scholarly journals In-Orbit Results and Attitude Analysis of the SNUGLITE Cube-Satellite

2020 ◽  
Vol 10 (7) ◽  
pp. 2507
Author(s):  
O-Jong Kim ◽  
Hanjoon Shim ◽  
Sunkyoung Yu ◽  
Yonghwan Bae ◽  
Changdon Kee ◽  
...  
Keyword(s):  
Low Cost ◽  
Satellite System ◽  
Attitude Estimation ◽  
Unit Cube ◽  
The Sun ◽  
Solar Panels ◽  
Linear Quadratic ◽  
National University ◽  
Seoul National University ◽  
Global Navigation Satellite

SNUGLITE (Seoul National University Global navigation satellite system Laboratory satellITE) is a two-unit cube satellite (CubeSat) with dimensions 10 × 10 × 23 cm that requires an attitude system for missions and ground station telecommunication. A linear-quadratic-Gaussian-based optimal attitude system for the CubeSat platform has been developed using low-cost sensors, with the in-orbit verification of the attitude system being is one of main study objectives. Since launch, the SNUGLITE CubeSat has continuously broadcast in-orbit status information. In this study, a methodology for the analysis of in-orbit attitude estimation results using received data is presented, and this was achieved by comparing two sun-pointing vectors, i.e., the sun-pointing vector calculated using estimated attitude with the positions of the sun and the satellite and the reference vector generated by the power levels of the solar panels. Because the satellite position was required for the attitude analysis, the verification of the performance of the own-developed on-board Global Positioning System (GPS) receiver is also briefly described. Analyses indicate that the attitude estimation of the SNUGLITE CubeSat has achieved an in-orbit real-time pointing accuracy with a root mean square of 6.1°.

Comparison and generalization of GNSS satellite attitude models

2021 ◽  
Author(s):  
Sebastian Strasser ◽  
Simon Banville ◽  
Andreas Kvas ◽  
Sylvain Loyer ◽  
Torsten Mayer-Gürr
Keyword(s):  
Orbital Plane ◽  
Satellite System ◽  
The Sun ◽  
Solar Panels ◽  
International Gnss Service ◽  
Satellite Attitude ◽  
Technological Advances ◽  
Steering Law ◽  
Global Navigation Satellite ◽  
Yaw Angle

<p>Global navigation satellite system (GNSS) constellations such as GPS, GLONASS, Galileo, and BeiDou and the Japanese regional system QZSS apply various satellite attitude modes during eclipse season, which is the period when the Sun is close to the orbital plane of the satellite. Due to different satellite manufacturers and technological advances over time, these modes can vary between constellations but also between different satellite types within a constellation. For some constellations, namely Galileo and QZSS, the satellite attitude law has been officially published by the satellite operator. For most other GNSS satellite types, researchers have developed attitude models, for example using reverse kinematic precise point positioning, that approximate the actual attitude behaviour.</p><p>Outside of eclipse seasons, GNSS satellites generally apply either a nominal yaw-steering or an orbit normal attitude law. While both modes point the antennas towards Earth, the former yaws the satellite around the antenna axis to point the solar panels towards the Sun, while the latter always keeps a fixed yaw angle. When a satellite applying a yaw-steering law is in eclipse season and close to the orbit noon or midnight point, it may have to yaw faster than physically possible to keep the nominal attitude. The various attitude modes used by the satellites aim to prevent this scenario by applying a modified attitude law during this period, for example by yawing at a constant rate around orbit noon/midnight or by switching to orbit normal mode.</p><p>Comparisons of attitude files generated by analysis centers of the International GNSS Service (IGS) within the scope of its 3<sup>rd</sup> reprocessing campaign show significant differences in some cases. This contribution compares all available attitude models with the aim of finding similarities that allow for generalization, which in turn simplifies the implementation of the various attitude modes into GNSS software packages. The developed functions have been implemented into the open-source software GROOPS (https://github.com/groops-devs/groops), which makes them publicly available and documented.</p>

scholarly journals Design of a Multiband Global Navigation Satellite System Radio Frequency Interference Monitoring Front-End with Synchronized Secondary Sensors

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2594
Author(s):  
Aiden Morrison ◽  
Nadezda Sokolova ◽  
James Curran
Keyword(s):  
Radio Frequency ◽  
Global Navigation Satellite System ◽  
Low Cost ◽  
Satellite System ◽  
Radio Frequency Interference ◽  
Navigation Satellite ◽  
Inertial Measurement ◽  
Front End ◽  
Global Navigation ◽  
Global Navigation Satellite

