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Wyświetlanie 1-15 z 16
Tytuł:
A New Approach to Measurement of Frequency Shifts Using the Principle of Rational Approximations
Autorzy:
Murrieta-Rico, F. N.
Petranovskii, V.
Sergiyenko, O. Y.
Hernandez-Balbuena, D.
Lindner, L.
Powiązania:
https://bibliotekanauki.pl/articles/220851.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency measurement
rational approximations
sensors
Opis:
When a frequency domain sensor is under the effect of an input stimulus, there is a frequency shift at its output. One of the most important advantages of such sensors is their converting a physical input parameter into time variations. In consequence, changes of an input stimulus can be quantified very precisely, provided that a proper frequency counter/meter is used. Unfortunately, it is well known in the time-frequency metrology that if a higher accuracy in measurements is needed, a longer time for measuring is required. The principle of rational approximations is a method to measure a signal frequency. One of its main properties is that the time required for measuring decreases when the order of an unknown frequency increases. In particular, this work shows a new measurement technique, which is devoted to measuring the frequency shifts that occur in frequency domain sensors. The presented research result is a modification of the principle of rational approximations. In this work a mathematical analysis is presented, and the theory of this new measurement method is analysed in detail. As a result, a new formalism for frequency measurement is proposed, which improves resolution and reduces the measurement time.
Źródło:
Metrology and Measurement Systems; 2017, 24, 1; 45-56
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laser frequency counting and frequency modulation width measurement from a FFT signal
Autorzy:
Křen, P.
Powiązania:
https://bibliotekanauki.pl/articles/221880.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
laser
modulation width
frequency measurement
optical frequency synthesizer
Opis:
A new method of optical frequency beat counting based on fast Fourier transform (FFT) analysis is described. Signals with a worse signal-to-noise ratio can be counted correctly comparing to the conventional counting method of detecting each period separately. The systematic error of FFT counting below 10 Hz is demonstrated and can be decreased. Additionally the modulation width of a frequency-stabilized laser with high frequency modulation index can be simultaneously measured during a carrier frequency measurement against an optical frequency synthesizer or other laser.
Źródło:
Metrology and Measurement Systems; 2012, 19, 3; 565-572
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A concept of a passive radar with quadrature microwave phase discriminators
Autorzy:
Rutkowski, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/221600.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
passive radar
instantaneous frequency measurement
IFM
microwave phase discriminator
phase of noise signal
Opis:
Passive radar does not have its own emitter. It uses so-called signals of opportunity emitted by non-cooperative illuminators. During the detection of reflected signals, a direct signal from a non-cooperative emitter is used as the reference signal. Detection of electromagnetic echoes is, in present day radars, performed by finding the maximum of the cross ambiguity function. This function is based on the multiplication of the received signal and the reference signal. Detection of echoes by means of a quadrature microwave phase discriminator QMPD was proposed in the work as an alternative solution for ambiguity function evaluation. This discriminator carries out vectorial summing of the received and the reference signals. The summing operations in QMPD are carried out with the aid of microwave elements and without the use of expensive digital signal processors. Definitions of the phase and phase difference of the so-called simple signals and noise signals were described. A proposal of a passive radar equipped with several independent quadrature microwave phase discriminators was presented. Ideas of algorithms of object detection and of the distance-to-object estimation designed for this radar have been also sketched.
Źródło:
Metrology and Measurement Systems; 2012, 19, 1; 95-104
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single parallel stubs as broadband microwave phase shifters
Autorzy:
Rutkowski, Adam
Powiązania:
https://bibliotekanauki.pl/articles/220484.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
phase shift
differential phase shift
microwave phase shifter
parallel stub
instantaneous frequency measurement
IFM
Opis:
Structures and characteristics of wideband small-size phase shifters made with the use of single parallel stubs are presented in this paper. The stubs can be short-circuited or open-circuited on termination. Such devices are well known, but are primarily used as components of filters or matching circuits. The novelty, then, comes from the establishment of simple, but helpful formulae, which enable to describe the insertion phase shift and differential phase shift of a line with short and open stubs connected in parallel. These equations can be very useful for designing complex microwave multi-ports. The results of simulations and measurements of the devices, which were designed and made, are shown herein. It was also proved that the presented device shave several usable operating frequency sub-bands, and that the differential phase shift values in the higher sub-bands are greater than those in the lower operating frequency ranges. Thanks to this, the described phase shifters can be used in more than one frequency sub-band. It was stated that in the conditions under analysis, larger phase shifts can be achieved using open-circuited stubs rather than short-circuited stubs. However, the phase shifters with shorted parallel stubs can operate in a wider frequency band.
