2: Satellite systems currently in service

2.1 Introduction

This section only describes systems that were operating and taking on new users at the time of its update. A number of companies were proposing to launch new satellite constellations while the update to this section was being drafted; these will be covered in future revisions once they enter service. Where possible, all descriptions of satellite systems are based on information that was publicly available at the time of the update. Information that has been supplied directly by the satellite industry (and is not otherwise published) is highlighted in the text.

Data rates (speed of transmission) are given in bits, kilobits or megabits, as appropriate. Message sizes are given in bytes (8 bits = 1 byte). International System of Units (SI) prefixes are used for bytes, so 1 kbyte (1 kilobyte) refers to 1 000 bytes and not to the binary kibibyte (1 024 bytes).

The satellite systems considered in this handbook are: Argos, DCS, Globalstar, Gonets, Inmarsat, Iridium, O3B, Orbcomm, Thuraya and VSAT.
 

2.2 Argos (information updated April 2018)

Website:	http://www.argos-system.org/
Type of orbit:	LEO, polar orbit
Number of satellites in operation:	6
Coverage:	global

It was established as a joint French-American project. The original partners were the French National Centre for Space Studies Centre national d'études spatiales (CNES), the United States National Oceanic and Atmospheric Administration (NOAA) and the United States National Aeronautics and Space Administration (NASA). The service became operational in 1978. Argos does not operate its own satellites; it is carried as part of the payload on meteorological observation satellites. As of 2015, the Argos constellation consisted of three United States (NOAA) satellites (NOAA-15, 18 and 19), two European satellites from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) (MetOp-A and B) and one Indian satellite (Satellite with ARGOS and ALTIKA (SARAL)). A third European satellite (MetOp-C) was due for launch in 2018, and a further launch was planned for 2020.

Argos downlinks data from the satellites through a network of ground stations. Messages received by the satellites are stored until the satellites are in range of a ground station (“store-and-forward”). The service has global coverage but can have relatively long latency.

Argos’s key feature is that it allows the use of extremely small, low-powered terminals. It is the only satellite system with terminals that are light enough to track birds. For tracking applications, Argos can also estimate the position of the terminal based on the Doppler shift of the radio signal, which eliminates the need for a separate positioning system such as GPS.

The Argos service is offered in two ways: there is a commercial service available at market rates, and a special, more economical rate for scientific users. The latter rate is determined by an organization called the Joint Tariff Agreement (JTA), which is a subprogramme of the Satcom Forum. (See http://www.argos-system.org/argos-jta/

Argos offers two types of service, Argos-2 and Argos-3. Argos-2 is available on all six satellites, operates at 400 bits per second and has a maximum message size of 32 bytes. The newer Argos-3 service is available on the four newer satellites in the constellation and offers a 4 800 bit per second “high-rate” service, allowing the transmission of larger messages of up to 576 bytes. Argos-3 also offers optional error corrective coding of messages.

A new service, Argos-4, was in development while the update to this section was being drafted, but the specifications had not yet been announced.

Argos is primarily a unidirectional service intended for collecting data from remote terminals. Argos-3 added a two-way service, but it is presently only offered by three satellites. The downlink data rate to remote terminals is 400 bits per second, and the downlink channel of the two-way service is mainly used to acknowledge receipt of messages.
 

2.3 DCS (information updated April 2018)

CGMS Website:	http://www.cgms-info.org/
CMA website:	http://www.cma.gov.cn/en2014/satellites/
EUMETSAT website:	https://www.eumetsat.int/website/home/Data/MeteosatServices/MeteosatDataCollectionServices/index.html
ISRO website:	https://www.isro.gov.in/applications/climate-environment-0
JMA website:	http://www.jma-net.go.jp/msc/en/general/system/dcs/index.html
NOAA website:	http://www.noaasis.noaa.gov/DCS/
Roshydromet website:	http://www.meteorf.ru/
Type of orbit:	Geostationary
Number of satellites in operation:	10
Coverage:	global excluding poles

The Data Collection Service (DCS) is a unidirectional service designed exclusively for the collection and redistribution of environmental data. It is commonly used to collect data from static automatic weather stations but has a range of other applications. It is free to use, which makes it very popular with less wealthy countries.

