In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling, the sampling rate can be set to the Nyquist rate of the input signal, rather than to the Nyquist rate of the output signal by making use of Zhu’s generalized sampling theorem. This claim is supported by measurements on a basestation power amplifier. The findings are that the model error obtained when the output signal is sampled at the Nyquist rate of the input signal is approximately 1.5 dB higher than when the sampling rate is set to the Nyquist rate of the output signal. However, if a sampling rate of twice the Nyquist rate of the input signal is used, which is still typically, much lower than the Nyquist rate of the output signal, the degradation is only 0.2 dB. These are important findings that will substantially ease the requirements on ADCs used in measurement setups used for amplifier modelling.

The need for accurate calibration of current meters in the picoampere range is continuously increasing. A traceable current source for calibration of meters in the 100 fA – 100 pA current range is here presented. The source is based on a low-frequency generator ramp generator, which charges and discharges a gas-dielectric capacitor. Current traceability is given by the measurement of voltage parameters with a sampling voltmeter, and by calibration of the capacitor at audio frequency. The source has been employed in the EUROMET.EM-S24 "Comparison of small current sources" supplementary comparison.

Specially designed bridges are used for standard platinum resistance thermometer (SPRT) calibration to achieve lowest uncertainty. Such bridges are expensive and their measuring speeds are slow. A new type of instrument reported a few years ago was compared against the bridge to see if it is possible to use the new instrument instead of the bridge for SPRT calibration in some cases. Four SPRTs were calibrated at the triple point of water and the freezing points of tin and zinc using a Model 6010T Bridge and the new instrument (Model 1590) simultaneously. At these calibration points the maximum differences between the two instruments were within 0.4 mK at the tin point, and within 0.7 mK at the zinc point. The maximum difference in resistance ratio W(t) at these points was within 0.9 ppm of the readings. The differences over the entire range from 0°C to 419.527°C were calculated for the four SPRTs. The maximum differences were within 0.1 mK close to 0°C, within 0.5 mK at 300°C and within 0.7 mK at 420°C. The comparison results show the new instrument can be used for SPRT calibration to achieve an expanded uncertainty (k = 2) as low as 1.5 mK.

The present paper shows the advantages and disadvantages of road vehicles weighing. By considering the use of Weigh-in-Motion (WIM) instruments and applying the Monte Carlo`s simulation method, it is possible to demonstrate some factors that actually interfere in the measurement process of road vehicles weighing. This process is one contribution to metrology for the sustainable development, as long as it collaborates for the maintenance, life time and security of the highways.

The article gives an overview about the present state of torque calibration facilities in the MIKES-RAUTE Mass and Force Laboratory in Lahti, Finland. The laboratory utilises four high-level torque calibration devices in a range from 0,1 N·m to 20 kN·m. Also in use are several facilities for the calibration and testing of torque wrenches and other torque devices. The main components of the calibration devices are described briefly. Beside that the main steps of the development history of the devices during the past 10 years – as a reaction to the needs of the customers – are presented.