scholarly journals DESAIN AWAL SISTEM SATELIT TELEKOMUNIKASI PERTAHANAN INDONESIA (PRELIMINARY DESIGN OF INDONESIAN MILITARY TELECOMUNICATION SATELLITE)

2017 ◽  
Vol 14 (2) ◽  
pp. 113
Author(s):  
Robertus Heru Triharjanto ◽  
Luqman Faturrohim ◽  
Ridanto Eko Poetro ◽  
Hari Muhammad
Keyword(s):  
Mobile Communications ◽  
Data Communication ◽  
Satellite System ◽  
Preliminary Design ◽  
Concept Design ◽  
Power Capacity ◽  
Satellite Mission ◽  
Design Constraints ◽  
Telecommunication Satellite ◽  
L Band

As the biggest archipelago in the world, Indonesia really needs satellite system to support its defense and security. Based on that, this research aims to produce the preliminary design of telecommunication satellite system needed for defense and security campaign in Indonesia. Per best practice in aerospace engineering, the satellite preliminary design is preceded by a satellite concept design. In the concept design process, the users’ requirements, in this case, the Indonesian military, are studied, and comparative study is done for military telecommunication satellite solution that other countries used. The results are the satellite mission requirements, and design constraints to be used in the satellite preliminary design. The preliminary design shows that 2 kinds of satellites are needed to accommodate the mission requirements. i.e. L-band for mobile communications and C-band for fixed-high-datarate communication. Based on the available slots and the design constraints, the L-band satellite will be placed at 123 E. The satellite will weigh 2200 kg, has a power capacity of 1 kW, and can provide data communication with the speed of 512 kbps. The C-band satellite, that will be placed at 118 E, will weigh 2400 kg, has power capacity of 1.5 kW, and can provide data communication with the speed of 10 Mbps. Both satellites can operate for 10 years. Abstrak:Indonesia sebagai negara kepulauan terluas di dunia amat memerlukan sistem satelit untuk menunjang sistem pertahanan dan keamanannya. Atas motivasi tersebut penelitian ini bertujuan untuk membuat desain awal sistem satelit telekomunikasi yang diperlukan untuk pertahanan dan keamanan di Indonesia. Sesuai kaidah perancangan satelit, proses desain awal didahului dengan pembuatan desain konsep. Pada proses desain konsep dilakukan pendefinisikan kebutuhan penggguna, dalam hal ini pihak TNI dan Kementerian Pertahanan, dan studi banding atas solusi satelit telekomunikasi pertahanan di mancanegara. Hasil desain konsep adalah persyaratan misi dan batasan desain, yang harus diacu pada tahap desain awal satelit. Desain awal, diantaranya, menetapkan desain muatan sehingga dapat mengakomodasikan misi, serta ukuran dan berat dari bus satelit, agar bisa memenuhi kebutuhan muatan. Hasil menunjukkan bahwa pemenuhan desain konsep hanya bisa dilakukan dengan desain awal 2 tipe satelit telekomunikasi, yakni dengan frekuensi L-band untuk komunikasi bergerak, dan frekuensi C-band untuk komunikasi statis dengan kecepatan tinggi. Sesuai ketersediaan slot yang menjadi batasan desain, satelit L-band akan ditempatkan di 123 BT. Satelit tersebut mempunyai berat 2200 kg, konsumsi daya 1 kW, dan dapat melayani komunikasi data dengan kecepatan 512 kbps. Satelit C-band, yang akan berada di 118 BT, mempunyai berat 2400 kg, kapasitas daya 1.5 kW, dan dapat melayani komunikasi data dengan kecepatan 10 Mbps. Kedua satelit tersebut dapat beroperasi selama 10 tahun.

scholarly journals From GPS Receiver to GNSS Reflectometry Payload Development for the Triton Satellite Mission

2021 ◽  
Vol 13 (5) ◽  
pp. 999
Author(s):  
Yung-Fu Tsai ◽  
Wen-Hao Yeh ◽  
Jyh-Ching Juang ◽  
Dian-Syuan Yang ◽  
Chen-Tsung Lin
Keyword(s):  
Satellite System ◽  
Low Earth Orbit ◽  
Export Control ◽  
Navigation Systems ◽  
Gps Receiver ◽  
Design Development ◽  
Satellite Mission ◽  
Essential Components ◽  
Gnss Reflectometry ◽  
Global Navigation Satellite

