Names of satellites of the Inmarsat system p. International satellite system for maritime communications inmarsat. Inmarsat standards for aviation

INMARSAT. An integral part GMDSS is the INMARSAT system. More than 80 countries participate in this organization, including Russia represented by the state enterprise Morsvyazsputnik.

Founded in 1979 to serve the maritime community, Inmarsat has since grown into the sole provider of global mobile communications. satellite communications for disaster and safety communications at sea, in the air and on land, as well as for commercial purposes.

From the satellite, the signal bounces off at one of twelve stations on Earth, and from there the message is sent to the regular landline telephone network. The devices can also be used as cell phones in places where there is a terrestrial radio network. Very promising were fiber optic transmission technology, then not quite mature, and video calling service, which is considered a system capable of revolutionizing business telephony. It is well known that only then the first forecast is fully realized.

In the early 1990s, systems were developed that could transmit large amounts of integrated numerical information over very wide transmission channels using fiber optic connections, radio support, and satellite bridge support. Based on these premises, at the end of the millennium there was an explosion of a huge number of services with enormous impact, supported by the technologies and systems that will be discussed in this article. Along with fixed links, they are widely used Various types radio systems that revolutionized personal and created new opportunities for access to the network; Ultra-wide bandwidth is supported by well-established fiber optic technology for short, medium, long and long haul transmissions, and with single or constellations of artificial satellites.

In accordance with the decisions of the 12th Inmarsat Assembly in 1999, the structure of the system has undergone significant changes. Since April 1999, the organization has been transformed into a commercial limited liability company, subject to the preservation of its interstate character, which is based on the inclusion of an Intergovernmental Organization (IGO) and the Assembly of the Parties.

The high capacity of fiber optics and satellites enables a wide range of new applications and services. The evolution of encoding techniques has made it possible to integrate information of a different nature, especially through integrated hypertext management systems, often with a multimedia nature, thanks to the evolution of digital processing and compression techniques for texts, sounds, images and sequences. Gaspar Galati, Maurizio Naldi.

At the beginning of the new millennium there is a significant development of technology, accompanied by important economic and socio-political reflections. Services can be distinguished between user services and user server services. From a technological point of view, there are two converging processes: on the one hand, the progress made in signal coding algorithms has significantly reduced the need to transmit resources for the same amount of transmitted information; on the other hand, the capacity of transmission systems has increased significantly both at network access and over long distances.

In accordance with the new structure, the Assembly forms the IGO Secretariat and elects the Director General to serve as the legal representative of the organization. The IGO, through the Assembly, monitors the preservation of the interstate character of the Organization and its fulfillment of all obligations to support the GMDSS. For this purpose, MPO has special promotion, giving it the right to veto Company recommendations that jeopardize the provision of GMDSS services.

Another fundamental trend is the mobility of the user, who can communicate with other users or access databases while moving across large areas as well as continents. There is a distinction between access mobility, terminal mobility and personal mobility.

Cable distribution systems. However, traditional transmission methods using pairs of wires or twisted copper do not achieve adequate transmission speeds to provide broadband services. To be able to take advantage of the enormous investment created by the capillary copper distribution network, technologies have been developed to allow speeds of up to several million bits per second. In the copper section, the telephone signal is transmitted together with signals of another nature, from which it is separated by a suitable device.

Basic services within the Inmarsat satellite communications network: direct dial telephone, telex, fax, Email and data communications for maritime, aircraft and onshore applications.

Inmarsat is used to provide communications during disasters and emergencies, and by the media to report news from areas where communications infrastructure is poor or non-existent.

The demarcation point between the fiber and copper sections can be placed more or less close to the end user. Separation of the telephone signal from other signals is made possible through the use of frequency division multiplexing. The interposition of a 20 kHz band between the two bands can significantly reduce interference phenomena. In the upper range, both a signal to the user and a return are transmitted. More precisely, the first 34 channels can be shared between two signals or dedicated only to the return signal.

Configuration

Inmarsat includes three components:

1. Space segment, since 1998, consisting of 5 3rd generation relay satellites located in geostationary orbits above the equator at an altitude of 35,000 km, with accurate geographical coordinates relative to the Earth (longitude). The radio transmitters of the Inmarsat-3 satellites have a rated power of 2800 W and are eight times more powerful than the 2nd generation devices, which have exhausted their service life and are decommissioned.

