Using GPS Near the Forest and Quality Control

Pirti, Atınç

doi:10.1179/sre.2005.38.298.286

Cited by 10 publications

(4 citation statements)

References 1 publication

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“…However it is noted in the figure that the station was surrounded by trees. The fact that the velocity estimated at ALIC significantly differed from the truth might be ascribed to signal attenuation due to tree leaves, and this deteriorates the positioning [30]. The top right figure of Figure 6 gives the environment of ONSA.…”

Section: Test Statistic Critical Regionmentioning

confidence: 99%

Accuracy of Deformation Rates from Campaign GPS Surveys Considering Extended Observation Session and Antenna Set-Up Errors

Turen

Şanli

2019

Remote Sensing

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GPS campaign measurements are still in use in the monitoring of ground deformation. Campaign measurements are frequently referred to because installing permanent stations are costly, and they cannot be installed at the desired density. Using the data from the International Global Navigation Satellite Systems (GNSS) Service (IGS) permanent GPS stations, the duration, sampling interval, etc. of the campaign measurements can be simulated. Thus, the contribution of the campaign data to the monitoring of the ground deformation can be evaluated. In this study, we carried out an experiment with the aim of determining the deformation of tectonic plates at the selected IGS stations more accurately considering by extending the observation duration to a full 24 h length. We also made an attempt to take into consideration the antenna set up errors developing a scenario referring to the information available in the literature. We have decimated the continuous data of 40 globally scattered IGS stations into monthly intervals between 2012 and 2016 and estimated the deformation rates at the IGS stations from a continuous time series of four years. The continuous time series solutions for those stations were produced by the Jet Propulsion Laboratory (JPL), NASA. We compare velocities (i.e., the deformation rates) determined from GPS campaigns (in which the sampling was performed monthly and four-monthly) with those of the continuous data. The major conclusion of this study is that the vertical velocity estimation accuracy of the GPS campaign measurements had been improved by about 85% by extending the session duration to 24 h. The repetition interval of GPS campaign measurements as per one observation every four months produced only slightly coarser accuracy (i.e., on the average 8% poorer) than those of the measurements repeated once every month.

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Section: Test Statistic Critical Regionmentioning

confidence: 99%

Accuracy of Deformation Rates from Campaign GPS Surveys Considering Extended Observation Session and Antenna Set-Up Errors

Turen

Şanli

2019

Remote Sensing

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“…This may cause problems at some of the engineering applications. At the applications where especially are performed around the forested areas, satellite vision has significant effects on positioning accuracy (Naesset, 1999;Pirti, 2005;Tachiki et al, 2005;Hasegawa and Yoshimura, 2007;Pirti, 2008). The other significant problem is orbital errors.…”

Section: Introductionmentioning

confidence: 99%

Accuracy Investigation of PPP Method Versus Relative Positioning Using Different Satellite Ephemerides Products Near/Under Forest Environment

Öcalan¹,

Erdoğan²,

Tunalıoğlu³

et al. 2016

Earth sci. res. j.

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System (GNSS) and Web-based online positioning services have become widespread. Owing to some advantages, such as work-duration and cost-effectiveness, many of users have implemented PPP method instead of the traditional relative positioning method for several applications. On GNSS applications the quality of satellite ephemerides products used for data evaluation is a significant factor that affects the results in post-processing solutions either applying relative or PPP methods on analyses. These products, classified as ultra-rapid, rapid and final orbits, are regularly provided by several national and international organizations to the users. In this paper, the accuracy of PPP method has been studied comparing the outcomes from various online Web services using different software and satellite ephemerides products. For this purpose, three test points were established on a place with completely free satellite visibility (AC01) and on the other two places with partially (YC01) and vastly (KC01) prevention of satellite signals near and within a forest area at Campus of Davutpaşa of the Yildiz Technical University of Istanbul. At these stations, static observations have been conducted with a time span of 6 hours on 4 th May 2015. The dataset collected using Topcon HiperPro receiver, a receiver for GPS and GLONASS data, was evaluated manually by means of the Bernese v5.2 (BSW) and GIPSY-OASIS v6.3 (Gipsy) scientific software. Moreover, the GNSS data were also proceeded using six different Web-based online services (AUSPOS, OPUS, CSRS-PPP, APPS, GAPS, Trimble-RTX) with ultra-rapid, rapid and final satellite ephemerides products. For the station with free satellite visibility (AC01), the analyses of outcomes indicate a coordinate accuracy of 1 cm for Web-based and manual data processing. That suggests relative good quality of orbit and clock corrections of satellites used by online data processing services for PPP. Furthermore, for station with partially (YC01) prevention of satellite signals, manual solutions have approximately 1 cm coordinate accuracies for n, e and u components. Moreover, when we compare the results among Web-based services, AUSPOS in relative solution and Trimble-RTX in PPP solution provides the best results. Here, one must emphasize that Trimble-RTX is a Web-based processing service for GNSS data (GPS, GLONASS, BeiDou, and QZSS) and operates an own global network of approximately 100 stations around the world for this purpose. For station with vastly (KC01) prevention of satellite signals, the best solutions were provided by APPS and CSRS-PPP using PPP approach among the Web-based services. Here, Trimble-RTX could not produce any solution. These results could demonstrate the benefit of multi constellation of GNSS in the areas with limited satellite visibility because of increasing of the number of measurements.En los años recientes, debido al incremento de operadores satelitales de corrección de órbita y tiempo para la evaluación de información en tiempo real y de postproceso, se ha generalizad...