The global positioning system (GPS) receiver has been one of the most important navigation systems for more than two decades. Although the GPS system was originally designed for near-Earth navigation, currently it is widely used in highly dynamic environments (such as low Earth orbit (LEO)). A space-capable GPS receiver (GPSR) is capable of providing timing and navigation information for spacecraft to determine the orbit and synchronize the onboard timing; therefore, it is one of the essential components of modern spacecraft. However, a space-grade GPSR is technology-sensitive and under export control. In order to overcome export control, the National Space Organization (NSPO) in Taiwan completed the development of a self-reliant space-grade GPSR in 2014. The NSPO GPSR, built in-house, has passed its qualification tests and is ready to fly onboard the Triton satellite. In addition to providing navigation, the GPS/global navigation satellite system (GNSS) is facilitated to many remote sensing missions, such as GNSS radio occultation (GNSS-RO) and GNSS reflectometry (GNSS-R). Based on the design of the NSPO GPSR, the NSPO is actively engaged in the development of the Triton program (a GNSS reflectometry mission). In a GNSS-R mission, the reflected signals are processed to form delay Doppler maps (DDMs) so that various properties (including ocean surface roughness, vegetation, soil moisture, and so on) can be retrieved. This paper describes not only the development of the NSPO GPSR but also the design, development, and special features of the Triton’s GNSS-R mission. Moreover, in order to verify the NSPO GNSS-R receiver, ground/flight tests are deemed essential. Then, data analyses of the airborne GNSS-R tests are presented in this paper.

Comparison of Piston Concept Design Solutions for Composite Cycle Engines Part II: Design Considerations

2021 ◽  
Author(s):  
Dimitrios Chatzianagnostou ◽  
Stephan Staudacher
Keyword(s):  
Gas Turbine ◽  
Design Space ◽  
Piston Compressor ◽  
Design System ◽  
Surface Load ◽  
Preliminary Design ◽  
Concept Design ◽  
Piston Engine ◽  
Engine Design ◽  
Cylinder Piston

Abstract Hecto pressure composite cycle engines with piston engines and piston compressors are potential alternatives to advanced gas turbine engines. The nondimensional groups limiting their design have been introduced and generally discussed in Part I [1]. Further discussion shows, that the ratio of effective power to piston surface characterizes the piston thermal surface load capability. The piston design and the piston cooling technology level limit its range of values. Reynolds number and the required ratio of advective to diffusive material transport limit the stroke-to-bore ratio. Torsional frequency sets a limit to crankshaft length and hence cylinder number. A rule based preliminary design system for composite cycle engines is presented. Its piston engine design part is validated against data of existing piston engines. It is used to explore the design space of piston components. The piston engine design space is limited by mechanical feasibility and the crankshaft overlap resulting in a minimum stroke-to-bore ratio. An empirical limitation on stroke-to-bore ratio is based on existing piston engine designs. It limits the design space further. Piston compressor design does not limit the piston engine design but is strongly linked to it. The preliminary design system is applied to a composite cycle engines of 22MW take-off shaft power, flying a 1000km mission. It features three 12-cylinder piston engines and three 20-cylinder piston compressors. Its specific fuel consumption and mission fuel burn are compared to an intercooled gas turbine with pressure gain combustion of similar technology readiness.

scholarly journals Steel-Concrete Composite Bridges: Design, Life Cycle Assessment, Maintenance, and Decision-Making

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
D. Martínez-Muñoz ◽  
J. V. Martí ◽  
V. Yepes
Keyword(s):  
Decision Making ◽  
Life Cycle ◽  
Impact Assessment ◽  
Concrete Bridges ◽  
Future Research ◽  
Preliminary Design ◽  
Design Constraints ◽  
Sustainable Solutions ◽  
Design Life ◽  
Composite Bridges

Steel-concrete composite bridges are used as an alternative to concrete bridges because of their ability to adapt their geometry to design constraints and the possibility of reusing some of the materials in the structure. In this review, we report the research carried out on the design, behavior, optimization, construction processes, maintenance, impact assessment, and decision-making techniques of composite bridges in order to arrive at a complete design approach. In addition to a qualitative analysis, a multivariate analysis is used to identify knowledge gaps related to bridge design and to detect trends in research. An additional objective is to make visible the gaps in the sustainable design of composite steel-concrete bridges, which allows us to focus on future research studies. The results of this work show how researchers have concentrated their studies on the preliminary design of bridges with a mainly economic approach, while at a global level, concern is directed towards the search for sustainable solutions. It is found that life cycle impact assessment and decision-making strategies allow bridge managers to improve decision-making, particularly at the end of the life cycle of composite bridges.

scholarly journals Derivation of global ionospheric Sporadic E critical frequency ( f o Es) data from the amplitude variations in GPS/GNSS radio occultations