The remaining 215 channels are always dedicated to the user signal. To separate the telephone signal from the rest, the frequency multiplication technique is still used, keeping the bandwidth from 0 to 4 kHz. In Europe, penetration has increased to more than 30 mobile lines per 100 inhabitants, with an annual growth rate of 55% and more than 60 operators. It is distinguished by wireless systems where mobility is limited to the home or urban area itself, also called low mobility systems, and large-scale cellular systems, which allow you to travel throughout the national territory or even abroad.

Satellite coordinates:

Atlantic Ocean Region – E

AOR–E

15.5 W

Pacific Ocean Region

POR

178E

Indian Ocean Region

IOR

64.5 E

In both cases, the area covered by the system is divided into elementary service areas called cells. In the simplest case of a home wireless system, the cell consists of one's own home, and user mobility outside the cell is not possible. In other cases, mobility from one cell to another is possible, and the transfer between two cells is called handover.

Standardization of mobile radio systems has been carried out in different ways, leading to the implementation of several systems, often distributed only on a national basis and incompatible with each other. The trend is to develop a standard on at least a continental basis and terminals capable of handling multiple systems, e.g. with two. End-of-life terminals may operate on multiple bands and in multiple modes based on software controlled by equipment.

Atlantic Ocean Region - W

AOR–W

54 W

On February 4, 1998, the fifth Inmarsat satellite was successfully launched and put into operation at station 25E. Thus, Inmarsat satellites cover almost the entire earth's surface with the exception of small subpolar regions beyond the 70th parallel. Currently, work is actively underway to create space segment Inmarsat fourth generation.

With implementation cellular communications in the second half of the 70s, second generation systems were introduced, characterized by a large number of radio channels, the possibility of handover and automatic update user location. systems are national.

In wireless systems, the connection between the user and the fixed network is guaranteed by a small base station. Signal transmission between the user and the base station can be accomplished by two methods based on time division or frequency division, respectively. The main characteristics of wireless systems are summarized.

2. Coastal earth stations (BCS or Land Earth Stations - LES)– gateways to terrestrial networks. Each BZS has a two or three-digit digital identifier (depending on the INMARSAT system) and belongs to the state in whose territory it is installed. The BZ codes for each ocean area are listed in the Inmarsat Maritime Communications Handbook.

In addition, network coordination stations are located in each ocean area (Network Coordination Stations - NCS), which provide selection free channels ship and coastal earth stations in accordance with subscriber requests and monitoring the use of dedicated channels.
In INMARSAT-A, the Atlantic Ocean region is served by the Southberry station (USA), the Indian Ocean - Yamaguchi (Japan) and the Pacific Ocean - Ibaraki (Japan). In INMARSAT-C, the region of the Atlantic Ocean is Goonhilly (UK), the Indian Ocean is Termipyli (Greece) and the Pacific Ocean is Sentosa (Singapore).

The entire territory is divided into areoles, each of which is covered by one of these stations. Each of these two bands is divided into 124 channels spaced at 200 kHz, and the mobile user occupies one of these channels from time to time. In particular, the service is available short messages, which allows the exchange of alphanumeric messages with a maximum length of 160 characters. This recommends using dual band terminals in areas with high density users.

In both cases, the non-recipient of the message perceives it as background noise. Due to greater processing complexity, internal access control is only available to authorized users, and what is important in satellite systems avoids the need to synchronize base stations.

The Satellite Control Centre, located at INMARSAT headquarters in London, carries out the main coordination functions of the system.

3. Mobile and fixed satellite communication stations of users (subscriber stations), operate in the range of 1.5÷1.6 GHz. Mobile stations include ship earth stations (SES - Ship Earth Stations) of various classes and Inmarsat standards.

Radio access techniques are also used to solve the last mile problem as they allow facilities to be installed quickly without civil work. In point-to-point and backbone applications, fiber optic transmission is the natural choice. In particular, in addition to the terrestrial network, the use of optical fibers has a significant impetus in submarine systems, not only for intercontinental, but also for short or medium distances, where the equivalent terrestrial connection is much longer and therefore less convenient.