The service is offered by geostationary meteorological satellites from the following agencies:
(a) NOAA (GOES-E and GOES-W satellites, covering the Americas);
(b) EUMETSAT (Meteosat-8 and Meteosat-11 satellites, covering the Atlantic Ocean, Europe, Africa and the Indian Ocean);
(c) JMA (Himawari 8 satellite, covering East Asia and the western Pacific Ocean);
(d) ISRO (Insat satellites, covering India);
(e) Roshydromet (Elektro-L satellite, covering Russia);
(f) CMA (Feng Yun satellites, covering China).

NOAA, EUMETSAT and JMA coordinate their DCS activities through a joint body called the Coordinating Group for Meteorological Satellites (CGMS). The Indian, Chinese and Russian satellites offer a DCS service only to users within their own countries. However, the other five satellites are available for use free of charge for meteorological, hydrological or geological data collection and redistribution, subject to the approval of the satellite operating agency. This free service is provided on the basis that the data collected is made publicly available via the WMO Information System (WIS).

The basic DCS transmission process is common across all operators. The transmissions are assigned to different users based on an allocated timeslot. The length of the slot depends on the bit rate of the transmission, which depends on both the user’s terminal and the satellite used. DCS transmitters are unidirectional and rely on an accurate clock to remain within their allocated timeslot. There is typically a 15-second guard period before and after each timeslot to allow for clocks that are too fast or too slow, making the total timeslot 30 seconds longer than the maximum time permitted per transmission.

The original DCS protocol operated at 100 bits per second but is now considered to be very old and slow, and the transmitters are quite power-hungry. Newer satellites have allowed the operators to offer higher data rates, but unfortunately these higher-rate services are not standardized:

(a) NOAA offers DCS rates of 300 bits per second and 1 200 bits per second on their GOES satellites in the Americas, with error corrective coding to protect against errors in transmission.

(b) EUMETSAT offers a “standard rate” service of 100 bits per second and a “high-rate” service of 1 200 bits per second on its satellites. The high-rate service also has error corrective coding and is more power-efficient than the service offered by the NOAA system. It has a flexible timeslot allocation scheme, which allows for the sending of large messages of up to 65 kilobytes or of shorter, more frequent transmissions, for example to collect data every five minutes rather than every hour.

(c) JMA offers DCS rates of 100 bits per second and 300 bits per second on its Himawari series satellite in East Asia and the western Pacific Ocean.

2.4 Globalstar (information updated April 2018)

Website:	http://www.globalstar.com
Type of orbit:	LEO
Number of satellites in operation:	24
Coverage:	North America, Europe, Middle East, East Asia, Australia. Limited coverage in Southern Hemisphere. No permission to operate in China or India. Little or no oceanic coverage.

Globalstar is a commercial service originally intended to be used as a mobile phone system. The present constellation of satellites is the second generation, launched between 2010 and 2013. Unlike some of the other LEO systems, Globalstar’s satellites do not have any on-board processing for calls and messages; all the processing is carried out by ground stations. Consequently, Globalstar can only provide good coverage where it has ground stations in operation. This means it has limited coverage at sea and in the polar regions. At the time of writing, the coverage maps showed limited coverage in South America, very little coverage in Africa and no coverage in China, India and central Asia. Globalstar’s traditional focus has been on the North American market, and more than 50 % of its customers are in the United States. Since its coverage is more limited, its strategy has been to compete on price, so its equipment and airtime tend to be cheaper than those of its competitors.

Globalstar’s “duplex” service (voice service) can be used to provide a circuit-switched data service at 9 600 bits per second. There is no packet-switched service; charges are per minute regardless of whether the voice service or the data service is used.

Globalstar also offers a “simplex” service (unidirectional service) that can be used to collect data from low-power terminals. The simplex service has better coverage than the duplex service and in principle offers coverage on all continents except Antarctica; however, Globalstar does not have permission to operate in every country.

A simplex message carries only nine bytes of data, and the service is billed per message. Multiple messages can be grouped together into a “message burst” to send larger amounts of data. The transmitter sends each message burst several times in order to make sure that it is received since it cannot receive an acknowledgement from the satellite. By default, the transmitters send each message burst three times, with an average of five minutes between transmissions (the spacing is randomized to reduce the risk of collisions with other transmissions). Duplicate messages are discarded at the ground station, so the customer is not billed more than once.
 

