GNSS hardware biases appear in code and phase observations, and originates both from the receiver and satellite hardware. These biases influence the accuracy in precise GNSS positioning if not handled properly. This thesis is based on two papers, where one is a review paper published in GPS Solutions, and the other is a research paper currently in review (resubmitted after minor revision) for Journal of Geodetic Science. The first paper compiles current results and gives an overview of those situations where biases are of the greatest importance for precise positioning. The second paper investigates the satellite dependency in two cases of relative phase biases. In the first paper, a review is given on how hardware biases influence precise GNSS positioning in various situations. These can roughly be divided into five cases: positioning not employing the ionosphere free combination to which the satellite clock corrections are aligned, GNSS based ionospheric modeling, determination of the phase ambiguity as an integer in PPP, and positioning with GLONASS. In the second paper, the satellite dependency for two cases of relative phase biases are investigated: relative between-receiver biases in single differenced phase observations from two receivers, relative between-signals biases in observation differences between two signals recorded by the same receiver and associated with the same carrier frequency. In both these cases a satellite dependency was discovered. The first case showed a difference of 0.8 mm between the greatest and smallest values, while the corresponding difference in the second case was 3.5 mm. It was also discovered that the biases in the first case varied periodically over time, and with a period of one sidereal day. The exact cause for these variations could however not be determined in the experiment, even though multipath could be excluded as their source. / Hårdvaru-relaterade biases kan beskrivas som små systematiska fel som uppkommer i kod- och bärvågs-observationer vid GNSS-mätning. Dessa uppstår i hårdvaran hos både satellit och mottagare, och inverkar på positionsosäkerheten vid noggrann GNSS-positionering om de inte hanteras. Denna avhandling är baserad på två artiklar, varav den ena är publicerad i GPS Solutions, och den andra är under granskning (återinskickad efter en mindre omarbetning) för Journal of Geodetic Science. Den första artikeln ger en överblick över hårdvaru-relaterade biases och de situationer då de är som mest betydelsefulla för noggrann positionering. Den andra artikeln undersöker om det eventuellt existerar ett satellit-beroende hos två fall av hårdvaru-relaterade biases för bärvågsobservationer. I den första artikeln tas fem fall upp som är särskilt betydelsefulla gällande hårdvaru-relaterade biases. Dessa är: positionering som inte använder den jonosfärsfria linjärkombination av GNSS-observationer som mottagna satellit-klock-korrektioner är anpassade för, GNSS-baserad jonosfärsmodellering, heltalsbestämning av periodobekanta vid PPP-positionering, positionering med flera GNSS-system, och positionering med Glonass specifikt. I den andra artikeln undersöks satellit-beroendet för två fall: relativa bärvågsobservationer mellan två mottagare, relative bärvågsobservationer mellan två signaler observerade av samma mottagare och med samma bärvågsfrekvens. I båda fallen upptäcktes ett satellitberoende. Variationerna i första fallet visade en differens mellan största och minsta värdet på ungefär 0.8 mm, medan motsvarande värde i andra fallet var ungefär 3.5 mm. Det visade sig också att hårdvaru-relaterade biases i det första fallet varierade periodiskt över tiden, med en period av ett sideriskt dygn. Den exakta orsaken för dessa variationerna kunde ej bestämmas, även om flervägsstörningar kunde uteslutas som källa. / <p>QC 20170926</p>

This master's project deals with location based systems and their application in information distribution. The work discuss kinds of getting actual location. Then it focuses on problems of developing applications and description of Microsoft technologies for mobile devices. Based on obtained theoretical information we present design, implementation and testing of our own location based system.

Due to the current research needs and the lack of commercial multi-channel, multi-constellation GNSS receivers, a two-board solution has been developed so it can be mated with and take advantage of the processing power of the FPGA board branded as MicroZed. In order to achieve the proposed goals, an initial phase for assessing and updating the older design, building, and testing of SiGe modules (including both the electronics and casings) has been carried out. The results included demonstrate performances at logging GPS-L1 data with similar C/N0 and AGC values as the previous versions of the modules and offering navigation solutions with accuracies of a few meters. Secondly, a first iteration and design proposal for the new generation receiver has been proposed for GPS and GLONASS L1 and L2, which has been manufactured and tested. Partial tests have been performed due to the flaws of the current revision of the MicroZed Board in regards to its communication peripherals, and the results have validated the receiver’s design provided certain modifications are considered for future iterations. Furthermore, voltage and frequency tests have provided results with an error of less than 7%, and signal tests have provided C/N0 values similar to those of the SiGe modules of around 47[dB-Hz] which will be a useful baseline for future iterations. Finally, a design proposal for an Interface Board used between the older NT1065_PMOD Board and other FPGA boards carrying the standardized FMC connectors has been added to the report and negotiations with manufacturers have been engaged.

Radio astronomy is the science of observing the heavens at radio frequencies, from a few kHz to approximately 300 GHz. In recent years, radio astronomy has faced a growing interference problem as radio frequency (RF) bandwidth has become an increasingly scarce commodity. A programmable real-time DSP least-mean-square interference canceller was developed and demonstrated as a successful method of excising satellite down-link signals from both an experimental platform at BYU, and the Green Bank Telescope at the National Radio Astronomy Observatory in West Virginia. A performance analysis of this cancellation system in the radio astronomy radio frequency interference (RFI) mitigation regime constitutes the main contribution of this thesis. The real-time BYU test platform consists of small radio telescopes, low noise RF receivers, and a state-of-the-art DSP platform. This programmable real-time radio astronomy RFI mitigation tool is the first of its kind. Basic tools needed for radio astronomy observations and the analysis and implementation of interference mitigation algorithms were also implemented in the DSP platform, including a power spectral density estimator, a beamformer, and an array signal correlator.