Orbcomm Ground Segment for Mobile Satellite Communications By Stojce Dimov Ilcev ([email protected]) – Mangosuthu University of Technology, Durban, South Africa Abstract: In this paper is introduced the Orbcomm system as a wide area packet switched and global two-way data transfer network providing satellite communication, tracking, monitoring and logistics services between mobile, remote, semi fixed or fixed Subscriber Communication Units (SCU) in Mobile Satellite Communications (MSC) and Gateway Earth Stations (GES) or Gateway Control Centres (GCC) accomplished via LEO satellites and Network Control Centres (NCC). Orbcomm Global, L.P., from Dulles, Virginia, USA equally owned by Teleglobe and the Orbital Sciences Corporation, provides global services via the world’s first LEO satellite-based data and messaging communications system. The US Federal Communications Commission (FCC) granted Orbcomm a commercial license in October 1994 and the Commercial service began in 1998. Orbital Sciences was the prime contractor for the design project of Orbcomm satellites. The Company owns and operates a network consisting in 36 Little LEO satellites and several GES deployed around the world, connecting small, low-power and commercially proven SCU terminals to private and public networks, including the Internet. Orbcomm delivers information to and from virtually anywhere in the world on a nearly real-time basis to the Terrestrial Telecommunication Network (TTN). The Orbcomm ground segment and subscriber transmitters (Tx) that provide a continuous 4.8 to even 9.6 Kb/s stream of downlink packet data to the receivers (Rx), and vice versa. Key Words: MSC, SCU, GES, GCC, Little LEO, Orbcomm, Space Segment, Ground Segment 1. Introduction Orbcomm communication network consists in 36 operational satellites in little LEO orbit at about 825 km above the Earth’s surface. Vital messages generated by a variety of space applications are collected and transmitted by an appropriate mobile or fixed SCU to the Orbcomm satellite. The satellite receives and relays these messages down to one of several GES. The GES then relays the message via certain satellite link or dedicated terrestrial line to the NCC. The NCC routes the message to the final addressee via Internet via E-mail to a personal computer, through terrestrial networks to a mobile subscriber unit or pager and to dedicated telephone or facsimile, see Figure 1. Messages originating outside the USA are routed through international GCC in the same way to its final destination. In reverse mode, messages and data sent to a remote SCU can be initiated from any PC onboard using common E- mail, Internet and X.400. The GCC or NCC then transmits the information via Orbcomm ground network [01]. Orbcomm serves customers with fixed and mobile units through distributors and so-called Value Added Resellers (VAR) , which 1
Transcript
Orbcomm Ground Segment for Mobile Satellite Communications
By Stojce Dimov Ilcev ([email protected]) – Mangosuthu University of Technology, Durban, South Africa
Abstract: In this paper is introduced the Orbcomm system as a wide area packet switched and global two-way data transfer network providing satellite communication, tracking, monitoring and logistics services between mobile, remote, semi fixed or fixed Subscriber Communication Units (SCU) in Mobile Satellite Communications (MSC) and Gateway Earth Stations (GES) or Gateway Control Centres (GCC) accomplished via LEO satellites and Network Control Centres (NCC). Orbcomm Global, L.P., from Dulles, Virginia, USA equally owned by Teleglobe and the Orbital Sciences Corporation, provides global services via the world’s first LEO satellite-based data and messaging communications system. The US Federal Communications Commission (FCC) granted Orbcomm a commercial license in October 1994 and the Commercial service began in 1998. Orbital Sciences was the prime contractor for the design project of Orbcomm satellites. The Company owns and operates a network consisting in 36 Little LEO satellites and several GES deployed around the world, connecting small, low-power and commercially proven SCU terminals to private and public networks, including the Internet. Orbcomm delivers information to and from virtually anywhere in the world on a nearly real-time basis to the Terrestrial Telecommunication Network (TTN). The Orbcomm ground segment and subscriber transmitters (Tx) that provide a continuous 4.8 to even 9.6 Kb/s stream of downlink packet data to the receivers (Rx), and vice versa.
Key Words: MSC, SCU, GES, GCC, Little LEO, Orbcomm, Space Segment, Ground Segment
1. Introduction
Orbcomm communication network consists in 36 operational satellites in little LEO orbit at about 825 km above the Earth’s surface. Vital messages generated by a variety of space applications are collected and transmitted by an appropriate mobile or fixed SCU to the Orbcomm satellite. The satellite receives and relays these messages down to one of several GES. The GES then relays the message via certain satellite link or dedicated terrestrial line to the NCC. The NCC routes the message to the final addressee via Internet via E-mail to a personal computer, through terrestrial networks to a mobile subscriber unit or pager and to dedicated telephone or facsimile, see Figure 1. Messages originating outside the USA are routed through international GCC in the same way to its final destination. In reverse mode, messages and data sent to a remote SCU can be initiated from any PC onboard using common E-mail, Internet and X.400. The GCC or NCC then transmits the information via Orbcomm ground network [01].
