Abstract: Method for stabilizing the frequency of a frequency synthesizer by means of a reference oscillator unit coupled to a voltage controlled oscillator (VCO) and a frequency synthesizer, wherein the synthesizer is provided with a phase locked loop (PLL) to stabilize the operation of the voltage controlled oscillator, wherein the reference oscillator unit is a MEMS (MicroElectromechanicalSystems) reference oscillator unit, the temperature of the MEMS reference oscillator unit is measured, and the output frequency is corrected according to the measured temperature by using a frequency/temperature function.

Abstract: This publication discloses a method and arrangement for determining the hardening depth of steel or other ferromagnetic substances without breaking the object being measured. According to the invention, a varying magnetic field, which causes magnetic Barkhausen noise (MBN), is created in the measurement object with the aid of a magnetization coil 13. The varying magnetic field is regulated in such a way that the maximum force of the magnetic field does not exceed the coercitive force of the unhardened part of the measurement object. The MBN caused is measured with the aid of an MBN sensor. The measured signal is filtered and Fourier transformed. The signal in the frequency range is integrated over a suitable frequency band, in order to determine the value depicting the energy of the MBN. This value correlates with the hardening depth and on the basis of this value it is thus possible to determine the hardening depth.

Abstract: Method for stabilizing the frequency of a MEMS (Micro Electro Mechanical Systems) reference oscillator, and a MEMS reference oscillator, wherein the method comprises following steps: using two or more MEMS components, wherein each MEMS component is characterized by a set of properties, and selectively combining the desired properties from the MEMS components.

Abstract: In a paper or paperboard machine measurements are conducted with at least one measurement means attached to an element in the paper or paperboard machine. The measurement means has two surfaces made of electrically conductive material and has insulating material between them. The change in the capacitance between the surfaces made of conductive material is measured.

Abstract: The invention relates to a method for identifying objects, in which method electromagnetic radiation is imposed on the object (22-25) to be identified. According to the invention, such an identification component is used that includes a plurality of vibrating beams (4), and the electrical energy converted from said mechanical energy of the vibrating beams (4) is detected.

Abstract: The invention relates to a method for attenuating magnetic interference in a test room (1, 2, 8, 9) equipped with a shield of ferromagnetic material, in which method the interfering magnetic field is measured and a compensating field is generated on the basis of the measurement result. According to the invention, the interfering field to be measured is resolved in three magnetic field components oriented in different directions, each one of said magnetic field components (x, y, z) is measured with the help of coils (3, 4, 5, 6) wound about the wall elements (1, 2, 8, 9) made from said ferromagnetic material in a manner wherein a flux component passing through at least one of the wall element (1, 2, 8, 9) made from said ferromagnetic material that is oriented parallel to one of said magnetic field components (x, y, z) is measured with the help of coils wound about said wall element.

Abstract: An AC/DC voltage reference system has at least one micromechanically fabricated electrode pair having first and second electrodes facing each other so that the electrodes are disposed at a distance from each other, whereby at least one of the electrodes is movable against a spring force. An AC signal is applied over the electrodes to establish an electrostatic force at a frequency substantially higher than the effective mechanical resonant frequency of the movable electrode. The system further includes an apparatus for detecting the AC voltage applied between the electrodes, thus forming an AC voltage reference.

Abstract: The invention relates to a method for controlling by electrical means the interelectrode distance of such a micromechanical electrode structure [(7,8)] in which at least one electrode [(7)] is attached elastically suspended on the surrounding structure, whereby the elastic properties of each electrode and the electrical control applied over the electrodes determine the interelectrode distance. According to the invention, the distance between the electrodes [(7,8)] is controlled by controlling the AC control current passing via the electrodes [(7,8)].

Abstract: The invention relates to a method for attenuating magnetic interference in a test room (1, 2, 8, 9) equipped with a shield of ferromagnetic material, in which method the interfering magnetic field is measured and a compensating field is generated on the basis of the measurement result. According to the invention, the interfering field to be measured is resolved in three magnetic field components oriented in different directions, each one of said magnetic field components (x, y, z) is measured with the help of coils (3, 4, 5, 6) wound about the wall elements (1, 2, 8, 9) made from said ferromagnetic material in a manner wherein a flux component passing through at least one of the wall element (1, 2, 8, 9) made from said ferromagnetic material that is oriented parallel to one of said magnetic field components (x, y, z) is measured with the help of coils wound about said wall element.

Abstract: The invention concerns a silicon micromechanical weight sensor (26). According to the invention, the weight sensor comprises at least two conducting electrodes (2, 15) displaced at a distance from each other, whereby one of the elastically suspended electrode surfaces (2) or, alternatively, a structure connected thereto, acts as the pan surface of the weight sensor.

Abstract: A SQUID magnetometer for low noise, stable measurement of magnetic fields. The magnetometer has a SQUID formed of two Josephson junctions connected in parallel in a superconducting ring. An external damping impedance is connected across the Josephson junctions. The damping impedance has a resistive component and a capacitive component. The damping impedance damps Josephson oscillations occurring at frequencies greater than the frequency response range of said magnetometer. An amplifier stage coupled to said Josephson junctions has a biasing impedance for damping the Josephson junctions in the frequency response range of the magnetometer.

Abstract: A method and apparatus for determination of orientation of fibers in a material such as a paper or paperboard web comprised of elongated fibers of high moisture content. The material is subjected to an alternating electric field (E) of the RF or microwave frequency range lying in the plane of the material and the change caused by the presence of the material in the alternating electric field (E) is measured. The direction of the alternating electric field (E) is altered during the measurement, whereby the material need not be rotated with respect to the resonator for the measurement.

Abstract: The invention relates to a method and arrangement for measuring using magnetic flow measurement, the flow velocity of a liquid, particularly water. In the solution according to the invention, a component that is in the same phase with the magnetic field is measured from the sinusoidal voltage induced in the electrodes. The solution according to the invention can be utilized, for example, in measuring the flow velocity of water flowing in a water pipeline.

Abstract: The invention relates to a method and apparatus for processing the output signal of a low-noise sensor, particularly a squid. According to the invention, the output signal is coupled back to the sensor input by means of a resistance is set to be suitable by adjusting the rate of the resistor from room temperature, for instance by means of voltage.

Abstract: The invention concerns a method and an apparatus for measuring the temperature of an electrically conductive material, said method being based on the measurement of the thermal noise of the material. In the method, the fluctuation of the magnetic field generated by the random motion of the charge carriers in the conductive material is measured using a resonant circuit (3) without contact with the material (1) under measurement. The apparatus comprises a sensor (5) provided with a resonant circuit (3), the reactance element of which is placed at a distance (s) from the material (1) whose temperature is to be measured, and a preamplifier (2), said sensor (5) being mounted inside a frame (20) made of a conductive material, such as copper.