2.5 Gonets (information updated April 2018)

Website:	http://www.gonets.ru/
Type of orbit:	LEO
Number of satellites in operation:	12
Coverage:	Global

Gonets is a Russian system with polar-orbiting satellites that operates using store-and-forward messaging. It has four gateway stations, all located in Russia. The service operates in the low UHF band, just below 400 MHz. It markets itself very much towards Russian customers.

Gonets provided more technical information about its system in response to a direct request:
(a) Messages are formed from one or more 1.5-kilobyte packets;
(b) Multiple packets can be used to send larger payloads;
(c) The maximum message size depends on the location of the terminal relative to the satellite orbits.

2.6 Inmarsat (information updated April 2018)

Website:	http://www.inmarsat.com/
Type of orbit:	Geostationary
Number of satellites in operation:	11
Coverage:	Global excluding poles

Inmarsat is a commercial service provider that grew out of the marine communications market. It now offers services to land, marine and aeronautical terminals and operates three different satellite constellations.

Inmarsat’s older satellites (Inmarsat-3 and Inmarsat-4 constellations) operate in the L-band frequency range (~1.5 GHz) and form the backbone of Inmarsat’s business. The newer Inmarsat-5 series operates in the Ka-band frequency range (26-30 GHz) and is used to provide higher-data-rate services, which Inmarsat calls “Global Xpress”.

Inmarsat offers many different services. Marine services are mostly branded “Fleet”, and aeronautical services are mostly branded “Swift”.

2.6.1 Land services

IsatHub is a lightweight, portable terminal that offers data rates of up to 384 kbits per second. The terminal includes a Wi-Fi hotspot and is designed to be used with laptops and smartphones. It incorporates an internal battery and can operate for 2.5 hours on battery power.

BGAN is Inmarsat’s medium-data-rate land service. It has a range of terminals, some of which can be vehicle-mounted, and offers data rates of up to 492 kbits per second.

BGAN HDR is a high-data-rate version of BGAN that is intended for television news broadcasts. It claims to offer a maximum data rate of 650 kbits per second. It is possible to “bond” two terminals together and obtain speeds of more than 1 Mbit per second.

BGAN Link is a BGAN service sold for use by corporate IT departments. It offers data rates of up to 492 kbits per second, with a data cap of 30 GB per month. There is also a version called “BGAN Link Backup” that is designed to be attractive for business continuity and to be used only when a terrestrial system fails.

BGAN M2M is a low-data-rate messaging service that can be used on both land and sea. It is typically used for tracking and telemetry applications. Terminals can send messages of 10 or 25 bytes and receive messages of up to 100 bytes. IsatM2M is an older service and may be retired in favour of the newer IsatData Pro.

IsatM2M is a low-data-rate messaging service that can be used on both land and sea. It is typically used for tracking and telemetry applications. Terminals can send messages of 10 or 25 bytes and receive messages of up to 100 bytes. IsatM2M is an older service and may be retired in favour of the newer IsatData Pro.

IsatData Pro is a low-data-rate messaging service that allows users to send messages of up to 6.4 kBytes and to receive messages of up to 10 kBytes. Marine-grade terminals are available for use at sea.
 

2.6.2 Marine services

FleetBroadband is a medium data rate marine service. There is a choice of three terminals of different sizes:
(a) FB150 - 150 kbits per second;
(b) FB250 - 250 kbits per second;
(c) FB500 - 432 kbits per second.

All three terminals also offer voice and SMS capability. The FB250 and FB500 terminals incorporate a GSM base station to allow voice and SMS forwarding from ordinary mobile phones.

FleetOne is a service intended for occasional marine use. It is sold with very flexible airtime terms and can be activated and deactivated whenever the user wishes. A low-cost service called “FleetOne Coastal” is available for vessels under 500 tons operating in coastal waters. FleetOne offers packet data transmission speeds of 100 kbits per second.

Inmarsat-C is a low-data-rate messaging service designed for marine safety applications. It offers packet data transmission speeds of 600 bits per second from a compact, low-cost terminal. There are two versions - “Inmarsat C” and “Inmarsat Mini C”. Inmarsat Mini C uses smaller, lower-power terminals. Inmarsat C is more than 25 years old and is likely to be replaced with a new type of service.

