Maritime Satellite Communications Research Articles

СОВРЕМЕННЫЙ СРЕЗ ЭКОНОМИЧЕСКИХ ПРОБЛЕМ ИННОВАЦИОННОГО РАЗВИТИЯ КОСМИЧЕСКОЙ ПРОМЫШЛЕННОСТИ

The article examines the global economic problems that arise when solving specific tasks in the context of high-tech (innovative) development of the space industry, requiring joint efforts of countries and financial support from international organizations. The role of various international organizations, such as the International Convention on Civil Aviation (ICAO), the International Organization for Maritime Satellite Communications, and the World Health Organization (WHO) in solving these problems is being evaluated. The importance of non-governmental organizations in the development of the space industry is noted. International cooperation and the unification of the efforts of the entire world community are key to progress in space exploration and the implementation of programs in this area.

Transforming Linear to Circular Polarization on Horn Antennas by Using Multiple-Layer Frequency Selective Surfaces.

This article presents a technique for transforming the polarization of a pyramidal horn antenna by adding multiple layers of frequency-selective surfaces in front of the aperture, in order to rotate the direction of the electric field. Thus, two orthogonal components with the same magnitude, phase-shifted by 90°, are generated. Each frequency-selective surface consists of skewed λ/2 dipoles. Compared to other similar structures, our antenna system combines the field radiated from the horn aperture with the field scattered by parallel frequency-selective surface structures spaced on the same principle as that for designing a Yagi-Uda antenna array. The proposed horn antenna with multiple frequency-selective surfaces can be used as a feed element for a parabolic reflector antenna for maritime satellite communication systems in the X-band or in the lower part of the Ku band, or as part of a sensor for finding the direction of arrival of a wave, in order to orientate an antenna system. The concept was successfully validated on the basis of simulation and measurements. The proposed technique provides a close to unit axial ratio together with a 3 dB increase in gain compared to the conventional horn antenna, at low manufacturing costs.

Research and Development of Mobile Marine Satellite Antenna System in Vietnam

Abstract: A second version of the mobile marine satellite communication signal receiver station has been designed, manufactured, assembled and tested using domestically engineered mechanical modules, commercial and low-cost integrated sensors, motors and drivers. The operating mechanical components have been developed in the form of independently operating modules with handling ease and high sensitivity at a “clearance” in the order of 10µm. The sensors are of high and firm integration and good noise compensation facilities. The appropriately developed automatic control algorithms and software allow efficient and safe searching and following the broadcasting satellite of the antenna device installed on a marine transport boat. Compared to the previous version, this new development has more optimal dimensions, is easier and more flexible to start up and operate with operating parameters of pitch: 15-80° (±0.5°), yaw: of 0-360° (±0.25°), and polarization angle of 0-360° (±0.5°). The antenna turn rates are of ~12°/s and 12°/s2. All the components of the complete system are water- and weather proof and packaged to ensure safe operation in marine conditions. Running tests have been successfully taken in real sunny weather conditions on a sea boat speeding at 30 km/h with a wind velocity up to 19 km/h. The article concludes that domestically engineered, the device is more financially efficient than imported counterpart equipments as well as promising in terms of technology transfer to mass production by domestic businesses.
 Keywords: Satellite receiver antenna, marine satellite antenna, antenna angle controller, sensors.
 References
 [1] B. Schneiderman, Executive Roundtable on Maritime and Energy Markets, Satellite Executive Briefing, Vol. 11 No. 8 (2018) 9.[2] L.M. Bradbury, D. Diaconu, S. Molgat Laurin, A.M. Beattie, C. Ma, I.S. Spydevold, H.C. Haugli, R.E. Zee, J. Harr, F. Udnæs, NorSat-2: Enabling advanced maritime communication with VDES, Acta Astronautica, 156 (2019) 44-50[3] Y.J. Song, P.S. Kim, D.G. Oh, et al., Development of mobile broadband interactive satellite access system for Ku/Ka band, International journal of satellite communications and networking, 24 (2007) 101-117. [4] Y.J. Song, M.S. Shin, B.H. Kim, et al, Development of mobile broadband satellite access system for Ka/Ku-band satellite communications, Ieice transactions on communications, e87b (2004) 2152-2161.[5] S. Pekowsky, G Pousset, Y. Levy, MobileTV Receiver Technology with special emphasis on DVB-SH, international journal of satellite communications and networking, 27 (2009) 275-293.[6] http://www.raysat.com/mobile_satellite_television_antennas.[7] Nguyễn Hữu Đức, Bùi Đình Tú, Nguyễn Thị Ngọc, Đồng Quốc Việt, Đỗ Thị Hương Giang, Trạm thu di động thông tin vệ tinh dựa trên sensơ từ trường độ nhạy cao ứng dụng trên tàu biển, Tuyển tập Hội thảo khoa học Công nghệ vũ trụ và ứng dụng, Hà Nội, 2014.[8] M. Geissler, F. Woetzel, M.Böttcher, S. Korthoff, A.Lauer, M.Eube, R. Gieron, Roman, Innovative phased array antenna for maritime satellite communications, EuCAP 2009. 3rd European Conference on Antennas and Propagation, (2009)735-739[9] http://www.orbit-cs.com/modular-maritime-communications-system[10] https://www.digisat.org/maritime-satcom-vsat[11] https://paracomm.co.uk/[12] https://www.intelliantech.com/?lang=en.[13] Nguyễn Hữu Đức, Báo cáo tổng kết đề tài đề tài “Thiết kế và chế tạo trạm thu di động thông tin vệ tinh dựa trên sensơ từ trường độ nhạy cao ứng dụng trên tàu biển”, Chương trình KH&CN quốc gia về Công nghệ vũ trụ giai đoạn 2013-2015, Hà Nội, 2016. 

