[dipl] Sähkötekniikan korkeakoulu / ELEC

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10 Gigabit-capable Passive Optical Network Transmission Convergence kerroksen suunnittelu
(Aalto University, 2010) Leino, Dmitri; Soila, Risto; Elektroniikan, tietoliikenteen ja automaation tiedekunta; Tirkkonen, Olav
Uusien laajakaistaisten tietoliikennepalvelujen ja kasvavan tiedonsiirtokapasiteetin tarpeen myötä kiinteiden liityntäverkkojen infrastruktuuri on muuttumassa sähköisestä optiseksi. Euroopan komission rahoittamassa Scalable Advanced Ring-based passive Dense Access Network Architecture (SARDANA)-tutkimusprojektissa tutkitaan seuraavan sukupolven passiivisten optisten liityntäverkojen teknologioita. Projektin päätavoitteena on pienentää passiivisiin optisiin liityntäverkkoihin liittyviä kustannuksia. Tämä diplomityö käsittelee SARDANA-testiverkon standardoimattoman 10 Gigabit-capable Passive Optical Network (XGPON) Transmission Convergence (TC)-kerroksen suunnittelua ja ensimmäistä toteutusta optisessa verkkopäätteessä (ONU:ssa). TC-kerros toteuttaa Medium Access Control (MAC)-protokollan. SARDANA XGPON TC (SXGTC)-kerros perustuu standardoituun ITU-T G.984.3 Gigabit-capable Passive Optical Network (GPON) TC (GTC)-kerroksen [ITU08] tarjoamaan ratkaisuun mutta eroaa tästä yksityiskohdiltaan. Kaikki SXGTC-kerroksen oleelliset yksityiskohdat peilataan GTC-kerrokseen. Suunniteltu SXGTC-protokolla tukee maksimissaan 9.95328 Gbps:n symmetrisiä tiedonsiirtonopeuksia. SXGTC-protokolla on optimoitu käsittelemään dataa 8 tavun sanoissa. Ensimmäinen ONU SXGTC-kerroksen toteutus ohjelmoitavassa Field Programmable Gate Array (FPGA)-piirissä esitellään funktionaalisten lohkojen avulla. Tämän implementaation tiedonsiirtonopeus alasuunnassa on 9.95328 Gbps 98 %:n kaistatehokkuudella ja yläsuunnassa 2.48832 Gbps 94.5 %:n kaistatehokkuudella SARDANA-testiverkkokonfiguraation tapauksessa.
110 kV:n johtojen ja sähköasemien saneerausvaihtoehdot
(2023-07-13) Saxell, Juha; Karvinen, Asmo; Niemelä, Esa; Sähkötekniikan korkeakoulu; Lehtonen, Matti
A 22 GHz prototype receiver for continuous comparison polarimetry
(2016-05-09) Haarto, Sam; Kirves, Petri; Wiik, Kaj; Sähkötekniikan korkeakoulu; Lähteenmäki, Anne
Radio astronomy is a subfield of astronomy that studies celestial objects that emit radio waves. As radio waves can penetrate dust, radio astronomy can study things that can't be seen in visible light. Radio astronomy studies the Sun, planets, gas and dust clouds of the Milky Way, pulsars, radio galaxies, quasars and cosmic background radiation. Polarimetry has been a quite recent addition to radio astronomy. Polarimetry studies the polarization of light and other transverse waves. The applications are present in a variety fields of astrophysics ranging from solar physics to cosmology. Polarimetry can be used to study for example the strength and orientation of magnetic fields in the space between planets in the Solar system and other planetary systems. It has given us insight into physical processes occurring in systems that range from our own solar system to high-redshift galaxies. The goal of this thesis was to build a prototype receiver for continuous comparison polarimetry. This prototype would be used as a testing device for the back-end planned for the Metsähovi's continuous comparison receiver. With this prototype receiver, one hopes to find and solve the possible problems that the final receiver might have, and also to ease with the adaptation of the new back-end. In addition to building a prototype receiver, the importance of polarization in radio astronomy was presented. Although a working prototype could not be achieved during this thesis an insight into the designing process was given. Designing, manufacturing and debugging of different components of the receiver was shown and future plans for the prototype was presented. Quite lossy 180-degree hybrids were produced. To proceed with the back-end testing new amplifier cards and a working back-end module should be acquired. Furthermore, the orthomode transducers of the prototype also need further testing to ensure their validity.
