In any communication system, including the satellite and the Internet, it is almost impossible to prevent unauthorized people from eavesdropping. When information is broadcast from a satellite or transmitted through the Internet, there is a risk of information interception. Security of image and video data has become increasingly important for many applications, including video conferencing, se...

This paper studies the performance of the clock transfer scheme for burst-mode communication systems for which data are received during short, equally spaced intervals. Its main focus is on satellite-based time-division multiple-access (TDMA) communication systems with data regeneration and switching onboard the satellite, although the results apply to other TDMA systems as well. The system ref...

Artificial satellites were first deployed in the late 1950s. They have since brought about enormous progress in telecommunications. All communication satellites in their simplest form are concerned mainly with information communication from a source (transmitter) on the ground to a sink (receiver) that is at a geographically dispersed location through a satellite in space (acting as a retransmi...

In this paper we highlight the fact that a huge amount of information is sent unsecured via satellite broadcast data channels (here: encapsulated in DVB-s). By applying straightforward data analysis it is possible for any attacker equipped with a digital satellite dish and a DVB card PC to derive extensive confidential information on single users (e.g., legal name, banking details, monthly inco...

Autonomous position determination in the Globalstar satellite communication system is discussed. ( ) The two-way communication between a user terminal on the earth’s surface and a single low earth orbit LEO satellite makes it possible to derive range and range-rate and determine the user terminal position instantly. Expected accuracy is presented, and a simple direct solution is given. INTRODUC...

In this paper, we give an overview of using High Altitude Platforms (HAPs) for providing wireless telecommunication and broadband communication services. Comparisons of HAPs, satellite and terrestrial systems are shown to illustrate unique characteristics of the system. Three architectures for HAP systems are discussed in terms of cooperation with terrestrial and satellite systems. Telecommunic...

A common challenge in developing small-satellite-based Earth-observation (EO) missions is getting the data to the ground. Typically, most satellites download data via space-to-ground radio-frequency (RF) links, communicating directly with fixed ground stations as the satellites fly within range. For many next-generation EO missions, such as hyperspectral imaging or SAR missions, the volume of d...

In this paper, we investigate the benefits of a MULTI-GNSS receiver in an interference environment. The global satellite navigation systems GPS, GALILEO, GLONASS and COMPASSwill be considered. The regional navigation systems QZSS and IRNSS are not part of the investigation. We assume that a future Multi-GNSS receiver will use only CDMA signals. Therefore, the FDMA signals of the GLONASS system ...

We developed a multimedia satellite network system based on the Internet protocol (IP) and personal computers. The system enables collaborative distance education between outdoor and indoor environments. Integration of IP technologies and satellite communications enhances the flexibility of the network system. The satellite communication system enables communicating to and from outdoor environm...