Orbcomm serves customers with fixed and mobile units through distributors and so-called Value Added Resellers (VAR), which provides whole product solutions and customer support to the end-users. Thus, customers from around the world currently rely on Orbcomm for a wide range of mobile and fixed site data applications including:1) Monitoring and controlling assets at remote or rural sites for oil and gas platforms, extraction and pipeline operations, meteorological centres, water stations, construction and agriculture, satellite SCADA (M2M) control, storage, custody transfer and electric power generation and distribution; 2) Messaging for truck and bus fleets anywhere, owner operators and remote workers; 3) Tracking and managing construction devices, locomotives, rail cars, trucks, trailers, containers, vessels, aircraft and locating and recovering stolen vehicles and cargo and 4) Weather data reports for general aviation and especially for small aircraft.
Figure 1. Orbcomm System Overview
Courtesy of Manual: “Orbcomm System Overview” by Orbcomm [02]
The Orbcomm ground segment, which has most of the intelligence of the Orbcomm entire system, comprises Gateway Earth Stations (GES), Control Centres and both mobile and fixed SCU user terminals worldwide. Otherwise, the Orbcomm space segment is controlled by one Satellite Control Centre (SCC) [01].Gateways, which include the GES, GCC and the NCC, are located at Orbcomm headquarters in Dulles. Within the USA, there are four GES located in Washington, Arizona, New York and Georgia. The several GES are located worldwide controlled by the US GCC managing the overall system. Orbcomm Gateways are connected to dial-up circuits, private dedicated lines, or the Internet. The SCU hand-held devices for personal messaging are fixed and mobile units for remote monitoring and tracking applications [01]. 1. Gateway Earth Station (GES) – Orbcomm is committed to continuing the deployment of additional regional GES to provide near-real-time service for all major areas of the world, as well as developing and launching a new generation of satellites that will enhance and expand the current system’s capabilities. All Orbcomm’s GES terminals link the ground segment with the space segment and will be in multiple locations worldwide. The GES provides the following functions: acquires and tracks satellites based on orbital information from the GCC; links ground and space segments from multiple worldwide locations; transmits and receives all transmissions from satellites; transmits and receives signals from the GCC or NCC; monitors status of local GES hardware and software and monitors the satellite system level performance “connected” to the GCC or NCC [01]. The GES terminal is redundant and has two steerable high-gain VHF antennas that track the satellites as they cross the sky. The GES transmits to a satellite at a frequency centered at 149.61 MHz and 56.7 Kb/s with a nominal power of 200 W. The GES receives 3 W transmissions from the satellite at 137 to 138 MHz range. These up and downlink channels have a 50 KHz bandwidth. The mission of the GES is to provide an RF communications link between the ground and the satellite constellation. It consists in medium gain tracking antennas, RF and modem equipment and communications hardware and software for sending and receiving data packets from and to users. An Orbcomm licensee requires a Gateway to connect to Orbcomm satellites in view of its service area. Namely, the Gateway consists in a GCC and one or more GES sites, as well as the network components that provide interfacility communications [01].
2. Gateway Control Centre (GCC) – The GCC terminals are located in a territory that is licensed to use the Orbcomm system and provide the following functions: locate wherever Orbcomm is licensed; link remote SCU with terrestrial-based Georgia systems; communicate via X.400, X.25, leased line, dial-up modem, public and private data networks and E-mail including the Internet.The Orbcomm GCC terminal efficiently integrates the Orbcomm infrastructure with new or existing customers and system providers.3. Network Control Centre (NCC) – The NCC is responsible for managing the entire Orbcomm communications network, elements and the USA Gateways through satellite telemetry monitoring, commanding and mission system analysis. It provides network management of Orbcomm’s satellite constellation and is staffed 24 hours a day by Orbcomm-certified controllers and has the following main functions: monitors real-time and back-orbit telemetry from the Orbcomm satellites; sends the real-time and stored commands to the satellites; provides the tools and information to assist engineering with resolution of the satellite structure and ground anomalies; archives satellite and ground telemetry data for analysis; monitors the performance of GES terminals and so on. The NCC manages and controls the entire Orbcomm satellite constellation, its processes and analyzes all satellite telemetry. The NCC is responsible for managing the Orbcomm system worldwide as well. In addition, through so call OrbNet, the NCC monitors message traffic for the entire Orbcomm system and manages all message traffic that passes through the US Gateway. The NCC is staffed 24 hours a day, 365 days a year and is located in Dulles, Virginia, USA. A backup NCC system was established in 2000, which permits the recovery of critical NCC functions in the event of an NCC site failure [03].4. Satellite Control Centre (SCC) – The SCC serves in a territory that is licensed to use the Orbcomm system and provides control of the Orbcomm satellite constellation.5. Satellite Communication Unit (SCU) – The SCU equipment are both mobile and fixed terminals used for connection to the Orbcomm satellite network through Gateway stations. The SCU terminal is a wireless VHF modem that transmits messages from a user to the Orbcomm system for delivery to an addressed recipient and receives messages from the Orbcomm system intended for a specific user. Manufacturers have different proprietary designs and each model must be approved by Orbcomm and adhere to the Orbcomm Air Interface Specification, Subscriber Communicator Specifications and Orbcomm Serial Interface Specification (if an RS-232 port is available).
