Methods for Improving Performance in Consumer Grade GNSS Receivers

Viimeisten kolmen vuosikymmenen aikana satelliittinavigointi on kehittynyt ammatti ja sotilaskäyttäjien tekniikasta kaikkien saatavilla olevaksi tekniikaksi. Varsinkin viimeisen 15 vuoden aikana, kun vastaanottimet alkoivat pienentyä ja halpenivat, on lisääntynyt määrä yrityksiä, jotka toimittavat GPS-laitteita satoihin erilaisiin sovelluksiin. Kaikille moderneille tekniikoille on myös tyypillistä, että tutkimukseen ja siihen liittyvään vastaanottimien kehittämiseen on käytetty valtavasti rahaa, mikä on johtanut huomattavaan parantumiseen vastaanottimen suorituskyvyssä. GPS-vastaanottimien kehitystyön lisäksi uusien maailmanlaajuisten satelliittinavigointijärjestelmien, kuten venäläisen GLONASS, kiinalaisen BeiDou- ja eurooppalaisen Galileo-järjestelmien käyttöönotto tarjoaa entistä enemmän mahdollisuuksia suorituskyvyn parantamiseen. Sekä GPS että nämä uudet järjestelmät ovat myös ottaneet käyttöön uudentyyppisiä signaalirakenteita, jotka voivat tarjota parempilaatuisia havaintoja ja siten parantaa kaikkien vastaanottimien suorituskykyä. Lopuksi menetelmät, kuten PPP ja RTK, jotka aiemmin olivat varattu ammattikäyttäjille, ovat tulleet kuluttajamarkkinoille mahdollistaen ennennäkemättömän suorituskyvyn jokaiselle satelliittinavigointivastaanottimien käyttäjälle. Tässä opinnäytetyössä arvioidaan tämän kehityksen vaikutusta sekä suorituskykyyn että vastaanottimen arkkitehtuuriin. Työssä esitellään yksityiskohtaisesti FGI:ssä kehitetyn ohjelmistopohjaisen vastaanottimen, FGI-GSRx:n. Tämän vastaanottimen avulla on työssä arvioitu miten sekä uudet konstellaatiot että uudet nykyaikaiset signaalit ja niitten seurantamenetelmät vaikuttavat suorituskykyyn ja vastaanotin arkkitehtuuriin. Tämän lisäksi on arvioitu PPP- ja RTK-tarkkuuspaikannusmenetelmien vaikutus FinnRefCORS-verkkoa käyttäen useiden erityyppisten vastaanottimien kanssa, mukaan lukien kuluttajalaatuiset vastaanottimet. Tulokset osoittavat, että enemmän konstellaatioita ja signaaleja käytettäessä paikannusratkaisun tarkkuus paranee 3 metristä 1,4 metriin hyvissä olosuhteissa ja yli 10-kertaiseksi tiheästi rakennetuissa kaupungeissa, jossa käytettävissä olevien signaalien määrä kasvaa kertoimella 2 käytettäessä kolmea konstellaatiota. Uusia moderneja modulaatiotekniikoita, kuten BOC-modulaatiota, käytettäessä tulokset osoittavat Galileo-ratkaisun tarkkuuden paranevan lähes 25%:lla ja esitelty uusi signaalinkäsittelymenetelmä lisää tällaisen tarkkuuden saatavuutta 50%:sta lähes 100%:iin. Lopuksi tarkkuuspaikannusmenetelmien tulokset osoittavat, että 15 cm:n tarkkuus on saavutettavissa, mikä on merkittävä parannus verrattuna 1,4 metrin tarkkuuteen. Näiden parannusten saavuttamiseksi on olennaista, että itse vastaanotin on mukautettu hyödyntämään näitä uusia signaaleja ja konstellaatioita. Tämä tarkoittaa, että nykyaikaisten kuluttajamarkkinoiden vastaanottimien suunnittelu on haastavaa ja monissa tapauksissa ohjelmistopohjainen vastaanotin olisi parempi ja halvempi valinta kuin uusien mikropiirien kehittäminen.For the last three decades, satellite navigation has evolved from being a technology for professional and military users to a technology available for everyone. Especially during the last 15 years, since the receivers started getting smaller and cheaper, there has been an increasing number of companies delivering Global Positioning System (GPS) enabled devices for hundreds of different kind of applications. Typical for any modern technology, there has also been an enormous amount of money spent on research and accompanied receiver development resulting in an immense increase in receiver performance. In addition to the development efforts on GPS receivers the introduction of new global navigation satellite systems such as the Russian Globalnaja Navigatsionnaja Sputnikovaja Sistema (GLONASS), the Chinese BeiDou, and the European Galileo systems offers even more opportunities for improved performance. Both GPS and these new systems have also introduced new types of signal structures that can provide better quality observations and even further improve the performance of all receivers. Finally, methods like Precise Point Positioning (PPP) and Real Time Kinematic (RTK) that earlier were reserved for professional users have entered into the consumer market enabling never before seen performance for every user of satellite navigation receivers. This thesis will assess the impact of this development on both performance as well as on receiver architecture. The design of the software defined receiver developed at FGI, the FGI-GSRx, is presented in detail in this thesis. This receiver has then been used to assess the impact of using multiple constellations as well as new novel signal processing methods for modern signals. To evaluate the impact of PPP and RTK methods the FinnRef Continuously Operating Reference Station (CORS) network has been used together with several different types of receivers including consumer grade off the shelf receivers. The results show that when using more constellations and signals the accuracy of the positioning solution improves from3 meters to 1.4 meters in open sky conditions and by more than a factor 10 in severe urban canyons. For severe urban canyons the available also increases by a factor 2 when using three constellations. When using new modern modulation techniques like high order BOC results show an accuracy improvement for a Galileo solution of almost 25 % and the presented new signal processing method increase the availability of such an accuracy from 50 % to almost 100 %. Finally, results from precise point positioning methods show that an accuracy of 15 cm is achievable, which is a significant improvement compared to an accuracy of 1.4 m for a standalone multi constellation solution. To achieve these improvements, it is essential that the receiver itself is adapted to make use of these new signals and constellations. This means that the design of modern consumer market receivers is challenging and in many cases a software define receiver would be a better and cheaper choice than developing new Application Specific Integrated Circuit (ASIC)’s