A 2D-laser scan produced by RGB-D that considers the physical size of the mobile robot.
(2022-10-17) Kuusisto, Mika; Deppe, Christian; Sähkötekniikan korkeakoulu; Kyrki, Ville
Simultaneous Localization and Mapping (SLAM) algorithms are a vital component of a mobile robot system in order for it to create a map and navigate through its environment. Depending on the complexity and size of the surroundings, different sensors and SLAM alternatives may be utilized. Laser rangefinders are traditionally popular sensor options, but their weakness is the restriction of measuring object distance only in a single plain. Therefore, laser vision cannot detect essential information out of their the field of view, which can lead to a collision. A complex environment is a space consisting of obstacles in various forms and sizes. In this work, the complex environment problem (the challenge of safely traveling through the environment) is approached with an RGB-D camera, which can produce a 3D point cloud of the scene. The point cloud is then converted into a 2D laser format to execute a particle filter based SLAM algorithm and create an occupancy map. This thesis studies the effect of restricting the height of the point cloud on the SLAM process so that the system considers the physical size of the mobile robot. Data sets were recorded in an office environment with different sizes and forms of obstacles positioned in the area. The evaluation considers five different elements of the system, which are mostly related to the SLAM process. The analysis includes visual evaluation of maps, resampling, and scan matching process (demonstrating the effect on SLAM), CPU load, and Root Mean Square Error(RMSE) for accuracy analysis. Results show that the point cloud could be restricted to the height of the mobile robot without a notable compromise on accuracy. It is also shown that a significant point cloud restriction before conversion into 2D laser, will increase scan matching failures and therefore affect the SLAM process.
3 Dimensional Electromagnetic Analysis of an Axial Active Magnetic Bearing
(2016-08-24) Panchal, Jay; Lantto, Erkki; Sähkötekniikan korkeakoulu; Belahcen, Anouar
In the rotating electrical machines, active magnetic bearing are basically performing the same role like mechanical bearings to support rotor. The function is based on the principle of magnetic levitation. The idea behind this involves creation of a magnetic field by supplying controlled currents in the bearing coil through amplifiers and complex power electronics. The accurate design of a magnetic bearing system incorporates many parameters before its implementation. The current work of the thesis encircles only the three dimensional (3D) modeling of axial active magnetic bearing (AMB). The static and dynamic models are analyzed for the bearing with a consideration of nonlinear material. In the study, the major emphasis is on the magnetic field, eddy current behavior and exerted magnetic forces in the magnetic bearing. The required input parameters for simulation are considered from the available two dimensional (2D) analysis for the same axial actuator. Elmer open source finite element tool is used in the entire work for making 3D simulations. Finally, the computed results are compared with the 2D case. As a part of the thesis work, a modified geometry is simulated to analyze eddy currents. The hypothesis in later task is the reduction of eddy current losses by providing a radial cut in the bearing ferromagnetic path. The radial cut brings asymmetry in the bearing and the three dimensional analysis provides the possibility to analyze the complete model. The results obtained in the above work provide a good understanding of 3D fields in axial AMB and the computed magnetic forces are in good agreement with the 2D results.