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Figure 2. Different Type of SCU Terminals
Courtesy of WebPages: “Orbcomm Satellite” by Orbcomm [02]
Different versions of SCU terminals are currently available, which include “black-box” industrial units that have RS-232C ports for data uploading and downloading. The following CSU terminals can integrate an internal GPS receiver including additional digital and analog input and output ports: a). Magellan GSC 100 is the world’s first handheld satellite terminal that allows sending and receiving text and E-mail messages to and from anywhere in the Orbcomm coverage area, see Figure 2 (1). This unit offers communication and navigation using the Orbcomm network and GPS system. Integrated GPS receiver capabilities allow one to identify position, plot and track course, store waypoints and send this information via communication modem to anyone, anywhere in the world. Unlike traditional landlines, cellular and paging systems, the GSC 100 and Orbcomm network operate from isolated parts of the world, where TTN systems do not reach customers. Messaging features allow worldwide messaging via Orbcomm satellite coverage, send and receive E-mail messages called GlobalGrams to any E-mail address, easy-to-use menu-driven interface, storing up to 100 messages and 150 addresses, sending and receiving messages at pre-selected time intervals and automatic wake-up [02]. The GPS features provide navigation and pointing location worldwide and displays position, speed, distance, time-to-go, continuously points to the destination and keeps on a true course, displays the trip’s progress with a track plotter, stores up to 200 user-defined waypoints, relays present speed and location by inserting GPS position into the GlobalGrams message. This unit is equipped with the telescopic whip antenna, rechargeable NiCad battery package and the universal AC converter, software update, data and power extension cables and instruction manuals. Optionally, it is possible to supply external GPS antennas, fixed Site VHF Antennas, Combined GPS/VHF Magnetic Mount Antennas and Combined GPS/VHF Roof or Trunk Top-Mount Antennas [04].
b). Panasonic Trailer Tracking Terminal KX-G7121 PANATRACKER has been created to help meet the demand for a rugged, low-cost and reliable trailer-tracking product. Utilizing a KX-G7101 model as its core it is shown in Figure 2 (2). Thus, this device is designed to be mounted in a covert manner (within the bulkhead’s two plywood shells) as typically found in most trailers today. Its built-in battery allows the device to communicate for up to two months should the trailer be disconnected from the tractor. When is connected to the tractor (truck), a built-in charger maintains the battery’s charge. Programming is similar to the KX-G7100 series, with the addition of several powerful and very easy to use “macro” type commands, designed specifically for this application. The KX-G7100 is second-generation product and has become the most popular of Orbcomm SCU. It is easily programmed with ready-to-use commands that are accessible using a simple terminal emulator or PC. This unit can be provided by the Software Developer’s Kit (SDK), thereby tapping into and utilizing the dedicated User Application Programming area provided in the SCU. This terminal has two programming SDK modes for maximum operational flexibility. One mode utilizes the resident “KX” command set, accessible using standard terminal emulator software such as Windows HyperTerminal. A second mode allows a C language program to be embedded and executed on the SCU for additional functionality. The SDK terminal contains all the tools needed to create, debug and implement a custom application. Namely, using this powerful tool substantially reducing application hardware costs. The SDK gives to users complete control of enhancements by allowing the development of applications in-house. Minimum hardware needs are PC-AT or compatible, CPU 80386 or higher and hard disk minimum 3MB for installation. The new Panasonic SCU KX-G7200 will replace the highly successful KX-G7100 communicators, thousands of which are currently in operation throughout the world.
