1,720,988 research outputs found
Testing a GNSS software receiver for end-user utilization
No full textSoftware Defined Receivers(SDR) can be a very useful tools both for researchers and surveyors since it is capable of extreme customization allowing user to access, visualize and modify signal processing blocks. In this paper we test the single point performance of the GNSS-SDR software receiver coupled with Nuand BladeRF x40 front-end feeded by an active u-blox GNSS antenna powered by a bias-tee needful to provide external gain. Four different tests have been carried out in two different scenarios located in Naples (Italy) employing two different antennas: the first dataset was acquired in a site expected to be a low-multipath environment while the second in a strong multipath scenario in Centro Direzionale (CDN) site using the same instrumentation. Both tests were carried out with two different antennas. Results achieved show how SDR is a good candidate to represent an innovative low-cost and flexible platform which can be used to get intermediate frequency data useful in the field of GNSS reflectometry and ionospheric scintillation analysis
Low-Cost Hardware PPP-RTK AR Time-to-Fix and Positioning Performance Assessment: A Preliminary Static Test
No full textOver the last years, researchers are struggling to develop solutions and services for smart and sustainable urban mobility creating dynamic shared spaces for both vehicles and pedestrians. Also, the deployment of autonomous vehicles has boosted the interest in precise, accurate, and robust position, navigation, and timing (PNT). Most of these services will be based primarily on the location of the vehicle relative to other vehicles, objects, and pedestrians in its vicinity. Therefore, the importance of a robust, ubiquitous, and reliable PNT can’t be overlooked. In the mass-market scenario, the challenge will be developing low-cost navigation equipment capable of providing navigation solutions that meet the accuracy, integrity, continuity, and availability requirements. This paper reports some preliminary tests aiming to investigate the phase-ambiguity fixing performance of a commercial precise point positioning real-time kinematic (PPP-RTK) correction service, employing a low-cost receiver. To assess the ambiguity resolution performance, we forced the receiver to restart the ambiguity search generating enough samples for statistic analysis. In this test, PPP-RTK has revealed a promising technique for decimetre-level accuracy positioning with low-cost receivers. Integer ambiguity fixed solutions reveal a DRMS of 0.09 m whereas float solutions reveal a DRMS of 0.45 m. When PPP-RTK corrections are not available, SPP/DGNSS solutions reveal a DRMS of 1.36 m. The test showed that the employment of cost-effective equipment along with the exploitation of correction services allows reaching decimetre/sub-metre accuracy in about 20 s and sub-decimetre accuracy in about 2 min once the integer ambiguity is fixed
Low-cost GNSS software receiver performance assessment
Full text linkThe Software-Defined Receiver (SDR) is a rapidly evolving technology which is a useful tool for researchers and allows users an extreme level customization. The main aim of this work is the assessment of the performance of the combination consisting of the Global Navigation Satellite Systems software receiver (GNSS-SDR), developed by CTTC (Centre Tecnològic de Telecomunicacions de la Catalunya), and a low-cost front-end. GNSS signals were acquired by a Nuand bladeRF x-40 front-end fed by the TOPCON PG-A1 antenna. Particular attention was paid to the study of the clock-steering mechanism due to the low-cost characteristics of the bladeRF x-40 clock. Two different tests were carried out: In the first test, the clock-steering algorithm was activated, while in the second, it was deactivated. The tests were conducted in a highly degraded scenario where the receiver was surrounded by tall buildings. Single-Point and Code Differential positioning were computed. The achieved results show that the steering function guarantees the availability of more solutions, but the DRMS is quite the same in the two tests
GNSS software defined receiver pseudorange error assessment
No full textSDR approach, applied to the field of GNSS, allows the implementation of high customizable low-cost GNSS Software Defined receivers. These can reveal as useful tools for navigation algorithms prototyping. In the FOSS scenario the most interesting SDR appears to be GNSS-SDR. In this paper we evaluate GPS L1 pseudorange error GNSS observations acquired by SDR; for this purpose a low-cost COTS u-blox GNSS receiver has been employed as term of comparison. Preliminary results suggest that SDR pseudorange are noisier than u-blox ones and this will probably reflect in the degradation of the single point solutions
