Satellite Constellation Survey

The following survey of existing and proposed satellite systems provides a quick overview of those satellite emitters which may, or are known to cause interference to radio astronomy (RA) observations. Since few satellite ground stations are located near RA sites, the greatest potential for RFI to VLA or VLBA observations is from those systems with downlinks near frequencies of prime interest to RA. Some examples are the GOES WXFAX at 1691 MHz, the proposed WorldSpace AmeriStar I with a broadcast signal just below 1491 MHz (AmeriStar I may "splash-over" into the southern US), and, of course, the CIS Glonass system, which bounds the critical 1612 MHz OH spectral line. Some of the proposed L-band LEO constellations are of particular concern to RA due to the fact that their emissions are not spatially grouped like the GEO satellites, and their lower orbit allows their transmissions to reach RA receivers at higher instantaneous power flux density levels.

Uplink (GHz)
Downlink (GHz)
1.632 - 1.661
13 - 13.5
1.53 - 1.559
10.75 - 10.95
CD Radio
2.31 - 2.36
28.6 - 29.1
29.5 - 30.0
18.8 - 19.3
19.7 - 20.2
5.945 - 6.405
3.72 - 4.18
1.610 - 1.6265
2.4835 - 2.5
16 Ku-band transponders
17.3 - 17.8
12.2 - 12.7
Final Analysis
0.1499 - 0.1501
0.137 - 0.1378
1.61 - 1.62135
5.091 - 5.250
2.4835 - 2.5
6.875 - 7.055
1.60256 - 1.61550
1.98 - 2.01
2.17 - 2.2
6.43 - 6.45
1.63 - 1.66
3.6 - 3.63
1.53 - 1.56
5.85 - 6.425
14.004 - 14.498
3.704 - 4.198
10.954 - 11.2
11.45 - 11.7
1.616 - 1.6265
29.1 - 29.3
1.616 - 1.6265
19.4 - 19.6
1.632 - 1.661
13.0 - 13.15
13.2 - 13.25
1.53 - 1.559
10.75 - 10.95
Navstar (GPS)
1.57542 and 1.2276
0.148 - 0.15
0.137 - 0.138
14.025 - 14.466
11.725 - 12.166
5.945 - 6.405
1.525 - 1.559
0.993 - 1.42
11.743 - 12.17
GEO - 2
0.148 - 0.15
0.137 - 0.138
28.6 - 29.1
18.8 - 19.3
7.025 - 7.075
1.452 - 1.492

Geosynchronous Earth Orbit constellation with n number of satellites in the constellation.
Low Earth Orbit constellation with n number of satellites in the constellation.
Mid Earth Orbit constellation with n number of satellites in the constellation.
Operational Constellation
Planned constellation to be in operation by the year yyyy
Constellation is up and is being tested. The constellation is planned to be operational by the year yyyy.

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The American Mobile Satellite Corporation offers a full range of mobile communications including telephone, digital broadcast dispatch, data and position reporting services. The AMSC-1 satellite provides coverage over the continental United States, Alaska, Hawaii, Puerto Rico, the Virgin Islands, and hundreds of miles of US coastal waters. AMSC's shareholders include Hughes Communications Inc., Singapore Telecom and AT&T Wireless Services.

The AMSC system has been in operation since 1995

Constellation Parameters for the AMSC System

Constellation: 1 Geosynchronous satellite AMSC-1 259°E
Uplink: 1.632 - 1.661 ; 13 - 13.5 GHz
Downlink: 1.53 - 1.559 ; 10.75 - 10.95 GHz
Lifetime: 12 years

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CD Radio

CD Radio plans to operate a nationwide CD-quality satellite digital radio service primarily for passengers in automobiles. CD radio service will be offered on a subscription basis and will be commercial free. CD Radio will construct, launch and operate two high power satellites covering the contiguous United States.

The CD Radio system is expected to be in operation by 1999.

