Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Gulzhan KASHAGANOVA"

Accuracy improvement of Fiber Bragg Grating peak wavelength demodulation using wavelet transform and various center wavelength detection algorithms DOI:10.15199/48.2016.06.15

Czytaj za darmo! »

The main feature of Fiber Bragg Gratings is that they perform a direct transformation of measured parameter into a shift in the center Bragg wavelength. This paper presents a possibility for extraction FBGs peak wavelength from spectra with high influence of noise by using wavelet transform. Spectra of tested FBG were measured in 20 points with different extending force applied to tested sample. Wavelet transform and various methods of center Bragg wavelength detection are jointly applied to improve wavelength detection accuracy. Experiment results shows that application of appropriate digital signal processing algorithms for denoising FBG spectra could greatly improve accuracy and linearity of fiber sensor processing characteristics. Streszczenie. Najważniejszą właściwością światłowodowych siatek Bragga (Fiber Bragg Gratings) jest liniowe przetwarzanie zmian mierzonej temperatury bądź odkształcenia na przesunięcie centralnej fali. Artykuł ten prezentuje możliwości wyznaczenia długości fali Bragga z widm silnie zaszumionych przy zastosowaniu transformaty Falkowej .Spectra rejestrowano w 20 punktach o różnych wartościach siły rozciągającej próbkę. Transformacja Falkowa oraz różne algorytmy wyszukiwania centralnej fali Bragga zostały zastosowane jednocześnie dla uzyskania poprawy precyzji wykreślania charakterystyki przetwarzania elementu mierzącego. Wyniki eksperymentu wskazują, że zastosowanie odpowiednich algorytmów cyfrowego przetwarzania sygnałów do widm FBG może w dużym stopniu poprawić dokładność wyznaczania charakterystyki przetwarzania światłowodowego czujnika. Poprawa dokładności demodulacji światłowodowych siatek Bragga dzięki użyciu transformaty falkowej i algorytmów detekcji centralnej długości fali Słowa kluczowe: Siatka Bragga, długość fali Bragga, transformata falkowa, czujnik naprężenia. Keywords: FBG, Bragg wavelength, wavelet transform, strain sensor. Introduction The main feature of fiber Bragg gratings is that they perf[...]

Analogue part of multichannel highly productive analog-digital system on converters and switches of current DOI:10.15199/48.2019.04.20

Czytaj za darmo! »

Analog-to-digital systems (ADS) are used to solve a wide class of problems in the measurement, signal recording and processing technique. Depending on the application area, they are subject to various requirements for accuracy, speed and productivity. For example, in measuring systems, a high absolute accuracy of the analog-to-digital conversion is sometimes required, and in the registration systems, a low linearity error is sufficient. Similarly, the primary analog signal in many sensors is converted to digital output signal using electronic circuits for signal processing and conditioning, incorporated into the sensor (i.e. the temperature and humidity sensors [1]) Regarding the same requirements for speed, they are determined by the spectra of the input analog signals and the possibility of their reproduction with minimal losses. In a number of cases, it is advisable to use such a complex characteristic as productivity. The basic unit of these systems is an analog-to-digital converter (ADC). Currently, there are basically three types of ADCs [2]: sigma-delta, pipelined and successive approximation. It should be noted that the first have high resolution, but their speed is relatively small [3, 4]. The highest speed is characterized by pipelined converters, but they have a sufficiently high power consumption and circuit complexity. Successive approximation ADCs have a significant productivity range and it can be further increased by introducing, for example, a weight redundancy [5, 6]. Relevance Quantitatively, the performance of the ADC can be estimated by analogy with digital computing devices [7], as the product of the display range (the length of the bit grid) by the frequency of the operations performed. For the ADC (part of the ADS), this will correspondingly be the product of the resolution of the analog-to-digital conversion (the number of conversion quanta) to the maximum frequency of execution of the conversions[...]

Spectral properties of Tilted Bragg Gratings with different tilt angles and variable surrounding conditions DOI:10.15199/48.2019.04.34

Czytaj za darmo! »

Fiber Bragg Gratings (FBGs) have become as an important field in technology of optical sensing due to their advantages in comparison to electronic counterparts. Most important advantages of this structures used as sensing elements are extremely small size, immunity to electromagnetic interference and ability to multiplexing of many structures in single fiber. They are generally very sensitive to temperature[1] changes and elongation of fiber with inscribed grating [2-4]. An important feature of FBGs used as sensing structures is that they are sensitive to many physical quantities which could lead to undesirable cross-sensitivity which occur in the same spectral response for changes of different quantities affecting the FBG. This property generally leads to requirement of temperature compensation. Scheme of internal structure and spectral characteristics of FBGs are presented in Fig. 1. The inconveniences resulting from spectral properties of conventional FBGs could be solved by performing a technological modifications e.g. by creating a chirp (variable period of internal refractive index perturbations in fiber core) to obtain desirable spectral properties. Fig.1. Scheme of internal refractive index structure in fiber core with inscribed Conventional FBG and spectral response in transmitted and reflected light Another possibility to change the spectral behaviour of gratings is creating the structure with introduced particular angle between planes of fiber core periodic fringes and fiber cross-section plane. In case of conventional gratings, planes of refractive index perturbations are parallel to crosssection plane of fiber while in tilted grating structure planes of internal fringes are angled in relation to cross-section plane with ΘTFBG angle [5,6]. Tilted fiber Bragg gratings (TFBGs) stand out by enhancement of resonances of backward-propagating cladding modes which is most evident effect of tilt angle introducing.[...]

 Strona 1