Satellite Research Papers - Academia.edu (original) (raw)

Satellite data are underutilized in many branches of operational oceanography. Users outside of the satellite community often encounter difficulty in discovering the types of satellite measurements that are available, and determining... more

Satellite data are underutilized in many branches of operational oceanography. Users outside of the satellite community often encounter difficulty in discovering the types of satellite measurements that are available, and determining which satellite products are best for operational activities. In addition, the large choice of satellite data providers, each with their own data access protocols and formats, can make data access challenging. The mission of the NOAA CoastWatch Program is to make ocean satellite data easier to access and to apply to operational uses. As part of this mission, the West Coast Node of CoastWatch developed the NOAA Ocean Satellite Course, which introduces scientists and resource managers to ocean satellite products, and provides them tools to facilitate data access when using common analysis software. These tools leverage the data services provided by ERDDAP, a data distribution system designed to make data access easier via a graphical user interface and vi...

TUSAT is a prospective Turkish Communication Satellite designed for providing mainly data communication and broadcasting services through Ku-Band and C-Band channels. Thermal control is a vital issue in satellite design process.... more

TUSAT is a prospective Turkish Communication Satellite designed for providing mainly data communication and broadcasting services through Ku-Band and C-Band channels. Thermal control is a vital issue in satellite design process. Therefore, all satellite subsystems and equipments should be maintained in the desired temperature range from launch to end of maneuvering life. The main function of the thermal control is to keep the equipments and the satellite structures in a given temperature range for various phases and operating modes of spacecraft during its lifetime. This paper describes the thermal control design which uses passive and active thermal control concepts. The active thermal control is based on heaters regulated by software via thermistors. Alternatively passive thermal control composes of heat pipes, multilayer insulation (MLI) blankets, radiators, paints and surface finishes maintaining temperature level of the overall carrier components within an acceptable value. The...

This paper presents a revision of the status of current standards dedicated to mobile services systems, using combined satellite and terrestrial components transmission. The objective is the analysis of a hybrid system compatible with... more

This paper presents a revision of the status of current standards dedicated to mobile services systems, using combined satellite and terrestrial components transmission. The objective is the analysis of a hybrid system compatible with DVB-SH and SDR technologies, taking as a basis the work and studies performed in MOVISAT project.

This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator for a broadband Ka-band multi-beam satellite system exploiting the new DVB-S2 standard with adaptive coding and... more

This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator for a broadband Ka-band multi-beam satellite system exploiting the new DVB-S2 standard with adaptive coding and modulation (ACM). This complete demonstrator allows in-depth verification and optimization of the ACM techniques applied to large satellite broadband networks, as well as complementing and confirming the more theoretical or simulation-based findings published so far. It is demonstrated that few ACM configurations (in terms of modulation and coding) are able to efficiently cope with a typical Ka-band multi-beam satellite system with negligible capacity loss. It is also demonstrated that the exploitation of ACM thresholds with hysteresis represents the most reliable way to adapt the physical layer configuration to the spatial and time variability of the channel conditions while avoiding too many physical layer configuration changes. Simple ACM adaptation techniques, readily implementable over large-scale networks, are shown to perform very well, fulfilling the target packet-error rate requirements even in the presence of deep fading conditions. The impact of carrier phase noise and satellite nonlinearity has also been measured. Copyright © 2009 John Wiley & Sons, Ltd.

Spread spectrum code-division multiple-access (CDMA) systems are currently considered as very attractive alternatives to the more familiar FDMA and TDMA systems, especially in the presence of multipath fading and external interference.... more

Spread spectrum code-division multiple-access (CDMA) systems are currently considered as very attractive alternatives to the more familiar FDMA and TDMA systems, especially in the presence of multipath fading and external interference. The problem of code selection in a CDMA system with a finite number of users is addressed in this paper. A simple and efficient method for the selection of finite code sets with relatively high processing gain from Gold and Kasami code families of relatively large sizes is described in detail. Selected code sets of period 63 are presented along with their overall average performance parameters for different number of users.

MEMS- Micro electro mechanical system. Over the last decade Micro-Electro-Mechanical System (MEMS) have evoked great interest in the scientific and engineering communities. They are formed by integration of electronic and mechanical... more

MEMS- Micro electro mechanical system. Over the last decade Micro-Electro-Mechanical System (MEMS) have evoked great interest in the scientific and engineering communities. They are formed by integration of electronic and mechanical components at micron level. MEMS has gained acceptance as viable products for many commercial and government applications. This paper will give an introduction to these exciting developments of MEMS, the fabrication technology used and application in various fields. Future applications of miniaturized space systems will have special needs on MEMS components. This paper addresses the needs, status and perspectives of the MEMS Technology for miniaturized space system from the perspectives of a spacecraft developer. First, the needs of the future space missions on MEMS components are discussed. Then, the state-of-the-art MEMS technologies are reviewed based upon these needs. Finally, perspectives of space-based MEMS technology will be addressed based on the analysis of both future mission needs and technological trends. Lastly, it concludes saying that MEMS have enough potential to establish a second technological revolution of miniaturization.