3-D collision checking for improving machine operator's spatial awareness
(2014-10-20) Liski, Toni; Terho, Sami; Sähkötekniikan korkeakoulu; Kyrki, Ville
In this thesis, methods to improve machine operator's spatial awareness are studied. The aim is to allow a machine to be teleoperated from distance. As a background, the research on the methods for environment modelling is reviewed, the comparison of environment representation methods, and an introduction to collision checking techniques is made. In this work, a novel approach to represent partly dynamic environment obtained from a staticly mounted range sensor was developed. In addition, a 2-D collision checking system using this representation to warn of possibly incoming collisions was developed. The developed environment model works precisely with partly dynamic environment when incoming range data is accurate enough and does not contain major artifacts or noise. When the environment model is created successfully, the collision checking system works accurately and is fast compared to pure 3-D collision methods.
3-D Eddy Current Modelling of Laminations to Study Edge Effects
(2016-02-15) Sundaria, Ravi; Rasilo, Paavo; Sähkötekniikan korkeakoulu; Arkkio, Antero
This thesis deals with analysis of eddy current losses in steel laminations and shows comparative study of 1-D coupled 2-D loss model with 2-D coupled 3-D loss model. Primary objective of the thesis is to analyze the edge effects in eddy current loss modelling which are ignored in traditionally available 1-D coupled 2-D loss models. Two separate cases, one with homogeneous and second with non-homogeneous flux density distribution across lamination were analyzed. For 1-D homogeneous case eddy current loss model was simulated using MATLAB while in house software FCSMEK was utilized in calculating 2-D eddy current losses in non-homogeneous flux distribution in a salient pole synchronous machine rotor pole. Lamination thickness of 2 mm used in synchronous machine rotor at industrial level to reduce manufacturing costs may have high edge effects and necessitates the requirement to carry out this thesis work. 3-D models of laminations are made with the help of softwares COMSOL and GMSH and FEM calculations are performed in software ELMER. The boundary conditions of 3-D model were excited from field solution of respective 2-D model. As a result of this thesis considerable amount of deviation in eddy current losses has been observed specially at higher thicknesses of steel laminations and frequency of flux density in both homogeneous and non-homogeneous cases.
33 kV tuulivoimamaakaapeloinnin tutkiminen
(2021-05-17) Kivisaari, Markus; Kouti, Tuomo; Sähkötekniikan korkeakoulu; Lehtonen, Matti
Tässä diplomityössä tutkitaan 33 kV keskijännitekaapelien ominaisuuksia tuulivoimala-asennuksissa. Ominaisuuksille esitetään standardien ja kirjallisuuden mukaisia laskentamenetelmiä ja näiden perusteella havainnollistetaan työssä käsiteltyjen kaapelityyppien toimintaa tuulivoimakäytössä. Tutkittuja osa-alueita ovat kaapelin asennus, kuormitettavuus, tehohäviöt, lämpenemä käytön aikana, taloudellinen mitoitus ja kosketussuojan jännitteet sekä virrat. Kuormitettavuuden havainnollistamisen tukena käytetään standardiin IEC 60287 perustuvaa laskentaohjelmaa. Jakeluverkoissa yleisesti käytettyjä keskijännitekaapelityyppejä käytetään myös tuulivoimaloissa. Tässä työssä valittiin tutkimuksen kohteeksi kaapeli-tyypit AHXAMK-W, AHXAMK-WP ja AHXCHBMK-W. Kaapelityyppi, asennustapa ja asennusympäristö vaikuttavat oleellisesti kaapelin kuormitettavuuteen, tehohäviöihin ja kosketussuojan jännitteisiin sekä kiertäviin virtoihin. Kaapelia mitoittaessa kannattaa kiinnittää huomiota käytönaikaisiin tehohäviöihin ja johtimen lämpötilaan, jotta tuulivoimalan sähkönsiirto olisi luotettavaa ja taloudellista.