This paper investigates the challenges of developing a multi-frequency radio frequency interference (RFI) monitoring and characterization system that is optimized for ease of deployment and operation as well as low per unit cost. To achieve this, we explore the design and development of a multiband global navigation satellite system (GNSS) front-end which is intrinsically capable of synchronizing side channel information from non-RF sensors, such as inertial measurement units and integrated power meters, to allow the simultaneous production of substantial amounts of sampled spectrum while also allowing low-cost, real-time monitoring and logging of detected RFI events. While the inertial measurement unit and barometer are not used in the RFI investigation discussed, the design features that provide for their precise synchronization with the RF sample stream are presented as design elements worth consideration. The designed system, referred to as Four Independent Tuners with Data-packing (FITWD), was utilized in a data collection campaign over multiple European and Scandinavian countries in support of the determination of the relative occurrence rates of L1/E1 and L5/E5a interference events and intensities where it proved itself a successful alternative to larger and more expensive commercial solutions. The dual conclusions reached were that it was possible to develop a compact low-cost, multi-channel radio frequency (RF) front-end that implicitly supported external data source synchronization, and that such monitoring systems or similar capabilities integrated within receivers are likely to be needed in the future due to the increasing occurrence rates of GNSS RFI events.

scholarly journals GNSS-Acoustic Observations of Seafloor Crustal Deformation Using a Wave Glider

2021 ◽  
Vol 9 ◽  
Author(s):  
Takeshi Iinuma ◽  
Motoyuki Kido ◽  
Yusaku Ohta ◽  
Tatsuya Fukuda ◽  
Fumiaki Tomita ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Crustal Deformation ◽  
Satellite Communication ◽  
Satellite System ◽  
Japan Trench ◽  
Research Vessel ◽  
Solar Panels ◽  
Wave Glider ◽  
Human Costs ◽  
Global Navigation Satellite

Crustal deformation of the seafloor is difficult to observe solely using global navigation satellite system (GNSS). The GNSS-acoustic (GNSS-A) technique was developed to observe seafloor crustal deformation, and it has produced a steady series of successful observations with remarkable results related to crustal deformation associated with huge earthquakes around the Japanese Islands. However, utilizing GNSS-A incurs very large financial and human costs as it requires the use of a research vessel as a surface platform and has a limited observation frequency, which is less than once a year at seafloor stations along the Japan Trench. To conduct frequent observations, an automatic GNSS-A data acquisition system was developed that operates via an unmanned surface vehicle (wave glider). The first observations using this system were performed at a seafloor station off Aomori Prefecture in July 2019. The wave glider was equipped with two GNSS antennas, an acoustic transducer, a microelectromechanical system gyroscope, and associated control and logging units. Data acquisition and autonomous activation of the seafloor stations were successfully executed by controlling the power supply to the payload via satellite communication with the wave glider. The glider rarely strayed off the configured course and the solar panels generated sufficient power to perform the observations although the weather was mostly cloudy. The GNSS-A data processing results show that the position of the station was determined with the same accuracy and precision as in previous observations performed using a research vessel.

scholarly journals Kinematic PPP Using Mixed GPS/Glonass Single-Frequency Observations

2019 ◽  
Vol 54 (3) ◽  
pp. 97-112
Author(s):  
Mostafa Hamed ◽  
Ashraf Abdallah ◽  
Ashraf Farah
Keyword(s):  
Low Cost ◽  
Satellite System ◽  
Single Frequency ◽  
Future Research ◽  
Frequency Data ◽  
Dual Frequency ◽  
Trajectory Data ◽  
Average Improvement ◽  
Kinematic Ppp ◽  
Global Navigation Satellite

Abstract Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Single-frequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-frequency, GPS/GLONASS GNSS receiver and single-frequency data have been processed. Net_Diff software was used for processing all the data. The results have been compared with a reference solution. Adding GLONASS satellites significantly improved the satellite number and Position Dilution Of Precision (PDOP) value and accordingly improved the accuracy of positioning. In the case of “ADIS” data, the 3D Root Mean Square Error (RMSE) ranged between 0.273 and 0.816 m for GPS only and improved to a range from 0.256 to 0.550 m for GPS/GLONASS for the 6 processed days. An average improvement ratio of 24%, 29%, 30%, and 29% in the east, north, height, and 3D position components, respectively, was achieved. For the kinematic trajectory, the 3D position RMSE improved from 0.733 m for GPS only to 0.638 m for GPS/GLONASS. The improvement ratios were 7%, 5%, 28%, and 13% in the east, north, height, and 3D position components, respectively, for the kinematic trajectory data. This opens the way to add observations from the other two constellations (Galileo and BeiDou) for more accuracy in future research.

