth orbit satellite system. (PDF) In: IEEE Communications Surveys. 1999, accessed June 29, 2017 .
  7. ↑ Iridium 9555 Tutorial: Preparing to Make a Call Outdoors
  8. ↑ http://www.sim-ticket.de/dokuwiki/doku.php?do=search&id=russland (link not available)
  9. ↑ boeing.com (PDF).
  10. ↑ usap.gov
  11. ↑ Website of the company Digital Voice Systems Inc.
  12. ↑ 31C3 talk by Sylvain from OsmocomGMR
  13. ↑ 28C3 talk by Sylvain from OsmocomGMR
  14. ↑ Voice quality from AMBE (+) on the website of Digital Voice Systems Inc.
  15. ↑ gsma.com
  16. ↑ ittc.ku.edu
  17. ↑ thedigitalship.com
  18. ↑ events.thedigitalship.com IRIDIUM CERTUS SM: MARITIME SATELLITE - COMMUNICATIONS REINVENTED - English (PDF)
  19. ↑ faa.gov Iridium Certus Update CPWG / 21 - English (PDF)
  20. ↑ a b networkinv.com Iridium Certus Land (English).
  21. ↑ networkinv.com Iridium Certus Maritime (English).
  22. ↑ networkinv.com Iridium Certus Aviation (English).
  23. ↑ investor.iridium.com ( Memento of May 24, 2018 in the Internet Archive ) Iridium media release of May 21, 2018 - Iridium Makes Maritime Industry History
  24. ↑ a b c d e International Mobile Satellite Organization: Report on the technical and operational assessment by the International Mobile Satellite Organization of the application to recognize and use the Iridium mobile satellite system in the GMDSS. (PDF) In: Recognition of Iridium mobile satellite system as a GMDSS service provider. November 27, 2015, accessed June 29, 2017 .
  25. ↑ ntrs.nasa.gov (PDF).
  26. ↑ a b http://investor.iridium.com/common/download/download.cfm?companyid=ABEA-3ERWFI&fileid=884163&filekey=57712E55-9372-4DD8-95D8-F0E4DD1710A4&filename=Iridium_2015_Anrufnual_Report
  27. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  28. ↑ Biggest global satellite operator opens for business in Russia . Retrieved November 25, 2016. 
  29. ↑ satelital-movil.com
  30. ↑ youtube.com
  31. ↑ Enhanced Mobile Satellite Services (EMSS) ( Memento from March 4, 2017 in the Internet Archive )
  32. ↑ spacenews.com
  33. ↑ blog.iridium.com
  34. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  35. ↑ https://www.dvorak.org/blog/2006/08/29/senator-ted-stevens-officiates-at-new-iridium-satellite-ground-station-in-alaska/ (link not available)
  36. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  37. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  38. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  39. ↑ earth.esa.int
  40. ↑ boeing.com (PDF).
  41. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  42. ↑ http://investor.iridium.com/2019-03-28-Iridium-Enhances-Network-with-New-Southern-Hemisphere-Ground-Station Iridium - Press Releases - Iridium Enhances Network with New Southern Hemisphere Ground Station
  43. ↑ a b Iridium System Overview ( Memento from December 2, 2008 in the Internet Archive )
  44. ↑ funkperlen.blogspot.ch Anton's Funkperlen - When trees stand in the way of the waves
  45. ↑ What's NEXT? ( Memento from April 6, 2008 in the Internet Archive )
  46. ^ Iridium Announces Successful First Launch of Iridium NEXT Satellites
  47. ↑ http://investor.iridium.com/2019-02-06-Iridium-Declares-Victory-3-Billion-Satellite-Constellation-Upgrade-Complete Iridium - Press Release - Iridium Declares Victory; $ 3 Billion Satellite Constellation Upgrade Complete
  48. ↑ https://spacenews.com/iridium-ends-legacy-satellite-service-switches-all-traffic-to-next-fleet/ SpaceNews - Iridium ends legacy satellite service, switches all traffic to Next fleet
  49. ↑ investor.iridium.com ( Memento from September 6, 2011 in the Internet Archive )
  50. ↑ investor.shareholder.com
  51. ↑ cdn2.hubspot.net
  52. ↑ investor.shareholder.com
  53. ↑ Gunter Krebs: Iridium-NEXT. In: Gunter's Space Page. October 22, 2018, accessed October 22, 2018 .
  54. ^ Iridium Communications Inc .: Iridium Completes Historic Satellite Launch Campaign . 2019. Archived from the original on January 11, 2019. Retrieved January 11, 2019.
  55. ↑ blog.iridium.com
  56. ↑ ridium NOW & NEXT ( Memento from June 16, 2012 in the Internet Archive )
  57. ↑ Handelsblatt: Iridium Satellite resumes telecommunications services
  58. ↑ Iridium in the Encyclopedia Astronautica (English)
  59. ↑ Gunter's Space Page: LM700
  60. ↑ Solingen observatory: Iridium Flares ( Memento from January 22, 2009 in the Internet Archive )
  61. ↑ Iridium System ( Memento from December 2, 2008 in the Internet Archive )
  62. ↑ nalresearch.com NetworkReference - Iridium Subscriber Unit
  63. ↑ spectrum.welter.fr (PDF) IMPACT OF UNWANTED EMISSIONS OF IRIDIUM SATELLITES ON RADIOASTRONOMY OPERATIONS IN THE BAND 1610.6-1613.8 MHZ
  64. ↑ marine.rutgers.edu Preliminary IRIDIUM Subscriber License Information
  65. ↑ sigidwiki.com SIGIDWIKI - Iridium
  66. ↑ Support ( Memento from January 1st, 2018 in the Internet Archive ) User Manual Iridium Pilot and Iridium Openport (English).
  67. ↑ Iridium Pilot® ( Memento from January 1, 2018 in the Internet Archive ) Iridium Pilot product website
  68. ↑ events.thedigitalship.com IRIDIUM CERTUS SM: MARITIME SATELLITE - COMMUNICATIONS REINVENTED - English (PDF)