Linear transmitter design for MSAT terminals

One of the factors that will undoubtedly influence the choice of modulation format for mobile satellites, is the availability of cheap, power-efficient, linear amplifiers for mobile terminal equipment operating in the 1.5-1.7 GHz band. Transmitter linearity is not easily achieved at these frequencies, although high power (20W) class A/AB devices are becoming available. However, these components are expensive and require careful design to achieve a modest degree of linearity. In this paper an alternative approach to radio frequency (RF) power amplifier design for mobile satellite (MSAT) terminals using readily-available, power-efficient, and cheap class C devices in a feedback amplifier architecture is presented

Adaptive Transmission Techniques for Mobile Satellite Links

Adapting the transmission rate in an LMS channel is a challenging task because of the relatively fast time variations, of the long delays involved, and of the difficulty in mapping the parameters of a time-varying channel into communication performance. In this paper, we propose two strategies for dealing with these impairments, namely, multi-layer coding (MLC) in the forward link, and open-loop adaptation in the return link. Both strategies rely on physical-layer abstraction tools for predicting the link performance. We will show that, in both cases, it is possible to increase the average spectral efficiency while at the same time keeping the outage probability under a given threshold. To do so, the forward link strategy will rely on introducing some latency in the data stream by using retransmissions. The return link, on the other hand, will rely on a statistical characterization of a physical-layer abstraction measure.Comment: Presented at the 30th AIAA International Communications Satellite Systems Conference (ICSSC), Ottawa, Canada, 2012. Best Professional Paper Awar

The 30/20 GHz communications system functional requirements

The characteristics of 30/20 GHz usage in satellite systems to be used in support of projected communication requirements of the 1990's are defined. A requirements analysis which develops projected market demand for satellite services by general and specialized carriers and an analysis of the impact of propagation and system constraints on 30/20 GHz operation are included. A set of technical performance characteristics for the 30/20 GHz systems which can serve the resulting market demand and the experimental program necessary to verify technical and operational aspects of the proposed systems is also discussed

Optical communication on CubeSats - Enabling the next era in space science

CubeSats are excellent platforms to rapidly perform simple space experiments. Several hundreds of CubeSats have already been successfully launched in the past few years and the number of announced launches grows every year. These platforms provide an easy access to space for universities and organizations which otherwise could not afford it. However, these spacecraft still rely on RF communications, where the spectrum is already crowded and cannot support the growing demand for data transmission to the ground. Lasercom holds the promise to be the solution to this problem, with a potential improvement of several orders of magnitude in the transmission capacity, while keeping a low size, weight and power. Between 2016 and 2017, The Keck Institute for Space Studies (KISS), a joint institute of the California Institute of Technology and the Jet Propulsion Laboratory, brought together a group of space scientists and lasercom engineers to address the current challenges that this technology faces, in order to enable it to compete with RF and eventually replace it when high-data rate is needed. After two one-week workshops, the working group started developing a report addressing three study cases: low Earth orbit, crosslinks and deep space. This paper presents the main points and conclusions of these KISS workshops.Comment: 7 pages, 5 figures, 2 tables, Official Final Report of KISS (Keck Institute for Space Studies) workshop on "Optical communication on CubeSats" (http://kiss.caltech.edu/workshops/optcomm/optcomm.html

Advanced Algorithms for Satellite Communication Signal Processing

Dizertační práce je zaměřena na softwarově definované přijímače určené k úzkopásmové družicové komunikaci. Komunikační kanály družicových spojů zahrnujících komunikaci s hlubokým vesmírem jsou zatíženy vysokými úrovněmi šumu, typicky modelovaného AWGN, a silným Dopplerovým posuvem signálu způsobeným mimořádnou rychlostí pohybu objektu. Dizertační práce představuje možné postupy řešení výpočetně efektivní digitální downkonverze úzkopásmových signálů a systému odhadu kmitočtu nosné úzkopásmových signálů zatížených Dopplerovým posuvem v řádu násobků šířky pásma signálu. Popis navrhovaných algoritmů zahrnuje analytický postup jejich vývoje a tam, kde je to možné, i analytické hodnocení jejich chování. Algoritmy jsou modelovány v prostředí MATLAB Simulink a tyto modely jsou využity pro ověření vlastností simulacemi. Modely byly také využity k experimentálním testům na reálném signálu přijatém z družice PSAT v laboratoři experimentálních družic na ústavu radioelektroniky.The dissertation is focused on software defined receivers intended for narrowband satellite communication. The satellite communication channel including deep space communication suffers from a high level of noise, typically modeled by AWGN, and from a strong Doppler shift of a signal caused by the unprecedented speed of an object in motion. The dissertation shows possible approaches to the issues of computationally efficient digital downconversion of narrowband signals and the carrier frequency estimation of narrowband signals distorted by the Doppler shift in the order of multiples of the signal bandwidth. The description of the proposed algorithms includes an analytical approach of its development and, if possible, the analytical performance assessment. The algorithms are modeled in MATLAB Simulink and the models are used for validating the performance by the simulation. The models were also used for experimental tests on the real signal received from the PSAT satellite at the laboratory of experimental satellites at the department of radio electronics.

Planning assistance for the 30/20 GHz program, volume 1

Functional requirements for the 30/20 GHz communication system, planning assistance for the 30/20 GHz program, and a review of specified conceptual designs and recommendations are provided