Federal Institute of Metrology

The instruments used for routine pollen monitoring are gradually changing from traditional impactors with manual data processing to automated pollen monitors using deterministic and/or machine-learning algorithms for data analysis. This manuscript compares pollen number concentration of Alnus sp., Betula sp., Corylus sp., and Poaceae measured by Hirst-type bioaerosol samplers and the SwisensPoleno automated bioaerosol monitor in Switzerland and Norway. Due to physical particle losses and the classification rate of the algorithms being well below unity, scaling factors had to be applied to the measurements of the SwisensPoleno to match those of the Hirst impactor. These scaling factors depended on the geographic location, i.e. differed significantly between Switzerland and Norway. The importance of adjusting the scaling factors according to the location of the monitoring network and the need for reporting the numerical values of these scaling factors in future scientific publications is emphasized.

CCEM.RF-K5.d.CL is the first BIPM key comparison in the radio-frequency and microwave domain to apply the collapsing-star scheme, in which the pilot laboratory provides the link between all participants. Scattering parameters are measured in the 2.4 mm coaxial line system up to 50 GHz. The measurand is two-dimensional and requires a multivariate evaluation. In contrast to earlier S-parameter comparisons, results are analyzed over all measured frequency points rather than over a few selected ones.

Modern power systems are undergoing a rapid transformation driven by the massive integration of renewable energy sources and converter-interfaced generation. This evolution has introduced complex dynamic phenomena, specifically Sub-Synchronous Oscillations (SSOs), which pose significant risks to grid stability. This paper proposes a novel detection algorithm, TFMcorr, which builds upon the Taylor-Fourier Multifrequency (TFM) estimator. By exploiting the derivative terms of the phasor expansion and implementing a cross-correlation analysis, the method effectively detects amplitude and phase modulations while differentiating them from spurious interferences. We employ extensive Monte-Carlo simulations and real-world datasets to quantify uncertainty and detection probability, demonstrating the algorithm's capability to detect SSO frequencies as low as 0.1 Hz with high reliability. Validation on real-world field data also confirms the algorithm's applicability in complex, multi-node environments, demonstrating accurate tracking of dynamic modulations.

Phasor Measurement Units (PMUs) are now employed worldwide, particularly for transmission grid monitoring and control, and they are expected to pervade medium voltage distribution. Moreover, research is continuously improving the achieved measurement performance, which in turn tightens the accuracy requirements for proper testing and certification. In this paper, we present the design, development, and characterization of a flexible PMU calibrator capable of reproducing both sinusoidal and distorted test conditions. When compared to conventional solutions, the key innovation is that the waveform supplied to the device under test is iteratively reacquired and adjusted so that the parameters of interest closely match the corresponding reference values. The calibrator is thus capable of compensating for the nonlinearity introduced by the generation system, so that normalized root mean square error values of about 0.02% are obtained. Therefore, the achieved accuracy may approach that characterizing the adopted measurement chain.

This abstract presents a bilateral comparison of microwave noise measurements conducted by the Swiss Federal Institute of Metrology and the US National Institute of Standards and Technology. The noise temperatures of two traveling standards were measured using systems at both national laboratories. A key feature of this comparison is the independence of the methodologies; the measurement systems utilize significantly different architectures and rely on distinct traceability paths. Preliminary results demonstrating the level of agreement across the 1 GHz to 12 GHz frequency range are presented.