«Ships Satellite System» - Free Essay Paper

Introduction

Today, there is much fascination with the incredible wonders of the outer space and communication technology. Satellite communications technology has showcased a response to imaginative dreams. Science has conceived ideas for communications through space, alongside the notable technological breakthroughs in the satellite communication system. Such advances draw from early innovations by Konstantin Tsiolkovsky from Russia (Rocket Equation), Hermann Oberth from Germany (Orbiting Rockets), Hermann Noordung from Austria (Geostationary Orbit) and the recent works of Arthur C. Clarke (Satellite Communications). Significantly, this technological evolution has resulted in the worldwide communications advancement and coverage. Thus, this report explores the context of Satellite Communication System in Marine Engineering.

Satellite Communication Systems (SCS) in Maritime

Satellite communication systems draw their inception in maritime in the late 1970s. The development also resulted in the establishment of the International Maritime Satellite Organization (INMARSAT). Weintrit notes that during their inception, SCS targeted international transoceanic communications. Nonetheless, after the privatization of the INMARSAT, SCS presented commercial, recreational and structural opportunities to the maritime sector. The privatization also elicited other players in this segment to pursue advancements in satellite communication for ships and fleet, including C-Band and other innovations. Such improvements saw the emergence of the Low-Earth Orbit (LEO) service providers such as Globalstar and Iridium in the late 1990s.

The SCS encompass either Active or Passive satellites. The Passive Satellite reflects received radio signals back to the Earth Stations. The Active Satellite functions as a Repeater; it receives signals, amplifies them and then transmits them back to Earth Stations. The process enhances signal strength at the receiving terminal to an appropriate level higher than passive satellite could transmit (Lisi; Weintrit).

How It Works

SCS functions similarly to relay stations. It integrates satellites to send radio transmissions between earth terminals. Notably, the process transverse two dimensions i.e. the space and land dimensions. Earth dimension embeds Mobile Earth Stations (MES) that receive signals from the satellites. The signals come in varying bandwidths and carry different loads of information. Occasionally, Earth Station will have operational links that integrate an active satellite and several earth terminals. Ideally, the station transmits to the satellite on a frequency (Up-Link) (Wang). Also, the land dimension encompasses the Land Earth Stations (LES). Entirely, all LES contain specially designed, sensitive receivers. They are equipped with these devices to overwhelm the Down-Link power loss and to facilitate extraction of the required communications information from the feeble signals received. Also, the land earth stations function as harbors for precisely designed preamplifiers mounted to antennas.

Conversely, the Space dimension entails satellites and telemetry control systems, like the track and control (TT & C) stations. Space dimension, precisely controls the satellites’ operations through telemetry links. It contains such equipment as receiver antennas, which filter, alter and amplify the signals. The signal is initially synthesized through digital equipment like Inmarsat-4 or Skynet 5 on board the satellite. Other equipment in SCS include the orbiting satellites. They amplify the received signals, convert and alter them to produce the Down-Link frequency, and sent back to the Earth Stations (Weintrit). The term ‘Orbiting’ depicts the elliptical or circular nature that the process covers. Moreover, other equipment entails Mobile Satellite Communications (MSC), Position and Reporting (P&R) e.g. EutelTRACS, OmniTRACS, and few maritime services utilizing satellite systems like the Inmarsat or PanAnSat constellations. According to Ilcev, there exist higher signal frequencies e.g. Ka-Band, which accommodate enormous bandwidths. Higher frequencies e.g. Ka-Band transmits more information than the smaller L–Band.  The disparity elicits a colossal competition amongst applications and users.

Commercial Satellite Networks

INMARSAT and Iridium Communications remain the most notable networks. Such systems offer services that are vital to federal, local, and state governments and commercial institutions in maintaining indispensable and secure communications. They perform their functions in areas where there is an absence of wire lines, or there is an existing wireless infrastructure. Expressively, the INMARSAT avails GMDSS coverage (global beam, Regional spot beam, and narrow spot beam) for aircraft, ships, and fleet. The networks come in Low Earth Orbit (LEO) (e.g. Iridium, Globalstar) and geostationary satellite orbit (GSO) (Inmarsat, Thuraya).  They are easy to obtain a signal, to connect and have high voice quality. They are also stronger and quite efficient for huge applications (Satworx.com).