Źródło:
Metrology and Measurement Systems; 2020, 27, 1; 91-102
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation of Goertzel-based frequency estimation for power quality monitoring in embedded measurement systems
Autorzy:
Rodrigues, Nuno M.
Janeiro, Fernando M.
Ramos, Pedro M.
Powiązania:
https://bibliotekanauki.pl/articles/2173880.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
power quality
frequency estimation
non-integer Goertzel
frequency interpolation
embedded measurement systems
Opis:
International standards from IEC and IEEE regulate power grid parameters such as the RMS value, frequency, harmonic and interharmonic distortion, unbalance or the presence of transients, that are important to assure the quality of distributed power. Standard IEC 61000-4-30 suggests the zero crossing algorithm for the measurement of the power grid frequency, but also states that different algorithms can be used. This paper proposes a new algorithm, the Fractional Interpolated Discrete Fourier Transform, FracIpDFT, to estimate the power grid frequency, suitable for implementation in resource limited embedded measurement systems. It is based on the non-integer Goertzel algorithm followed by interpolation at non-integer multiples of the DFT frequency resolution. The proposed algorithm is validated and its performance compared with other algorithms through numerical simulations. Implementation details of the FracIpDFT in an ARM Cortex M4 processor are presented along with frequency measurement results performed with the proposed algorithm in the developed system.
Źródło:
Metrology and Measurement Systems; 2022, 29, 3; 455--468
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit
Autorzy:
Chabowski, K.
Piasecki, T.
Dzierka, A.
Nitsch, K.
Powiązania:
https://bibliotekanauki.pl/articles/221804.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
impedance
converter
AD5933
system-on-a-chip
measurement
Opis:
As it contains elements of complete digital impedance meter, the AD5933 integrated circuit is an interesting solution for impedance measurements. However, its use for measurements in a wide range of impedances and frequencies requires an additional digital and analogue circuitry. This paper presents the design and performance of a simple impedance meter based on the AD5933 IC. Apart from the AD5933 IC it consists of a clock generator with a programmable prescaler, a novel DC offset canceller for the excitation signal based on peak detectors and a current to voltage converter with switchable conversion ratios. The authors proposed a simple method for choosing the measurement frequency to minimalize errors resulting from the spectral leakage and distortion caused by a lack of an anti-aliasing filter in the DDS generator. Additionally, a novel method for the AD5933 IC calibration was proposed. It consists in a mathematical compensation of the systematic error occurring in the argument of the value returned from the AD5933 IC as a result. The performance of the whole system is demonstrated in an exemplary measurement.
Źródło:
Metrology and Measurement Systems; 2015, 22, 1; 13-24
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methods of DC/DC converter transfer function measurements, based on data acquired in the time domain
Autorzy:
Walczak, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/220796.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
DC–DC converters
frequency characteristics
transfer function measurement
Opis:
The measurement of frequency characteristics, like magnitude and phase, related to a specific transfer function of DC–DC converters, can be a difficult task - especially when the measured signal approaches the boundary of a small-signal model validity (i.e. 1/3 of the switching frequency fS ). It is hard to find a paper where authors mention the measurement techniques they use to draw frequency characteristics. Meanwhile the presence of noise in the output signal does not enable to directly measure the gain and the phase shift between the input and output signals. In such situations additional analysis is required in order to achieve a reliable result. This paper contains a description of a few methods that can be used to analyse measured signals in order to determine the gain and the phase shift of a specific transfer function. They enable to verify mathematical models in a wide range of frequencies (up to 1/3 fS ). The methods use signals measured in the time domain and can be implemented in mathematical software such as Matlab or Scilab.
Źródło:
Metrology and Measurement Systems; 2019, 26, 4; 661-671
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High frequency metrology for intracardiac ablation: in-vivo results
Autorzy:
Rouane, A.
Bru, P.
