The significance of the Skylab altimeter experiment results and potential applications

The Skylab Altimeter Experiment has proven the capability of the altimeter for measurement of sea surface topography. The geometric determination of the geoid/mean sea level from satellite altimetry is a new approach having significant applications in many disciplines including geodesy and oceanography. A Generalized Least Squares Collocation Technique was developed for determination of the geoid from altimetry data. The technique solves for the altimetry geoid and determines one bias term for the combined effect of sea state, orbit, tides, geoid, and instrument error using sparse ground truth data. The influence of errors in orbit and a priori geoid values are discussed. Although the Skylab altimeter instrument accuracy is about + or - 1 m, significant results were obtained in identification of large geoidal features such as over the Puerto Rico trench. Comparison of the results of several passes shows that good agreement exists between the general slopes of the altimeter geoid and the ground truth, and that the altimeter appears to be capable of providing more details than are now available with best known geoids. The altimetry geoidal profiles show excellent correlations with bathymetry and gravity. Potential applications of altimetry results to geodesy, oceanography, and geophysics are discussed

Tijek postupka procjene izvedbenog stanja izmjere – problemi i izazovi

The purpose of this paper is to present the range of surveying works carried out during geodetic as-built inventory of buildings and utility infrastructure. The theoretical part of this essay complies grounds for legal basis on territory of Poland, which are core part of geodetic and cartographic studies. Moreover, the phases of geodetic as-built inventory are being discussed, in the light of applicable rules. Particular attention is being paid to the topic of situational and height measurements. The paper discusses methods of measurement used, precision groups and objects subjected to inventory measurement are being listed. The practical part of this paper regards surveying as-built inventory of single-family house. In this study we discuss the consequential procedures that contractors need to fallow during the construction process, this includes preliminary actions, field work, and individual elaboration of the findings. Post-completion documentation, gathered in the form of technical frame, after obtaining a positive verification test result was included in the Head Office of Geodesy and Cartography.Ovaj članak ima za svrhu prikazati opseg geodetskih radova provedenih na popisu izvedbenih stanja zgrada i komunalne infrastrukture. Teorijski dio ovog rada donosi pravila za pravnu osnovu na teritoriju Poljske, koja su ključni dio geodetskih i kartografskih studija. Povrh toga, razmatraju se faze popisa izvedbenog stanja geodetskih radova s obzirom na važeća pravila. Posebna je pažnja posvećena temi situacijskih i visinskih mjerenja. U radu se razmatraju primijenjene metode mjerenja te su popisane skupine preciznosti i skupine objekata koje su predmet inventarnih mjerenja. Praktični dio ovog rada uzima u obzir izmjeru izvedenog inventara jedne obiteljske kuće. U ovoj studiji razmatramo posljedične postupke koje građevinari moraju slijediti tijekom procesa gradnje, a to uključuje preliminarne radnje, terenski rad i pojedinačnu elaboraciju rezultata. Naknadna dokumentacija prikupljena u obliku tehničkog okvira, nakon dobivanja pozitivnog rezultata testa verifikacije, dostavljena je Glavnom uredu za geodeziju i kartografiju

