scholarly journals High Quality Zenith Tropospheric Delay Estimation Using a Low-Cost Dual-Frequency Receiver and Relative Antenna Calibration

2020 ◽  
Vol 12 (9) ◽  
pp. 1393 ◽  
Author(s):  
Andreas Krietemeyer ◽  
Hans van der Marel ◽  
Nick van de Giesen ◽  
Marie-Claire ten Veldhuis
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Calibration Method ◽  
Single Frequency ◽  
Tropospheric Delay ◽  
Limiting Factor ◽  
Dual Frequency ◽  
High Quality ◽  
Mean Square Errors ◽  
Antenna Calibration

The recent release of consumer-grade dual-frequency receivers sparked scientific interest into use of these cost-efficient devices for high precision positioning and tropospheric delay estimations. Previous analyses with low-cost single-frequency receivers showed promising results for the estimation of Zenith Tropospheric Delays (ZTDs). However, their application is limited by the need to account for the ionospheric delay. In this paper we investigate the potential of a low-cost dual-frequency receiver (U-blox ZED-F9P) in combination with a range of different quality antennas. We show that the receiver itself is very well capable of achieving high-quality ZTD estimations. The limiting factor is the quality of the receiving antenna. To improve the applicability of mass-market antennas, a relative antenna calibration is performed, and new absolute Antenna Exchange Format (ANTEX) entries are created using a geodetic antenna as base. The performance of ZTD estimation with the tested antennas is evaluated, with and without antenna Phase Center Variation (PCV) corrections, using Precise Point Positioning (PPP). Without applying PCVs for the low-cost antennas, the Root Mean Square Errors (RMSE) of the estimated ZTDs are between 15 mm and 24 mm. Using the newly generated PCVs, the RMSE is reduced significantly to about 4 mm, a level that is excellent for meteorological applications. The standard U-blox ANN-MB-00 patch antenna, with a circular ground plane, after correcting the phase pattern yields comparable results (0.47 mm bias and 4.02 mm RMSE) to those from geodetic quality antennas, providing an all-round low-cost solution. The relative antenna calibration method presented in this paper opens the way for wide-spread application of low-cost receiver and antennas.

Investigation of a L1-optimized choke ring ground plane for a low-cost GPS receiver-system

2018 ◽  
Vol 12 (1) ◽  
pp. 55-64
Author(s):  
Li Zhang ◽  
Volker Schwieger
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Single Frequency ◽  
Limiting Factor ◽  
Test Field ◽  
Gps Receiver ◽  
Dual Frequency ◽  
Multipath Effect ◽  
Receiver System ◽  
Multipath Signal

AbstractBesides the geodetic dual-frequency GNSS receivers-systems (receiver and antenna), there are also low-cost single-frequency GPS receiver-systems.The multipath effect is a limiting factor of accuracy for both geodetic dual-frequency and low-cost single-frequency GPS receivers. And the multipath effect is for the short baselines dominating error (typical for the monitoring in Engineering Geodesy). So accuracy and reliability of GPS measurement for monitoring can be improved by reducing the multipath signal.In this paper, the self-constructed L1-optimized choke ring ground plane (CR-GP) is applied to reduce the multipath signal. Its design will be described and its performance will be investigated.The results show that the introduced low-cost single-frequency GPS receiver-system, which contains the Ublox LEA-6T single-frequency GPS receiver and Trimble Bullet III antenna with a self-constructed L1-optimized CR-GP, can reach standard deviations of 3 mm in east, 5 mm in north and 9 mm in height in the test field which has many reflectors. This accuracy is comparable with the geodetic dual-frequency GNSS receiver-system. The improvement of the standard deviation of the measurement using the CR-GP is about 50 % and 35 % compared to the used antenna without shielding and with flat ground plane respectively.

scholarly journals Potential of Cost-Efficient Single Frequency GNSS Receivers for Water Vapor Monitoring

2018 ◽  
Vol 10 (9) ◽  
pp. 1493 ◽  
Author(s):  
Andreas Krietemeyer ◽  
Marie-claire ten Veldhuis ◽  
Hans van der Marel ◽  
Eugenio Realini ◽  
Nick van de Giesen
Keyword(s):  
Water Vapor ◽  
Low Cost ◽  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Small Scale ◽  
Reference Network ◽  
Tropospheric Delay ◽  
Dual Frequency ◽  
Gnss Receivers ◽  
Cost Efficient

