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    Wyświetlanie 1-7 z 7
    Tytuł:
    Recognizing the Sequences of Code Manipulated Short LFM Signals
    Autorzy:
    Leszczyński, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/176689.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sonar
    LFM signal
    matched filtering
    Opis:
    Noise-like binary sequences combined with signals with linear frequency modulation might be suc- cessfully used to increase the reliability of the recognition of both probe and communication signals in the presence of natural and artificial interference. To identify such formed sequences the usage of the two-step matched filtering was suggested and the probabilistic model of the recognition of noise-like code sequences transferred by LFM signals was developed.
    Źródło:
    Archives of Acoustics; 2012, 37, 3; 295-300
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimization of Short Probe Linear Frequency Modulated Signal Parameters
    Autorzy:
    Pogribny, W.
    Leszczyński, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/176953.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sonar
    LFM signal
    matched filtering
    Opis:
    In many physical experiments, linear frequency modulated (LFM) signals are widely used to probe objects in different environments, from outer-space to under- water. These signals allow a significant improvement in measurement resolution, even when the observation distance is great. For example, using LFM probe signals in underwater investigations enables discovery of even small objects covered by bottom sediments. Recognition of LFM (chirp) signals depends on their compression based on matched filtering. This work presents two simple solutions to improve the resolution of the short chirp signals recognition. These methods are effective only if synchronization between the signal and matched filter (MF) is obtained. This work describes both the aforementioned methods and a method of minimizing the effects of the lack of synchronization. The proposed matched filtering method, with the use of n parallel MFs and other techniques, allows only one sample to be obtained in the main lobe and to accurately locate its position in the appropriate sampling period Ts with accuracy Ts/n. These approaches are appropriate for use in probe signal processing.
    Źródło:
    Archives of Acoustics; 2011, 36, 4; 861-871
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Filtering Property of Signal Sampling in General and Under-Sampling as a Specific Operation of Filtering Connected with Signal Shaping at the Same Time
    Autorzy:
    Borys, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/226441.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal sampling
    filtering
    discrete-time Fourier transform
    Opis:
    In this paper, we show that signal sampling operation can be considered as a kind of all-pass filtering in the time domain, when the Nyquist frequency is larger or equal to the maximal frequency in the spectrum of a signal sampled. We demonstrate that this seemingly obvious observation has wide-ranging implications. They are discussed here in detail. Furthermore, we discuss also signal shaping effects that occur in the case of signal under-sampling. That is, when the Nyquist frequency is smaller than the maximal frequency in the spectrum of a signal sampled. Further, we explain the mechanism of a specific signal distortion that arises under these circumstances. We call it the signal shaping, not the signal aliasing, because of many reasons discussed throughout this paper. Mainly however because of the fact that the operation behind it, called also the signal shaping here, is not a filtering in a usual sense. And, it is shown that this kind of shaping depends upon the sampling phase. Furthermore, formulated in other words, this operation can be viewed as a one which shapes the signal and performs the low-pass filtering of it at the same time. Also, an interesting relation connecting the Fourier transform of a signal filtered with the use of an ideal low-pass filter having the cut frequency lying in the region of under-sampling with the Fourier transforms of its two under-sampled versions is derived. This relation is presented in the time domain, too.