Positioning Domain Assessment of Multi Constellation Dual Frequency Lowcost Receivers in an Highly Degraded Scenario
No full textThe objective of this paper is to test in a degraded environment the performances of two different type of low-cost GNSS receivers. The first one is a typical low-cost hardware: the u-blox ZED-F9P GNSS module interfaced with u-center evaluation and a commercial front-end while the second one is a Software-Defined Receiver (SDR) software developed by Centre Tecnològic Telecomunicacions Catalunya coupled with a Nuand BladeRF x40. In order to investigate the performance of the hardware involved we applied our analysis to the measurements captured in a strong multipath scenario. Four different tests have been carried out employing the two receivers and coupled with two different antennas. Results achieved shows that the employment of the more performing antenna leads to better positioning results. The DRMS (Distance Root Mean Square) of horizontal position errors decreases of about the 54% and the 40% for the SDR and the u-blox, respectively. Nonetheless, the Nuand bladeRF shows poor positioning results with respect to those obtained with u-blox. The results achieved shows that Nuand is not yet suitable for surveying purposes. The reason resides in the poor quality of the reference clock of the on-board oscillator that doesn’t assure an appropriate stability
Low-Cost GNSS and PPP-RTK: Investigating the Capabilities of the u-blox ZED-F9P Module
No full textGNSS has become ubiquitous in high-precision applications, although the cost of high-end GNSS receivers remains a major obstacle for many applications. Recent advances in GNSS receiver technology have led to the development of low-cost GNSS receivers, making high-precision positioning available to a wider range of users. One such technique for achieving high-precision positioning is Precise Point Positioning-Real Time Kinematic (PPP-RTK). It is a GNSS processing technique that combines the PPP and RTK approaches to provide high-precision positioning in real time without the need for a base station. In this work, we aim to assess the performance of the low-cost u-blox ZED-F9P GNSS module in PPP-RTK mode using the low-cost u-blox ANN-MB antenna. The experiment was designed to investigate both the time it takes the receiver to resolve the phase ambiguity and to determine the positioning accuracies achievable. Results showed that the u-blox ZED-F9P GNSS module could achieve centimeter-level positioning accuracy in about 60 s in PPP-RTK mode. These results make the PPP-RTK technique a good candidate to fulfill the demand for mass-market accurate and robust navigation since uses satellite-based corrections to provide accurate positioning information without the need for a local base station or network. Furthermore, due to its rapid acquisition capabilities and accurate data georeferencing, the technique has the potential to serve as a valuable method to improve the accuracy of the three-S techniques (GIS, remote sensing, and GPS/GNSS)
Developing a low-cost GNSS/IMU data fusion platform for boat navigation
No full textMethods of measuring a vessel's motioninvolve the use of expensive and complex Inertial Navigation Systems (INS). Cargo or passenger transport ships can afford the implementation of such systems while private small boat market has been cut off. The alternatives for small boat INS navigation are few. This paper investigates the potentiality of GNSS/IMU data fusion, experimenting low-cost hardware like Aceinna openIMU 300ZI and a GNSS receiver based on u-blox ZED-F9P module. The final goal is to build a lowcost self-powered system and assess the performance in small boats navigation tests. To address this goal the INS shall be light-weight, cost-effective, and easy to- install
Structure-from-Motion 3D Reconstruction of the Historical Overpass Ponte della Cerra: A Comparison between MicMac® Open Source Software and Metashape®
Full text linkIn recent years, the performance of free-and-open-source software (FOSS) for image processing has significantly increased. This trend, as well as technological advancements in the unmanned aerial vehicle (UAV) industry, have opened blue skies for both researchers and surveyors. In this study, we aimed to assess the quality of the sparse point cloud obtained with a consumer UAV and a FOSS. To achieve this goal, we also process the same image dataset with a commercial software package using its results as a term of comparison. Various analyses were conducted, such as the image residuals analysis, the statistical analysis of GCPs and CPs errors, the relative accuracy assessment, and the Cloud-to-Cloud distance comparison. A support survey was conducted to measure 16 markers identified on the object. In particular, 12 of these were used as ground control points to scale the 3D model, while the remaining 4 were used as check