The development of maritime satellite communications since 1976

This research note runs on from the note published by the author in this issue of IJMH. It describes the development of Maritime Satellite Communications (MSC) systems for all type of commercial and military seagoing and inland sailing vessels since the 1970s. The main functions of MSC systems are to enhance the safety and security of seagoing vessels, mainly by alerting and Search and Rescue (SAR) operations, and to improve communication facilities between ships and shore infrastructures. The first MSC Geostationary Earth Orbit (GEO) system for military applications was developed in 1976 by the US and other partners, which soon became available for merchant ships. The next step was the development of an independent and international MSC system. To overcome the disadvantages associated with HF/VHF radio propagation and frequency congestions, the International Maritime Organization (IMO) in 1979 encouraged all member nations to establish Maritime Mobile Satellite Communication (MMSC) systems. At the behest of IMO and United Nations (UN) Maritime Body, and pursuant to the Convention on the International Maritime Satellite Organization, signed by 28 countries in 1976, the International Maritime Satellite (INMARSAT) Organization was founded.

From wooden pigeons to Telstar: Precursors of modern maritime satellite communications

This research note identifies the precursors of the satellite communications systems that are basic to modern shipping activity. It comprises two main sections: first, an outline is provided of the evolution of communication technology from the earliest experiments in rockets in the fifth century BC to the 1950s; second, there is a discussion of the significant development of satellite technology in the 1960s and 1970s.

Sea Surface Reflection and Power Attenuation Analysis of Radio Wave in UHF Satellite Communications

Ultra High Frequency (UHF) band is increasingly widely used in military maritime satellite communications due to its good communication performance. Electromagnetic wave emitted by satellite is reflected when reaching the sea surface, and multipath fading is very serious which causes interference on the received signal, especially when satellite elevation angle is low. In this paper, the UHF band multipath effects of sea surface were studied following the general principles of modeling in multipath effects. The numerical simulation was made based on Rayleigh criterion and the judgment basis was obtained which determines whether the specula reflected component or diffuse reflected component dominates in the reflected wave, and then the reflection coefficient of sea surface in different polarization modes were calculated. Finally, the power attenuation of reflected wave relative to direct wave for different wind speeds were simulated and analyzed. Numerical simulation results show that the greater the wind speed is, the greater the power attenuation of reflected wave will become and the more serious multipath fading will be. In addition, diffuse reflection attenuation is more serious than specular reflection. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.4787

Broadband Circularly Polarized Microstrip Antenna with Coplanar Parasitic Ring Slot Patch for L-Band Satellite System Application

A novel capacitive-coupled probe-fed circularly polarized (CP) microstrip antenna with coplanar parasitic ring slot patch has been proposed for the International Maritime Satellite (INMARSAT) and the Global Positioning System (GPS) applications. The key feature of the design is employing capacitive-coupled four-probe feeds to increase impedance bandwidth and adopting coplanar parasitic ring slot patch to enhance CP bandwidth. The feed network is compact and neat using only T-junction power dividers and phase shifters with shunted short-circuited microstrip stubs for lightning protection. The characteristics of the proposed antenna have been studied by simulation and experiment. The final antenna can produce a ${ S}_{11} 14 dB impedance bandwidth of nearly 27%, a 3-dB axial-ratio bandwidth of nearly 16%, and a gain of higher than 8 dB in the whole maritime satellite communication work band.