Constellation Parameters for the CD Radio System

Constellation: 2 Geosynchronous satellites [I] 80°W, [II]110°W
Uplink: 7.1 GHz
Downlink: 2.31 - 2.36 GHz
Lifetime: 15 years

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Celestri (

The Celestri System is a proposed communications network formed from an integrated family of advanced communcations satellites, ground stations and terrestrial equipment that is designed to provide a broad range of multimedia, video and data services to communications carriers, multinational corporations, small- and medium-sized business, as well as telecommuters and other customers throughout the world.

Once completed and operational, the Celestri System will combine Geosynchronous Earth Orbit (GEO) satellites and Low-Earth Orbit (LEO) satellites with earth-based control equipment and interfaces. The GEO satellites, commonly known for providing broadcast services such as television, are fixed in high altitude (22,300 miles). A constellation of 63 LEO satellites, orbiting at 900 miles above the Earth, would provide telecommunications carriers, businesses and consumer customers instant access to broadband network infrastructure and true bandwidth-on-demand. Additional LEO satellite capabilities would be integrated with the Celestri System to provide interactive communications to include high-speed, large-volume data trunking and backhaul services.

The Celestri global broadband communications network is expected to be in operation by 2003.

Constellation Parameter for the Celestri System

Satellites: 63 LEO - 9 GEO -- 7 planes, each with 9 LEO satellites
Uplink: 28.6 - 29.1 and 29.5 - 30.0 GHz
Downlink: 18.8 - 19.3 and 19.7 - 20.2 GHz
Lifetime: 8 years (10 years expendables)

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The Comsat Corporation owns and operates a domestic C-band satellite system (Comstar D4). Provides international satellite services for communications between the United States and overseas points using the Intelsat and Inmarsat networks. As the US signatory to both consortiums, it offers a wide variety of voice, data, facsimile, and video services to US international service carriers and the broadcast, aeronautical, international land-mobile, and maritime communities. Furnishes domestic video services through the Comstar satellites.

The Comstar system has been operational since 1981.

Constellation Parameters for the Comstar System

Constellation: 1 Geosynchronous satellite
Uplink: 5.945 - 6.405 GHz
Downlink: 3.72 - 4.18 GHz
Lifetime: Comstar has exceeded its expected 7 year lifetime (in-orbit since 1981)

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The Constellation Satellite system is designed to provide seamless coverage of all points on the earth's surface. The system consists of an equatorial plane of satellites providing continuous service to tropical regions and seven inclined planes of satellites for complete global coverage. The satellites use simple frequency changing transponders to reduce technical risk and provide system flexibility. A phased growth strategy matches Constellation system capacity and capabilities with market requirements.

The Constellation system is expected to be in operation by the year 2000.

Constellation Parameters for the Constellation System

Constellation: 11 equatorial, 35 inclined orbit, plus in-orbit spares
Uplink: 1.61 - 1.6265 GHz
Downlink: 2.4835 - 2.5 GHz
Lifetime: 5 years

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DirecTV (

DirecTV operates the United States' premiere direct broadcast satellite (DBS) television entertainment system. Up to 150 channels of compressed digital video and audio subscription entertainment is available at consumers' homes equipped with the DSS satellite receiving system. DSS equipment includes an 18-inch satellite dish, digital receiver and remote control. Three satellites each feature 16 120-watt Ku-band transponders with DBS-2 and -3 configured to provide 8 transponders at 240 watts each. Programming is uplinked to satellites from the DirecTV Castle Rock Broadcast Center in Castle Rock, CO. Satellites are operated by Hughes Communications Inc.'s Operations Control Center in El Segundo, CA.

DirecTV has been in operation since 1993.

Constellation Parameters for the DirecTV System

Constellation: 3 Geosynchronous satellites
Transponders: 16 Ku-band (11 DirecTV, 5 USSB)
Lifetime: 12 years (nominal)

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EchoStar (

EchoStar Communications Corporation is a manufacturer and distributor of satellite television systems worldwide. Over 150 channels of digital video, audio and data services are delivered to homes throughout the continental United States since the launch of EchoStar II in September 1996. EchoStar and its subsidiaries deliver direct-to-home (DTH) satellite television products and services to customers worldwide. The company provides equipment distribution, sales, installation, and service; consumer financing; programming distribution; and research and development activities.

EchoStar has been in operation since 1995.