Powiązania:
https://bibliotekanauki.pl/articles/221888.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
impedance matching
voltage measurement cell
current measurement cell
high frequency energy
Opis:
Cardiac Radiofrequency (RF) ablation is a commonly used clinical procedure for treating many cardiac arrhythmias. However, the efficacy of RF ablation may be limited by two factors: small ventricular lesions and impedance rise, leading to coagulum formation and desiccation of tissue. In this paper, a high frequency (HF) energy ablation system operating at 27.12 MHz based on an automated load matching system was developed. A HF energy matched probe associated to the automated impedance matching device ensures optimal transfer of the energy to the load. The aim of this study was to evaluate this energy for catheter ablation of the atrioventricular junction. In vivo studies were performed using 10 sheep to characterize the lesions created with the impedance matching system. No cardiac perforation was noted. No thrombus was observed at the catheter tip. Acute lesions ranged from 3 to 45 mm in diameter (mean šSD = 10.3š10) and from 1 to 15 mm in depth (6.7š3.9), exhibiting a close relationship between HF delivered power level and lesion size. Catheter ablation using HF current is feasible and appears effective in producing a stable AV block when applied at the AV junction and large myocardial lesions at ventricular sites.
Źródło:
Metrology and Measurement Systems; 2012, 19, 3; 603-610
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distance measurement errors in silent FM-CW sonar with matched filtering
Autorzy:
Marszal, J.
Salamon, R.
Powiązania:
https://bibliotekanauki.pl/articles/220637.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silent sonar
frequency modulation
continuous wave
matched filtering
distance measurement
errors
Doppler effect
Opis:
The secretiveness of sonar operation can be achieved by using continuous frequency-modulated sounding signals with reduced power and significantly prolonged repeat time. The application of matched filtration in the sonar receiver provides optimal conditions for detection against the background of white noise and reverberation, and a very good resolution of distance measurements of motionless targets. The article shows that target movement causes large range measurement errors when linear and hyperbolic frequency modulations are used. The formulas for the calculation of these errors are given. It is shown that for signals with linear frequency modulation the range resolution and detection conditions deteriorate. The use of hyperbolic frequency modulation largely eliminates these adverse effects.
Źródło:
Metrology and Measurement Systems; 2012, 19, 2; 321-332
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the Extremely Low Frequency Magnetic Field Emission from Laptop Computers
Autorzy:
Brodić, D.
Powiązania:
https://bibliotekanauki.pl/articles/221562.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
classification
ELF
EMF
laptop
measurement
Opis:
This study addresses the problem of magnetic field emission produced by the laptop computers. Although, the magnetic field is spread over the entire frequency spectrum, the most dangerous part of it to the laptop users is the frequency range from 50 to 500 Hz, commonly called the extremely low frequency magnetic field. In this frequency region the magnetic field is characterized by high peak values. To examine the influence of laptop’s magnetic field emission in the office, a specific experiment is proposed. It includes the measurement of the magnetic field at six laptop’s positions, which are in close contact to its user. The results obtained from ten different laptop computers show the extremely high emission at some positions, which are dependent on the power dissipation or bad ergonomics. Eventually, the experiment extracts these dangerous positions of magnetic field emission and suggests possible solutions.
Źródło:
Metrology and Measurement Systems; 2016, 23, 1; 143-154
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monitoring of phase jitter in fibre optic time and frequency transfer systems
Autorzy:
Salwik, K.
Śliwczyński, Ł.
Krehlik, P.
Powiązania:
https://bibliotekanauki.pl/articles/221405.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
jitter measurement
phase comparison
fibre optics
time and frequency transfer
bidirectional
optical amplifier
Opis:
The phase jitter enables to assess quality of signals transmitted in a bi-directional, long-distance fibre optic link dedicated for dissemination of the time and frequency signals. In the paper, we are considering measurements of jitter using a phase detector the detected frequency signal and the reference signal are supplied to. To cover the wideband jitter spectrum the detected signal frequency is divided and - because of the aliasing process - higher spectral components are shifted down. We are also examining the influence of a residual jitter that occurs in the reference signal generated by filtering the jitter occurring in the same signal, whose phase fluctuations we intend to measure. Then, we are discussing the evaluation results, which were obtained by using the target fibre optic time and frequency transfer system.
