Polarimetric impulse response and polarimetric transfer function for time-sequential polarimeters

1990 ◽  
Author(s):  
Russell A. Chipman
Keyword(s):  
Transfer Function ◽  
Impulse Response

scholarly journals Identification of Nonlinear Systems: Volterra Series Simplification

10.14311/976 ◽  
2007 ◽  
Vol 47 (4-5) ◽  
Author(s):  
A. Novák
Keyword(s):  
Nonlinear System ◽  
Nonlinear Systems ◽  
Transfer Function ◽  
Linear System ◽  
Impulse Response ◽  
Volterra Series ◽  
Series Representation ◽  
Multimedia Systems ◽  
Audio Amplifier ◽  
Enormous Number

Traditional measurement of multimedia systems, e.g. linear impulse response and transfer function, are sufficient but not faultless. For these methods the pure linear system is considered and nonlinearities, which are usually included in real systems, are disregarded. One of the ways to describe and analyze a nonlinear system is by using Volterra Series representation. However, this representation uses an enormous number of coefficients. In this work a simplification of this method is proposed and an experiment with an audio amplifier is shown. 

A Frequency-Domain INS/GPS Dynamic Response Method for Bridging GPS Outages

2010 ◽  
Vol 63 (4) ◽  
pp. 627-643 ◽  
Author(s):  
Mohammed El-Diasty ◽  
Spiros Pagiatakis
Keyword(s):  
Neural Network ◽  
Transfer Function ◽  
Dynamic Response ◽  
Dynamic System ◽  
Least Squares ◽  
Frequency Domain ◽  
Impulse Response ◽  
Time Domain ◽  
Response Model ◽  
Response Method

We develop a new frequency-domain dynamic response method to model integrated Inertial Navigation System (INS) and Global Positioning System (GPS) architectures and provide an accurate impulse-response-based INS-only navigation solution when GPS signals are denied (GPS outages). The input to such a dynamic system is the INS-only solution and the output is the INS/GPS integration solution; both are used to derive the transfer function of the dynamic system using Least Squares Frequency Transform (LSFT). The discrete Inverse Least Squares Frequency Transform (ILSFT) of the transfer function is applied to estimate the impulse response of the INS/GPS system in the time domain. It is shown that the long-term motion dynamics of a DQI-100 IMU/Trimble BD950 integrated system are recovered by 72%, 42%, 75%, and 40% for north and east velocities, and north and east positions respectively, when compared with the INS-only solution (prediction mode of the INS/GPS filter). A comparison between our impulse response model and the current state-of-the-art time-domain feed-forward neural network shows that the proposed frequency-dependent INS/GPS response model is superior to the neural network model by about 26% for 2D velocities and positions during GPS outages.

scholarly journals Projeto de um Estetoscópio Digital para Ausculta Cardíaca

2019 ◽  
Author(s):  
Victor Hugo Ferreira Silva
Keyword(s):  
Transfer Function ◽  
Impulse Response ◽  
Frequency Band ◽  
Fourier Transforms ◽  
Least Squares Method ◽  
Finite Impulse Response ◽  
Gibbs Phenomenon ◽  
Signal Frequency ◽  
Diagnostic Tools ◽  
Low Frequencies

Trying to spread the use of cardiovascular diseases diagnostic tools, this undergraduate thesis had the purpose of creating a digital stethoscope prototype by creating a signal conditioning board composed by filters and amplifiers that emphasize the auscultation frequency band, and by creating a software for the analysis and processing of the cardiac auscultation signal using Matlab tools. The conditioning circuit transfer function modulus (which represents the input and output voltage ratio) was theorically and experimentally estimated. This value has behaved as expected for almost all the auscultation signal frequency band (16 to 1 kHz), just presenting a signal attenuation under the auscultation low frequencies. (16 to 20 Hz). Now the phase response obtained by the transfer function argument (which represents the output and input phase offset) was only theorically estimated but also presented a nonlinear response at low frequencies (16 to 20 Hz). The developed software made use of finite impulse response digital filters implemented by the least squares method to filter the frequencies not present in the auscultation band. Fast Fourier Transforms implemented by the recursive method were also utilized to analyze the signal in the frequency domain. To minimize the Gibbs phenomenon and the spectral leakage Hann windowing functions were utilized. To compensate the delay introduced by the finite impulse response filters the zero-phase filtering technique were utilized. The results had demonstrated that the software frequency response also was satisfactory at high frequencies, differently that at low frequencies. But in contrast, the auscultation samples were successfully filtered on the question of making the heart sounds distinguishable in the phonocardiograms, making possible that the heart rate and sound duration analysis were successfully executed.

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