The development of optical transmission systems is due to advances in both fiber optic, amplification and transmission technologies. Two phenomena that limit the distance that a fiber optic connection can cover are attenuation and dispersion.

Each SZS has its own identification number, consisting of 7 or 9 digits, where the 1st is the INMARSAT standard identifier, the next 3 digits are the code of the country to which the SZS belongs (Maritime Identification Digits - MID), the remaining three (five) digits are the number , assigned to this SZS.

The INMARSAT standard identifiers are as follows:

INMARSAT–A – ........................1

INMARSAT–В – ........................3

However, the phenomenon of scattering is the expansion of the optical pulse as the fibers intersect. At high bit rates, this increase can lead to overlap of adjacent pulses and a greater likelihood of error in receiving the transmitted information. There are two types of dispersion for different reasons: chromatic dispersion and polarization dispersion. The first of them is related to the dependence of the propagation time along the fiber on the wavelength: the emitted optical pulse actually consists of several wavelengths, and since different lengths waves have different propagation times, different pulse components arrive at different times at the end of the fiber, so color dispersion is related to the spectral width of the transmitted pulse and the link length.

INMARSAT–C – ........................4

INMARSAT–Aero – ...................5

INMARSAT–M – ........................6

Additionally, the SZS may have a second identification number, which is used only in the radiotelephone channel and is intended for an additional telephone, fax machine or data transmission device, and this equipment may be in auto-answer mode.
Only one identification number can be used at a time. When operating in telex mode, the SZS telex answerback consists of an identification number followed by four letters (usually the call sign of the ship's radio station).

The time width of the received pulse is proportional to the product of the spectral width of the transmitted pulse and the length of the fiber segment. An important difference between the two dispersions is that while chromatic dispersion is a deterministic phenomenon and can be compensated for, polarization dispersion is difficult to eliminate.

Another reason for advancement in optical communication systems is the introduction of optical amplifiers. Recently, regenerators have been replaced by amplifiers that work directly on optical signal without the need for optical-electrical conversion and vice versa. Erbium-doped fibers and are therefore called active ergal fiber amplifiers and, unlike regenerators, allow the amplification of all optical flows placed within their bandwidth, regardless of the modulation rate and size.

The operational requirements for ship earth stations providing two-way communications are set out in IMO Resolution A.698(17).

INMARSAT system

ERA-Service LLC- official agent representing interests CJSC MVS Global Telecommunications", official representative FSUE Morsvyazsputnik, which is an operator / provider of communication services in the Inmarsat system according to all standards and in all oceanic regions; international settlement organization SU04 on the basis of License No. 5274 of the Ministry of Communications of the Russian Federation.
Within the framework of the concluded agreement ERA-Service LLC provides two-way 24/7 communication services (telephone, fax, telex, data transmission) in a global automatic international system mobile satellite communications Inmarsat, and also provides payments for communication services in the Inmarsat system and international ship radio traffic.

Their introduction made it possible to increase the repetition step, reducing the number of applications you inserted at a particular link, with increased overall reliability. This method makes it possible to transmit on the same optical fiber a set of channels characterized by different carrier wavelengths; it is analogous to a frequency division multiplex in the optical field. The maximum number of channels that can be allocated on an optical fiber is currently about 40.

The most important systems to which Italy is connected are listed here. Disseminate news about personal safety and health, and educational programs V developing countries, for example, on the African continent, are one of the targets of investors.

The international company Inmarsat (headquartered in London) was originally created to ensure the safety of navigation. Over the years, Inmarsat communications have found numerous users on land and in the air, especially in regions where traditional communications are unreliable or non-existent.
Having retained the original status of an international organization, Inmarsat in April 1999. became a private limited company (Inmarsat Ltd.) registered in the UK.
The new international company Inmarsat is also based in London and is governed by a trusted Board of 13 directors.

Inmarsat has more than 170,000 users, served by approximately 200 system service providers in more than 80 countries. Inmarsat also has other partners, including equipment manufacturers, suppliers software products, system integrators (systems engineering enterprises) and enterprises selling services and equipment. Inmarsat is in an exceptional position, having licenses to operate the system in 171 countries. This provision appeared back in 1979. Inmarsat became a pioneer in the development and creation of a global satellite communications system. With more than 20 years of experience behind it, Inmarsat currently operates four generations of its own geostationary satellites.
Technically, the Inmarsat system consists of orbital group satellites located in geostationary orbit, a network of on-shore satellites earth stations) and user terminals. The call from the subscriber terminal arrives via satellite to the BZ, which then routes it to the appropriate terrestrial network. IN reverse direction a call from a subscriber arrives at the BZ, which routes it to the terminal. Thus, all connection establishment functions are performed by the base station; satellites are used only for signal relay.