scholarly journals Terrain changes from images acquired on opportunistic flights by SfM photogrammetry

2017 ◽  
Vol 11 (2) ◽  
pp. 827-840 ◽  
Author(s):  
Luc Girod ◽  
Christopher Nuth ◽  
Andreas Kääb ◽  
Bernd Etzelmüller ◽  
Jack Kohler
Keyword(s):  
Low Cost ◽  
Rapid Change ◽  
Satellite System ◽  
Light Transport ◽  
Area Of Interest ◽  
Accuracy And Precision ◽  
Global Navigation Satellite ◽  
The Cost ◽  
Gnss Data

Abstract. Acquiring data to analyse change in topography is often a costly endeavour requiring either extensive, potentially risky, fieldwork and/or expensive equipment or commercial data. Bringing the cost down while keeping the precision and accuracy has been a focus in geoscience in recent years. Structure from motion (SfM) photogrammetric techniques are emerging as powerful tools for surveying, with modern algorithm and large computing power allowing for the production of accurate and detailed data from low-cost, informal surveys. The high spatial and temporal resolution permits the monitoring of geomorphological features undergoing relatively rapid change, such as glaciers, moraines, or landslides. We present a method that takes advantage of light-transport flights conducting other missions to opportunistically collect imagery for geomorphological analysis. We test and validate an approach in which we attach a consumer-grade camera and a simple code-based Global Navigation Satellite System (GNSS) receiver to a helicopter to collect data when the flight path covers an area of interest. Our method is based and builds upon Welty et al. (2013), showing the ability to link GNSS data to images without a complex physical or electronic link, even with imprecise camera clocks and irregular time lapses. As a proof of concept, we conducted two test surveys, in September 2014 and 2015, over the glacier Midtre Lovénbreen and its forefield, in northwestern Svalbard. We were able to derive elevation change estimates comparable to in situ mass balance stake measurements. The accuracy and precision of our DEMs allow detection and analysis of a number of processes in the proglacial area, including the presence of thermokarst and the evolution of water channels.

scholarly journals GNSS-ISE: Instruction Set Extension for GNSS Baseband Processing

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 465 ◽  
Author(s):  
Krzysztof Marcinek ◽  
Witold A. Pleskacz
Keyword(s):  
Flash Memory ◽  
Low Cost ◽  
Satellite System ◽  
Microprocessor System ◽  
Instruction Set ◽  
Advantages And Disadvantages ◽  
Wide Range ◽  
Instruction Set Extension ◽  
Baseband Processing ◽  
Global Navigation Satellite

This work presents the results of research toward designing an instruction set extension dedicated to Global Navigation Satellite System (GNSS) baseband processing. The paper describes the state-of-the-art techniques of GNSS receiver implementation. Their advantages and disadvantages are discussed. Against this background, a new versatile instruction set extension for GNSS baseband processing is presented. The authors introduce improved mechanisms for instruction set generation focused on multi-channel processing. The analytical approach used by the authors leads to the introduction of a GNSS-instruction set extension (ISE) for GNSS baseband processing. The developed GNSS-ISE is simulated extensively using PC software and field-programmable gate array (FPGA) emulation. Finally, the developed GNSS-ISE is incorporated into the first-in-the-world, according to the authors’ best knowledge, integrated, multi-frequency, and multi-constellation microcontroller with embedded flash memory. Additionally, this microcontroller may serve as an application processor, which is a unique feature. The presented results show the feasibility of implementing the GNSS-ISE into an embedded microprocessor system and its capability of performing baseband processing. The developed GNSS-ISE can be implemented in a wide range of applications including smart IoT (internet of things) devices or remote sensors, fostering the adaptation of multi-frequency and multi-constellation GNSS receivers to the low-cost consumer mass-market.

scholarly journals Testing Multi-Frequency Low-Cost GNSS Receivers for Geodetic Monitoring Purposes

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4375
Author(s):  
Veton Hamza ◽  
Bojan Stopar ◽  
Tomaž Ambrožič ◽  
Goran Turk ◽  
Oskar Sterle
Keyword(s):  
Low Cost ◽  
Base Point ◽  
Satellite System ◽  
Gnss Receivers ◽  
The Difference ◽  
Short Baselines ◽  
Height Component ◽  
Global Navigation Satellite ◽  
High Level ◽  
Positional Precision

