Danijel Šugar - Academia.edu (original) (raw)

Papers by Danijel Šugar

The first geomagnetic survey using the onsite variometer in Croatia was realized within the bilat... more The first geomagnetic survey using the onsite variometer in Croatia was realized within the bilateral project ‘Joint Croatian-Hungarian Geomagentic Repeat Station survey and Joint Geomagnetic Field model‘ on the repeat stations Krbavsko polje (KRBP), Sinjsko polje (SINP) and Palagruža (PALA) in the period 19-31 July 2010. The results presented in this paper rely on the survey on PALA repeat station performed in the period 27-31 July 2010. In addition to usual equipment used for declination D and inclination I determination i.e. nonmagnetic fluxgate theodolite Zeiss 020A with DMI D&I electronic unit, the magnetic field during the survey was observed and monitored with onsite dIdD variometer. The time variability of the geomagnetic field elements differences between the variometer station (VAR) and repeat station (RS) (i.e. baselines) noticed on KRBP location were more pronounced on SINP and PALA repeat station locations. One of possible explanations of such a temporal changes can be the significant conductivity contrast between the Adriatic sea and the mainland that can result in spatial field variation in small spatial and temporal scales, even in large distances. Moreover, the temporal change of total intensity (F) gradient was detected by two PPM sensors observing on the same vertical (one above the other). Despite of noticed temporal change, the dIdD calibration parameters have been determined enabling the determination of the baselines and subsequent spatial reduction from VAR station to the repeat station. In such conditions, the repeat station was operating as a temporary geomagnetic observatory. The quiet-time difference between the geomagnetic elements on each repeat station and THY reference observatory was determined from 60 minutes long sliding windows provided the STDEV of the difference was < 0.3 nT in X, Y, Z components and F as well. In such a way determined quiet- time level differences have shown significant fluctuations, so they were determined considering several geomagnetic observatories surrounding Croatian territory (CTS, FUR, GCK, PAG, THY). Consequently, the quiet-time differences from 60 minutes sliding windows simultaneously determined with data from all surrounding observatories have provided more reliable results. Absolute set observations collected at the repeat station were reduced to reference observatories using reduction methods based on the assumption that transient (including diurnal) variations of the magnetic field are identical at both repeat station and chosen reference observatory (without and with consideration of the secular variation difference between the repeat station and reference observatory). Definitive geomagnetic element reduced values were given as weighted average (based on STDEV and SCATTER) taking into consideration all surrounding reference observatories. The comparison of different data reduction method results has shown that reduction to a quiet-time level provides better accuracy estimations. In order to provide reliable quiet-time level determinations, it is desirable that the repeat station is surrounded by several reference observatories at acceptable distances and that the survey is carried out during quiet external field conditions. Further investigations should be taken in order to clarify the impact of the high conductivity contrast to the temporal change of the geomagnetic field spatial gradients.

The continental part of the CGRSN (Croatian Geomagnetic Repeat Stations Network) network consisti... more The continental part of the CGRSN (Croatian Geomagnetic Repeat Stations Network) network consisting of 8 repeat stations was established and surveyed in 2004. The network has reached its actual shape in 2008 after the setup of two additional repeat stations on the island of Losinj and Palagruža. Due to the usage of different instrumentation and coordinate determination methodology during the network setup in 2004 and 2008, as well as due to the heterogeneity of the realization of the CSRS, within the survey in 2010 the CGRSN network was observed with GNSS (Global Navigation Satellite System) receivers Trimble R8 and Topcon Hyper PRO and coordinates were determined with GPPS (Geodetic Precision Positioning Service) service of the CROPOS (CROatian POsitiong System) system. The coordinate transformation based on the T7D model as well as the transformation using unique transformation parameters were carried out and subsequently the azimuth values were calculated from the obtained coordinates. The comprehensive analysis of the results was presented and the corrections for the transition of the azimuth values determined in heterogeneous realization of the national CSRS to the homogeneous and global ETRF2000 were given.