Tijek postupka procjene izvedbenog stanja izmjere – problemi i izazovi

The purpose of this paper is to present the range of surveying works carried out during geodetic as-built inventory of buildings and utility infrastructure. The theoretical part of this essay complies grounds for legal basis on territory of Poland, which are core part of geodetic and cartographic studies. Moreover, the phases of geodetic as-built inventory are being discussed, in the light of applicable rules. Particular attention is being paid to the topic of situational and height measurements. The paper discusses methods of measurement used, precision groups and objects subjected to inventory measurement are being listed. The practical part of this paper regards surveying as-built inventory of single-family house. In this study we discuss the consequential procedures that contractors need to fallow during the construction process, this includes preliminary actions, field work, and individual elaboration of the findings. Post-completion documentation, gathered in the form of technical frame, after obtaining a positive verification test result was included in the Head Office of Geodesy and Cartography.Ovaj članak ima za svrhu prikazati opseg geodetskih radova provedenih na popisu izvedbenih stanja zgrada i komunalne infrastrukture. Teorijski dio ovog rada donosi pravila za pravnu osnovu na teritoriju Poljske, koja su ključni dio geodetskih i kartografskih studija. Povrh toga, razmatraju se faze popisa izvedbenog stanja geodetskih radova s obzirom na važeća pravila. Posebna je pažnja posvećena temi situacijskih i visinskih mjerenja. U radu se razmatraju primijenjene metode mjerenja te su popisane skupine preciznosti i skupine objekata koje su predmet inventarnih mjerenja. Praktični dio ovog rada uzima u obzir izmjeru izvedenog inventara jedne obiteljske kuće. U ovoj studiji razmatramo posljedične postupke koje građevinari moraju slijediti tijekom procesa gradnje, a to uključuje preliminarne radnje, terenski rad i pojedinačnu elaboraciju rezultata. Naknadna dokumentacija prikupljena u obliku tehničkog okvira, nakon dobivanja pozitivnog rezultata testa verifikacije, dostavljena je Glavnom uredu za geodeziju i kartografiju

DiFX2: A more flexible, efficient, robust and powerful software correlator

Software correlation, where a correlation algorithm written in a high-level language such as C++ is run on commodity computer hardware, has become increasingly attractive for small to medium sized and/or bandwidth constrained radio interferometers. In particular, many long baseline arrays (which typically have fewer than 20 elements and are restricted in observing bandwidth by costly recording hardware and media) have utilized software correlators for rapid, cost-effective correlator upgrades to allow compatibility with new, wider bandwidth recording systems and improve correlator flexibility. The DiFX correlator, made publicly available in 2007, has been a popular choice in such upgrades and is now used for production correlation by a number of observatories and research groups worldwide. Here we describe the evolution in the capabilities of the DiFX correlator over the past three years, including a number of new capabilities, substantial performance improvements, and a large amount of supporting infrastructure to ease use of the code. New capabilities include the ability to correlate a large number of phase centers in a single correlation pass, the extraction of phase calibration tones, correlation of disparate but overlapping sub-bands, the production of rapidly sampled filterbank and kurtosis data at minimal cost, and many more. The latest version of the code is at least 15% faster than the original, and in certain situations many times this value. Finally, we also present detailed test results validating the correctness of the new code.Comment: 28 pages, 9 figures, accepted for publication in PAS

Calibration and evaluation of Skylab altimetry for geodetic determination of the geoid

The author has identified the following significant results. The Skylab altimeter experiment has proven the capability of the altimeter for measurement of sea surface topography. The geometric determination of the geoid/mean sea level from satellite altimetry is a new approach having significant applications in many disciplines including geodesy and oceanography. A generalized least squares collocation technique was developed for determination of the geoid from altimetry data. The technique solves for the altimetry geoid and determines one bias term for the combined effect of sea state, orbit, tides, geoid, and instrument error using sparse ground truth data. The influence of errors in orbit and a priori geoid values are discussed. Although the Skylab altimeter instrument accuracy is about plus or minus 1m, significant results were obtained in identification of large geoidal features such as over the Puerto Rico trench. Comparison of the results of several passes shows that good agreement exists between the general slopes of the altimeter geoid and the ground truth, and that the altimeter appears to be capable of providing more details than are now available with best known geoids

Interaction of marine geodesy, satellite technology and ocean physics

The possible applications of satellite technology in marine geodesy and geodetic related ocean physics were investigated. Four major problems were identified in the areas of geodesy and ocean physics: (1) geodetic positioning and control establishment; (2) sea surface topography and geoid determination; (3) geodetic applications to ocean physics; and (4) ground truth establishment. It was found that satellite technology can play a major role in their solution. For solution of the first problem, the use of satellite geodetic techniques, such as Doppler and C-band radar ranging, is demonstrated to fix the three-dimensional coordinates of marine geodetic control if multi-satellite passes are used. The second problem is shown to require the use of satellite altimetry, along with accurate knowledge of ocean-dynamics parameters such as sea state, ocean tides, and mean sea level. The use of both conventional and advanced satellite techniques appeared to be necessary to solve the third and fourth problems