Ship's Satellite Systems
Since the launching of the first satellite system to space in 1957, marine communication and navigation has been enhanced significantly. At & T, American Telecommunication Giant, launched Telstar, its first Communication satellite in 1962 (Oleson and McGuire 45). Since that time, a number of communication satellites were placed into the Earth's orbit (Oleson and McGuire 45). Satellites have been applied in different areas including military, telecommunication, maritime and space exploration among others. The current report aims at understanding the use of satellites in the maritime vessels.
Communication Satellites Systems
A satellite is basically a self-contained communication system that has the ability to receive signals from Earth and resend these signals back through the use of transponders, which are an integrated transmitter and receivers of radio signals (Oleson and McGuire 63). The main part of the satellite includes the communication system that encompasses antennas and transponders, the power system made up of solar panels that provide power, and the propulsion system composed of rockets that propel the satellites to the orbit. In the maritime field, the satellite communication system, such as Inmarsat, offers efficient communication links to the ship at the sea (Grace and Mohorcic 41). Such links use a VSAT type of device to connect to the geosynchronous satellites that in turn connect the ship to the land-based point of presence of the appropriate nation's telecommunication and navigation systems. For the ship to communicate effectively via satellites, a Mobile Satellite Service (MSS) is fixed on the ship. The MSS terminals offer the most encouraging applications including mobile phones and broadband terminals that promote global communication capability services (Grace and Mohorcic 47).
In maritime communication, Land Earth Stations are land-based radio stations developed for extra-planetary communication with the space satellites. Land stations are located on the surface of the Earth and communicate with satellites trough transmission and reception of radio waves at very high frequencies. The Land earth station may have an itinerant or fixed position. However, most Land Earth Stations are used to receive telemetry information or follow satellites outside the geostationary orbit (Oleson and McGuire 75). Ships use satellites to communicate since they are usually too far away to use conventional means of communication. In order to relay information, the Earth station transmits data to the uplink satellite. Transponder translates the signal and relays it to the other earth station called downlink. However, for the ship to communicate effectively, it needs to have the prerequisite hand ware capability on-board. The ship needs to have broadband satellite communication with the capability of permitting IP networking. Nevertheless, to achieve such capability, VSAT systems are used to connect the ships to the satellite-based network. Furthermore, there needs to be a gyro-stabilized antenna, position control unit and the network equipment that enables the IP routine (Grace and Mohorcic 61).
Mobile Earth satellites are radio receivers or transmitters that are placed on aircraft, ship or a vehicle, and used for satellite communication. They are critical in the communication and navigation system of the ship since they provide effective two-way communication in locations where land Earth Satellites are non-existent or beyond reach (Grace and Mohorcic 69). The Mobile Earth Satellite comprises of the transportable trifold antenna, intelligent network management system, stabilizer, and converter in redundancy configuration that are mounted on the upper ship deck.
Orbit satellites are satellites that revolve around the Earth and are composed of equipment that scans and transmits the data back to the Earth. There are two types of orbiting satellites; they are geostationary and polar-orbiting satellites (Oleson and McGuire 45). Geostationary satellites orbit at a speed that makes them remain constant over the same area of the Earth thus they view a specific area of the planet. Polar orbit satellites move around the orbit that makes them pass over a designed area at the same time of the day. However, in the maritime field, geostationary orbiting satellites are the most useful since they provide infrared images about the weather thus guiding the ship activities deep in the ocean (Oleson and McGuire 56).
Major Commercial Satellite Networks
There are a number of commercial satellites used for communication that include but not limited to TerreStar-1 and Iridium. Terre Star-1 is a US-based satellite used in the provision of mobile communications in North America (Grace and Mohorcic 89). The signal from the satellite is transmitted by an 18 meters reflector on the satellite, with a launch mass of 6.91 tonnes, an aspect that makes it one of the most massive single satellites to be launched in the geosynchronous transfer orbit, and the biggest commercial satellite ever built and launched. The satellite is designed to function with a network of the ground-based signal amplifiers to allow service in areas the satellite could not reach such as urban canyons (Oleson and McGuire 105). Telestar-1 provides users with the ability to access data and voice services across the United States, Virgin Island, Puerto Rico, and offshore coastal waters. Iridium is one of the largest satellites that offer communication for the pages, mobile phones, and transceivers across the globe. The satellite has a global reach since it covers the entire Earth's service.
