PICO
Lately, multi-frequency GNSS signal availability have become more commonplace, while dual-frequency receiving capability, previously restricted to expensive geodetic-grade instruments, appeared in cost-efficient and low-cost receivers. Therefore, large networks of GNSS stations with high positioning accuracy can now be deployed at limited cost, benefitting a variety of geoscience applications.
To take advantage of the developments in dual-frequency capabilites, GFZ and spin-off company maRam developed the tinyBlack GNSS receiver. The tinyBlack is compact, robust, versatile and low-power. It is equipped with one of various GNSS receiver boards and can be integrated with additional sensors. It provides a flexible, economical solution for geoscientific monitoring stations for, e.g., tectonic, volcanic and earth engineering monitoring. We evaluate the geodetic performance of different dual-frequency receiver boards in the tinyBlack.
We conduct a zero-baseline test, comparing three different receiver boards (Septentrio AsteRx-m3, Ublox and SwiftNav Piksi) in a tinyBlack receiver and a separate, reference receiver (Septentrio PolaRx5). All boards have at least dual-frequency (L1/L2, E1/E5b) support and were simultaneously connected to a static geodetic choke-ring antenna. We first check data quality with GNut/Anubis, including observation availability, multipath linear combination, and signal-to-noise ratio. We then analyse PPP solutions with GFZ-provided precise orbits and satellite clock offsets, computing both daily and sub-daily kinematic coordinates. We compare observation residuals, coordinate estimates, and troposphere estimates. We find that the Ublox and Piksi receivers struggle more with multipath effects than the geodetic-grade receivers, despite using the same antenna in a good test location with a clear view of the sky. We also find that the Piksi has fewer observations, including a hard-coded low-elevation-angle cutoff. Probably as a consequence, it also the highest signal-to-noise ratio and lower residuals than the Piksi. PPP daily coordinate performance is vertically worse than, and horizontally comparable horizontally with, the cost-efficient receivers. Sub-daily coordinate performance is worst with the Piksi.
We also conduct a test step-wise moving antenna test to evaluate the capability of the Piksi receiver specifically to recover known displacement. We move the antenna by 5 cm every hour, alternatively forwards and backwards in a repeated 2-hour cycle, both horizontally (north-south) and vertically in separate tests. We compute kinematic PPP solutions with GFZ-provided precise orbits and clock offsets. We find that the average amplitude of the step can be recovered successfully and that both the standard deviation of the amplitudes and the scatter of coordinates at each point in the cycle is greater for the vertical component.
We finally perform data quality controls and show network-solution estimated coordinates of four GNSS stations in a field installations. The stations are co-located with seismometers installed in Italy as part of the DETECT (DEnse mulTi-paramEtriC observations and 4D high resoluTion imaging) project, which aims to acquire a dense multiparametric dataset imaging near-fault, active, slow tectonic deformation in a portion of the southern Apennines mountains with destructive historical seismicity.
In conclusion, we appreciate the developments spurred by the availability of dual-frequency signals and look forward to further field applications of dual-frequency receivers for geoscience research.
How to cite: D'Acquisto, M., Ramatschi, M., and Männel, B.: Cost-efficient dual-frequency GNSS receivers: quality assessment for geophysical applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7129, https://doi.org/10.5194/egusphere-egu25-7129, 2025.