While attached to a launch vehicle, satellites are subjected to intense dynamic loads throughout the flight, mainly at lift-off. Part of the vibrations is due to the propulsion system and is transmitted along the launch vehicle to the... more

While attached to a launch vehicle, satellites are subjected to intense dynamic loads throughout the flight, mainly at lift-off. Part of the vibrations is due to the propulsion system and is transmitted along the launch vehicle to the satellite by the payload adaptor fitting (PAF). This paper analyzes the influence of interstage sections and PAF damping on the acceleration response of the payload to launcher longitudinal vibrations. Simple mass-spring-damper models were used, considering the satellite and the stages as rigid bodies connected by springs and dampers. The satellite response to an oscillating force applied on the first stage was evaluated. The results show that when the damping in the inter-stage is high, the launch vehicle moves as a single mass, exciting the satellite as a moving base. If the damping is low, the stages move separately and the satellite will be excited by higher frequency modes. Moreover, lower PAF damping lead to higher accelerations at the second mode frequency and lower accelerations at higher frequencies, while the interstages damping showed little influence on the response around the second mode frequency but a direct effect on higher frequencies. The study was performed by implementing the models in a MATLAB routine.

The VSAT LINK analysis is done for calculating link margin analysis using turbo-c program. This article describes various parameters such as satellite name and transmission and reception parameters and the total link analysis. This... more

The VSAT LINK analysis is done for calculating link margin analysis using turbo-c program. This article describes various parameters such as satellite name and transmission and reception parameters and the total link analysis. This particular VSAT is used in AIRDEFENCE applications. I. INTRODUCTION Link margin calculation is an important for the best use of receiving signals from satellites which are in GEO SYNCHRONOUS orbits. In this paper the TX and RX parameters, and satellite parameters are described and link margin is calculated by hand calculation and also a turbo –c program is executed for calculation of C/N (CARRIER TO NOISE) up link and down link AND Eb/No is also calculated. Also the following is the new VSAT LINK DESIGN CALCULATION FOR L-BAND communication.

This paper presents the main achievements of a project, focused on the design of an integrated system composed of a satellite segment and a MANET to provide telecommunication services in emergency scenarios, in terms of network design,... more

This paper presents the main achievements of a project, focused on the design of an integrated system composed of a satellite segment and a MANET to provide telecommunication services in emergency scenarios, in terms of network design, focusing in particular on the development of the interface between the two systems and showing the results of field trials. Copyright # 2007 John Wiley &

ANALOG BEAM FORMING RADAR FEATURES AND FUNCTIONS - Mechanical Steeing of Reflector of Array Elements - Hardwired - An Example of Analog Beam Forming is a Radar Using Spherical Transmitting Antenna was Surrounded by three Spherical... more

ANALOG BEAM FORMING RADAR FEATURES AND FUNCTIONS
- Mechanical Steeing of Reflector of Array Elements
- Hardwired
- An Example of Analog Beam Forming is a Radar Using Spherical Transmitting Antenna was Surrounded by three Spherical Luneberg
- Lens Receiving Antennas each Covering A One – Third Sector of Space. The TX Antenna was a spherical Phased Array of several Thousand elements with only
- A Fraction of these energized at any one time to form a directive beam. Each energized array elements was driven from a separate power amplifier which obtained its properly phased input signal from a Luneberg – Lens
- Conventional Phased array radars like patriot and agies are the other examples.
Disadvantages:
1. Difficult to setup and expensive
2. Sideleobe levels are high

A constellation of remote sensing small satellite system has been developed for infrastructure monitoring in India by using Synthetic Aperture Radar (SAR) Payload. The low earth orbit (LEO) constellation of the small satellites is... more

A constellation of remote sensing small satellite system has been developed for infrastructure monitoring in India by using Synthetic Aperture Radar (SAR) Payload. The low earth orbit (LEO) constellation of the small satellites is designed in a way, which can cover the entire footprint of India. Since India lies a little above the equatorial region, the orbital parameters are adjusted in a way that inclination of 36 degrees and RAAN varies from 70-130 degrees at a height of 600 km has been considered. A total number of 4 orbital planes are designed in which each orbital plane consisting 3 small satellites with 120-degrees true anomaly separation. Each satellite is capable of taking multiple look images with the minimum resolution of 1 meter per pixel and swath width of 10 km approx. The multiple look images captured by the SAR payload help in continuous infrastructure monitoring of our interested footprint area in India. To support the mission, each small satellite is supplied with ...