Merits and Demerits of Satellite over Terrestrial Communications
The use of satellites in communication offers many advantages over native communication. The satellites cover a wide range of area that significantly surpasses that of the terrestrial system (Li et al. 54). Its wide coverage permits its application in the maritime field where other conventional means are incapable of reaching. Furthermore, mobile communications are easy to establish using satellite communication. It also offers precise communication, especially when communication takes place via satellites. In regard to cost, satellites are economical to utilize especially when communicating over long distances (Oleson and McGuire 45). When compared to optical fiber communication, satellite communication permits the transmission of high-quality signals. Apart from that, the sending and receiving stations are usually independent of the distance. Though the use of satellites offers a number of benefits over the terrestrial communication, it has its disadvantages. The initial cost of developing and launching a satellite to the orbit is very high, only feasible for telecommunication giants (Grace and Mohorcic 55). There is also a large transmission delay when communicating using satellite compared to terrestrial communication, as an aspect that reduces the efficiency of the satellites in data transmission. Lastly, the satellite bandwidth is gradually becoming used up, notwithstanding that it’s almost impossible to repair a satellite once launched.
Brief Description of VSAT System
VSAT is a two-way ground station with a dish antenna that is less than 3 meters long. It is composed of two parts, a transceiver placed above the ship deck and in line with the satellite and a device placed below the deck to interface with the Trans receiver (Acharya 76). The VSAT dish antenna is usually mounted above the ship deck and provides a data rates range of 4Kbs up-to 4Mbs. However, some modules can reach a max downlink of 16mbs. It is uniquely designed to provide connectivity under the most severe conditions on the sea. It also permits IT solutions that include fax, email, web browsing and voice calls among others (Acharya 103).
SAT-TV System On Board a Ship
In the Maritime field, SAT-TV system permits people to get favorite programs even while traveling by ship. Such a system enables the user to access a wide range of television content that would be unavailable through conventional means deep in the ocean. The marine SAT TV system is composed of a satellite TV antenna, a TV and a satellite TV receiver (Maini and Agrawal 45). The antenna tracks and receives the video signals. The size of the antenna usually varies from 15” to 24” in diameter. Satellite TV receiver is used to decode the TV signals from the SAT-TV antennas and forward these signals to the TVs. Due to their capability, Maritime SAT-TV satellites are designed to track and receive signals from TV satellites even during extreme weather conditions, prevalent in the deep seas (Maini and Agrawal 56). The SAT TV antennas are mounted above the deck while the receiver and the decoder are usually installed below the deck of the ship.
Fleet Broadband Technology
Fleet board technology is a powerful communication system that makes it easy for the captain and the entire ship crew to communicate through text messages, emails and faxes around the world. The Fleet Board Technology provides the ship crew with a wide range of applications that are based on core functionality (Acharya 36). It permits the ship crews access to IP connection for e-mail and internet access that includes secure VPN. It guarantees the crew member an interrupted bandwidth for the data session or application that requires specific bandwidth, as well as voice and data services simultaneously. The technology makes it easy and efficient to communicate with the crew member within the entire ship fleet (Acharya 67).
Satellite AIS (S-AIS)
Satellite AIS (S-AIS) is a tracking system that is used to track ships and other maritime vessels through the exchange of electronic data via satellites and AIS ground stations. It is referred to as S-AIS when satellites are used to identify the systems signatures (Li et al. 45). The data from AIS supports the information from the marine radar, thus playing a major role in avoiding collision between water vessels. In the future, S-AIS will become a major infrastructure component for the maritime authority and will be applied in monitoring and reporting on marine activity in the oceans (Li et al. 67). The major satellites offering AIS services include OrbComm, Iridium Prime and INMARSAT among others.
Conclusion
In conclusion, it is evident that satellite communication has revolutionized the mode of communication in the maritime field. Since 1957, such satellites as Inmarsat, Iridium and OrbComm among others have been sent to orbit for communication, military and space exploration. Apart from that, a wide range of devices that use satellite signals has been developed especially for the maritime use. The use of satellites has been found to provide coverage to a wide area compared to terrestrial communication, hence making it a more preferred means of communication. In the future, satellite communication is likely to remain a predominant mode of communication across different sectors.