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Wyświetlanie 1-5 z 5
Tytuł:
Improved method for phase wraps reduction in profilometry
Autorzy:
Du, G.
Wang, M.
Zhou, C.
Si, S.
Li, H.
Lei, Z.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173793.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase unwrapping
zero-padding
Fourier transform
carrier-frequency
profilometry
Opis:
In order to completely eliminate, or greatly reduce the number of phase wraps in 2D wrapped phase map, Gdeisat and co-workers proposed an algorithm, which uses shifting the spectrum towards the origin. But the spectrum can be shifted only by an integer number, meaning that the phase wraps reduction is often not optimal. In addition, Gdeisat’s method will take much time to make the Fourier transform, inverse Fourier transform, select and shift the spectral components. In view of the above problems, we proposed an improved method for phase wraps elimination or reduction. First, the wrapped phase map is padded with zeros, the carrier frequency of the projected fringe is determined by high resolution, which can be used as the moving distance of the spectrum. And then realize frequency shift in spatial domain. So it not only can enable the spectrum to be shifted by a rational number when the carrier frequency is not an integer number, but also reduce the execution time. Finally, the experimental results demonstrated that the proposed method is feasible.
Źródło:
Optica Applicata; 2017, 47, 2; 295-306
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimization of maximum errors in universal approximation of the unit circle by a polygon
Autorzy:
Borkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/221779.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
unit circle
approximation by polygon
LIDFT
interpolated DFT
zero padding
Opis:
This paper presents a universal approximation of the unit circle by a polygon that can be used in signal processing algorithms. Optimal choice of the values of three parameters of this approximation allows one to obtain a high accuracy of approximation. The approximation described in the paper has a universal character and can be used in many signal processing algorithms, such as DFT, that use the mathematical form of the unit circle. One of the applications of the described approximation is the DFT linear interpolation method (LIDFT). Applying the results of the presented paper to improve the LIDFT method allows one to significantly decrease the errors in estimating the amplitudes and frequencies of multifrequency signal components. The paper presents the derived formulas, an analysis of the approximation accuracy and the region of best values for the approximation parameters.
Źródło:
Metrology and Measurement Systems; 2011, 18, 3; 391-402
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Continuous and discontinuous linear approximation of the window spectrum by least squares method
Autorzy:
Borkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/221777.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
data window
spectrum approximation
interpolated DFT
LIDFT
spectrum estimation
zero padding
Opis:
This paper presents the general solution of the least-squares approximation of the frequency characteristic of the data window by linear functions combined with zero padding technique. The approximation characteristic can be discontinuous or continuous, what depends on the value of one approximation parameter. The approximation solution has an analytical form and therefore the results have universal character. The paper presents derived formulas, analysis of approximation accuracy, the exemplary characteristics and conclusions, which confirm high accuracy of the approximation. The presented solution is applicable to estimating methods, like the LIDFT method, visualizations, etc.
Źródło:
Metrology and Measurement Systems; 2011, 18, 3; 379-390
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double Block Zero Padding Acquisition algorithm for GPS software receiver
Autorzy:
Prasad, S. V. S.
Powiązania:
https://bibliotekanauki.pl/articles/384697.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
GPS
acquisition
weak signal
multi-constellatio
Double Block Zero Padding Acquisition
DBZP
FMDBZP
Opis:
Several methods of acquisition have been developed so far which aim at accelerating the acquisition process and detection of weak GPS signals. In many of these the search is parallelized in code or frequency space. However, sometimes the number of samples in code periods based on sampling frequency is not equal to required number of Radix-2 FFT algorithm. So it is again computing the DFT normal method without FFT. The main purpose and objective of this project is to implement a fast and robust for weak signal acquisition algorithm “Double Block Zero Padding Acquisition” (DBZP) for GPS L1 civilian signal. Technique is developed even for the signals where number of samples in the code period taken for correlation is not satisfying the required number for Radix-2 algorithm. It is also suitable for weak GPS signals acquisition, which require Pre-detection, or integration (correlation) Time (PIT) to be long.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2018, 12, 4; 58-63
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systematic errors of the LIDFT method: analytical form and verification by a Monte Carlo method
Autorzy:
Borkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/221176.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
LIDFT
multifrequency signal
interpolated DFT
spectrum estimation
zero padding
unit circle
approximation by polygon
Opis:
This paper derives analytical formulas for the systematic errors of the linear interpolated DFT (LIDFT) method when used to estimating multifrequency signal parameters and verifies this analysis using Monte-Carlo simulations. The analysis is performed on the version of the LIDFT method based on optimal approximation of the unit circle by a polygon using a pair of windows. The analytical formulas derived here take the systematic errors in the estimation of amplitude and frequency of component oscillations in the multifrequency signal as the sum of basic errors and the errors caused by each of the component oscillations. Additional formulas are also included to analyze particular quantities such as a signal consisting of two complex oscillations, and the analyses are verified using Monte-Carlo simulations.
Źródło:
Metrology and Measurement Systems; 2012, 19, 4; 673-684
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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