REVISITING THE ROLE OF OBSERVATION SESSION DURATION ON PRECISE POINT POSITIONING ACCURACY USING GIPSY/OASIS II SOFTWARE

The accuracy of GPS precise point positioning (PPP) was previously modelled as a function of the observing session duration T. The NASA, JPL’s software GIPSY OASIS II (GOA-II) along with the legacy products was used to process the GPS data. The original accuracy model is not applicable anymore because JPL started releasing its products using new modelling and analysis strategies as of August 2007, and the legacy products are no longer available. The developments mainly comprise the new orbit and clock determination strategy, second order ionosphere modelling, and single station ambiguity resolution. Previously, the PPP accuracy was studied using v 4.0 of the GOA-II. The accuracy model showed coarser results compared to that of the relative positioning. Here, we processed the data of the International GNSS Service (IGS) stations to refine the accuracy of GOA-II PPP from version 6.3. Considering the above changes we refined the accuracy of PPP. First we modified the previous model used for the accuracy assessment. Then we tested out this model using straightforward polynomial and logarithmic models. The tests indicate the previous formulation still satisfactorily models the accuracy using refined coefficient values Sn = 7.8 mm, Se = 6.8 mm, Sv = 29.9 mm for T ≥ 2 h

ON THE PERFORMANCE OF GNSS LEVELLING OVER STEEP SLOPES

In geodetic applications variety, one of the main current focuses is recently to determine the heights of ground stations with high accuracy. Specially the possibility of acquiring 3D information of the point positioning with high accuracy is opening up new strategies of investigating the heighting. Global Navigation Satellite System (GNSS) for 3D positioning is undergoing rapid developments andGNSS heighting can be an alternative to terrestrial techniques of height measurements. This paper presents a research study on the use of GNSS heighting in the case of steep slopes and multipath issue. Short baseline solution strategieswere performed by using Bernese Software v. 5.0. The analysis results are also compared to the results of techniques of the terrestrial levelling. The results showthat GNSS can be used as an practical surveying method to the terrestrial levelling with comparable accuracies. Furthermore, one can save up to 1 hour using GNSSinstead of geometric levelling over a steep slope of a 100 m. On the other hand, as usual multipath is the primary error source decreasing the efficiency of GNSS, and it has been studied experimentally in this paper

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology

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

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

REVISITING THE ROLE OF OBSERVATION SESSION DURATION ON PRECISE POINT POSITIONING ACCURACY USING GIPSY/OASIS II SOFTWARE

The accuracy of GPS precise point positioning (PPP) was previously modelled as a function of the observing session duration T. The NASA, JPL's software GIPSY OASIS II (GOA-II) along with the legacy products was used to process the GPS data. The original accuracy model is not applicable anymore because JPL started releasing its products using new modelling and analysis strategies as of August 2007, and the legacy products are no longer available. The developments mainly comprise the new orbit and clock determination strategy, second order ionosphere modelling, and single station ambiguity resolution. Previously, the PPP accuracy was studied using v 4.0 of the GOA-II. The accuracy model showed coarser results compared to that of the relative positioning. Here, we processed the data of the International GNSS Service (IGS) stations to refine the accuracy of GOA-II PPP from version 6.3. Considering the above changes we refined the accuracy of PPP. First we modified the previous model used for the accuracy assessment. Then we tested out this model using straightforward polynomial and logarithmic models. The tests indicate the previous formulation still satisfactorily models the accuracy using refined coefficient values Sn = 7.8 mm , Se = 6.8 mm , Sv = 29.9 mm for T ≥ 2 h

On the performance of GNSS levelling over steep slopes

In geodetic applications variety, one of the main current focuses is recently to determine the heights of ground stations with high accuracy. Specially the possibility of acquiring 3D information of the point positioning with high accuracy is opening up new strategies of investigating the heighting. Global Navigation Satellite System (GNSS) for 3D positioning is undergoing rapid developments and GNSS heighting can be an alternative to terrestrial techniques of height measurements. This paper presents a research study on the use of GNSS heighting in the case of steep slopes and multipath issue. Short baseline solution strategies were performed by using Bernese Software v. 5.0. The analysis results are also compared to the results of techniques of the terrestrial levelling. The results show that GNSS can be used as an practical surveying method to the terrestrial levelling with comparable accuracies. Furthermore, one can save up to 1 hour using GNSS instead of geometric levelling over a steep slope of a 100 m. On the other hand, as usual multipath is the primary error source decreasing the efficiency of GNSS, and it has been studied experimentally in this paper