SCS and Terrestrial Systems

Pros

Satellite systems have characteristic advantages over conventional terrestrial long distance transmissions. Satellite links have capabilities to withstand propagation disparities, which often interfere with the hf radio.  They are quite reliable. Satellite communications also exhibit wider coverage, high attenuation of cable or wire facilities. It can handle numerous communications channels (Akos). Hence, they have capacity to span long terrestrial distances. With satellite communications, applications no longer need the repeater stations, previously vital for troposcatter links or line-of-sight. SCS have ability to withstand sophisticated techniques aimed at anti-jam modulations. Additionally, the systems flexibility overwhelms the application of terrestrial systems as they can easily be loaded into cargo planes, and transported to remote areas. Trained personnel and crew can mount the terminals in a very short time.

Cons

Satellite communications endure limitations that encompass the technical attributes of the orbital parameters and satellites.  Notably, the active SCS through the downlink receives inadequate power owing to weight restrictions mounted on the satellite. Resultantly, the system relies on the inefficient solar cell as the only feasible energy source, generating a mere 50watts, which has low rf power. Akos also describes that the up-Link receiver sensitivity predispose the system to excessive signal loss at the satellite. The antenna only captures a slight amount of the transmitted signal power. Lastly, the location of earth stations (terminals) and the satellite orbit influences the availability of a satellite and its capacity to function as a relay station for a pair of ground terminals. It implies that the satellite is visible to both stations. Elliptical orbits also influence this availability (Zone of Mutual Visibility) (Akos).

VSAT System

The Very Small Aperture Terminal system brings communications’ redress into marine management. The system helps to address the increasing demand for stronger bandwidth at sea. It avails a broadband communications at sea that is quite comparable to the transmission data rate (1 Mbps), which was conventionally used while on shore (Gou and Cui). It delivers the cost-effective means to maritime broadband communications, allowing fleet management to enhance emailing, internet services, etc. Further, the system offers land-based broadband communications environment to onboard vessels. Communication can be used through a broad array of applications for the operational and social reasons. Extensive data users e.g. cruise staff applications may effectively use VSAT system.

SAT TV System

Designers of this system aim at addressing the need for maritime professionals. It draws from rugged materials and sophisticated technology, to help it withstand the harshest environments.  SAT TV installations require that a compact antenna should be enacted onto the vessel and connected to internal units via IP routing and Ethernet hub settings. With SAT TV, every location on the sea can access voice and high-speed data communications, fast tracking technology and satellite acquisition with the SAT TV system (Wang). The INMARSAT effectively provides the SAT TV services.

Fleet Broadband Technology

Fleet broadband technology remains the most modest technology enhanced on sea fleet and vessels. It has the top-of-the-range capacity to maximize operations. It has shown reliability, even with the worst environmental conditions. Indeed, the system offers up to 432kbps for users and applications while on the sea and offshore (Akos). The system provides services like the standard IP data used with telephony, emailing, internet services, weather reporting, voice services, ECDIS vessel routing and managing shipment.

Satellite AIS (S-AIS)

S-AIS is a terrestrial-based Automatic Identification System (AIS). It offers mere shore-based coverage to monitor and track sea vessels. The Satellite AIS (S-AIS) effectively enhances maritime safety and security at sea, ports and offshore. The SOLAS guidelines regulate the application of S-AIS (Weintrit).

Apparently, ORBCOMM and GMDSS have elicited prospective applicability. The new technology aims at overwhelming the challenges faced by the AIS (S-AIS). They have distinctive satellite-based AIS data services that facilitate cost-effective monitoring of vessels to location precision and maritime safety. Currently, the Raymarine 33STV is on market demand. It is ultra-compact for sea vessels, and has capacity to monitor a range of DVB compatible DSS (DirectTV) satellites using the S-AIS.

Conclusion

The current study explored the satellite communications systems, described the overview of the satellite hardware on board a ship, the external equipment signals/information required for a ship’s satellite system to realize their functionality. It also highlighted the underlying pros and cons over the applicability of satellite communications systems as compared to terrestrial systems.  It is worth noting that satellite technology expressively impacts the marine radio and radar maintenance. Importantly, there exist an immense potential for satellite technology to help address issues in the contemporary marine sector.