Methods and technologies for dynamic measurements have been developed and used for decades. To enable robust metrological traceability, uncertainty analysis methods for various applications have been derived and published by many scientists. In Europe, several research projects funded within European metrology research programmes (EMRP, EMPIR, Partnership on Metrology) have been focusing in dynamic measurements of mechanical, thermal and electrical quantities to provide new measurement and calibration methods. The European Metrology Network “Mathmet” drives the development of analytical methods related to dynamic measurement applications. The importance of dynamic measurement solutions has been boosted by digitalisation and rapid growth of computer power. Artificial intelligence combined with sensor fusion and sensor networks brings dynamism to wider measurement applications but may hide serious vulnerabilities to time dependent disturbances. At the moment most calibrations are performed under static conditions, i.e. the time dependency of the measurand is considered as a very small contribution to the overall calibration uncertainty. Calibrations at static conditions are often preferred due to practical reasons even if dynamic calibrations are available. In its recent strategy, the European Metrology Network “Smart North” has identified dynamic measurements as a field of regional competence and service development within Nordic and Baltic countries. This paper reviews most relevant research results and currently available calibration services in Europe. The study is focused on measurement needs related to machinery, combustion engines and electrical grids. Potential future needs for NMI level services in the region are analysed by considering specific needs of local industry, societal resilience and northern climate.

Present day GNSS offers a variety of signals from different satellite constellations and at various frequencies. This paper is based on the work conducted in the project SiL 2.0 and will focus on the study of multi-constellation/multi-frequency GNSS signals as received on top of construction equipment as part of the SiL 2.0 dissemination solution. This paper aims to study the impact of foliage and reflective environments on the various signals of multi-constellation GNSS with a focus on GPS and Galileo. Signal strength indicators (SSI) have been used as a measure to understand the shadowing environment around a stationary GNSS antenna mounted on an excavator. It is quite clear from the analysis that traditional GPS L2 signals, C2W and L2W, are weaker in strength than the L2C and L1 C/A signals, and this is found to be consistent for all of the GPS satellites. The effect of signal degradation due to bending over sharp metallic edges is also discussed.