3D convolutional neural networksfor classification of magneticresonance images
(2020-08-17) Li, Anqiang; Kärkkäinen, Leo; Sähkötekniikan korkeakoulu; Laakso, Ilkka
3D LiDAR-based autonomous valet parking system
(2022-03-21) Huang, Tzu-Lin; Fricke, Stefan; Sähkötekniikan korkeakoulu; Quan, Zhou
In an automated valet parking (AVP) scenario, drivers are allowed to hand over control in the drop-off zone while the vehicles electronically connect to the parking service system. The service provider is in charge of allocating parking lots to vehicles, generating navigation routes to the target location. The problem of autonomous parking is complicated regarding possible collisions due to obstacles in the environment, which requires precise path planning and vehicle control. In this thesis, we introduced a parking system framework with laser-based sensor technology. Relying on laser sensor information from infrastructure, obstacles are able to be identified and vehicles can be accurately localized and safely controlled. Then we focused on the path planning algorithm, the existing methods are first researched and implemented to find collision-free, smoothed paths for vehicles to drive, and finally experiments for perpendicular and parallel parking.
3D modeling and control of the vehicle dynamics at medium-low speed
(2023-05-15) Tilocca, Mario; Zhou, Quan; Sähkötekniikan korkeakoulu; Gastone Pietro, Rosati Papini
3D Reconstruction of Small Solar System Bodies using Rendered and Compressed Images
(2020-03-16) Schwarzkopf, Gabriel; Slavinskis, Andris; Sähkötekniikan korkeakoulu; Praks, Jaan
Synthetic image generation and reconstruction of Small Solar System Bodies and the influence of compression is becoming an important study topic because of the advent of small spacecraft in deep space missions. Most of these missions are fly-by scenarios, for example in the Comet Interceptor mission. Due to limited data budgets of small satellite missions, maximising scientific return requires investigating effects of lossy compression. A preliminary simulation pipeline had been developed that uses physics-based rendering in combination with procedural terrain generation to overcome limitations of currently used methods for image rendering like the Hapke model. The rendered Small Solar System Body images are combined with a star background and photometrically calibrated to represent realistic imagery. Subsequently, a Structure-from-Motion pipeline reconstructs three-dimensional models from the rendered images. In this work, the preliminary simulation pipeline was developed further into the Space Imaging Simulator for Proximity Operations software package and a compression package was added. The compression package was used to investigate effects of lossy compression on reconstructed models and the possible amount of data reduction of lossy compression to lossless compression. Several scenarios with varying fly-by distances ranging from 50 km to 400 km and body sizes of 1 km and 10 km were simulated and compressed with lossless and several quality levels of lossy compression using PNG and JPEG 2000 respectively. It was found that low compression ratios introduce artefacts resembling random noise while high compression ratios remove surface features. The random noise artefacts introduced by low compression ratios frequently increased the number of vertices and faces of the reconstructed three-dimensional model.
3rd Generation Partnership Project Long Term Evolution - mobiiliverkon suorituskyvyn hallinta
(Aalto University, 2011) Laine, Lasse; Yilmaz, Osman; Tietoliikenne- ja tietoverkkotekniikan laitos; Hämäläinen, Jyri
Long Term Evolution (LTE) on 3rd Generation Partnership Project:in (3GPP) uusin, suorituskyvyltään edeltäjiään huomattavasti kehittyneempi mobiiliverkkostandardi. Verkon rakentaminen on operaattorille aina valtava investointi, jonka vuoksi operaattorit luonnollisesti haluavat maksimoida verkon tuoton samalla minimoiden sen ylläpitämisen aiheuttamat kustannukset. Verkon tuottoa voidaan parantaa optimoimalla sen suorituskykyä ja verkon ylläpitokustannuksia pienentää automatisoimalla verkonhallinnan toimintoja. Ratkaiseva vaihe verkon suorituskyvyn optimointiprosessissa on verkon suorituskyvyn arviointi. Tässä diplomityössä kuvataan LTE:n tärkeimmät verkon suorituskyvyn tunnusluvut, joiden avulla verkon toimintaa voidaan arvioida kokonaisvaltaisesti. Lisäksi diplomityössä esitellään verkonhallinnan toimintoja automatisoiva Self-Organizing-Networks (SON) -konsepti ja sen tyypilliset käyttösovellukset. Työssä arvioidaan myös näiden käyttösovellusten toteuttamiskelpoisuutta, vahvuuksia sekä heikkouksia. Diplomityön viimeisessä osassa tutkitaan järjestelmätason simulaatioiden avulla SON -konseptin Cell Outage Compensation (COC) -käyttösovellusta, jonka tavoitteena on vähentää tukiasemien vikaantumisista verkon käyttäjille aiheutuvaa haittaa. Osiossa tutkitaan tyypillisen vikaantumisen vaikutuksia, valitaan kontrolliparametrit COC -algoritmille sekä kehitetään COC -funktio. Tehdyissä simulaatioissa kehitetty COC -funktio onnistui vähentämään vikaantumisen vaikutuksia merkittävästi.