Bespilotne letjelice (BPL) pronalaze sve siru primjenu za vojne, komercijalne i osobne namjene. K... more Bespilotne letjelice (BPL) pronalaze sve siru primjenu za vojne, komercijalne i osobne namjene. Komercijalna primjena BPL-a za geodetske namjene povezana je s imanjem jasnih i jednoznacnih pokazatelja tocnosti i pouzdanosti rezultata senzorskih sustava instaliranih na njima. Proizvođaci BPL-a ne daju zadovoljavajuce informacije o tocnosti i pouzdanosti ugrađenih senzorskih sustava sto utjece na njihovu usporenu primjenu u geodeziji. U ovom radu predstavljeni su postupci testiranja senzorskih sustava BPL-a razvijeni na Geodetskom fakultetu Sveucilista u Zagrebu i stecene spoznaje.

Geomagnetska informacija tj. deklinacija i njena sekularna varijacija i danas je strateski znacaj... more Geomagnetska informacija tj. deklinacija i njena sekularna varijacija i danas je strateski znacajna. Starija od pet godina, ona nije valjana pa je njena obnova nužnost ; zastarjela geomagnetska informacija jedan je od razloga obnove modela ili karata. Temeljna svrha Tehnicko-ekonomske analize odgovoriti je na pitanje na koji nacin korisniku -OS RH- sustavno i kontinuirano osigurati aktualnu i tocnu geomagnetsku informaciju.

In this paper short overview of the homogeneous field of stable geodetic points setting up, using... more In this paper short overview of the homogeneous field of stable geodetic points setting up, using GPS technology, on islands Rab as well as islands Goli and Grgur, is given. Special note is putted to the applying of different GPS instruments types, surveying methodology, as well as to the access of base vector processing and network adjustment. Comparison of coordinates in ETRS89 datum between the final common adjustment (all three phases together) and every individual adjustment in three separate phases is carried out. Finally, comparison of old coordinates of trigonometric points with newly defined based on GPS surveying, common adjustment and transformation from ETRS89 to the existing HDKS (Croatian National Coordinate System) is yielded out. Sažetak. U radu se daje kratki pregled uspostave homogenog polja stalnih geodetskih točaka GPS tehnologijom na otoku Rabu, te na otocima Goli i Grgur. Poseban osvrt dan je primjeni različitih tipova GPS uređaja, metodologiji opažanja, kao i ...

Umrežavanjem referentnih GNSS stanica, zajedničkom obradom i računanjem korekcija znatno se poveć... more Umrežavanjem referentnih GNSS stanica, zajedničkom obradom i računanjem korekcija znatno se povećavaju mogućnosti modeliranja pogrešaka ovisnih o udaljenosti u RTK metodi pozicioniranja. Prednosti koje se na taj način postižu su: povećana točnost pozicioniranja, skraćeno vrijeme inicijalizacije, opažanje za vrijeme jačih atmosferskih utjecaja. Međusobna udaljenost referentnog i pokretnog GNSS prijamnika kod klasične RTK metode doseže do 10 odnosno 20 km, a umrežavanjem permanentnih stanica ta se udaljenost povećava na 70-100 km. Za potrebe računanja i distribucije mrežnih RTK korekcija razvijeno je više koncepata koji osiguravaju homogenu točnost pozicioniranja. Zbog njihove aktualnosti i implementacije u aktivnim GNSS mrežama u Europi i svijetu prikazane su osnove FKP, VRS i MAC koncepata. Prikazane su i mogućnosti primjene koncepata mrežnih RTK rješenja kako na strani korisnika (rover) tako i na strani sustava umreženih GNSS CORS stanica, te su izloženi RTCM formati za odašiljanje...