Dual-frequency Global Navigation Satellite Systems (GNSSs) enable the estimation of Zenith Tropospheric Delay (ZTD) which can be converted to Precipitable Water Vapor (PWV). The density of existing GNSS monitoring networks is insufficient to capture small-scale water vapor variations that are especially important for extreme weather forecasting. A densification with geodetic-grade dual-frequency receivers is not economically feasible. Cost-efficient single-frequency receivers offer a possible alternative. This paper studies the feasibility of using low-cost receivers to increase the density of GNSS networks for retrieval of PWV. We processed one year of GNSS data from an IGS station and two co-located single-frequency stations. Additionally, in another experiment, the Radio Frequency (RF) signal from a geodetic-grade dual-frequency antenna was split to a geodetic receiver and two low-cost receivers. To process the single-frequency observations in Precise Point Positioning (PPP) mode, we apply the Satellite-specific Epoch-differenced Ionospheric Delay (SEID) model using two different reference network configurations of 50–80 km and 200–300 km mean station distances, respectively. Our research setup can distinguish between the antenna, ionospheric interpolation, and software-related impacts on the quality of PWV retrievals. The study shows that single-frequency GNSS receivers can achieve a quality similar to that of geodetic receivers in terms of RMSE for ZTD estimations. We demonstrate that modeling of the ionosphere and the antenna type are the main sources influencing the ZTD precision.

Improving the antenna performance for Zenith Tropospheric Delay estimations with consumer-grade antennas and a low-cost dual-frequency receiver

2020 ◽  
Author(s):  
Andreas Krietemeyer ◽  
Hans van der Marel ◽  
Marie-claire ten Veldhuis ◽  
Nick van de Giesen
Keyword(s):  
Low Cost ◽  
Satellite System ◽  
Efficient Estimation ◽  
Tropospheric Delay ◽  
Dual Frequency ◽  
Antenna Performance ◽  
Cost Efficient ◽  
Global Navigation Satellite ◽  
The Cost ◽  
Mean Square Errors

<p>The recent release of mass-marked dual-frequency receivers opens up the opportunity to facilitate the cost-efficient estimation of Zenith Tropospheric Delays (ZTDs) from Global Navigation Satellite System (GNSS) observations. We present results of ZTD estimations from a low-cost dual-frequency GNSS receiver (U-blox ZED-F9) equipped with a range of different quality and priced antennas. It is demonstrated that the receiver itself is able to produce high quality ZTD estimations with higher grade antennas. However, the noise introduced by applying the ionosphere-free linear combination in Precise Point Positioning (PPP), makes the low-cost antenna performance initially a major challenge. With Root Mean Square Errors (RMSE) between 15 mm and 24 mm for low-cost antennas the results were at first not adequate for meteorological purposes. We demonstrate an easy-to-apply relative antenna calibration that increased the ZTD accuracy significantly for the tested low-cost antennas. After applying antenna corrections the error is reduced to a level that is adequate for meteorological applications (RMSE ~4 mm).</p>

Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations

2020 ◽  
Vol 14 (2) ◽  
pp. 167-175
Author(s):  
Li Zhang ◽  
Volker Schwieger
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Single Frequency ◽  
Spatial Correlations ◽  
Raw Data ◽  
Multipath Effect ◽  
Temporal Correlations ◽  
Multipath Effects ◽  
Gnss Receivers ◽  
Multipath Signals

AbstractThe investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls).Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications.

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 Variation of Static-PPP Positioning Accuracy Using GPS-Single Frequency Observations (Aswan, Egypt)

2017 ◽  
Vol 52 (2) ◽  
pp. 19-26 ◽  
Author(s):  
Ashraf Farah
Keyword(s):  
Precision Agriculture ◽  
Precise Point Positioning ◽  
Low Cost ◽  
High Accuracy ◽  
Single Frequency ◽  
Dual Frequency ◽  
Differential Gps ◽  
Positioning Accuracy ◽  
Comparable Accuracy ◽  
Positioning Technique

Abstract Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.

scholarly journals Feasibility of Using Low-Cost Dual-Frequency GNSS Receivers for Land Surveying

