Acta Astronautica 57 (2005) 230–238 www.elsevier.com/locate/actaastro Chaosoverchaos:Anewapproachforsatellitecommunication CleversonM.P.Marinho a , ∗ ,ElbertE.N.Macau b ,TakashiYoneyama a a Instituto Tecnológico de Aeronáutica-ITA, Brazil b Instituto Nacional de Pesquisas Espaciais-INPE, Brazil Abstract The chaotic dynamics can be exploited for the implementation of efficient and simple communication systems. Chaos communication explores chaotic synchronization to transmit information appropriately codified on the chaotic invariant set. This work studied control techniques and chaos synchronization, taking advantage of the chaotic evolution of the Chua circuit operating in double scroll regime and Lorenz system. Two forms were approached to taking advantage of peculiar characteristics of chaotic systems to transmit information. The first form uses small perturbation to encode the information inthesymbolicdynamicsofthedoublescrollsystem.Thesecondoneuseschaoticoscillationstomaskthecodifiedchaotic signal.Theperformanceofthesystemisinvestigated,aswellasitsbehaviorwhenusedtotransmitinformationoveramodel ofarealchannelwithlimitedbandwidth. ©2005PublishedbyElsevierLtd. 1. Introduction Digital communications over satellite data links play an extreme fundamental and important role in our modern society [1]. Actually, efficient, fast and reliablecommunicationnetworksaretheframeworks of our globalized world. Those worldwide networks can only be envisioned through satellite data links. However, as the demand for worldwide data trans- mission increases exponentially, more important are thetechnologybreakthroughstoallowoverpassesthe limitsofthedatatransmissioncapacityofthenowa- days data links [2]. In this scenario, communication ∗ Corresponding author. E-mail addresses: cleverson@directnet.br (C.M.P. Marinho), elbert@lac.inpe.br (E.E.N. Macau), takashi@ita.br (T.Yoneyama). 0094-5765/$-see front matter © 2005 Published by Elsevier Ltd. doi:10.1016/j.actaastro.2005.03.019 with chaos strategies may be envisioned as good so- lutiontobeexploited [3–8].Theintrinsiccomplexity embedded on the chaotic dynamics, with its infinite and numerable unstable periodic orbits, and infinite irregular aperiodic orbits allow the conception of a varietyofhighlyefficientcodificationschemeonthe chaotic evolution; the sensitivity of chaos to small perturbations of chaotic systems allows them to be controlled with very small perturbations, with con- trolling signal power orders of magnitude below the powerneededtoproduceandsustainthechaoticsys- tem [2,3,6]. Furthermore, as the chaotic dynamics is due to the non-linear characteristics of the electronic components,thecommunicationwithchaosstrategies can use all the operation excursion of those devices, which per se magnify the information capacity that any communication channel can sustain. As a result,