Fleet-77 is Inmarsat’s higher-end marine safety service. It will be retired in 2020, but in the meantime offers data services at speeds of up to 64 kbits per second. The lower-bandwidth Fleet 33 and Fleet 55 services will be retired in 2018.

Fleet Xpress is a high-data-rate service for the marine market that uses the Global Xpress satellite network. It offers downlink speeds of up to 8 Mbits per second and uplink speeds of up to 4 Mbits per second.

2.6.3 Aeronautical services

Swift64 is an aeronautical service that provides a 64 kbit per second ISDN-style circuit. Up to four circuits can be bonded to create a 256 kbit per second channel. It can also offer a packet data service at the same data rates (billed by the byte, rather than by the minute).

SwiftBroadband is the aeronautical equivalent of FleetBroadband, with data rates of 200-700 kbits per second depending on the terminal used.

JetConneX is a high-data-rate aeronautical service that uses the Global Xpress satellite network. It offers data rates of up to 50 Mbits per second to aircraft in flight.

2.7 Iridium (information updated April 2018)

Website:	http://www.iridium.com/
Type of orbit:	LEO
Number of satellites in operation:	66
Coverage:	global

Iridium is a commercial satellite operator that uses a large constellation of LEO satellites to provide voice and data services. Its original constellation dates from the 1990s and is presently being replaced by new satellites. As of mid-March 2018, Iridium had had four successful launches out of a planned total of eight, with the remaining launches due to occur later in 2018. The new constellation is known as “Iridium Next”, and the services that it will provide will be called “Iridium Certus”; these services are not yet for sale commercially. The services discussed in this article are those for sale as of April 2018, which are all operated by the original 1990s constellation.

Iridium’s network design is much more complex than that of most of its competitors. Every satellite is cross-linked to its neighbours by microwave links, allowing calls and data to pass between the satellites. An Iridium-to-Iridium phone call is handled entirely by the satellites and never via a ground station. Iridium’s ground stations are used as gateways to terrestrial networks, either to the phone network or to the Internet.

Because the Iridium satellites are in a low Earth orbit, they move rapidly with respect to the ground and are only in view for ten minutes at a time. The network is designed to hand over calls automatically to another satellite, but this is not entirely reliable, and it is quite common for calls to be cut off after four or five minutes. This effect is more noticeable if the user is in a valley or on a mountainside, where terrain may obstruct the view of the “next” satellite. The Pilot service accesses multiple satellites at the same time using multiple antennas within the module and does not suffer from this handover problem.

Iridium offer several types of data service:

(a) Short Burst Data (SBD) - a two-way message-based service;
(b) Iridium Burst - a one-way broadcast message service;
(c) Circuit Switched Data (CSD) - a 2.4 kbit per second dial-up data service;
(d) Pilot - a medium-data-rate service offering Internet Protocol connectivity at speeds of up to 134 kbits per second.

2.7.1 Short Burst Data

Short Burst Data (SBD) is a message-based service intended for applications which need relatively small amounts of data, a small terminal and low power consumption. SBD messages are relatively small (270 bytes for messages from the network to the terminal, or 340 bytes for messages sent by the terminal) and are charged by the byte, usually with a minimum charge per message. They are passed through the Iridium network with a latency of under 20 seconds, and Iridium’s network centre then delivers them using email or a simple IP socket interface. SBD modems are typically integrated into scientific instruments and consumer products (Garmin’s InReach communicators, for example), and can be integrated with the user’s own equipment if that suits the application. Iridium does sell a fully weatherproofed SBD modem, branded as Iridium Edge, that can be attached to a PC or datalogger.

2.7.2 Circuit Switched Data and Router-Based Unrestricted Digital Internetworking Connectivity Solutions

Circuit Switched Data (CSD) is the data equivalent of an Iridium voice call. It offers a 2.4 kbit per second full duplex stream. This is extremely slow by modern standards but still usable for basic data exchange. CSD can be used to provide extremely slow internet access (“Iridium Direct Internet”) and to access private networks. Iridium’s Router-Based Unrestricted Digital Internetworking Connectivity Solutions (RUDICS) service allows hundreds or thousands of CSD calls to be routed to and from a private network and is intended for customers with large numbers of devices deployed in the field. Iridium sells a portable terminal, “Iridium GO”, which is designed to share a single CSD connection with a computer, tablet or smartphone over Wi-Fi. CSD is also available on Iridium’s handsets or using a modem that is designed for integration into the user’s own equipment.