2020 ◽  
Vol 7 (7) ◽  
pp. 200320 ◽  
Author(s):  
Bingkun Yu ◽  
Christopher J. Scott ◽  
Xianghui Xue ◽  
Xinan Yue ◽  
Xiankang Dou
Keyword(s):  
Critical Frequency ◽  
Detection Threshold ◽  
Low Frequency ◽  
Satellite System ◽  
Global Scale ◽  
Satellite Mission ◽  
Frequency Detection ◽  
Sporadic E ◽  
The Uk ◽  
Global Navigation Satellite

The ionospheric sporadic E (Es) layer has a significant impact on the global positioning system (GPS)/global navigation satellite system (GNSS) signals. These influences on the GPS/GNSS signals can also be used to study the occurrence and characteristics of the Es layer on a global scale. In this paper, 5.8 million radio occultation (RO) profiles from the FORMOSAT-3/COSMIC satellite mission and ground-based observations of Es layers recorded by 25 ionospheric monitoring stations and held at the UK Solar System Data Centre at the Rutherford Appleton Laboratory and the Chinese Meridian Project were used to derive the hourly Es critical frequency ( f o Es) data. The global distribution of f o Es with a high spatial resolution shows a strong seasonal variation in f o Es with a summer maximum exceeding 4.0 MHz and a winter minimum between 2.0 and 2.5 MHz. The GPS/GNSS RO technique is an important tool that can provide global estimates of Es layers, augmenting the limited coverage and low-frequency detection threshold of ground-based instruments. Attention should be paid to small f o Es values from ionosondes near the instrumental detection limits corresponding to minimum frequencies in the range 1.28–1.60 MHz.

A Design Approach for Storage Spar Buoy Platforms in the Concept and Preliminary Design Phases

2002 ◽  
Author(s):  
Richard David Schachter ◽  
Carlos Gomes Jordani ◽  
Antonio Carlos Fernandes
Keyword(s):  
Weight Control ◽  
Method Development ◽  
Design Method ◽  
Design Approach ◽  
Preliminary Design ◽  
Concept Design ◽  
Structural Topology ◽  
General Arrangement ◽  
Control Stability ◽  
Definition Of

The objective of this work is to present a design approach for the Concept and Preliminary Design Phases of Storage SPAR Buoy Platforms and to describe how the design method was developed. The influence of a VIV porosity device on the design is taken into consideration. The inherent advantages of Spar concepts for Petrobras’ applications for 1250 m, are discussed and compared with other concepts. The Spar concept was chosen. The design method development was carried out by means of a brainstorming process, using sketches and the creation of interactive flowcharts of the design processes (similar to a design spiral) comprising the main design factors, their sequencing and interrelations, for both the Concept and Preliminary Design phases. The intent of the design approach is to provide the designer with means to define quick and efficiently the optimal hull dimensions for a pre-established scenario. For the Concept Design, the method includes the definition of the main dimensions, the Wellbay, the structural topology and compartmentation, general arrangement, weight control, stability (intact, damaged and flooded), motions and mooring. A discussion on the influence of the VIV porosity device on the dimensioning and mooring of the Spar Platform is provided. A concept design application example is presented.

Mobile communications via satellite in the 1990s

1984 ◽  
Vol 312 (1519) ◽  
pp. 41-54
Keyword(s):  
Mobile Communications ◽  
Current System ◽  
Satellite System ◽  
Data Communications ◽  
Polar Orbiting Satellite ◽  
Offshore Industry ◽  
Maritime Community

The world’s only satellite organization providing mobile communications on a commercial basis is the International Maritime Satellite Organization (Inmarsat). This paper reviews the origins of the organization and the needs of the shipping and offshore industry that led to its formation. The current system and its operations are described. The success achieved so far by Inmarsat in providing the satellite capacity for telephone, telex, facsimile and data communications to the maritime community makes it apparent that the system could also be used to provide capacity to the aeronautical community. Also, studies are now being made on future configurations of the system in which it may be possible to integrate a polar-orbiting satellite system, such as Sarsat-Cospas. Inmarsat is proceeding with the procurement of a new series of satellites that would come into operation from 1988. This paper reviews the enhanced capabilities that these new satellites will provide in the context of the requirements for mobile communications via satellite in the next decade.

Concept Design of 15m class Light Weight Deployable Antenna Reflector for L-band SAR Application

2016 ◽  
Author(s):  
Kazuyuki Nakamura ◽  
Nobuko Nakamura ◽  
Satoru Ozawa ◽  
Akihisa Uematsu ◽  
Hirokazu Hoshino ◽  
...  
Keyword(s):  
Light Weight ◽  
Concept Design ◽  
L Band ◽  
Antenna Reflector
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