Constellation Parameters for the EchoStar System

Constellation: 4 Geosynchronous satellites
Uplink: 17.3 - 17.8 GHz
Downlink: 12.2 - 12.7 GHz
Lifetime: 15 years

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Final Analysis (

Final Analysis is a privately held aerospace and telecommunications company. Specializing in innovative approaches to small satellite production, the company was founded on a commitment to space commercialization. Within the first four years of operation, Final Analysis has grown from a small engineering contractor to an end-to-end turnkey provider of spacecraft and launch vehicle services. Services include spacecraft design, analysis and fabrication, launch vehicle analysis and support services. An experimental satellite (FAISAT-2v) was successfully launched in 1997. 8 more launches are planned between 1999 & 2003.

Final Analysis is planned to be in operation by 2003.

Constellation Parameters for the Final Analysis System

Constellation: 38 operational satellites in 7 planes with 6 in-orbit spares
Uplink: 149.9 - 150.05 MHz
Downlink: 137 - 137.825 MHz

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Globalstar (

Globalstar is a low earth orbit satellite-based mobile communications system that will provide wireless voice, data, fax, and position locating service to worldwide users, beginning in 1998. It will allow calls with hand-held, vehicle-mounted and fixed-remote telephones from anywhere to anywhere and will route calls through existing public and private cellular and fixed telephone networks.

Globalstar is planned to be operational in mid-1998.

Constellation Parameters for the Globalstar System

Constellation: 48 LEO satellites
Uplink: 1.61 - 1.62135 and 5.091 - 5.250 GHz
Downlink: 2.4835 - 2.5 and 6.875 - 7.055
Lifetime: 7.5 years

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The Glonass system is a space-based radio positioning system which provides suitably equipped users with highly accurate position, velocity and time data. Receivers operate passively, thus allowing an unlimited number of simultaneous users. Receivers are available with dual Glonass/GPS compatibility.

Glonass has been in operation since 1988.

Constellation Parameters for the Glonass System

Constellation: 20 LEO satellites
Frequency bands: 1.60256 - 1.615.5 GHz
Lifetime: 2 years

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The Geosynchronous Operational Environmental Satellite takes the moving pictures of clouds used on TV weather broadcasts.

The GOES system has been operation since 1994.

Constellation Parameters for the GOES System

Constellation: 2 Geosynchronous satellites with 1 in-orbit spare.
Uplink: 2.2091 GHz
Downlink: 1.691 and 1.6857 GHz

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ICO-Global (

ICO-Global is a spin-off from Inmarsat, which owns 15% of the corporation. The rest is presently owned by Inmarsat Signatories and by Hughes (the builder of the satellite).

The ICO System is scheduled to begin launches in late 1998 and is planned to be operational in 1999.

Constellation Parameters for the ICO System

Constellation: 2 planes each with 5 satellites plus 2 in-orbit spares.
Uplink: 1.98 - 2.01 GHz
Downlink: 2.17 - 2.2 GHz
Lifetime: 12 years

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Inmarsat (

Established in 1979 to serve the maritime community, Inmarsat is now the world's largest provider of global mobile satellite communications for commercial and distress and safety applications, at sea, in the air and on land. To provide its services, Inmarsat uses its own Inmarsat-2 satellites and leases the Marecs B2 satellite from the European Space Agency, maritime communications subsystems (MCS) on several Intelsat V satellites, and capacity on 3 Marisat satellites from Comsat.

The Inmarsat-2 system has been operational since 1990. The Inmarsat-3 system has been operational since 1996.

Constellation Parameters for the Inmarsat (-2 and -3) System

Constellation: 8 GEO (4 for -2 and 4 for -3)
Uplink: 1.63 - 1.66 and 6.43 - 6.45 GHz (both systems)
Downlink: 1.53 - 1.56 and 3.6 - 3.63 GHz (both systems)
Lifetime: 10 years [-2] - 13 years [-3]

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Intelsat (

Intelsat owns and operates the world's most extensive global communications satellite system. With 1995 revenues over US $805 million, the Intelsat system provides transoceanic, regional and domestic telephone and television services. It also offers, via a 26-satellite global system, business services such as international video, teleconferencing, facsimile, data, and telex.