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c). The SelComm EL-2000 Terminal (Stellar Communicator Manager) model is illustrated in Figure 2 (3). The Stellar product of the Windows applications Development Tool SelComm enables customers to program, configure, monitor and debug their Stellar Communicator. In fact, the Orbcomm satellite data products are designed for the use on the Orbcomm satellite network for two way short burst messaging, tracking, managing, monitoring and logistics for maritime, land (road and rail) and aeronautical applications including Satellite Asset Tracking (SAT) and SAT and Fleet Management (SATFM) and Satellite Supervisory Control and Data Acquisition (SCADA) or Machine-to-Machine (M2M) as well.d). Quake Q1500 is a satellite modem with GPS and Magnetic Mount VHF Antenna using a 12 VDC Power Supply, including Windows-based Programming Software, shown in Figure 2 (4). This briefcase kit contains everything necessary to program custom applications and exercise all basic hardware functions. Quake is a world leader in developing other products that facilitate and enable SAT, SATFM and SCADA connections utilizing state-of-the-art advances in embedded engineering and communication technologies. By utilizing a network of sensors, including the GPS for location information, Quake devices find application in the areas of SATFM, telematics, transportation and logistics, security and utility metering.
3. Conclusion
The Orbcomm system allows mobile and fixed users to communicate, track, monitor, control and manage mobile and remote assets for purpose of SATFM, SCADA or M2M, command and logistics applications at sea, on the ground and in the air. These small devices are a very new satellite communications tools available for all professionals in transportation, business people, oil and gas, agriculture and remote environment to everyone who likes to have satellite messaging, tracking and logistics using Little LEO Orbcomm satellite systems everywhere.
Otherwise, the different nomenclature of LEO satellites is usually known as Non-GEO (Geostationary Earth Orbits) satellites. Compared to the Big LEO systems, the smaller size of the Little LEO system enables simple data processing of non-voice store-and-forward features. The Orbcomm Little LEO system provides low speed data transfer to MSC and fixed machines almost globally. Unfortunately, Orbcomm network is not covering African Continent only, so they have project to establish few GES within Africa including one in South Africa, and in the future to offer real global service. In such a way, South Africa will have good opportunity to use Orbcomm satellite network for purpose of SAT, SATFM, SCADA or M2M, especially for road and railways transport. Through a network of LEO satellites and regional GES, users can communicate with their mobile or fixed assets anywhere in the world. This system is operational, robust and provides service to customers worldwide today. However, Orbcomm is in a position to offer low-cost and high-quality service to each customer. Orbcomm committed staff are committed and dedicated to fulfilling the specific needs of all potential users, such as SAT, SATFM and logistics of trailers and containers, locomotives, rail cars, road vehicles, heavy equipment, fishing vessels and barges; and to provide SCADA or M2M monitoring and controlling fixed sites such as electric utility metres, water levels, oil and gas storage tanks, wells, pipelines and environmental projects and a two-way messaging service for consumers, commercial and government entities.
4. References
[01] Ilcev D. S. “Global Mobile Satellite Communications for Maritime, Land and Aeronautical Applications”, Book, Springer, Boston, 2005.[02] WebPages from Internet: “Orbcomm System” and “Orbcomm Products” [03] Gallagher B., “Never Beyond Reach”, Inmarsat, London, 1989. [04] Richharia M., “Mobile Satellite Communications – Principles & Trends”, Addison-Wesley, Harlow, 2001.
Author:
Stojce Dimov Ilcev received two BEng degrees in Mobile Radio Engineering and in Maritime Navigation from the Faculty of Maritime Studies at Kotor of Podgorica University, Montenegro; received BSc Eng (Hons) degree in Maritime Communications from the Maritime Faculty of University at Rijeka, Croatia; and received MSc degree in Electrical Engineering from the Faculty of Electrical Engineering, Telecommunication department of University at Skopie, Macedonia, in 1971, 1986 and 1994, respectively. His Doctoral dissertation in Satellite Communications, Navigation and Surveillance (CNS) was positive evaluated in 2000 by Telecommunication department of Faculty of Electrical Engineering “Nikola Tesla” of Belgrade University, Serbia. In 1995 he also passed an on-site GMDSS training at Military Maritime Training Centre in Varna, Bulgaria. He holds the certificates for Radio operator 1st class (Morse), for GMDSS 1st class Radio Electronic Operator and Maintainer and for Master Mariner.
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Prof. Ilcev is currently working as a Senior Research Professor in Space Science at Mangosuthu University of Technology (MUT) in Durban, South Africa and as Director for establishment of National Space Institute (NSI). His research concentrated over 45 years on all aspects of Radio and Satellite CNS systems, networks, technology transfer, navigation and logistics, including safety and security in all transportation systems.