As Global Navigation Satellite System (GNSS) positioning technology rapidly advances, Precise Point Positioning (PPP) has found widespread application in the mass market, particularly for vehicle navigation. PPP enhanced by atmospheric corrections was proven to be an effective rapid high-precision positioning method for wide-area users. The Quasi‐4‐Dimension Ionospheric Modeling (Q4DIM) is a flexible atmospheric model that enables enhanced PPP positioning from wide-area to regional applications. It divides the slant ionospheric delays (SIDs) from a station network into various clusters based on the latitude and longitude of the Ionosphere Piercing Point (IPP), satellite elevation, and satellite azimuth. These clusters are used for the correction of atmospheric errors in PPP and ionosphere monitoring. As devices capable of GNSS positioning become increasingly available in the mass market, effectively utilizing these observations could significantly reduce costs and broaden the range of rapid PPP services. In this contribution, we developed a crowdsourcing Q4DIM approach, where users upload SIDs verified for integrity to the cloud server, which classifies and stores the data based on accuracy, location, and the level of services utilized. Then, the cloud server constructs and disseminates diversity Q4DIM maps according to the different level attributes of SIDs. Finally, the users utilize the updated Q4DIM maps to achieve faster and more precise positioning. 144 sets of control experiments are conducted with observations from European Continuously Operating Reference Stations (CORS). Stations with an average inter-station distance of about 200 km are chosen as reference stations that are used for extracting the original Q4DIM map. The remaining stations are established as dynamically estimated crowdsourced stations for extracting the crowdsourced Q4DIM map. Results show that the performance of PPP enhanced by the crowdsourced Q4DIM map is significantly improved than those of the original Q4DIM map. The positioning error series of the original solution converges within 9 epochs to within 10 cm in the horizontal direction and 20 cm in the vertical direction, while the positioning error series of the crowdsourced solution reaches 2.3 cm in the horizontal direction and 7.6 cm in the vertical direction in 2 epochs. Compared to the original solution, the positioning accuracy of the new method improved by 48.2% in the horizontal direction and 41.2% in the vertical direction.
How to cite: Wang, B., Gu, S., Zhu, J., and Hu, J.: A Cost-Effective Crowdsourced Q4DIM Method for Rapid PPP Implementation in Wide Areas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3961, https://doi.org/10.5194/egusphere-egu25-3961, 2025.
The ionospheric delay is a major error source in the Global Navigation Satellite System (GNSS) positioning, and its accurate estimation is essential for Precise Point Positioning Real-Time Kinematic (PPP-RTK). Traditionally, ionospheric delay estimation relies on a network of permanently deployed high-end geodetic GNSS receivers, which are costly and thus inaccessible for most consumer applications. Moreover, this approach is limited by the sparse spatial distribution and low temporal resolution of the network, leading to significant estimation errors in uncovered environments.
On the other hand, due to the global density and accessibility of low-cost GNSS receivers, such as smartphones, there is a strong demand to develop new methods for precise ionospheric delay estimation using them. Moreover, multi-frequency and multi-constellation GNSS chipsets are now embedded in smartphones including carrier phase observations essential for precise positioning. These advances support the investigation and development of new methods to enable precise real-time GNSS positioning even using smartphones. However, few studies have focused on the application and evaluation of such methods for PPP-RTK positioning.
Therefore, this study aims to develop methods to estimate ionospheric effects using low-cost GNSS receivers and demonstrate that it can provide reliable ionospheric corrections. Additionally, we evaluated ionospheric corrections using two real-time satellite orbit, clock, and code bias products, namely the satellite-based BeiDou PPP-B2b and ground-based Centre National d’Etudes Spatiales (CNES). First, the ionospheric delay estimates generated by a single reference smartphone with uncombined PPP and quality control measures based on solution separation testing is evaluated using of the real-time satellite orbit, clock, and code bias products from BeiDou PPP-B2b and CNES, respectively. Next, the generated ionospheric delay from two correction models is compared to that produced by a high-end geodetic receiver. Finally, the generated ionospheric corrections are applied to single-station-based PPP-RTK to assess its positioning performance under kinematic conditions. A field test was conducted using two Google smartphones on April 7, 2024, in Calgary. We expect to achieve decimeter-level slant ionospheric corrections accuracy compared to geodetic receiver with the two correction models used. Additionally, the positioning accuracy is expected to approach that of PPP-RTK results using geodetic receivers as base stations, significantly outperforming float PPP.
How to cite: Zhang, Y., Jiang, Y., and Gao, Y.: Evaluation of the ionospheric corrections generated by smartphone and application to PPP-RTK, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14897, https://doi.org/10.5194/egusphere-egu25-14897, 2025.