The Intelsat system has been in operation since 1981.

Constellation Parameters for the Intelsat System

Constellation: 3 Geosynchronous satellites.
Uplink: 5.85 - 6.425 and 14.004 - 14.498 GHz
Downlink: 3.625 - 4.198 and 10.954 - 11.2 and 11.45 - 11.7 GHz
Lifetime: The Intelsat satellites have exceeded their expected lifetime of 7 years.

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Iridium (;

The IRIDIUM ® System: A commercial, satellite-based, wireless personal communications network that permits any type of telephone transmission -- voice, data, fax, or paging -- to reach its destination anywhere on Earth, at any time. Expected to be fully operational by 1998, the system will allow subscribers to use pocket-sized, hand-held IRIDIUM ® units to transmit through a constellation of 66 satellites and communicate with any telephone in the world.

In May 1997, the first five Iridium satellites were launched from Vandenburg, AFB in Lompoc CA. As of May 12, 1998, 67 satellites have been launched. In-orbit testing is underway, and commercial service is on track to commence in September, 1998.

Constellation Parameters for the Iridium System

Constellation: 72 satellites - six orbital planes, 11 operational satellites and one on-orbit spare per plane.
Frequencies: L-band: (1616 - 1626.5 MHz) for voice communication with Iridium subscribers;

Ka-band: (19.4 - 19.6 GHz for downlinks; 29.1 - 29.3 GHz for uplinks) for gateway and earth terminal transmissions.

Lifetime: design life of five to eight years

System designed by Motorola, Inc.

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TMI Communications is the owner and operator of the MSAT network. TMI is the only company authorized by the Canadian government to own and operate a mobile communications satellite for provision of mobile satellite services in Canada. MSAT-1 transforms North and Central America, including up to 400km offshore, Mexico and most of the Caribbean into a single communications cell.

The MSAT system has been in operation since 1996.

Constellation Parameters for the MSAT System

Constellation: 1 Geosynchronous satellite
Uplink: 1.632 - 1.661 and 13.0 - 13.15 and 13.2 - 13.25 GHz
Downlink: 1.53 - 1.559 and 10.75 - 10.95 GHz
Lifetime: 12 years

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Navstar (GPS)

The Navstar global positioning system (GPS) is a space-based radio positioning system which provides suitably equipped users with highly accurate velocity, position and time data. GPS receivers operate passively, thus allowing an unlimited number of simultaneous users.

The GPS system has been in operation since 1989.

Constellation Parameters for the GPS System

Constellation: 24 satellites in 6 planes of 10,900 nautical mile semi-Geosynchronous circular orbit.
Frequency bands: 1.57542 and 1.2276 GHz
Lifetime: 7.5 years

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Odyssey (

The Odyssey communications satellite system will provide global, satellite-based cellular personal communications services, including voice, fax, data, and short message services.

The Odyssey system is planned to be in operation by 2000.

Constellation Parameters for the Odyssey System

Constellation: 12 medium earth orbit satellites
Uplink: 1.61 - 1.62135 GHz
Downlink: 2.4835 - 2.5 GHz
Lifetime: 15 years

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Orbcomm (

Orbcomm is a two-way global wireless communications system offering packet switched data, messaging, monitoring, and geopositioning services. With a full constellation of satellites, Orbcomm provides seamless global coverage utilizing low cost, personal portable communicators.

The Orbcomm system is planned to be in operation by 1999.

Constellation Parameters for the Orbcomm System

Constellation: 36 LEO satellites
Uplink: 0.148 - 0.15 GHz
Downlink: 0.137 - 0.138 GHz
Lifetime: 5 years

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In March 1981, Satellite Business Systems began delivering integrated voice, data, electronic mail, and video communications transmissions over the first all digital domestic commercial communications satellite system operating in K-band.