4G Technology Features and Evolution towards IMT-Advanced
(Aalto University, 2010) Reya, Lionel Fuependap Metuge; Husso, Mika; Elektroniikan, tietoliikenteen ja automaation tiedekunta; Hämäläinen, Jyri
Kiinteiden- ja mobiilipalveluiden kysyntä kasvaa nopeasti ympäri maailmaa. Älykkäiden päätelaitteiden, kuten iPhone:n ja Nokia N900:n markkinoilletulo yhdistettynä näiden korkeaan markkinapenetraatioon ja korkealuokkaiseen käyttäjäkokemukseen lisäävät entisestään palveluiden kysyntää ja luovat tarpeen jatkuvalle innovoinnille langattomien teknologioiden alalla tavoitteena lisäkapasiteetin ja paremman palvelunlaadun tarjoaminen. Termi 4G (4th Generation) viittaa tuleviin neljännen sukupolven mobiileihin langattomiin palveluihin, jotka International Telecommunications Union:in Radiocommunication Sector (ITU-R) on määritellyt ja nimennyt International Mobile Telecommunications-Advanced (IMT-Advanced). Nämä ovat järjestelmiä, jotka pitävät sisällään IMT:n ne uudet ominaisuudet, jotka ylittävät IMT-2000:n vaatimukset. Long Term Evolution-Advanced (LTE-Advanced) ja IEEE 802.16m ovat IMT-A sertifiointiin lähetetyt kaksi pääasiallista kandidaattiteknologiaa. Tässä diplomityössä esitellään kolmannen sukupolven järjestelmien kehityspolku LTE:hen ja IEEE 802.16e-2005 asti. Lisäksi työssä esitetään LTE-Advanced:n ja IEEE 802.16m:n uudet vaatimukset ja ominaisuudet sekä vertaillaan näiden lähestymistapoja IMT-A vaatimusten täyttämiseksi. Lopuksi työssä luodaan katsaus LTE ja IEEE 802.16e-2005 (markkinointinimeltään Mobile WiMAX) -järjestelmien markkinatilanteeseen.
5G and Wi-Fi Performance in Underground Mining
(2024-01-22) Rajani, Jagdeesh; Requena, Jose Costa; Sähkötekniikan korkeakoulu; Collin, Jari
5G is being deployed widely in commercial and private networks because it promises higher throughput and less delays compared to the other mobile and Wi-Fi networks’ performance. This thesis is a case study for comparison of the 5G and Wi-Fi networks performance in the testbed underground mining network of Sandvik mine. The motivation for this research is to determine actual delays and packet losses in the underground mining network in a 5G standalone (SA) network deployment, and as well as Wi-fi4 deployment. Furthermore, the research seeks to benchmark and compare the network performance of both technologies and draw conclusions regarding whether 5G meets the anticipated performance standards and has any advantage for underground mining operations. The case study is about benchmarking the TCP and UDP data throughput, and latency in the mobility scenario in the underground mining testbed. The different TCP, UDP throughput and latency results in the case study indicates that Wi-fi has more variability in the bit rate over time and the data rate seems to be less consistent for TCP and with higher packet losses for UDP. Though 5G had a higher Avg RTT compared to Wi-fi but 5G seems to have more consistent network performance with lower standard deviation (Sdev) value and stable packet delivery with zero packet loss in the latency test results. Therefore, TCP, UDP data throughput and latency in mobility tests confirm that 5G in underground Sandvik mine is likely to be a reliable network with better performance.