Umrežavanjem referentnih GNSS stanica, zajednickom obradom i racunanjem korekcija znatno se povec... more Umrežavanjem referentnih GNSS stanica, zajednickom obradom i racunanjem korekcija znatno se povecavaju mogucnosti modeliranja pogresaka ovisnih o udaljenosti u RTK metodi pozicioniranja. Prednosti koje se na taj nacin postižu su: povecana tocnost pozicioniranja, skraceno vrijeme inicijalizacije, opažanje za vrijeme jacih atmosferskih utjecaja. Međusobna udaljenost referentnog i pokretnog GNSS prijamnika kod klasicne RTK metode doseže do 10 odnosno 20 km, a umrežavanjem permanentnih stanica ta se udaljenost povecava na 70-100 km. Za potrebe racunanja i distribucije mrežnih RTK korekcija razvijeno je vise koncepata koji osiguravaju homogenu tocnost pozicioniranja. Zbog njihove aktualnosti i implementacije u aktivnim GNSS mrežama u Europi i svijetu prikazane su osnove FKP, VRS i MAC koncepata. Prikazane su i mogucnosti primjene koncepata mrežnih RTK rjesenja kako na strani korisnika (rover) tako i na strani sustava umreženih GNSS CORS stanica, te su izloženi RTCM formati za odasiljanje...

Sensors

CROPOS, as the Croatian GNSS network, was modernized and upgraded to support the Galileo system i... more CROPOS, as the Croatian GNSS network, was modernized and upgraded to support the Galileo system in 2019. Two of CROPOS’s services—VPPS (Network RTK service) and GPPS (post-processing service)—were assessed for the contribution of the Galileo system to their performance. A station used for field testing was previously examined and surveyed to determine the local horizon and to carry out a detailed mission planning. The whole day of observation was divided into several sessions, each with a different visibility of Galileo satellites. A special observation sequence was designed: VPPS (GPS-GLO-GAL), VPPS (GAL-only), and GPPS (GPS-GLO-GAL-BDS). All observations were taken on the same station with the same GNSS receiver, Trimble R12. Each static observation session was post-processed in Trimble Business Center (TBC) in two different ways: considering all available systems (GGGB) and considering GAL-only observations. A daily static solution based on all systems (GGGB) was considered as th...

The 20th edition of the seminar Satellite methods in geodesy and cadastre – GNSS seminar 2017 was... more The 20th edition of the seminar Satellite methods in geodesy and cadastre – GNSS seminar 2017 was organized by the Institute of Geodesy of the Faculty of Civil Engineering, Brno University of Technology and held on February 2nd 2017. The seminar took place in the great lecture hall of the Faculty of Civil Engineering and was attended by approximately 80 participants from Czech Republic, Slovakia, Poland and Croatia. The Faculty of Geodesy of the University of Zagreb was represented by Prof. Dr. Miljenko Lapaine and Dr. Danijel Šugar, who held the lecture GNSS Research Activities at the Faculty of Geodesy, University of Zagreb.U organizaciji Instituta za geodeziju Građevinskog fakulteta Tehničkog sveučilišta u Brnu (Češka Republika), 2. veljače 2017. održano je jubilarno 20. izdanje seminara Satelitske metode u geodeziji i katastru – GNSS seminar 2017. Seminar je održan u velikoj predavaonici u zgradi Građevinskog fakulteta, a skupu je prisustvovalo oko 80 sudionika iz Češke, Slovačk...

Annals of Geophysics

The knowledge of the azimuth of the reference mark is of crucial importance in the determination ... more The knowledge of the azimuth of the reference mark is of crucial importance in the determination of the declination which is defined as the ellipsoidal (geodetic) azimuth of the geomagnetic meridian. The accuracy of the azimuth determination has direct impact on the accuracy of the declination. The orientation of the Declination-Inclination Magnetometer is usually carried out by sighting the reference mark in two telescope faces in order to improve the reliability of the observations and eliminate some instrumental errors. In this paper, different coordinate as well as azimuth determination methods using GNSS (Global Navigation Satellite System) observation techniques within VPPS (High-Precision Positioning Service) and GPPS (Geodetic-Precision Positioning Service) services of the CROPOS (CROatian POsitioning System) system were explained. The azimuth determination by the observation of the Polaris was exposed and it was subsequently compared with the observation of the Sun using ho...