Massively Extended Modular Monitoring and a Second Life for Upper Stages

Launching science and technology experiments to space is expensive. Although commercial spaceflight has resulted in a drop of prices, the cost for a launch is still significant. However, most of theweight that is needed to conduct experiments in space belongs to the spacecraft’s bus and it is responsiblefor power distribution, thermal management, orbital control and communications. An upper stage, on the other hand, includes all the necessary subsystems andhas to be launched in any case. Many upper stages (e.g. ARIANE5) will even stay in orbit for severalyears after their nominal mission with all their subsystems intact but passivated.We proposea compact system based on a protective container and high-performance Commercial-off-the-Shelf (COTS) hardwarethat allows cost-efficient launching oftechnology experiments by reusing the launcher’s upper stage and its subsystems. Addingacquisition channels for various sensors gives the launch provider the ability to exploitthe computational power of the COTS hardwareduring the nominal mission. In contrast to existing systems,intelligent and mission-dependent data selection and compression can beapplied to the sensor data.In this paper, we demonstrate the implementation and qualification of a payload bussystem based on COTScomponentsthat is minimallyinvasive to the launcher(ARIANE5)and its nominal missionwhile offering computational power to both the launch provider and a potential payloaduser. The reliability of the COTS-based system is improvedby radiation hardening techniques and software-based self-test detecting and counteracting faults during the mission

Hybridization of GNSS and On-Board Sensors for Validating the Aurora Ecosystem

This paper presents a hybrid navigation algorithm based on loose coupling of the on-board speedometer and inertial sensors of a land vehicle with a GNSS receiver. An Extended Kalman Filter estimating ten error states is used as the hybridization framework. The algorithm is developed to serve as a baseline for the evaluation of the navigation infrastructure of the Aurora ecosystem which is an Arctic test bed for autonomous vehicles and intelligent transport systems. In the experimental tests we focus on the performance of the navigation algorithm during GNSS outages. First, the tests indicate that the quality of GNSS updates has an immediate effect on how fast the position errors accumulate when GNSS becomes unavailable. Second, using low-cost sensors together with the current navigation infrastructure available at the Aurora test site, GNSS position fixes need to be obtained at intervals no longer than 4 seconds in order to maintain a 95 % horizontal positioning accuracy better than 0.2 meters. The results serve as a basis for recommendations for further development of the Aurora ecosystem, suggesting that further positioning infrastructure could be deployed for guaranteeing a navigation performance adequate for autonomous vehicles

Approaching the Heisenberg limit with two mode squeezed states

Two mode squeezed states can be used to achieve Heisenberg limit scaling in interferometry: a phase shift of $\delta \phi \approx 2.76 /$ can be resolved. The proposed scheme relies on balanced homodyne detection and can be implemented with current technology. The most important experimental imperfections are studied and their impact quantified.Comment: 4 pages, 7 figure

New national and regional biological records for Finland 8. Contributions to agaricoid, gastroid and ascomycetoid taxa of fungi 5