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1956
Author(s):  
Natalia Wielgocka ◽  
Tomasz Hadas ◽  
Adrian Kaczmarek ◽  
Grzegorz Marut
Keyword(s):  
Real Time ◽  
Field Experiments ◽  
Low Cost ◽  
Base Station ◽  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Signal Acquisition ◽  
Dual Frequency ◽  
Static Mode ◽  
Land Surveying

Global Navigation Satellite Systems (GNSS) have revolutionized land surveying, by determining position coordinates with centimeter-level accuracy in real-time or up to sub-millimeter accuracy in post-processing solutions. Although low-cost single-frequency receivers do not meet the accuracy requirements of many surveying applications, multi-frequency hardware is expected to overcome the major issues. Therefore, this paper is aimed at investigating the performance of a u-blox ZED-F9P receiver, connected to a u-blox ANN-MB-00-00 antenna, during multiple field experiments. Satisfactory signal acquisition was noticed but it resulted as >7 dB Hz weaker than with a geodetic-grade receiver, especially for low-elevation mask signals. In the static mode, the ambiguity fixing rate reaches 80%, and a horizontal accuracy of few centimeters was achieved during an hour-long session. Similar accuracy was achieved with the Precise Point Positioning (PPP) if a session is extended to at least 2.5 h. Real-Time Kinematic (RTK) and Network RTK measurements achieved a horizontal accuracy better than 5 cm and a sub-decimeter vertical accuracy. If a base station constituted by a low-cost receiver is used, the horizontal accuracy degrades by a factor of two and such a setup may lead to an inaccurate height determination under dynamic surveying conditions, e.g., rotating antenna of the mobile receiver.

Assessment of single-frequency observations in GNSS Tropospheric Tomography

2020 ◽  
Author(s):  
Robert Weber ◽  
Zohreh Adavi ◽  
Marcus Franz Glaner
Keyword(s):  
Water Vapor ◽  
Low Cost ◽  
Temporal Structure ◽  
Single Frequency ◽  
Dual Frequency ◽  
Alternative Approach ◽  
Spatio Temporal ◽  
Gnss Network ◽  
Vapor Distribution ◽  
Reconstructed Model

<p>Water vapor is one of the most variable components in the Earth’s atmosphere, which has a significant role in the formation of clouds, rain and snow, air pollution and acid rain. Therefore, increasing the accuracy of estimated water vapor can lead to more accurate predictions of severe weather, upcoming storms, and reducing natural hazards. In recent years, GNSS has turned out to be a valuable tool for remotely sensing the atmosphere. GNSS tomography is one of the most valuable tools to reconstruct the Spatio-temporal structure of the troposphere. However, locating dual-frequency receivers with a sufficient spatial resolution for GNSS tomography of a few tens of kilometers is not economically feasible. Therefore, in this research, the feasibility of using single-frequency receivers in GNSS tomography as a possible alternative approach has been investigated. The accuracy of the reconstructed model of water-vapor distribution using low-cost receivers is verified using radiosonde measurements in the area of the EPOSA (Echtzeit Positionierung Austria) GNSS network, which is mostly located in the east part of Austria for the period DoYs 233-246 in 2019.</p>

scholarly journals A Dual Frequency Dielectric Resonator Antenna for Wireless Communication Applications

2019 ◽  
Vol 9 (1S5) ◽  
pp. 99-102
Keyword(s):  
Wireless Communication ◽  
Dielectric Resonator ◽  
Dielectric Material ◽  
Low Cost ◽  
Ground Plane ◽  
Strip Line ◽  
Dielectric Resonator Antenna ◽  
Dual Frequency ◽  
Rectangular Slot ◽  
High Dielectric

A dual frequency Dielectric Resonator antenna for wireless communication applications in the S and C bands with an operating frequency of 2.65GHz and 4.62GHz is presented. The patch is a dielectric material with a high dielectric constant value of 20. A 50Ω strip line is considered as feed and is coupled to the dielectric radiator via the rectangular slot etched in ground plane. The slot etched in ground plane is made so as to facilitate the power form the feed line to the radiator. The overall dimension of the antenna is 100mm×35mm×0.8mm. A dual frequency antenna has been proposed which will be operational at the frequencies of 2.65GHz and 4.62GHz with a gain of 4.42dB and 7.78dB respectively. Low cost FR4 material is been used as the laminate base for the antenna which will act as the dielectric material.

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