2.7.3 Iridium Burst

Iridium Burst is a broadcast service designed to send the same message to many field terminals. It is intended to be primarily an alerting service and could be used to send urgent messages, such as tsunami warnings, to many different locations. Because it is a broadcast service, the terminals do not incur airtime charges while waiting for an alert to arrive.

2.7.4 Pilot

Iridium’s highest-bandwidth service is Pilot, which was originally sold in the marine market and now also has a land variant. One Pilot terminal can connect up to three simultaneous voice calls and provides internet access at up to 134 kbits per second. The Land Station version has the same specifications as the marine version. Data is charged by the megabyte and can be bought in bundles for applications that require large quantities. Pilot works by steering multiple beams from the antenna to access several Iridium satellites at once, so having a clear line of sight in all directions around the antenna helps to ensure good performance. As a marine terminal, one key advantage it has over other services is that it contains no moving parts, and unlike a geostationary system, it has no mechanical tracking, making it cheaper and lighter than other services. However, it can only deliver a fraction of the data rate of a geostationary system. Pilot is powered with a voltage of 11-32 V DC (although an AC adaptor is supplied) and consumes approximately 30 W when connected.

Note: The previous version of Pilot was known as Iridium OpenPort. Now Iridium uses “Pilot” to refer to the terminal and “OpenPort” to refer to the data service. The terms are often used interchangeably.

2.8 Kepler (information updated April 2019)

Website:	https://www.kepler.space/
Type of orbit:	Low Earth Orbit (LEO)
Number of satellites in operation:	2
Coverage:	Global

Kepler Communications is a Canadian start-up company operating a constellation of small satellites in polar orbit. They were founded in 2015 and their first two satellites were launched in 2018. A third launch is planned for 2019. Their initial service is a store-and-forward service for moving large volumes of data - hundreds of megabytes per satellite pass. They currently promise data delivery within 12 hours. The service is bidirectional - data can be delivered to a remote site as well as collected from it. The service operates in Ku-band (12-14GHz) and uses currently VSAT-style equipment with motorised antennas that track the satellites. This gives Kepler a relatively high terminal cost (at least $25,000 USD) at present, but their airtime charges are low given the high volume of data they can handle - they claim to have the lowest price per gigabyte in the industry. Kepler offer both marine and land-based terminals, and claim their system is also compatible with existing Ku-band marine VSAT installations. A typical Kepler terminal offers 100Mbit/s downlink and 30Mbit/s uplink, though of course that data may not be delivered to its destination for several hours.

2.9 O3B (information updated April 2018)

Website:	https://www.ses.com/networks/maritime/maritime-powered-o3b
Type of orbit:	Medium Earth Orbit (MEO)
Number of satellites in operation:	12
Coverage:	equatorial coverage to around 45 degrees latitude north and south

O3B is a wholesale satellite operator that provides high-bandwidth, low-latency internet connectivity to telecom providers in less-developed countries. Its constellation is unusual in that it operates with MEO satellites, meaning that a tracking antenna is required at the terminal. The use of MEO satellites allows for lower latency and higher data rates than would be possible on an equivalent geostationary satellite.

O3B was originally an independent company but is now owned by SES of Luxembourg (best known for the Astra series of broadcast satellites). O3B also provides services to the marine market, particularly for cruise ships, where a large amount of bandwidth is needed. O3B states that it offers up to 1 Gbit per second to ships. O3B terminals typically comprise two or more large tracking dish antennas (typically 1.8 or 2.4 m in diameter); two antennas are used to ensure that there is continuous coverage as the satellites drop below the horizon.

2.10 Orbcomm (information updated April 2018)

Website:	http://www.orbcomm.com/
Type of orbit:	Low Earth Orbit (LEO)
Number of satellites in operation:	16 (OG2 constellation), 25 (OG1 constellation)
Coverage:	global excluding poles

Orbcomm operates its own satellite networks (known as OG1 and OG2) and sells terminals and airtime for Inmarsat’s IsatData Pro network. This entry concentrates on OG1 and OG2.

