A functional description of a communications satellite beacon receiver is presented. The system, designed primarily for LES-5/6, is capable of reliable unattended operation, and provides a frequency and time reference for fixed and highly mobile satellite communications terminals. Theoretical and experimental data are given, with particular emphasis on automatic acquisition and tracking of the ...

There is an increasing demand for interconnecting LAN's at high data rates, e.g. remote X-Applications. Due to the lack of B-ISDN before the second decade of the next century, satellite systems are the only alternative. We compare the End-to-End cell delay of a geostationary satellite system with a low earth orbit satellite system by means of simulation. The comparison shows that the use of LEO...

This paper presents the evaluation performance of a hybrid satellite constellation network which provides internet access based Transport Control Protocol (TCP). The evaluated satellite network uses the constellation topology operating on Low Earth Orbit (LEO). The COMMStellationTM satellite system implemented using network simulator 2 (NS-2). In this paper, we modified a congestion window cont...

Abstmct Satellite networks provide global coverage and support a wide range of services. Low Earth Orbit (LEO) satellites provide short round trip delays and are becoming increasingly important. One of the challenges in LEO satellite networks is the development of specialized and efflcient routing algorithms. In this work, a datagram routing algorithm for LEO satellite networks is introduced. T...

In this paper, combined GPS and GLONASS positioning systems are discussed and some solutions have been proposed to improve the accuracy of navigation. Global Satellite Navigation System (GNSS) is able to provide position, velocity and time with respect to coordinated universal time. GNSS positioning is based on received satellite signals, so its performance is highly dependent on the quality of...

Based on the study of HLA (High Level Architecture) and OPNET-HLA interface, the dynamic control of simulation process and the real-time update of simulation for LEO (Low-Earth-Orbit) satellite communication system were achieved on multiple computers. In the distributed interactive simulation, a satellite’s location is controlled, then the end-to-end delay time and the routing table of Iridium ...

Single-Carrier Orthogonal Frequency Division Multiplexing (SC-OFDM) is a transmission technique particularly suitable for satellite transmission due to its low envelope variations and to the advantages brought by its natural compatibility with zero roll-off. Moreover, low complexity per-carrier equalization is possible in the frequency domain. This paper proves the high performance of SC-OFDM t...

SIS is a Satellite controller Integrated with Star sensors, which has been developed as a prototype model of a compact, low-cost satellite controller. SIS integrates attitude sensors into a star sensor and integrates several electronics for star identification, attitude determination, attitude control, and data handling into a single processing unit. SIS meets high reliability requirements by a...

Ultra small scale satellites have a very demanding and limited mass and power budget specification; therefore, mostly the design constraints prevent the use of small scale camera. In this paper, an imaging capturing subsystem is proposed for ultra small satellite, which includes low power consumption components; the developed imaging capturing subsystem was studied, simulated and successfully i...

The gravity field dedicated satellite missions like CHAMP, GRACE, and GOCE are supposed to map the Earth’s global gravity field with unprecedented accuracy and resolution. New models of Earth’s static and time-variable gravity field will be available every month as one of the science products from GRACE. Here we present an alternative method to estimate the gravity field efficiently using the i...