    Źródło:
    International Journal of Electronics and Telecommunications; 2020, 66, 3; 589-594
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of a novel FPGA-based system for filtering audio signals using a finite impulse response filters
    Autorzy:
    Lipowski, Adrian
    Majewski, Paweł
    Pluta, Sławomir
    Powiązania:
    https://bibliotekanauki.pl/articles/2055238.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    audio filtering
    FIR filter
    FPGA
    signal processing
    Opis:
    In this article, an analysis of an innovative system for filtering signals in the audible range (16 Hz - 20 kHz) on programmable logic devices using a filters with a finite impulse response, is presented. Mentioned system was neat combination of software and hardware platform, where in the program layer a multiple programming languages including VHDL, JavaScript, Matlab or HTML were used to create completely useful application. To determine the coefficients of polynomial filters the Matlab Filter Design & Analysis Tool was used. Thanks to the developed graphic layer, a user-friendly interface was created, which allows easily transfer the required coefficients from the computer to the executive system. The practical implementation made on the FPGA platform, specifically on the Altera DE2- 115 development kit with the FPGA Cyclone IV, was compared with simulation realization of Matlab FIR filters. The performed research confirm the effectiveness of filtration in real time with up to 128th order of the filter for both audio channels simultaneously in FPGA-based system.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 1; 19--26
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Short-term positioning accuracy based on mems sensors for smart city solutions
    Autorzy:
    Grzechca, Damian
    Paszek, Krzysztof
    Powiązania:
    https://bibliotekanauki.pl/articles/220713.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electro-mechanical system
    received signal strength indicator
    positioning
    filtering
    Opis:
    The paper presents a method of obtaining short-term positioning accuracy based on micro electro-mechanical system (MEMS) sensors and analysis of the results. A high-accuracy and fast-positioning algorithm must be included due to the high risk of accidents in cities in the future, especially when autonomous objects are taken into account. High-level positioning systems should consider a number of sub-systems such as global positioning system (GPS), CCTV – video analysis, a system based on analysis of signal strength of access points (AP), etc. Short-term positioning means that there are other locating systems with a sufficiently high degree of accuracy based on, e.g. a video camera, but the located object can disappear when it is hidden by other objects, e.g. people, things, shelves etc. In such a case, MEMS sensors can be employed as a positioning system. The paper examines typical movement profiles of a radio-controlled (RC) model and fundamental filtering methods in respect of position accuracy. The authors evaluate the complexity and delay of the filter and the accuracy of the positioning in respect of the current speed and phase of movement (positive acceleration, constant) of the object. It is necessary to know whether and how the length of the filter changes the position accuracy. It has been shown that the use of fundamental filters, which provide solutions in a short time, enables to locate objects with a small error in a limited time.
    Źródło:
    Metrology and Measurement Systems; 2019, 26, 1; 95-107
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A robust fixed-lag smoothing algorithm for dynamic systems with correlated sensor malfunctions
    Autorzy:
    Grishin, Y. P.
    Janczak, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/199833.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    outliers
    robust signal processing
    nonlinear filtering
    fault detection
    systems with changing structures
    Opis:
    A new robust fixed-lag smoothing algorithm for fault-tolerant signal processing in stochastic dynamic systems in the presence of correlated sensor malfunctions has been developed. The algorithm is developed using a state vector augmentation method and the Gaussian approximation of the current estimate probability density function. The algorithm can be used in the real-time fault-tolerant control systems as well as in radar tracking systems working in the complex interference environment. The performance of the developed algorithm are evaluated by simulations and compared with smoothing and nonlinear filtering algorithms.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 3; 517-523
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of multiband filtering, empirical mode decomposition and short-time fourier transform used to extract physiological components from long-term heart rate variability
    Autorzy:
    Adamczyk, Krzysztof
    Polak, Adam G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2052173.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heart rate variability
    nonstationary signal analysis
    multiband filtering
    empirical mode decomposition
    short-time Fourier transform
    Hilbert transform
    Opis:
    Heart rate is constantly changing under the influence of many control signals, as manifested by heart rate variability (HRV). HRV is a nonstationary, irregularly sampled signal, the spectrum of which reveals distinct bands of high, low, very low and ultra-low frequencies (HF, LF, VLF, ULF). VLF and ULF components are the least understood, and their analysis requires HRV records lasting many hours. Moreover, there are still no well-established methods for the reliable extraction of these components. The aim of this work was to select, implement and compare methods which can solve this problem. The performance of multiband filtering (MBF), empirical mode decomposition and the short-time Fourier transform was tested, using synthetic HRV as the ground truth for methods evaluation as well as real data of three patients selected from 25 polysomnographic records with a clear HF component in their spectrograms. The study provided new insights into the components of long-term HRV, including the character of its amplitude and frequency modulation obtained with the Hilbert transform. In addition, the reliability of the extracted HF, LF, VLF and ULF waveforms was demonstrated, and MBF turned out to be the most accurate method, though the signal is strongly nonstationary. The possibility of isolating such waveforms is of great importance both in physiology and pathophysiology, as well as in the automation of medical diagnostics based on HRV.
    Źródło:
    Metrology and Measurement Systems; 2021, 28, 4; 643-660
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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