Network management.

Traffic through Inmarsat satellites is monitored and managed by a Network Operations Center (NOC) located at Inmarsat headquarters in London. NOC operation is supported by Network Coordination Stations (NCS). The main task of NCS is to allocate channels to the base station and the terminal for establishing a connection. There is one NCS for each ocean region and standard (A, B, C, etc.). All NCS constantly exchange operational information among themselves and with the NOC.


User terminals.

User terminals are divided into several large groups, so-called standards. Terminals of each standard have the same set of services provided. Here a brief description of existing standards:

  • Standard A is the very first type of Inmarsat terminal. Provides voice and telex transmission over an analog channel. It can also provide high-speed data transfer (64Kbps). Currently, terminals of this standard are not produced. Inmarsat plans to stop supporting them.
  • Standard B is a digital version of Standard A, providing voice, fax (2.4 Kbit/s), low-speed data transmission (2.4 Kbit/s), telex, HSD). Available in ship, land and vehicle versions.
  • Standard M - portable version standard B, the first Inmarsat terminal, housed in a housing the size and appearance of an ordinary briefcase. Provides voice, fax (2.4 Kbps) and data (2.4 Kbps). Currently being replaced by Mini-M and M4 (GAN) terminals.
  • The Mini-M standard is a smaller and cheaper version of the M standard. It provides the same services as the M standard, but has the dimensions of an average laptop.
  • The GAN(M4) standard is an extended version of Mini-M. Originally called MultiMedia Mikni-M, hence M4. With the same dimensions, it additionally provides ISDN (64/56 KBit/s) and MPDS mode. MPDS is a mode specially designed to provide economical and comfortable Internet browsing. When communicating in MPDS mode, payment is charged for the amount of information transmitted/received, and not for the connection time, as in other cases. The data transfer rate in MPDS mode is not guaranteed, but can reach 64 Kbps.
  • Fleet is a marine version of GAN. It comes in three versions, differing in functionality (and price). The most functional is F77, then F55 and F33.
  • SWIFT is an aviation version of GAN.
  • Standard C - provides the exchange of text messages both between terminals and with various terrestrial data networks - X25, Internet, X400. In the marine version it can be equipped with a built-in GPS receiver. It features small dimensions of the antenna and interface unit. In the Mini-C version, the interface unit is combined with the antenna while maintaining its dimensions.
  • Standard D and D+ - global pager. D+ is distinguished by the ability to send short messages.


Inmarsat satellites.

The satellites are located at four points above the equator, each of them serving its own part of the earth's surface, the so-called ocean region. There are 4 ocean regions:

  • Atlantic-East (AOR-E), the satellite is located at 15.5°W.
  • Atlantic-West (AOR-W), the satellite is located at 54° W.
  • Pacific (POR), satellite located at 178° East.
  • Indian (IOR), satellite located at 64°E.

Each of the ocean regions has its own international dialing codes used for calls in the terminal-to-terminal and shore-to-terminal directions in telex mode:

  • Atlantic East (AOR-E): 581
  • Atlantic-West (AOR-W): telephone - 874, telex - 584
  • Pacific (POR): telephone - 872, telex - 582
  • Indian (IOR): telephone - 873, telex - 583

For telephony, since 01/01/2009, a single code 870 has been used, denoting “all satellite regions”. Previously used telephone codes ocean regions (871,872,873,874) are officially returned to the ITU.
The Inmarsat satellite control center is located in London, the tracking and telemetry collection stations are in Canada, China and Italy.