The SBS spacecraft are among the HS 376 series of satellites built by Hughes Aircraft Company's Space and Communications Group and designed for SBS to provide private business communication services to large American companies. SBS ordered three satellites in December 1977. Two of the satellites, launched November 15, 1980, and September 24, 1981, are in synchronous orbit 22,300 miles above the equator. The third SBS satellite became the first to be placed in space by NASA's Space Shuttle on November 11, 1982, during its premier commercial flight. A fourth satellite, ordered in late 1981, was launched on the Space Shuttle on August 30, 1984. A fifth SBS was launched on an Ariane rocket on September 8, 1988.

The SBS system has been in operation since 1980.

Constellation Parameters for the SBS System

Constellation: 4 GEO satellites (SBS 2, 4, 5, & 6) at 289°E, 283°E, 237°E, and 286°E
Uplink: 14.025 - 14.466 GHz
Downlink: 11.725 - 12.166 GHz


The Solidaridad is a Geostationary Telecommunications Satellite system. It has 18 active C-band transponders, 16 active Ku-band transponders and 1 L-band channel for service to users traveling by land, sea, or air and in rural areas. All bands cover Mexico and the C- and Ku-band coverage extends into the southwestern United States. In addition, spot beams in Ku-band reach such major U.S. cities as Chicago, Dallas, Houston, Los Angeles, Miami, New York, San Antonio, San Francisco, Washington D.C., and Tampa, C-band coverage includes the Caribbean and Central and South America.

The Solidaridad System has been operational since 1993.

Constellation Parameters for the Solidaridad System

Constellation: 2 GEO satellites
Uplink: 1.6265 - 1.6605 and 5.945 - 6.405 GHz
Downlink: 1.525 - 1.559, 0.993 - 1.42, and 11.743 - 12.17 GHz
Lifetime: 14 years


This satellite system provides ultra low-cost two-way communications and positioning determination capabilities.

The Starsys system has been operational since 1997.

Constellation Parameters for the Starsys System

Constellation: 24 LEO satellites
Uplink: 0.148 - 0.15 GHz
Downlink: 0.137 - 0.138 GHz
Lifetime: 5 years

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Teledesic (

The Teledesic Network is a high-capacity broadband network that combines the global coverage and low latency of a low-Earth-orbit constellation of satellites, the flexibility and robustness of the Internet, and "fiber-like" Quality of Service. Essentially an "Internet-in-the-Sky," the Teledesic Network brings affordable access to interactive broadband communication to all areas of the Earth, including those areas that could not be served economically by any other means.

Pre-production is to begin in 1999. The first satellite launch is scheduled for sometime in the year 2001. The entire constellation is scheduled to be operational in 2002.

Constellation Parameters for the Teledesic System

Constellation: 288 plus spares - 12 planes, each with 24 satellites.
Uplink: 28.6 - 29.1 GHz
Downlink: 18.8 - 19.3 GHz
Lifetime: 10 years

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WorldSpace (

WorldSpace will offer 216 near-CD quality channels, of which 90 will be devoted to pay audio services. The remainder will be offered to international broadcast stations. The US aeronautical and space test uses in the 1435 - 1525 MHz band were believed so essential to national defense and to the commercial space industry that the United States rejected the worldwide allocation to satellite audio broadcasting in the 1452 - 1492 MHz band. The US chose instead to allocate the band 2310 - 2360 MHz to satellite Digital Audio Radio Services.

WorldSpace will broadcast to special "StarMan" radios, capable of solar power operation and text readout. The radios will connect to other devices such as portable computers, for E-mail, fax, and image display. The FCC apparently will not permit WorldSpace to broadcast to the United States - there is no broadcasting allocation in this band for the US - but the company said that with a suitable receive antenna, listeners in the US, Europe, or Russia could pick up the signal. We believe that this will effect RFI at the VLA and the VLBA.

WorldSpace receivers are planned to be available in 1999.

Constellation Parameters for the WorldSpace System

Constellation: 3 Geosynchronous satellites. 21°E, 95°W, 105°E
Uplink: 7.025 - 7.075 GHz
Downlink: 1.452 - 1.492 GHz

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Information for this survey was taken from the linked WWW sites and others, the "Phillips 1997 World Satellite Almanac", and Bennett Z. Kobb's "Spectrum Guide, 3rd Edition".

Modified on Friday, 26-Sep-2008 12:09:30 MDT by Stephan Witz