The increasing availability and affordability of low-cost Global Navigation Satellite System (GNSS) systems have made them a viable alternative for various geospatial applications. However, their performance and positioning accuracy require rigorous evaluation, especially when compared to geodetic-grade GNSS systems. This study investigates the accuracy of low-cost GNSS systems in positioning by comparing their results with those obtained from high-precision geodetic GNSS systems.
To evaluate the performance of low-cost GNSS systems, campaign type GNSS measurements were conducted at four points using both low-cost and geodetic GNSS systems. The collected data were processed using the Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP) and the AUSPOS relative positioning services. The positioning results from these services were analyzed to assess the performance of low-cost GNSS systems relative to their geodetic counterparts. Preliminary findings indicate that low-cost GNSS systems exhibit promising accuracy levels in comparison to geodetic systems. The results highlight the potential and limitations of low-cost GNSS technology for scientific and practical applications.
This study contributes to the growing body of knowledge on low-cost GNSS technologies and provides insights into their applicability in fields such as tectonic monitoring and geodetic research. Future work will focus on refining processing techniques to further enhance the reliability of low-cost GNSS systems.
How to cite: Akpinar, B., Aydin, C., Özarpacı, S., Aykut, N. O., Özdemir, A., Oku Topal, G., Güneş, Ö., Karabulut, F., Ayruk, E. T., Çetinkaya, H., Turğut, M., Beytut, B. B., and Doğan, U.: Positioning Accuracy of Low-Cost GNSS Systems: A Comparative Study with Geodetic Solutions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19213, https://doi.org/10.5194/egusphere-egu25-19213, 2025.
In this study, we investigate the effect of antenna setup errors upon on the accuracy of position velocities produced from GNSS campaign measurements when gaps in data. Our motivation in this study is to demonstrate the changes in station velocities in time series caused by certain antenna measurement errors, in addition to the reduced frequency of data obtained from campaign-style measurements, which are preferred due to maintenance costs, permanent stations being damaged or even lost while monitoring natural events. We used seven stations from the continuous GPS time series of JPL, NASA from a global network of the IGS. For each station, we generated 1460 data for four years synthetic GNSS campaign time serieswithout gaps and 48 data with one measurement campaign per month. Subsequently, by creating data gaps through monthly campaigns, velocity estimates were made from datasets consisting of 32, 24, 16, and 8 data respectively. The same datasets were augmented with Gaussian noise simulating ±1-3 mm of antenna setup error. Velocity estimates were also made from these augmented datasets. Rms values calculated from antenna error-free datasets ranged between 0.1~0.5 mm for North, 0.2~0.5 mm for East, and 0.5~1.3 mm for Up directions. Rms values also calculated from antenna error datasets ranged between 0.2~0.9 mm for North, 0.2~0.7 mm for East, and 0.5~1.1 mm for Up directions. All velocity estimates were subjected to student t tests. About 1% variation was found for all components, both with and without antenna setup errors. The effect of antenna setup errors on data gaps in campaign-style measurements was demonstrated.
Keywords: GPS time series; GPS campaigns; Velocity estimation; Gaps in data; Antenna Setup Errors.
How to cite: Tuna, M. and Turen, Y.: The Effects of Antenna Setup Errors upon velocities of GNSS campaign measurement when gaps in data., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12633, https://doi.org/10.5194/egusphere-egu25-12633, 2025.
Developed since 2019, the CentipedeRTK network is a permanent collaborative GNSS network whose main objective is to make RTK positioning freely available, mainly using low-cost receivers and antennas. Since its creation, the network has grown considerably, well beyond the borders of France, and now includes more than 800 base stations. The main sector using the network is agriculture, but more and more public and private organisations and individuals are also using it.