This report presents the results from the third project of the CLOSE effort (Chalmers,Lantmäteriet, Onsala, RISE). The first project, CLOSE-RTK, investigated error sources inNetwork-RTK and simulated how to improve the performance. The results were used as a basisfor the densification, improvement and development of SWEPOS(https://swepos.lantmateriet.se/ ) during the last decade. The second project investigated how theionosphere effects the Network-RTK services.When the SWEPOS network are densified, the measurement uncertainty in the services arereduced. Thus, there is a need to continuously work in order to minimize effects from allsignificant error sources. Based on indications and experience from some 25 years operation ofSWEPOS, we have here focused on effects and error sources related to GNSS referencestations. Several new GNSS monuments are installed in the vicinity of the new Twin telescopesat the Onsala Space Observatory. Four good locations for permanent GNSS installations wereequipped with steel-grid masts serving as monuments for permanent GNSS installations. In twoof these, the installation has been untouched over a period extending over one year, while twohave been used to experiment with different installations of antennas, radomes, masthead, andthe environment of the receiving systems. The purpose of CLOSE-RTK III has been both toimprove the knowledge of the station-dependent effects in SWEPOS, and to quantify sucheffects by analyzing the collected observational data. Thus, the first work package has had theultimate goal to provide knowledge and recommendations when building a new GNSS stationand choosing the equipment to be used. The first work package also addresses the issue of somespecific station-dependent effects such as the monument stability as a function of airtemperature and sun radiation. The most important and significant results from these testsrelates to the effects of using different radomes and antennas. The influence of adding a tribrachbetween the antenna and the mast as well as adding a microwave-absorbing plate at the stationshas been investigated in detail. Furthermore, this study has looked in to the problem with birdslanding on the antennas in order to keep watch over the surrounding. A bird-detection algorithmhas been developed within the project.In second work package we investigate the necessity, and possibility, to develop methods forstation-dependent calibration in addition to the antenna-specific calibrations used to today.Since the performance of positioning services, e.g. Network-RTK, is steadily improved the errorsources related to the continuously operating reference stations may soon be limiting factors forfurther improvement of performance. Station dependent effects are thus important in highaccuracy GNSS positioning. Electrical coupling between the antenna and its near-fieldenvironment changes the characteristics of the antenna from what has been determined in e.g.absolute robot or chamber calibration.When using the presently available antenna models GNSS determination of the heightdifference between the SWEPOS pillar antennas and the surrounding reference antennas gave ~10 mm too low heights for the SWEPOS antennas. This error was derived from a comparisonwith conventional terrestrial surveys. The result varied significantly between days, and alsobetween different processing strategies. PCO/PCV errors derived from GNSS phase differencesshowed clear elevation-angle signatures that may cause systematic differences in the estimatedheight component and atmospheric delay, respectively. Electromagnetic coupling between theantenna and a metal plate below the antennas is probably contributing to the systematicPCO/PCV errors found.Starting already in 2008 and continued in this project we have developed methods andcarried out in-situ station calibration of the core permanent reference stations in SWEPOS. The station calibration intends to determine the electrical center of the GNSSantenna, as well as the PCV (phase center variations) when the antenna is installed at aSWEPOS station. The purpose of the calibration has been to examine the site-dependenteffects on the height determination as well as to establish site-dependent PCVs as acomplement to absolute calibrations of the antenna-radome pair.Our results have implications on a number of practical applications. To be mentioned isdetermination of the “local tie” between the GNSS reference point and the one from otherinstrumentation at fundamental geodetic stations. Usually, the L1 observable are used whileobserving the local GNSS networks in order to get as precise results as possible. But when usedin the IGS, the L3 (ionosphere-free) observable is used and also solving for troposphere delays.Thus, an error at the 1 cm level is easily introduced due to PCO/PCV errors.Since there are also other concepts emerging for precise real-time positioning, besides the so farused VRS-concept, the potential of these new concepts (MAC and PPP) are investigated inwork package three. Basically, the requirements from the infrastructure are invariant of thechosen concept if we aim for a certain level of performance. There is e.g. an ongoingdevelopment of real time methods for Precise Point Positioning (PPP) based on local or regionalaugmentation systems often referred to as PPP-RTK. The present development also includednew satellite signals and systems, thus, make available a three-frequency technique. The reportalso provides a schematic plan how such a service, based on PPP-RTK or rather Network-RTK,could be provided in the region of the Baltic Sea.Finally, the design of a high precision positioning service for the Baltic Sea are investigated.Motivation is that international vessel-traffic could be further optimized if the uncertainty ofvertical component in the navigation could be improved. The performance in the “Baltic Seanavigation service” would benefit from installation of some few off-shore GNSS referencestations that would be possible to locate to relatively shallow waters!

The performance of GNSS based positioning services is improving to the benefit of the users, and the uncertainties from densified RTK networks for construction work is approaching the sub-centimeter level also in the vertical. The error sources related to the continuously operating reference stations (CORS) may therefore soon be limiting factors for further improvement of performance. Station dependent effects are thus important in high accuracy GNSS positioning. Electrical coupling between the antenna and its near-field environment changes the characteristics of the antenna from what has been determined in e.g. absolute robot or chamber calibrations. Since the first initial tests back in 2008, Lantmäteriet together with Chalmers University of Technology and Research Institute of Sweden (RISE), has carried out in-situ station calibration of its network of permanent reference stations, SWEPOS. The station calibration intends to determine the electrical center of the GNSS antenna, as well as the PCV (phase center variations) when the antenna is installed at a SWEPOS station. One purpose of the calibration is to examine the site-dependent effects on the height determination in SWEREF 99 (the national reference frame). Another purpose is to establish PCV as a complement to absolute calibrations of the antenna-radome pair. In this paper we present both the methodology for observation procedure in the field and the method for the analysis, together with results of the station-dependent effects on heights as well as PCV from the analysis. Some strength and weakness of our method for GNSS station calibration are discussed at the end.

Aims. We report about a 230? GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). Methods. We installed VLBI equipment and measured the APEX station position to 1? cm accuracy (1σ). We then observed 3C 279 on 2012 May 7 in a 5? h 230? GHz VLBI track with baseline lengths of 2800? Mλ to 7200? Mλ and a finest fringe spacing of 28.6? μas. Results. Fringes were detected on all baselines with signal-to-noise ratios of 12 to 55 in 420? s. The correlated flux density on the longest baseline was ∼0.3? Jy beam-1, out of a total flux density of 19.8? Jy. Visibility data suggest an emission region ≤ 38? μas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 1010? K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ∼ 38? μas. Conclusions. With APEX the angular resolution of 230? GHz VLBI improves to 28.6? μas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40? μas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.