Multipath Effect Analysis of Sea Surface in Maritime Satellite Communications

Ultra High Frequency (UHF) band is increasingly widely used in military maritime satellite communications due to its good communication performance. When the electromagnetic wave reaches the sea surface, it is reflected. The reflected wave and direct wave enter the receiver in the form of a superimposed vector, which will inevitably produces multipath fading at the receiving end. This paper followed the general principles of modeling in multipath effects, and the UHF band multipath effects of sea surface were studied. The judgment basis was obtained which determines whether the specula reflected wave dominates in the reflected wave based on Rayleigh criterion, and then the reflection coefficient of sea surface were calculated. Finally, the power attenuation of reflected wave relative to direct wave for different wind speeds were simulated and analyzed.

Dual-mode quadruple ridge waveguide feed for broadband satellite communications

A novel and compact dual-channel multimode waveguide system is described, which permits two distinct frequency channels, such as C-band and Ku-band, to be propagated simultaneously. The system is also dual-moded at both the lower and the upper frequencies, thus enabling polarisation switching between orthogonal linear signals or between left and right hand circularly polarised transmissions. The development is primarily motivated by the desire to provide extended range and global coverage, for a maritime satellite communications system, employing a single antenna platform.

Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications

In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA) employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC) between ships and Coast Earth Station (CES) via Geostationary Earth Orbit (GEO) or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users can be solved by using MA technique, such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Space Division Multiple Access (SDMA) and Random (Packet) Division Multiple Access (RDMA). Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MA to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.

Improved Low-Profile Helical Antenna Design for INMARSAT Applications

A new low-profile variable pitch angle cylindrical helical antenna employing a copper strip as impedance transformer is proposed in this paper. Under the circumstance of a limited antenna height, the circular polarization performance of the antenna has been enhanced by changing the pitch angle and the input impedance matching has been improved by adjusting the copper strip match stub. The design method of the proposed antenna is given. The optimal antenna structure for INMARSAT application has been fabricated and measured. The measured results show that in the whole maritime satellite communication work band the VSWR is less than 1.2, its antenna gain is higher than 9 dBi, and the axial ratio is lower than 2.5 dB. The experimental results have a good agreement with the simulations. The proposed antenna is compact and easy tuning. It provides a promising antenna element for maritime satellite communication applications.

An L-strip fed stacked patch antenna for maritime satellite communications

A practical antenna has been designed and developed for INMARSAT mobile satellite communications. The design uses low cost materials such as foam and copper foil to create a stacked microstrip antenna array. Several techniques were adopted to enhance the impedance bandwidth and axial ratio bandwidth. The final design parameters were optimized by EM simulation. Finally, the L-strip fed six-element stacked microstrip antenna array was constructed and tested. Simulated and measured results show that in the whole INMARSAT work band, the VSWR of the antenna is less than 1.6, its antenna gain is higher than 15dB and wide-angle axial ratio (AR) 3dB is more than 21°. The antenna has been successfully used with a HNS 9201 terminal.

Simple, small antenna terminal for maritime satellite communications

A simple printed antenna that can be utilised for maritime satellite communications is presented. The antenna is based on a dual linearly polarised proximity coupled microstrip antenna on an extended hemispherical dielectric lens. The resulting small printed antenna is impedance matched over both the transmit (14.0-14.5 GHz) and receive (12.25-12.75 GHz) bands and has a gain of 21 and 20 dBi, respectively, over these frequency ranges.

Antenna Stabilizing Control System Employing Strapdown 2 Axis Azimuth/Elevation Method for Maritime Satellite Communications.

A two-axis antenna-stabilizing control device which does not need a level sensor has been developed. The control incorporates a zero-servo method which zeros the two gyro outputs by rotating an antenna both with an azimuth motor and an elevation-servo motor. This method simplifies control. In addition, the mounts can be miniaturized and made light-weight. By using three accelerometers fitted directly on to the antenna, it is possible to calculate an elevation of the antenna and an inclination correction value around the azimuth axis. In experiments using a Scorsby Table, it was confirmed that pointing errors were less than a few degrees.