points to assess the quality of the scaling procedure by examining the residuals. Results indicate that the sparse clouds obtained are comparable. MicMac® has mean image residuals equal to 0.770 pixels while for Metashape® is 0.735 pixels. In addition, the 3D errors on control points are similar: the mean 3D error for MicMac® is equal to 0.037 m with a standard deviation of 0.017 m, whereas for Metashape®, it is 0.031 m with a standard deviation equal to 0.015 m. The present work represents a preliminary study: a comparison between software packages is something hard to achieve, given the secrecy of the commercial software and the theoretical differences between the approaches. This case study analyzes an object with extremely complex geometry; it is placed in an urban canyon where the GNSS support can not be exploited. In addition, the scenario changes continuously due to the vehicular traffic
A low-cost multi-GNSS PPP-RTK solution for precision agriculture: a preliminary test
No full textThe agriculture and food sector will increasingly play a major role in the well-being of humanity. World-scale events, such as wars, climate changes, desertification, pandemic, etc., revealed how fragile humanity is from the point of view of food supply. Therefore, precision farming can provide a remarkable positive contribution to the primary sector globally at various levels. Nowadays, the employment of platforms for product data capture related to farming production and management is extensively available in several fields through local devices. Those systems comprehend sensors, automatic guidance systems with Global Navigation Satellite Systems (GNSSs), and central processing systems. Specifically, GNSS technology plays a central role in the autonomous guidance of tractors and farming robots. Until some years ago, high accuracy was a prerogative of expensive geodetic receivers whereas today high accuracy can be achieved also with low-cost receivers thanks to several factors, among all: the increased availability of GNSS interoperable constellations as well as the accessibility to several augmentation techniques both satellite-and ground-based. These factors are triggering the diffusion of autonomous machinery for farming purposes. This research aims to investigate the performance of a commercial Precise Point Positioning-Real Time Kinematic (PPP-RTK) correction service, employing a low-cost receiver. Two tests have been carried out with two different-grade antennas (a geodetic and a low-cost one). The tests showed that the employment of cost-effective equipment along with the exploitation of correction services allows reaching subdecimetre-level precision in less than one minute when employing a geodetic antenna; accuracy slightly degrades to decimetre-level with the low-cost antenna but the integer ambiguity is resolved in less time. Mean time-to-fix attests to 57 s for test 1 (geodetic antenna) and 30 s for test 2 (low-cost antenna). The times to obtain the first float ambiguity solution are equal to about 15 s for both tests. Integer ambiguity fixed solutions reveal a DRMS of 0.09 m and 0.012 m for test 1 and test 2, respectively. Float solutions reach a DRMS of 0.45 m and 0.63 m for test 1 and test 2, respectively. Lastly, when corrections are not available at all, single point positioning solutions reveal a DRMS of 1.36 m for test 1 and 3.15 m for test 2
GNSS-SDR pseudorange quality and single point positioning performance assessment
No full textIn recent years, we have witnessed a growing demand for GNSS receiver customization in terms of modification of signal acquisition, tracking, and processing strategies. Such demands may be addressed by software-defined receivers (SDRs) which refers to an ensemble of hardware and software technologies and allows re-configurable radio communication architectures. The crux of the SDRs is the replacement of the hardware components through software modules. In this paper, we assess the quality of GNSS observables acquired by SDR against the selected u-blox low-cost receiver. In the following, we investigate the performance level of single point positioning that may be reached with an ultra-low-cost SDR and compare it to that of the low-cost GNSS receiver. The signal quality assessment revealed a comparable performance in terms of carrier-to-noise density ratio and a significant out-performance of the u-blox over SDR in terms of code pseudorange noise. The experimentation in the positioning domain proved that software-defined receivers may offer a position solution with three-dimensional standard deviation error at the level of 5.2 m in a single point positioning mode that is noticeably poorer accuracy as compared to the low-cost receiver. Such results demonstrate that there is still room for SDR positioning accuracy improvement
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