5G Micro-Cell Deployment in Coexistence with Fixed Services
(2016-10-27) Abdallah, Khaled; Tercero, Miurel; Sähkötekniikan korkeakoulu; Jantti, Riku
This study deals with the coexistence between 5G networks and Fixed Services (FS), where fixed links (FL) is one application that is considered. To meet the demanding requirements of 5G systems, it is expected that 5G systems will require spectrum in high frequency bands. Most likely, these systems will have to share spectrum with fixed services. This thesis assesses the mutual interference between a micro-cell deployment and the fixed link, and examines the feasibility of the coexistence based on the interference requirements. The results indicate that the downlink (DL) interference that 5G generates towards the fixed link, surpasses the protection criteria for primary-secondary sharing in a co-channel case. However, the interference generated by the uplink (UL) transmission of the 5G system stays below the required threshold when an antenna array composed of 16 elements is used. In downlink (DL) communication, coexistence conditions were improved when lower transmit power was used. Thus, coexistence could be feasible in case the micro-layer was used only in UL. Frequency Division Duplexing (FDD) systems could be used in 5G communication systems to enable this feature.
5G New Radio Physical Layer Signal Processing with Configurable Wavefront Parallel Processor
(2024-08-19) Kumar, Navneet; Galaro, Joseph; Sähkötekniikan korkeakoulu; Halonen, Kari
The advent of 5G NR mobile communication systems necessitates higher internet speeds. While higher processing speeds are required at all levels of the system to achieve this goal, this research focuses on increasing the processing speed at the physical layer with a focus on flexible implementation. The thesis studies a new digital architecture, Configurable Wavefront Parallel Processor (cWAFER) for the hardware block (IP) in the system-on-chip (SoC) executing signal processing in the baseband and digital front end. This thesis implements beamforming, channel estimation, and decimation filter processing using cWAFER architecture to study power, performance, silicon area, and precision to determine the suitability of this architecture for 5G SoCs. Additionally, this work also contributes to the cWAFER architecture by adding a new instruction set, to enhance performance. The thesis further makes a significant contribution by developing a Python-based bit and cycle-accurate Instruction Set Simulator (ISS) to model the architecture. Finally, the thesis work closes with some conclusions drawn from the analysis of the presented implementation. This thesis research has yielded two Intellectual Property Rights (IPR) filings, currently confidential. Additionally, three journal publications based on this work are currently under development.
5G Uplink Frequency Offset Compensation with an Autoencoder
(2021-03-15) Pitkänen, Mikko; Olivès, Jean-Luc; Sähkötekniikan korkeakoulu; Wichman, Risto
The emerging fifth generation 5G cellular networks face strict requirements for the quality of service. Accurate and fast algorithms need to be deployed to deliver the promised high data rates and low latencies. One of those algorithms, the frequency offset compensation, is the focal point of this thesis. The goal is to develop a machine learning model for frequency offset compensation in a 5G base station receiver. The feasibility of the model is evaluated based on comparisons to an existing conventional algorithm. Denoising autoencoders are selected as the machine learning method for this thesis. The most significant novelty of this approach is that an autoencoder does not use an external estimate of the frequency offset. The autoencoder models are developed with the PyTorch framework in the Python programming language. The development work is conducted in three paths, each focusing on one autoencoder architecture. The data for the machine learning solution is generated with a link-level simulator that can simulate communication scenarios between a transmitter and a receiver. In addition to monitoring the autoencoders' performance at training time, the trained models are integrated into the link-level simulator to examine their impact on the whole signal processing chain of the receiver. Most of the developed models demonstrate poorer performance than the conventional algorithm. It was verified that the training data contains all the needed information in order to compensate for the frequency offset ideally, but the autoencoders did not learn to utilize this information. However, the positive results in this thesis indicate that an autoencoder-based algorithm can outperform the conventional method especially at higher frequency offsets. It was also discovered that an autoencoder trained for a narrow frequency offset range is able to generalize outside of that range to some extent.
