Channel Communication Optimization for a Power Constrained Satellite
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
In this project two problems are addressed: choosing the best High Power Amplifier (HPA)from 3 given ones, and obtaining a software model for them so the communication channelcan be tested and optimized on the ground during mission design. In order to do this, differentmodels were studied, some of them chosen and implemented, and the results studied. In theend one of the 3 amplifiers showed best performance, and the software enabled furthertesting for the communications group.The design of an optimized, robust and reliable communication channel is vital for any satellite.It allows the mission to maximize the payload transmitted data, the satellite tracking bytelemetry, the variations performed by telecommand, and is basically the only way to ensurethe health of the satellite, fix the problems which may come during the mission, modify themission, obtain the payload data and in general access to most of the usages of the satellite.Therefore the channel design must be optimized, and as many simulations as necessary whileon-earth performed to ensure the performance is the desired one.The High Power Amplifier (HPA) is a vital element of any satellite, since it maximizes the powerfor Payload instruments, for communication purposes and for the satellite performance.Satellite communication waves travel hundreds or thousands of kilometers, and are affectedby a wide variety of impairments when within the atmosphere. To overcome this and ensure areliable channel we need high power transmission. This is even more important when we usesmall satellites which are constrained in power mostly due to size and cost limitations. Withnowadays computational power, these small satellite missions can perform successful andmeaningful projects, but they also require a thorough design to maximize its resources. HPAsprovide this capability, but also high nonlinearities that need to be studied and corrected ifnecessary if they provoke distortion in the transmitted signal, so information can satisfactorilyexchange information between sender (Ground Station) and receiver (satellite) using amodulation and coding (MODCOD) scheme.For this project different algorithms were developed from several models, in order to assessthe usage of 3 different amplifiers and coding schemes. The most successful algorithm was anIterative Batch Least Squares solution adapted from the Orbit Determination problem using aPoza-Sarkozy-Berger (PSB) model. When implemented with the channel simulator, the bestperformance was observed using the deviation from the regression line of the shift coefficients,at expenses of a new simulation re-arranging the frequency measurements from the HPAsusing the Vector Network Analyzer (VNA).In this report the problem and project are introduced, the models and implementedalgorithms described and the results presented.
Place, publisher, year, edition, pages
2012. , 112 p.
Technology, Satellite, Communication, Communications, Power Amplifier, HPA, RF, Modelling
IdentifiersURN: urn:nbn:se:ltu:diva-56660Local ID: d6a53088-a1e4-4cf2-a892-ab03bba88a50OAI: oai:DiVA.org:ltu-56660DiVA: diva2:1030047
Subject / course
Student thesis, at least 30 credits
Space Engineering, master's level
Validerat; 20121025 (anonymous)2016-10-042016-10-04Bibliographically approved