Along the Mediterranean coastlines, intense and localized rainfall events are responsible for numerous casualties and several million euros of damage every year. Numerical forecasts of such events are rarely skillful, because they lack... more

Along the Mediterranean coastlines, intense and localized rainfall events are responsible for numerous casualties and several million euros of damage every year. Numerical forecasts of such events are rarely skillful, because they lack information in their initial and boundary conditions at the relevant spatio-temporal scales, namely O(km) and O(h). In this context, the tropospheric delay observations (strongly related to the vertically integrated water vapor content) of the future geosynchronous Hydroterra satellite could provide valuable information at a high spatio-temporal resolution. In this work, Observing System Simulation Experiments (OSSEs) are performed to assess the impact of assimilating this new observation in a cloud-resolving meteorological model, at different grid spacing and temporal frequencies, and with respect to other existent observations. It is found that assimilating the Hydroterra observations at 2.5 km spacing every 3 or 6 h has the largest positive impact ...

Satellite communication systems play an important role in the deployment of a global communication infrastructure, and the increasing demand for frequency bands with large bandwidth availability to satisfy satellite communications... more

Satellite communication systems play an important role in the deployment of a global communication infrastructure, and the increasing demand for frequency bands with large bandwidth availability to satisfy satellite communications applications requirements makes the exploration of higher and higher frequency ranges of a vital importance. In this paper, an introduction to the WAVE (W-Band Analysis and VErification) mission is presented, in addition to a general overview of the payload architecture and the related perspective applications and services. WAVE is a new project proposed for the Italian Space Agency (ASI) to design and develop a W-band geostationary payload with the aim of performing the experimental studies of the W-band channel and possible utilization in satellite data communications.

Lake Chad's challenges are so important that its draining requires thoughtfulness for its long-term refloating. Possessing two major tributaries that are the Logone and Chari, a track would be to value the waters that spread at their... more

Lake Chad's challenges are so important that its draining requires thoughtfulness for its long-term refloating. Possessing two major tributaries that are the Logone and Chari, a track would be to value the waters that spread at their surroundings creating flood plains, this following the meeting of obstacles in their bed. With this in mind, it seems necessary to control the volumes of these waters and justify from this result the need to use them. Satellite images display content rich in information that is very relevant in a hydrological study context; their exploitation may prove to be an effective tool. It is with that perspective that we have proposed a method for estimating water volumes by transforming a satellite image by a method known as interferometric into a usable digital model known under the acronym DEM (Digital elevation model). Then by performing operations for treating depressions and flat areas, generating flow directions and the water flow accumulation network and subsequently determining volumes on specific sections of the Lake Chad tributaries showing wastage by using the DEM.

The development of analytical software for big Earth observation data faces several challenges. Designers need to balance between conflicting factors. Solutions that are efficient for specific hardware architectures can not be used in... more

The development of analytical software for big Earth observation data faces several challenges. Designers need to balance between conflicting factors. Solutions that are efficient for specific hardware architectures can not be used in other environments. Packages that work on generic hardware and open standards will not have the same performance as dedicated solutions. Software that assumes that its users are computer programmers are flexible but may be difficult to learn for a wide audience. This paper describes sits, an open-source R package for satellite image time series analysis using machine learning. To allow experts to use satellite imagery to the fullest extent, sits adopts a time-first, space-later approach. It supports the complete cycle of data analysis for land classification. Its API provides a simple but powerful set of functions. The software works in different cloud computing environments. Satellite image time series are input to machine learning classifiers, and th...

Because their broad spatial and temporal coverage, satellites provide the main source of fire data for Amazonia. A key to the application of these tools for environmental studies is the appropriate interpretation of the data they provide.... more

Because their broad spatial and temporal coverage, satellites provide the main source of fire data for Amazonia. A key to the application of these tools for environmental studies is the appropriate interpretation of the data they provide. To enhance the interpretation of satellite fire data for this region, we collected ground-based data on fires in 2001 and 2002 using a simple and passive method, and statistically related these data to corresponding estimates from AVHRR and MODIS fire products using error matrices. Multiple methods of analyses from simple to complex produced qualitatively similar results. Total accuracies for both fire products were very high (>99%) and dominated by accurate (>99%) non-fire detection. Kappa statistics and fire-detection accuracies were substantially lower, with omission errors higher than commission errors. Results calculated using several different sets of spatial-matching parameters of analysis showed that Kappa was 1– 10.6% for AVHRR, and 0–1.4% for MODIS. User’s accuracy for fires was 0–40% for AVHRR and 3–100% for MODIS. Producer’s
accuracy for fires was 0–8% for AVHRR and 0–1% for MODIS. Statistical evaluations of potential explanatory factors showed that fire size and sampling time were dominant factors for low accuracies. Results from this study indicate that current satellite fire products are providing a limited sample of the fire activity in the region, and that ground-based analyses can substantially contribute to the interpretation of these products.