Two genera: Marchandiomyces, Rectipilus and 16 species of agaricoid and gastroid fungi (Basidiomycota): Clitopilus daamsii, Coprinopsis canoceps, Coprinopsis laanii, Cortinarius albolens, Cortinarius flexibilifolius, Cortinarius megacystidiosus, Cortinarius russulaespermus, Cortinarius tillamookensis, Inocybe assimilata, Laccaria chibinensis, Laccaria violaceibasis, Lactarius porninsis, Lycoperdon mammiforme, Marchandiomyces aurantiacus, Psathyrella pygmaea and Rectipilus fasciculatus are reported here as new to Finland. One genus of ascomycetoid fungi (Ascomycota): Balsamia and four species: Balsamia platyspora, Barbatosphaeria arboricola, Calycellina betulina and Geoglossum elongatum are reported here as new to Finland. A new combination for Belonium betulinum (under Calycellina betulina) is proposed. Information of species recently published elsewhere: Cortinarius alboamarescens, Cortinarius ochroamarus, Cortinarius pastoralis, Cortinarius fulvescentoideus, Cortinarius nymphatus, Cortinarius pseudobulliardioides, Cortinarius tenuifulvescens, Inocybe caprimulgi, Inocybe lacunarum, Inocybe substellata and Lamelloclavaria petersenii is brought here together. New records of little collected and rare taxa: Bovista tomentosa, Geastrum floriforme, Hygrophorus exiguus, Hysterangium crassum, Lactarius serifluus, Lepiota pseudolilacea, Leucopaxillus tricolor, Sarcosphaera coronaria, Scleroderma verrucosum, Squamanita contortipes, Tulostoma niveum and Volvariella reidii are also listed. Corrections of previous information are given on: Hysterangium coriaceum (under Hysterangium crassum) and Lepiota clypeolarioides (under Lepiota pseudolilacea)

Response Prediction in Chronic Hepatitis C by Assessment of IP-10 and IL28B-Related Single Nucleotide Polymorphisms

Background: High baseline levels of IP-10 predict a slower first phase decline in HCV RNA and a poor outcome following interferon/ribavirin therapy in patients with chronic hepatitis C. Several recent studies report that single nucleotide polymorphisms (SNPs) adjacent to IL28B predict spontaneous resolution of HCV infection and outcome of treatment among HCV genotype 1 infected patients. Methods and Findings: In the present study, we correlated the occurrence of variants at three such SNPs (rs12979860, rs12980275, and rs8099917) with pretreatment plasma IP-10 and HCV RNA throughout therapy within a phase III treatment trial (HCV-DITTO) involving 253 Caucasian patients. The favorable SNP variants (CC, AA, and TT, respectively) were associated with lower baseline IP-10 (P = 0.02, P = 0.01, P = 0.04) and were less common among HCV genotype 1 infected patients than genotype 2/3 (P<0.0001, P<0.0001, and P = 0.01). Patients carrying favorable SNP genotypes had higher baseline viral load than those carrying unfavorable variants (P = 0.0013, P = 0.029, P = 0.0004 respectively). Among HCV genotype 1 infected carriers of the favorable C, A, or T alleles, IP-10 below 150 pg/mL significantly predicted a more pronounced reduction of HCV RNA from day 0 to 4 (first phase decline), which translated into increased rates of RVR (62%, 53%, and 39%) and SVR (85%, 76%, and 75% respectively) among homozygous carriers with baseline IP-10 below 150 pg/mL. In multivariate analyses of genotype 1-infected patients, baseline IP-10 and C genotype at rs12979860 independently predicted the first phase viral decline and RVR, which in turn independently predicted SVR. Conclusions: Concomitant assessment of pretreatment IP-10 and IL28B-related SNPs augments the prediction of the first phase decline in HCV RNA, RVR, and final therapeutic outcome

Exploring GNSS crowdsourcing feasibility: Combinations of measurements for modeling smartphone and higher end GNSS receiver performance

GNSS receiver data crowdsourcing is of interest for multiple applications, e.g., weather monitoring. The bottleneck in this technology is the quality of the GNSS receivers. Therefore, we lay out in an introductory manner the steps to estimate the performance of an arbitrary GNSS receiver via the measurement errors related to its instrumentation. Specifically, we do not need to know the position of the receiver antenna, which allows also for the assessment of smartphone GNSS receivers having integrated antennas. Moreover, the method is independent of atmospheric errors so that no ionospheric or tropospheric correction services provided by base stations are needed. Error models for performance evaluation can be calculated from receiver RINEX (receiver independent exchange format)data using only ephemeris corrections. For the results, we present the quality of different receiver grades through parametrized error models that are likely to be helpful in stochastic modeling, e.g., for Kalman filters, and in assessing GNSS receiver qualities for crowdsourcing applications. Currently, the typical positioning precision for the latest smartphone receivers is around the decimeter level, while for a professional-grade receiver, it is within a few millimeters