Global Navigation Satellite System (GNSS) technology is widely used for geodetic monitoring purposes. However, in cases where a higher risk of receiver damage is expected, geodetic GNSS receivers may be considered too expensive to be used. As an alternative, low-cost GNSS receivers that are cheap, light, and prove to be of adequate quality over short baselines, are considered. The main goal of this research is to evaluate the positional precision of a multi-frequency low-cost instrument, namely, ZED-F9P with u-blox ANN-MB-00 antenna, and to investigate its potential for displacement detection. We determined the positional precision within static survey, and the displacement detection within dynamic survey. In both cases, two baselines were set, with the same rover point equipped with a low-cost GNSS instrument. The base point of the first baseline was observed with a geodetic GNSS instrument, whereas the second baseline was observed with a low-cost GNSS instrument. The results from static survey for both baselines showed comparable results for horizontal components; the precision was on a level of 2 mm or better. For the height component, the results show a better performance of low-cost instruments. This may be a consequence of unknown antenna calibration parameters for low-cost GNSS antenna, while statistically significant coordinates of rover points were obtained from both baselines. The difference was again more significant in the height component. For the displacement detection, a device was used that imposes controlled movements with sub-millimeter accuracy. Results, obtained on a basis of 30-min sessions, show that low-cost GNSS instruments can detect displacements from 10 mm upwards with a high level of reliability. On the other hand, low-cost instruments performed slightly worse as far as accuracy is concerned.

A Novel GNSS Attitude Determination Method Based on Primary Baseline Switching for A Multi-Antenna Platform

2020 ◽  
Vol 12 (5) ◽  
pp. 747
Author(s):  
Peng Zhang ◽  
Yinzhi Zhao ◽  
Huan Lin ◽  
Jingui Zou ◽  
Xinzhe Wang ◽  
...  
Keyword(s):  
Attitude Determination ◽  
Low Cost ◽  
Satellite System ◽  
Poor Quality ◽  
Integrated Navigation ◽  
Determination Method ◽  
Integrated Navigation System ◽  
Determination System ◽  
Vehicle Test ◽  
Global Navigation Satellite

The global navigation satellite system (GNSS)-based attitude determination system has attracted more and more attention with the advantages of having simplified algorithms, a low price and errors that do not accumulate over time. However, GNSS signals may have poor quality or lose lock in some epochs with the influence of signal fading and the multipath effect. When the direct attitude determination method is applied, the primary baseline may not be available (ambiguity is not fixed), leading to the inability of attitude determination. With the gradual popularization of low-cost receivers, making full use of spatial redundancy information of multiple antennas brings new ideas to the GNSS-based attitude determination method. In this paper, an attitude angle conversion algorithm, selecting an arbitrary baseline as the primary baseline, is derived. A multi-antenna attitude determination method based on primary baseline switching is proposed, which is performed on a self-designed embedded software and hardware platform. The proposed method can increase the valid epoch proportion and attitude information. In the land vehicle test, reference results output from a high-accuracy integrated navigation system were used to evaluate the accuracy and reliability. The results indicate that the proposed method is correct and feasible. The valid epoch proportion is increased by 16.2%, which can effectively improve the availability of attitude determination. The RMS of the heading, pitch and roll angles are 0.52°, 1.25° and 1.16°.

scholarly journals RTK GNSS-Assisted Terrestrial SfM Photogrammetry without GCP: Application to Coastal Morphodynamics Monitoring

2020 ◽  
Vol 12 (11) ◽  
pp. 1889 ◽  
Author(s):  
Marion Jaud ◽  
Stéphane Bertin ◽  
Mickaël Beauverger ◽  
Emmanuel Augereau ◽  
Christophe Delacourt
Keyword(s):  
Standard Deviation ◽  
Low Cost ◽  
Laser Scanner ◽  
Satellite System ◽  
Mean Error ◽  
Ground Control Points ◽  
Participatory Science ◽  
Gnss Network ◽  
Global Navigation Satellite

The present article describes a new and efficient method of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) assisted terrestrial Structure-from-Motion (SfM) photogrammetry without the need for Ground Control Points (GCPs). The system only requires a simple frame that mechanically connects a RTK GNSS antenna to the camera. The system is low cost, easy to transport, and offers high autonomy. Furthermore, not requiring GCPs enables saving time during the in situ acquisition and during data processing. The method is tested for coastal cliff monitoring, using both a Reflex camera and a Smartphone camera. The quality of the reconstructions is assessed by comparison to a synchronous Terrestrial Laser Scanner (TLS) acquisition. The results are highly satisfying with a mean error of 0.3 cm and a standard deviation of 4.7 cm obtained with the Nikon D800 Reflex camera and, respectively, a mean error of 0.2 cm and a standard deviation of 3.8 cm obtained with the Huawei Y5 Smartphone camera. This method will be particularly interesting when simplicity, portability, and autonomy are desirable. In the future, it would be transposable to participatory science programs, while using an open RTK GNSS network.

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