The study describes significant outcomes of the ‘Metrology for Meteorology’ project, MeteoMet, which is an attempt to bridge the meteorological and metrological communities. The concept of traceability, an idea used in both fields but with a subtle difference in meaning, is at the heart of the project. For meteorology, a traceable measurement is the one that can be traced back to a particular instrument, time and location. From a metrological perspective, traceability further implies that the measurement can be traced back to a primary realization of the quantity being measured in terms of the base units of the International System of Units, the SI. These two perspectives reflect long-standing differences in culture and practice and this project – and this study – represents only the first step towards better communication between the two communities. The 3 year MeteoMet project was funded by the European Metrology Research Program (EMRP) and involved 18 European National Metrological Institutes, 3 universities and 35 collaborating stakeholders including national meteorology organizations, research institutes, universities, associations and instrument companies. The project brought a metrological perspective to several long-standing measurement problems in meteorology and climatology, varying from conventional ground-based measurements to those made in the upper atmosphere. It included development and testing of novel instrumentation as well as improved calibration procedures and facilities, instrument intercomparison under realistic conditions and best practice dissemination. Additionally, the validation of historical temperature data series with respect to measurement uncertainties and a methodology for recalculation of the values were included.

Climate change and its consequences require immediate actions in order to safeguard the environment and economy in Europe and in the rest of world. Aiming to enhance data reliability and reduce uncertainties in climate observations, a joint research project called MeteoMet-Metrology for Meteorology started in October 2011 coordinated by the Italian Istituto Nazionale di Ricerca Metrologica (INRiM). The project is focused on the traceability of measurements involved in climate change: surface and upper air measurements of temperature, pressure, humidity, wind speed and direction, solar irradiance and reciprocal influences between measurands. This project will provide the first definition at the European level of validated climate parameters with associated uncertainty budgets and novel criteria for interpretation of historical data series. The big challenge is the propagation of a metrological measurement perspective to meteorological observations. When such an approach will be adopted the requirement of reliable data and robust datasets over wide scales and long terms could be better met.

Travelling Ionospheric Disturbances (TIDs) appear as Medium-Scale TIDs at mid-latitudes and as polar cap patches at high latitudes. Both can have a negative impact on GNSS measurements although the amplitude is of tenths of a TECU. Due to their spatial extension they affect GNSS measurements using receivers separated with distances up to ~1000 km. We present statistical measures of the ionospheric spatial variability as functions of time in solar cycle, annual season, and time of day for different geographical locations in Europe. In order to perform this spatial characterization of the ionosphere, we have used archived GPS data from a thirteen year period, 1999-2011, covering a complete solar cycle. We find that the ionospheric spatial variability is larger for the northern areas than for the southern areas. This is especially pronounced at solar maximum. For the more northern areas, the ionospheric variability is greater during night time than during day time, while for central Europe the variability is larger during day time. At solar maximum, the variability is larger during the months October and November and smaller in June and July.

Real Time Kinematic (RTK) is a system that utilises Global Navigation Satellite Systems (GNSS) to provide accurate positioning in real time. The contribution of the troposphere, the ionosphere and local effects, such as receiver noise and multipath are the most significant error sources affecting network RTK measurements We show how measurements with network RTK are affected by these different error sources under varying circumstances such as time of year or time of the day, network infrastructure, satellite systems and processing techniques We find that, for Scandinavian conditions, the effect of the ionospheric spatial variability on network RTK measurements is greater during nighttime than during daytime. The effect is also largest in the months October and November and smallest in the months of June and July. A densification of the reference network from 70 km to 35 km between the reference stations results in improved measurements. The error in the measured vertical position coordinate is reduced from 26 mm to 17 mm. The access to new GNSS reduces error in the measured vertical position coordinate from 26 to 21 mm. By using the L3-combination, the contribution from the ionosphere is reduced to virtually zero. However, this has been at the expense of the local errors