Sea surface scattering calculations in maritime satellite communications

A method extending the Kirchhoff classical approach for mobile maritime satellite communications is presented. Carrier to specular and carrier to multipath ratios are evaluated from scattering by the rough sea surface calculations using the boundary perturbation method. They are compared with experimental results and with other experimental models. The results illustrate the limited effects of the wind speed and significant wave height, the important dependence on the elevation angle and the very large effects of the ship motions. >

Mobile satellite communications - current status of maritime systems

Any review of the development of maritime satellite communications is essentially the history of Inmarsat and its predecessor system, Marisat. With perhaps two qualifications, one might extend the definition to mobile satellite communications generally. In the land mobile satellite communications domain two companies, Geostar and Qualcomm, have also made their mark. Geostar was recently declared bankrupt but Qualcomm continues to go from strength to strength.We are frequently asked ‘what is Inmarsat?'. The term Inmarsat is generally used, and used herein, to mean the permanent staff (the Directorate), Land Earth Station (LES) operators, manufacturers and value-added service providers who offer mobile satellite communications products or services via the satellites and other infrastructure which makes up the Inmarsat system. It is, essentially, a partnership but within it there is also internal competition. LES operators compete in the provision of telecommunications services (quality is consistently high, but they each decide what services to offer and at what tariffs). Manufacturers compete to secure market dominance and profitabilty for their products. Not all will be equally successful. More than anything, Inmarsat is a global partnership dedicated to meeting mankind's need to communicate while on the move. It aims to do so cost-effectively and using satellites.

Digital signal transmission characteristics in maritime satellite communications

AbstractDigital signal transmission will be used widely in the future mobile satellite communication system to realize an efficient operation of the system and to provide diversified service. In the global mobile satellite communication system, such as maritime and aeronautical communications where a wide service area is required, the influence of the multipath fading due to sea surface reflection at low elevation angle on the digital signal transmission characteristics is a particular problem.This paper deals with the application of the digital transmission system to the INMARSAT (International Maritime Satellite Organization), which provides the international maritime satellite communication service. The configuration of the digital maritime satellite communication system, which was developed for experimental purpose, as well as the result of analysis of the digital signal transmission characteristics in the low‐elevation maritime communication experiment, are presented.Based on the result of field experiment, the required power margin for low elevation operation is evaluated, and a means to secure a high‐quality communication is discussed. Thus, a guideline is presented for the digital transmission system design in mobile satellite communication, affected by the sea surface multipath fading.

Fan rib type deployable mesh antenna for satellite use

This paper presents a design for satellite-borne 3.5 m deployable mesh reflector for the Japanese maritime satellite communication system. The features of this antenna are compactness, lightness and high deployment reliability. The measured characteristics for the engineering model are also given.

Reduction method of pointing error of El/AZ mount for maritime satellite communications

AbstractDevelopment of small marine antennas has a very important role in the maritime satellite communications with small ships, especially for Japan which has a relatively large number of small fisherboats. As the satellites become larger in size in the future, the shipborne antennas will tend to become smaller. We propose a control method for the antenna mount against ship motions to assure pointing the communication satellite. The two‐axis EL/AZ mount has a light weight and a small size, which gives rise to a large pointing error when the satellite is near the zenith or when the AZ axis is near the control limit for avoiding twisting the cables. We have developed an algorithm to reduce the pointing errors within the pitching amplitudes of the ship. The principle and the experimental results of this system are described.

Fade duration statistics of<tex>L</tex>-band multipath fading due to sea surface reflection

Multipath fading in maritime satellite communications may be caused by a combination of sea surface reflection and tropospheric effects such as ducting and scintillations. Among them, multipath fading due to sea reflection is dominant when receiving satellite signals by use of a wide beamwidth antenna. In this paper, fade duration statistics of multipath fading due to sea surface reflection are analyzed using the data obtained by on-board experiments on the L -band (1.54 GHz). Results indicate that the mean value of fade duration and fade occurrence interval can be determined from the fading power spectrum with fairly good precision, and that the probability density function for a given time percentage, ranging from 50 to 99 percent, approximates well with the exponential distribution. Finally, based on the results obtained, a simple method for estimating the mean values of fade duration and fade occurrence interval is presented.