Inmarsat operates three generations of satellites: Inmarsat-I2, I3 and I4. The Inmarsat I2 satellites were built by British Aerospace (now BAE Systems), launched in 1990-1992 and had a design life of 10 years. Currently, the I2-F3 satellite is decommissioned, I2-F1, F2 and F4 are used as backup for the Pacific, Western Atlantic and Indian regions, and are also leased.
The Inmarsat I3 satellites were built by Lockheed Martin Astro Space (now Lockheed Martin Missiles & Space), which was responsible for spacecraft, and European Matra Marconi Space (now Astrium), which developed communications equipment. The satellites were launched in 1996-98. A total of 5 satellites were launched. The I3 satellites introduced the concept of zonal beams - each of them is capable of generating a global and up to seven zonal beams. Thanks to the use of zonal beams, it became possible to develop more compact user terminals, such as Inmarsat-M and Mini-M.
The I4 satellites are the latest addition to the Inmarsat satellite constellation. Two of the planned three satellites have been launched. The I4 satellites are the basis of Inmarsat's new broadband network. Each of the I4 satellites has more capacity than the three I3 satellites. Compared to the previous generation, the power has been increased by 60 times, the efficiency of spectrum use has been increased by 12 times, and the sensitivity of receivers has been increased by 25 times.

Like its predecessors, the I4s have a global beam covering 1/3 of the earth's surface and 19 wide zonal beams covering the same area and supporting the latest Inmarsat terminals, such as Fleet F77 128K, Fleet F55, Fleet F33. There are also 228 narrow area beams that support the BGAN network. BGAN terminals have data transfer rates of up to 492 kBit/s.

INMARSAT BGAN system

BGAN system is the first in the world to be publicly available mobile network communications, providing simultaneous voice communication and high-speed data transmission from almost any point on land using one portable device. It is also the first network of its kind to offer guaranteed on-demand connection speeds. The data transfer rate in the BGAN network can reach 500 Kbps.
So, when working in remote locations, you can use the same services and applications as in the office.

BGAN uses the power of Inmarsat 4th generation satellites - I4. Currently, 3 satellites are in use - I4 Americas (put into operation on 01/07/2009, located at 98°W), I4 EMEA (will be located at 25°E, put into operation after repositioning on 02/02/2009) and I4 Asia-Pacific (currently located at 64°E, after repositioning (from 02/06/2009 to 02/24/2009) will be located at 143.5°E. Thus, after the completion of the transfer of I4 satellites to new orbital positions (according to the plan, all operations should be completed on February 24, 2009) Inmarsat system BGAN will be the first commercially available global system broadband satellite communications.
For communication, the L-band is used: from 1.5 to 1.6 GHz. The channel occupies a 200 kHz band.
The BGAN network consists of user terminals, relay satellites in geostationary orbit and a ground complex. The terrestrial complex includes base stations located in Fucino (Italy) and Burum (Netherlands), as well as a gateway for connecting to terrestrial networks. Unlike previous Inmarsat standards, the ground equipment is owned by Inmarsat and not by its partners. Both BZS are connected to each other and to the gateway via high-speed data transmission channels.
The following figures show communication schemes for individual and group subscribers:


  • Standard IP Services

Variable Bit Rate (VBR) Data Transmission
-IP background class data transmission (as defined by 3G industry standards)
-Maximum channel speed up to 492 Kbps for transmission and reception

  • IP Streaming Services

Guaranteed bit rate service
-Availability upon request
-QoS with streaming class (as defined by 3G industry standards)
-32, 64, 128, 256 Kbps for transmission and reception

  • Voice communication

4Kbps circuit-switched voice services
-Calls are made using an external handset or headset (some terminals can connect via Bluetooth)
-Voice mail
-Additional services: call waiting, call barring, call holding, forwarding

64 kBit/s
-Unlimited/limited data streams (UDI/RDI)
-Digital and analogue mode
-Support is implemented on certain types of terminals

SMS exchange between BGAN terminals
-Supports the ability to exchange SMS with terrestrial cellular networks

The BGAN terminal is controlled using a standard software interface, common for all types of terminals - BGAN LaunchPad. BGAN LaunchPad exists in versions for Windows 2000, XP, MacOS 9.2, 10.1, Linux RedHat 9.
Main properties of BGAN LaunchPad:

  • Easy to use
  • Step-by-step navigation instructions satellite terminal and connection setup
  • Possibility of individual configuration of data transfer parameters depending on the specific application
  • Preset user access settings, for example to limit access to streaming data
  • Online access to credentials and billing system information
  • Personal and corporate versions
  • Access to text messaging (SMS) and phone services


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