The geoscience community quickly became interested in the network, first as users of RTK positioning (for sea level monitoring, drone surveys, etc.) and then for post-processing of the raw measurements from the base stations. Since mid-2022, the RENAG network data centre has therefore been archiving the data from the base stations on a daily basis with the aim of using them for geoscience applications. A first study based on data acquired in 2023 has demonstrated the value of these data for monitoring atmospheric water vapour over continental France.
Here we focus on the use of data acquired by CentipedeRTK base stations located in mainland France to monitor geophysical movements on a regional scale. To this end, the daily positions of the CentipedeRTK stations estimated in PPP using GipsyX are analysed and compared with those estimated for nearby permanent stations belonging to conventional networks. There is a slight deterioration in the repeatability of the mean positions (15 to 20% depending on the component). The time series show an increase in dispersion, but a very good consistency of the variations is still observed. The discrepancies observed can be explained by the equipment of the CentipedeRTK stations, in particular their antenna, as well as by the direct environment of the stations, which is not always as optimal as that of conventional stations.
These results will be used to develop a set of recommendations for CentipedeRTK contributors and will help to increase the value of the data collected by the network's base stations for geoscience applications.
How to cite: Bosser, P., Ancelin, J., Métois, M., Rolland, L., and Vidal, M.: Monitoring of geophysical deformations on a regional scale using the low-cost GNSS collaborative network CentipedeRTK , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11878, https://doi.org/10.5194/egusphere-egu25-11878, 2025.
A precise information on Snow Water Equivalent (SWE) and Liquid Water Content (LWC) is essential for various applications, e.g. for optimized operations of hydropower plants, for improved flood forecast, and for cryosphere research.
Global Navigation Satellite System (GNSS) receivers and antennas can be used to measure the snow water equivalent, snow height and liquid water content. The GNSS receivers are much more cost-effective and easy to install than other sensors such as snow scales and pillows. Our set-up consists of two GNSS receivers/ antennas, whereas one GNSS antenna is placed on the ground (i.e. below) the snow and serves as actual sensor.
The other GNSS antenna is placed on a pole above the snow and serves as reference antenna. We use the pseudorange, carrier phase and carrier to noise power ratio observables from both GPS and Galileo. The pseudorange and carrier phase measurements of both GNSS antennas are combined in double difference measurements to eliminate orbital errors, clock errors and atmospheric delays.
The snow has three effects on the GNSS signals: The first one is a time delay caused by the reduced speed of signal propagation in snow. The second effect is the refraction at the air-snow interface according to Snell's law. The third effect is the signal attenuation which is mainly driven by the LWC.
These three effects of the snow affect only the lower GNSS antenna, i.e. the double differencing does not eliminate the effects of the snow. It only eliminates the atmospheric delays being common to both GNSS antennas.
The presentation covers a precise modeling of GNSS carrier phase and pseudorange measurements, and a mathematical description of the SWE and LWC estimation from the GNSS carrier phase, pseudorange and carrier to noise power ratio measurements. We investigate different parameterizations and evaluate their impact on the SWE solution. We show the measurement results for a snow monitoring station of ANavS at an Alpine test-site for the complete previous winter period 2023/ 2024.
How to cite: Henkel, P., Lamm, M., and Koch, F.: Precise Estimation of Snow Water Equivalent based on GPS and Galileo Measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19702, https://doi.org/10.5194/egusphere-egu25-19702, 2025.
Global Navigation Satellite System (GNSS) technology, thanks to its high accuracy, is appropriate for monitoring structures, natural and anthropogenic hazards, as well as navigation and positioning. The Galileo High Accuracy Service (HAS) augmentation service recently released by the European Space Agency (ESA) is a new solution that could accelerate the development of mass-market technologies using the Global Navigation Satellite System (GNSS). Galileo HAS is designed to provide horizontal and vertical accuracies of 20 cm and 40 cm, respectively; it can be used in all legacy GNSS applications from structural monitoring to drone trajectory tracking using low-cost GNSS receivers.