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“…Using its precise positioning capability, GNSS can determine the locations of activity centres. These locations can be easily accessed using GNSS waypoint navigation [1,2,9,10].…”

Section: Introductionmentioning

confidence: 99%

“…The phenomenon of a satellite signal reaching an antenna by more than one path (direct and some reflected paths) is called multipath. This multipath can cause large variations in position and is perhaps the largest cause of large errors in position fixes under forest canopy [1,9,10,11].…”

Section: Introductionmentioning

confidence: 99%

The seasonal effects of deciduous tree foliage in CORS-GNSS measurements (VRS/FKP)

2016

Teh. vjesn.

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Original scientific paper This article examines the performance and use of GNSS based data acquisition systems in the seasonal effects of deciduous tree foliage. As a general rule, a clear view of the sky is preferred when using GNSS for determining location. Season in the case of deciduous trees is the parameter affecting GNSS signal attenuation. As a result of this attenuation, positions computing weak signals tend to be less accurate. This means that using GNSS in forest is one of the most demanding uses of technology and one that requires particular attention when evaluating GNSS receivers that will be used in such an environment. This paper evaluates GNSS positional accuracy, precision and performance in the forest area. The obtained horizontal differences for three baselines in April between CORS-VRS/FKP and Total station survey results are ±(1÷3) cm. The height differences obtained for three baselines in April between CORS-FKP and Total station survey results are ±(2÷4) cm. Keywords: accuracy; CORS; FKP; GNSS; RTN; season; VRS Sezonski učinci lišća listopadnog drveća u CORS-GNSS mjerenjima (VRS/FKP)Izvorni znanstveni članak U ovom se članku istražuje učinkovitost i uporaba sustava prikupljanja podataka temeljenih na GNSS u sezonskim učincima lišća listopadnog drveća. Kao opće pravilo, poželjan je jasan pogled na nebo kada rabimo GNSS za određivanje položaja. Sezona u slučaju bjelogorice je parametar koji utječe na prigušenja GNSS signala. Kao rezultat ovog prigušenja, pozicije koje izračunavaju slabe signale manje su točne. To znači da je uporaba GNSS u šumi jedna od najzahtjevnijih uporaba ove tehnologije i ona koja zahtijeva posebnu pozornost prilikom ocjenjivanja GNSS prijamnika koji će se rabiti u takvom okruženju. U radu se procjenjuje GNSS položajna točnost, preciznost i učinkovitost u šumskom području. Dobivene horizontalne razlike za tri polazišta u travnju između CORS-VRS/FKP i ukupnog rezultata nadzorne stanice su ±(1÷3) cm. Dobivene visinske razlike za tri polazišta u travnju između CORS-FKP i ukupnog rezultata nadzorne stanice su ±(2÷4) cm.

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Using GPS Near the Forest and Quality Control

Cited by 10 publications

References 1 publication

Accuracy of Deformation Rates from Campaign GPS Surveys Considering Extended Observation Session and Antenna Set-Up Errors

Accuracy of Deformation Rates from Campaign GPS Surveys Considering Extended Observation Session and Antenna Set-Up Errors

Accuracy Investigation of PPP Method Versus Relative Positioning Using Different Satellite Ephemerides Products Near/Under Forest Environment

The seasonal effects of deciduous tree foliage in CORS-GNSS measurements (VRS/FKP)

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