An innovative mathematical solution for a time-efficient IVS reference point determination

The improvement of the local ties between different observation methods (GPS, VLBI, etc.) improves the quality of the ITRF considerably. The IVS reference point of a VLBI radio telescope is defined as the intersection between the azimuth- and elevation-axis or, if they do not intersect, the intersection of the right-angle projection from the elevation-axis onto the azimuth-axis. In the past, these axes have been estimated by fitting 3D circles, e.g. (Eschelbach et al., 2003) or (Dawson et al., 2006). The data acquisition for the determination of the circles requires that the telescope has to be moved into clearly defined positions; therefore, the basic station process (data gathering for the intrinsic telescope task) is disturbed. In this paper we present an alternative mathematical model, which computes the reference point without circle fitting. This algorithm does not need observations from predefined telescope positions and therefore the station\u27s downtime can be reduced. The parameter estimation of this non-linear problem is implemented in two steps. At first we are using the Levenberg-Marquardt-Algorithm for a pre-evaluation to find stable approximate values (Madsen et al., 2004), which we use for the main least-square-model in a second step

New Technologies for the Real 3D Reference Point Determination

For local tie determination accuracy the reference point determination is required. This paper discusses the advantages of new cinematic measurement techniques as robot tacheometers and laser trackers. Laser radar will be of advantage to detect reflector deformations

Grundlegende Aspekte zur Bestimmung der Leistungsfähigkeit von Robottachymetern

Today more and more total stations are equipped with tracking features, which enable the user to induce the instrument to aim at targets or to follow a moving prism automatically. These instruments are called robot tacheometers. After a brief review of their functionality and of possible applications, potential error sources relating to the additional features are discussed, regarding separately the static mode (including stop-and-go) and the cinematic mode. Furthermore, systematic and stochastic aspects are characterized. Evaluation strategies for the determination of the performance of robot tacheometers are presented: on the one hand the testing only procedures which prove the instruments’ features according to the manufacturers’ specifications and on the other hand the calibration functions with the possibility to increase the instruments’ accuracy. The requirement for specific examination and calibration methods is shown, which is a demanding task, because a new dimension, time, is involved

Geringe Unsicherheit und ein hoher Grad des Vertrauens - zum Abschied von Bernhard Heck

Die Metrologie lehrt, dass eine Messgröße ohne Angabe der Messunsicherheit, die dem Messwert vernünftigerweise zuzuordnende Streubreite, wertlos ist. Dieser Beitrag zeigt den Mehrwert der Messunsicherheit unter Angabe des Grades des Vertrauens gegenüber der bisher in der Geodäsie gebräuchlichen empirischen Standardabweichung auf und schlägt den Bogen zur Zusammenarbeit mit meinem Kollegen Bernhard Heck