The Orbcomm OG1 constellation was launched in the mid-1990s and uses marine-band VHF radio to communicate with data terminals. It is strictly a message-based service and operates using the store-and-forward delivery method, sending the messages to a series of gateways. OG1 operates at an uplink speed of 2.4 kbits per second and a downlink speed of 4.8 kbits per second to the user’s terminal. Message sizes are not fixed but are typically a few tens of bytes.

The second-generation OG2 constellation became fully operational in 2016, and Orbcomm states that it allows larger message sizes and higher throughput. OG2 operates at an uplink speed of 4.8 kbits per second and a downlink speed of 7.2 kbits per second. Orbcomm publishes relatively little information about how this system works; interested parties are advised to contact the company directly to request the technical datasheets.

Orbcomm’s modems often combine satellite with cellular connectivity. This is particularly valuable if the modem is mounted on a platform that moves between populated and remote areas, as it allows cheaper cellular service to be used where it is available while retaining the satellite as a backup.

2.11 Thuraya (information updated April 2018)

Website:http://www.thuraya.com/
Type of orbit:	Geostationery
Number of satellites in operation:	2 (all services) + 1 offering M2M service only in North America
Coverage:	full services cover Europe, most of Africa (Angola and northwards), the Middle East, central and East Asia (but not Siberia), Australia. Very limited oceanic coverage, confined to areas of the east Atlantic close to Europe, the northern part of the Indian Ocean and parts of the western Pacific between Japan and Australia. M2M services are additionally available in central and North America, excluding Alaska and arctic Canada.

Thuraya is a Dubai-based satellite provider that provides telephony and data services. It offers a range of terminals, from handheld satellite phones to larger self-pointing units that can be mounted on land vehicles or ships.

Thuraya’s data services consist of:
(a) Circuit switched data (essentially a voice channel used for data), 9.6 kbits per second;
(b) GmPRS - packet switched data, 60 kbits per second downlink speed, 15 kbits per second uplink speed;
(c) “Streaming IP” at guaranteed speeds of 384 kbits per second;
(d) Conventional IP at peak data rates of up to 444 kbits per second downlink speed and 404 kbits per second uplink speed.

The CSD and GmPRS services are available on Thuraya’s voice handsets and XT-Hotspot (a portable Wi-Fi hotspot). The high-rate IP services need a dedicated terminal about the size of a laptop computer.

Thuraya also has an M2M service, currently only available on the dedicated FT2225 terminal. Thuraya does not publish the data rates offered by this service, although they are described as “low”, “medium” and “high” at different price points. The M2M service is the only Thuraya service that operates in North America because it is operated in partnership with Ligado and ViaSat.

Thuraya also offers a range of modem modules for integration into other equipment or commercial products. See http://thuraya.com/developer-zone

2.12 VSAT (information updated April 2018)

Most of the services described in this handbook are fully integrated: the user buys a terminal, installs it, buys an airtime contract and is ready to go. This is “retail” satcom; the user can buy a single terminal and does not have to worry about the rest of the system. However, there is also a “wholesale” satcom business, as used by telecom companies, broadcasters and other large companies with complex communications requirements.

In wholesale satcom, the user rents bandwidth on one or more geostationary satellites, typically agreeing to a long-term lease, and provides his or her own terminals. These could be owned by the user (typically on his or her own building, land vehicle or ship) or supplied under contract from a service provider. One very common arrangement is to use a service provider to act as the hub of the network (from a dedicated Earth station or teleport with many antennas serving different customers); the service provider can also provide routing to the Internet, the telephone network or private corporate networks. The high-end satcom industry views any terminal using an antenna 2 m in diameter or smaller as a “very small aperture terminal” (VSAT); these are “very small” by comparison with the 10 m or larger antennas used by telecom providers.

A VSAT ideally suits a situation in which the user has a continuous need to communicate with a remote location. It can be customized to suit the user’s needs but is necessarily complex to plan and install. There are dedicated service companies that will do this for a fee.

There is a type of VSAT that is more suitable for retail customers. This is known as a “Shared VSAT” and is typically sold by a service provider that leases the satellite bandwidth and provides a suitable terminal. These systems are typically used to provide internet access to rural areas and often use contention to share bandwidth between multiple users, meaning that the service slows down as more and more users log on.