1st Croatian Conference on Earthquake Engineering

CROPOS (Croatian Positioning System) is a Croatian permanent GNSS (Global Navigation Satellite Sy... more CROPOS (Croatian Positioning System) is a Croatian permanent GNSS (Global Navigation Satellite System) network featuring 33 stations distributed over the national territory at an average distance of 70 km between stations. The system was established in 2008, in the meantime enlarged and improved, and eventually, in summer 2019 it was upgraded to support observations of the European Galileo satellite system (in addition to previously supported GPS and GLONASS systems). Within the project of CROPOS's upgrade co-funded by the EU (European Union), all permanent GNSS stations were equipped with the newest Trimble Alloy receivers and Trimble Zephyr 3 Geodetic antennas, whereas the software of the control center (Trimble Pivot Platform) was upgraded to a newer version. One of the CROPOS's stations (ZAGR) is located (more precisely its antenna) on the roof of the building where three faculties of the University of Zagreb (Geodesy, Civil Engineering, Architecture) are headquartered. For the first time, the effects of the M5.5 Zagreb earthquake, combined surface and building motion, have been identified and assessed by the GNSS method supported by E5, E5a, E5b, and E5AltBOC signals of Galileo satellites. By analysis of 1 Hz processing results, the effects of the earthquake being far above the noise level, have been discerned leading to the assessment of kinematic behaviour of the station caused by M5.5 earthquake. ZAGR station at the approx. 9 km distance from the estimated epicentre, have shown movements in the range of approx. 13 cm in direction N-S and approx. 6 cm in direction E-W, whereas some movements in the vertical direction were identified to be slightly above the noise level. Although the kinematic behaviour was pronounced, there haven't been revealed permanent displacements as a consequence of M5.5 earthquake. One second (1 Hz) resolution results have enabled a thorough analysis of the kinematic behaviour of ZAGR station and potential of the GNSS method.

Zbornik radova IV kongresa o katastru u Bosni i Hercegovini - s međunarodnim sudjelovanjem, 2019

САВРЕМЕНА ТЕОРИЈА И ПРАКСА У ГРАДИТЕЉСТВУ, 2018

HPPS service of the CROPOS system is today a fast, reliable, precise and commonly used tool for c... more HPPS service of the CROPOS system is today a fast, reliable, precise and commonly used tool for coordinates determination in Croatia. The advantages of a networked RTK method are well known, but in some situations, a single-base RTK method could be a reliable method for coordinates determination, even without a base station having known coordinates. Single-base RTK method with Autonomous base start can be set up on any (unknown) station with a clear sky and GNSS satellites visibility enabled. Differential corrections are usually broadcast to the rover GNSS receiver via a communication link, enabling the coordinates determination with cm-level precision in real time. Simultaneously, the base GNSS receiver collects static observations for base station determination in post-processing and subsequent rover coordinates shift. In this paper, the above mentioned method was tested on the ground, together with TILT option integrated into newest Topcon GNSS receiver.

Izvješća Državne geodetske uprave o znanstveno-stručnim projektima iz 2002. godine, 2004

International scientific conference on Magnetism – Geomagnetism : Biomagnetism MGB 2008, 2008

Geomagnetic networks in Croatia consist of the repeat stations network, and the part of network f... more Geomagnetic networks in Croatia consist of the repeat stations network, and the part of network for field mapping nowadays. The Croatian Geomagnetic Repeat Stations Network was established in 2004. Herewith, the setup of two additional repeat stations in 2008 is described. Lessons learned during the repeat station surveys of 2004, 2007, and 2008 are revealed. The design of the dense Croatian Geomagnetic Network for Field Mapping, that is to consist of approximately 90 stations with the average distance from one station to another of 25 km, is presented. The setup and the survey of the first third of the network, covering the southern Dalmatia, including islands, was completed in summer 2008. The instruments and procedures used, as well as the experiences gained are described. In addition, the attempts to determine the total intensity of geomagnetic field on the Adriatic volcanic islands of Jabuka and Brusnik are presented.

5. CROPOS konferencija - Zbornik radova, 2018