64-QAM –signaalin optimoitu vastaanottomenetelmä HSDPA:ssa
(Helsinki University of Technology, 2008) Pitkänen, Sampo; Huuhtanen, Timo; TkL; Faculty of Electronics, Communications and Automation; Elektroniikan, tietoliikenteen ja automaation tiedekunta; Simula, Olli; Prof.
HSDPA on vuonna 2002 UMTS-verkkoihin lisätty ominaisuus. Sen avulla laskevalla siirtotiellä mobiililaitteiden huippunopeudeksi saadaan 14.4 megabittiä sekunnissa. Vuonna 2007 standardoitiin uusia HSDPA-ominaisuuksia, niiden mukana uusi modulaatiotyyppi 64-QAM. 64-QAM:in avulla suurin siirtonopeus saadaan nostettua 21.6:n megabittiin sekunnissa. Sekä lähettimiä että vastaanottimia on päivitettävä uuden modulaatiotyypin tukemiseksi. Vastaanottopäässä signaalin amplitudi täytyy ensin estimoida tarkasti jotta signaali voidaan vastaanottaa oikein. Signaali pitää vielä tämän jälkeen demoduloida riittävällä tarkkuudella. Samankaltaisia algoritmeja on käytetty jo vanhemmissa HSDPA-versioissa, mutta 64-QAM on huomattavasti herkempi virheille. Tässä työssä amplitudiestimointia ja demodulointia varten testattiin kolmea eri algoritmivaihtoehtoa. Algoritmien vertailuun käytettiin fyysisen kerroksen HSDPA-simulaattoria, jossa käytettiin standardin mukaisia realistisia parametreja. Lopputuloksena yksiselitteisesti parasta tapaa estimoida amplitudia ei löytynyt, mutta kaksi ehdokkaista osoitti hyviä ominaisuuksia. Parhaaksi demodulointialgoritmiksi osoittautui yksinkertaistettu versio optimaalisesta MAP-ilmaisimesta, joka hoitaa demoduloinnin yksiulotteisesti.
Aalto-1 -satelliitin spektrikamerateknologian validointi avaruusympäristöön
(2013-05-20) Näsilä, Antti; Viherkanto, Kai; Department of Radio Science and Engineering; Radiotieteen ja -tekniikan laitos; Sähkötekniikan korkeakoulu; Hallikainen, Martti
Tässä työssä suoritettiin Aalto-1 -nanosatelliitin spektrikameran pietso-aktuoidun Fabry–Perot Interferometrin avaruuskvalifiointi. Spektrikamera tulee olemaan Aalto-1 -satelliitin päähyötykuorma. Avaruuskvalifiointia varten suunniteltiin ja toteutettiin avaruustestikampanja, joka sisälsi lämpösyklauksen lämpökaapissa, tärinä- ja shokkitestit, taajuus- ja askelvasteiden mittaukset tyhjiössä. Lopuksi suoritettiin myös sarja testejä termovakuumikammiossa. Fabry–Perot Interferometrin suorituskyvylle asetettiin seuraavat spesifikaatiot: läpäisy 0.1–0.3, spektraalinen resoluutio 10–30 nm, spektrinen vakaus 0.2 nm/°C sekä säätönopeus < 30 ms. Tämän lisäksi vaaditiin myös selviytymistä lämpötila- (-45–65°C) ja laukaisuympäristöistä. Muutamien korjausten jälkeen Fabry–Perot -moduuli läpäisi kaikki kvalifikaatiotestit ja spesifikaatiot täytettiin, joten moduuli on kvalifioitu avaruusolosuhteisiin onnistuneesti.

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