Performance of RTK Positioning in Forest Conditions: Case Study
ABSTRACT This paper presents the performance of the real-time kinematic (RTK) technique in very severe conditions. The measurements were conducted in forest conditions during two different experiments. Two Global Positioning System receivers were used: an Ashtech Z-Surveyor and a Z-Xtreme. Radiomodems were used for transmitting RTK corrections from a reference station to a rover. The RTK measurements were performed during quite good satellite configuration. The use of RTK technology, based on the Ashtech Z-Xtreme receiver as a rover in forest terrain, allowed centimeter accuracy to be obtained. However, practical experiments showed that there is a need for redundant independent RTK solutions based on repeated independent ambiguity reinitializations. Although gross errors might occur, the RTK technique can be very helpful technology for centimeter positioning in woodland areas.
SourceAvailable from: Paweł Przestrzelski[Show abstract] [Hide abstract]
ABSTRACT: W niniejszym artykule zaprezentowano technologię rejestrowania dokładnych pomiarów RTK w czasie rzeczywistym z częstotliwością pozycjonowania większą niż 1 Hz. Przedstawiono aplikację stworzoną specjalnie do tego celu, podstawowe algorytmy aplikacji oraz szereg rozwiązań, które umożliwiły zastosowanie opracowanej technologii w praktyce geodezyjnej. Poniższe opracowanie zawiera również syntetyczną charakterystykę środowiska programistycznego Delphi, opis urządzeń wykorzystanych w opracowanej technologii RTK oraz ich konfigurację. Na koniec poruszono również problematykę transmisji danych przy pomocy konwerterów RS232 – USB wraz z proponowanym jego rozwiązaniem.
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ABSTRACT: Precise estimates of the covariance parameters are essential in least-squares collocation (LSC) in the case of increased accuracy requirements. This paper implements restricted maximum likelihood (REML) method for the estimation of three covariance parameters in LSC with the Gauss-Markov second-order function (GM2), which is often used in interpolation of gravity anomalies. The estimates are then validated with the use of an independent technique, which has been often omitted in the previous works that are confined to covariance parameters errors based on the information matrix. The crossvalidation of REML estimates with the use of hold-out method (HO) helps in understanding of REML estimation errors. We analyzed in detail the global minimum of negative log-likelihood function (NLLF) in the estimation of covariance parameters, as well, as the accuracy of the estimates. We found that the correlation between covariance parameters may critically contribute to the errors of their estimation. It was also found that knowing some intrinsic properties of the covariance function may help in the scoring process.Studia Geophysica et Geodaetica 03/2014; 58. DOI:10.1007/s11200-013-1213-z · 0.75 Impact Factor
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ABSTRACT: This paper presents a reliable technology for GPS/Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS) surveying under difficult observational conditions, i.e., in forest environments. The technology is based on the rapid static and Real-Time Kinematic (RTK) methods. Test surveys for the developed technology were carried out on a point in a dense forest, with a high degree of difficulty for satellite access. The coordinates of the point were determined by three GPS/GLONASS receivers positioned in a line on a special base, which were separated by a fixed distance of 0.5 m. The test surveys were conducted using Topcon HiPer Pro receivers with 10-Hz RTK positioning and gathering data at a sampling rate of 10 Hz. Practical tests for the presented technology showed that rapid static surveys based on three rover GPS/GLONASS receivers were a quite efficient technology in forest environments (unlike the RTK) and allowed for reliable centimeter accuracy of the determined positions to be obtained in 5-min observational sessions.IEEE Transactions on Geoscience and Remote Sensing 01/2015; 53(2):1029-1038. DOI:10.1109/TGRS.2014.2332372 · 2.93 Impact Factor