Optical Inter-Satellite Links: Applications in Defense

2014

Satellite communication is one of the most impressive spin-offs from the space programs and has made a major contribution to the pattern of international communication. A communication satellite is basically an electronic communication package placed in orbit whose prime objective is to initiate or assist another through space. This paper will explain overview of satellite communications, its working, types of satellites and services provided by these communications. This communication further includes satellite orbits and their comparison. We had also discussed satellite merits and demerits which made this communication successful along with its applications in today world (usage). New invention satellites are also discussed.

2018

During the past four years, the laser communication terminal on board of Alphasat GEO-stationary satellite has achieved the successful execution of more than 1300 optical links which implies more than 24.000 tasks for the planning system. This laser terminal in combination with a Ka-Band system constitutes the TDP1 technology demonstrator. Approximately half of the links were inter-satellite optical links, using the Sentinels low orbit satellites of the EU Copernicus program (S1A, S1B, S2A and S2B) as communication partner with the aim of supporting in orbit commissioning activities and TDP1 experimentation purposes. The other half of the links used the transportable adaptive optical ground station of the DLR (T-AOGS ) located currently at Tenerife, Spain as counter terminal. These optical satellite to ground links prepare the way not only to GEO feeder links, but also for connecting the space segment to HAPs, airborne terminals or LEO direct to earth links. In contrast to pure inter satellite links the satellite to ground links involve the atmosphere and local weather conditions. Adopting the operational concept established for inter satellite links, a certain percentage of the planned links cannot be conducted (e.g. due to clouds). The conducted links were used to characterizing the T-AOGS, characterize the atmospheric conditions as well as optimize and test coding schemes. Most of the tasks executed by the LCTs and the Ka-Band have been based in the TESAT input delivered to the MCC (operated by DLR GSOC), further processed and finally transferred to the spacecraft control center.

In this work, the experimental development of an optical payload for free space communications is presented. This payload is designed to operate in the SATEX I mission that consist in an experimental LEO microsatellite development with federal government support in a multiinstitutional effort in Mexico for technological and research purposes. This experiment consists in the design and implementation of a transmitter in 830 nm like the information channel (downlink) and a photo receiver in the 530 nm that collect the earth station beacon (uplink) for acquisition and pointing purposes. We have projected as primary goal make BER and attenuation measurements in the downlink channel. The technical looks of design of all the subsystems are presented included the link calculation, the characterization of the prototype and the expected performance.

Indian Journal of Science and Technology

Objectives: The need for constricting, lightweight, low-power electronics-aggravated by the thriving demand for large data flow rate and bandwidth is urging the use of optical technologies in defense and space. Free space optical (FSO) communication links have promising eminence over microwave communication links with high speed, low weight, and increased security so that they can be boarded conveniently on the satellite. Methods/findings: The advancement of the optical components and systems has made it very predominant along with its acceptability in space and defense. Yet a couple of significant components to be dealt with are tracking problems with misalignment of the transmitter and receiver apertures and the progressions because of barometrical conditions. Efficiency of the FSO communication system is seriously rotted due to the angle of arrival (AoA) variance and including error pointing. The optical transmitter can be perfectly coordinated with the receiver by utilizing the pointing, acquisition, and tracking (PAT). However, this method is to be carried out under the airborne platform with required restrictions namely size, weight, and power. Application: An overview of promising inter-satellite applications with the challenges have been discussed which sway the performance of the system and make the communication link unattainable. The FSO communication possesses an advantage over two existing technologies optical fiber communication and wireless communication. Hence, the significant use of FSO is intersatellite optical wireless communication (Is OWC) links, which will be deployed in the future in space.

IEEE Journal of Selected Topics in Quantum Electronics, 2000

This paper describes the achievements in optical intersatellite communication based on technology developments that started in Europe (European Space Agency) more than 30 years ago. In 2001, the world-first optical intersatellite communication link was established (between the SPOT-4 and Advanced Relay and TEchnology MIssion Satellite (ARTEMIS) satellites), proving that optical communication technologies can be reliably mastered in space. In 2006, the Japanese Space Agency (JAXA)

2010 IEEE Aerospace Conference, 2010

A national concept for the implementation of a network of ground stations for small satellite missions is being designed. This network shall support the newly conceived small satellite program in Peru. Currently Peruvian engineers conduct investigations on how to carry out this challenging project, which is expected to gain not only Peru but also the Peruvian industry. The proposed network shall be supported not only by Peruvian government institutions, but also by national and international universities. The establishment of such a program has already been started and a couple of European entities and universities are interested in becoming co-partner within the project. The ground stations will be located in remote places in Peru thus providing wide communication coverage, permitting longer contact capabilities between the satellite and the ground, and creating a complex space and ground based system. A network including these places will cover a landscape area larger than one million km 2. In general small satellites use a low data rate downlink. Due to less number of access and low power capacity the usage of an UHF transmitter is the only possibility. This network will widen the contact capability with the satellites and consequently there will be more opportunity to dump a higher amount of data. Since the communication system for small satellites is developing in a rapid pace, this network would be beneficial to dump data faster than before allowing the collection and distribution of data in an effective manner for the users. This will permit generating more accurate data generation from the instruments or from the spacecraft itself. At a first level the network will be implemented with UHF band antennas, which in the future will be expanded with S-band antennas. This Peruvian network will be functional for our national small satellite program and also for all the satellite missions that currently operate on radio amateur frequencies.

The transfer of information from source to destination i.e transmitter to receiver is called the communication. Basically communication is possible in two ways they are wire communication and the other one is wireless communication. The satellite communication is a best example for the wire-less communication. In this paper we are first giving a brief satellite history and next why we are using satellite for communication and the orbital model. How the satellites stay in orbits and orbit types. After we are concentrating how an artificial satellite is launched. And what components required for satellite designers. And after we are giving few applications and key research challenges.

2016

Laser communications systems are wireless connections through the atmosphere. They work similarly to fibre optic links, except the beam is transmitted through free space under line of sight condition. Laser is a generic term used for light amplification by stimulated emission of radiation. A laser is a device that emits light i.e. electromagnetic radiation through a process called stimulated emission. Laser communication is the key area in wireless communication. This paper gives an overview of techniques used, features, applications, advantages and disadvantages of laser light. Index Terms – Intersatellite communication, optical communication, wireless communication, free space communication.