Źródło:
Metrology and Measurement Systems; 2018, 25, 3; 487-497
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement and Analysis of Partial Discharge using an Ultra-High Frequency Sensor for Gas Insulated Structures
Autorzy:
Wang, G.
Kil, G.-S.
Powiązania:
https://bibliotekanauki.pl/articles/221519.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas insulated structures
partial discharge
ultra-high frequency sensor
conversion
Opis:
Although the gas insulated structures have a high degree of reliability, the unavoidable defects are primary reason of their failures. Partial discharge (PD) has been regarded as an effective indication for condition monitoring and diagnosis of gas insulated switchgears (GISs) to ensure their reliable and stable operation. Among various PD detection methods, the ultra-high frequency (UHF) technique has the advantages of on-line motoring and defect classification. In this paper, there are presented 7 types of artificial electrode systems fabricated for simulation of real insulation defects in gas insulated structures. A real-time measurement system was developed to acquire defect patterns in a form of phase-resolve partial discharge (PRPD) intensity graph, using a UHF sensor. Further, the discharge distribution and statistical characteristics were extracted for defect identification using a neural network algorithm. In addition, a conversion experiment was proposed by detecting the PD pulse simultaneously using a non-induction resistor and a UHF sensor. A relationship between the magnitude of UHF signal and the amplitude of apparent charge was established, which was used for evaluation of PD using the UHF sensor.
Źródło:
Metrology and Measurement Systems; 2017, 24, 3; 515-524
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of a high-precision digital multimeter by the laboratory of calibration of multifunction electrical instruments of INRIM
Autorzy:
Galliana, Flavio
Lanzillotti, Marco
Powiązania:
https://bibliotekanauki.pl/articles/220993.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
digital multimeter
calibration
measurement uncertainties
low-frequency electrical measurements
performance index
measurement specifications
Opis:
A metrological verification of a high precision digital multimeter was made by the laboratory of calibration of programmable electrical multifunction instruments of the National Institute of Metrological Research (INRIM) in order to verify its accuracy and stability. The instrument had been tested for a period of six months for five low-frequency electrical quantities (DC and AC Voltage and Current and DC Resistance). Its stability and precision were compared with the accuracy specifications of the manufacturer. As a new approach, a performance index of the DMM was introduced and evaluated for each examined measurement point. The DMM showed a satisfactory agreement with its specifications to be considered at the level of other top-class DMMs and even better in some measurements points.
Źródło:
Metrology and Measurement Systems; 2019, 26, 2; 283-296
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of Short-Circuit Effects on Transformer Winding with SFRA Method and Impact Test
Autorzy:
Gutten, M.
Janura, R.
Šebök, M.
Korenčiak, D.
Kučera, M.
Powiązania:
https://bibliotekanauki.pl/articles/221649.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transformer
mechanical effects
measuring methods
frequency response
impact test
Opis:
The paper presents theoretical and experimental analyses of a possible effect of the short-circuit forces on the transformer winding. The first part of the paper is focused on creation and activity of the radial and axial forces during a short circuit. It shows dimensions, direction and − of course − the resulting mechanical stress. The presented equation shows basic dependencies of these mechanical forces created in the transformer winding. Finally, the paper presents experimental methods of diagnosing and analysing the effects of short-circuit forces on the transformer winding.
Źródło:
Metrology and Measurement Systems; 2016, 23, 4; 521-529
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of instantaneous shaft speed by advanced vibration signal processing-application to wind turbine gearbox
Autorzy:
Zimroz, R.
Urbanek, J.
Barszcz, T.
Bartelmus, W.
Millioz, F.
Martin, N.
Powiązania:
https://bibliotekanauki.pl/articles/220531.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speed tracking
speed estimation
instantaneous frequency
spectrogram
wind turbines
Opis:
Condition monitoring of machines working under non-stationary operations is one of the most challenging problems in maintenance. A wind turbine is an example of such class of machines. One of effective approaches may be to identify operating conditions and investigate their influence on used diagnostic features. Commonly used methods based on measurement of electric current, rotational speed, power and other process variables require additional equipment (sensors, acquisition cards) and software. It is proposed to use advanced signal processing techniques for instantaneous shaft speed recovery from a vibration signal. It may be used instead of extra channels or in parallel as signal verification.
Źródło:
Metrology and Measurement Systems; 2011, 18, 4; 701-711
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 16

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