This study evaluates the use of Galileo HAS with geodetic grade as well as low-cost receivers, analysing the results obtained in static, pseudo-kinematic, and kinematic solutions. The results indicate that Galileo HAS currently provides positioning accuracy at a to that comparable level of less than 10 cm, regardless of the use of geodetic or low-cost receivers. The results of integrating Galileo HAS with low-cost receivers show that it represents an important step in the development of available real-time positioning solutions.
In addition, the study showed that Galileo HAS meets key requirements in monitoring water vapour in the troposphere, as well as seismic displacement, by achieving real-time accuracy levels required for seismic displacement tracking and weather modelling. Comparative analyses with other GNSS correction streams show that HAS has lower accuracy in selected statistics, such as vertical accuracy. However, its near-global availability and high accuracy still make it a viable alternative.
How to cite: Marut, G., Hadas, T., Kazmierski, K., Kudłacik, I., and Bosy, J.: Advancing Real-Time GNSS Applications: Performance of Galileo HAS in Precision Navigation and Low-Cost Receiver Integration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8972, https://doi.org/10.5194/egusphere-egu25-8972, 2025.
Low-cost GNSS technology has recently expanded as an alternative to geodetic receivers in many applications, including pedestrian navigation, autonomous vehicles, atmospheric monitoring, and precision agriculture. Considering the capabilities of the receiver in terms of power consumption, size, and cost, together with the ability to record multi-GNSS observations, the low-cost receivers and patch antennas have appealed to many users. However, there exist some challenges to be addressed. Such hardware is inherently sensitive to the multipath effect, and the noise level in the observations is relatively higher, resulting in a lower carrier-to-noise density ratio (C/N0). More outliers are encountered for kinematic applications in challenging environments such as urban areas. Therefore, both realistic stochastic modeling (e.g., C/N0-dependent) and the identification of outlier observations are crucial issues for achieving reliable positioning when low-cost GNSS hardware is used. This study aims to investigate pedestrian navigation performance using low-cost GNSS and to enhance positioning accuracy through the implementation of the improved Single Point Positioning (SPP) algorithm, thanks to the code sequence. The technique employs a powerful quality control scheme to mitigate outlier observations. The method consists of two main steps: (i) If the products or measurements used for epoch-by-epoch solutions are troublesome for certain satellites, the median absolute deviation (MAD) method is applied to eliminate these observations. (ii) The remaining observations are then reweighted using a standardized residual-based Institute of Geodesy and Geophysics (IGG) III method during the least-squares. A kinematic test experiment was conducted to validate the usefulness of the approach for which observations were collected from four satellite systems with a 2-s sampling interval of approximately 20 min using a low-cost GNSS antenna (u-blox ANN-MB-00-00) and receiver (u-blox ZED-F9P). The multi-GNSS SPP solution with code observations of GPS L1, GLONASS G1, Galileo E1, and BDS-3 B1 frequencies was performed in this dataset. A GNSS station very close to the study area was used to obtain the reference trajectory with the post-process kinematic method. Analyzing only the fixed coordinates together with the corresponding SPP solution coordinates, resulted in an RMS value of about 0.50 m achieved in the horizontal component. Results showed how the utilization of proposed techniques can enhance basic SPP solutions that yield meter-level horizontal positioning accuracy. Moreover, the suggested technique improved multi-GNSS SPP solution RMS values by 33% in the horizontal and 19% in the vertical component compared with solutions without outlier detection. A comparison was also made using the findings from two distinct software packages to verify the consistency of the outcomes. The results of the evaluation indicate that the SPP algorithm exhibits comparable performance to that of the other software and validates the effectiveness of the employed technique. Finally, the GPS/GLONASS/Galileo/BDS-3 SPP, exhibiting a 3D RMS value slightly better than 2 m for pedestrian navigation, illustrates the capabilities of low-cost GNSS technology.
How to cite: Birinci, S., Sogukkuyu, F., and Saka, M. H.: Improving pedestrian navigation performance with robust methods for low-cost multi-GNSS , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11204, https://doi.org/10.5194/egusphere-egu25-11204, 2025.
