scholarly journals Spectral analysis of discrete signals with high frequency resolution

2019 ◽  
pp. 270-282
Author(s):  
О.В. Осипов
Keyword(s):  
Spectral Analysis ◽  
High Frequency ◽  
Time Complexity ◽  
Fourier Transforms ◽  
Electronic Devices ◽  
Digital Signal ◽  
Frequency Resolution ◽  
Frequency Responses ◽  
Discrete Signals ◽  
To Receive

Представлены алгоритмы прямого и обратного быстрого преобразований Фурье (БПФ), позволяющие обрабатывать дискретные сигналы с высоким частотным разрешением, в том числе с небольшим количеством отсчетов получать амплитудночастотные характеристики с длиной набора частот, большей, чем длина исходного дискретного сигнала. Временная сложность разработанных алгоритмов для прямого и обратного БПФ равна O(N R log2 N), где R частотное разрешение спектральной характеристики (отношение длины набора частот к длине N набора отсчетов сигнала). Разработанные методы позволят увеличить разрешающую способность отечественных систем цифровой обработки сигналов и могут быть реализованы в электронике и программном обеспечении для спектрального анализа. Algorithms of direct and inverse fast Fourier transforms are discussed. These algorithms allow one to process discrete signals with high frequency resolution, including with a small number of frequency samples, and to receive the frequency responses with a set length of frequencies greater than the length of the original discrete signal. The time complexity of the developed algorithms for the direct and inverse FFT is O(N R log2 N), where R is the frequency resolution of the spectral characteristic (the ratio of the length of a set of frequencies to the length N of a set of signal samples). The developed methods allow one to increase the resolution of systems of digital signal processing and can be implemented in electronic devices and in software for spectral analysis.

scholarly journals Review on the Millimeter-Wave Generation Techniques Based on Photon Assisted for the RoF Network System

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jiangnan Xiao ◽  
Chuang Zhao ◽  
Xingxing Feng ◽  
Xu Dong ◽  
Jiangli Zuo ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Electronic Devices ◽  
Low Frequency ◽  
Digital Signal ◽  
Development Trend ◽  
Wave Generation ◽  
Communication Link ◽  
Network System ◽  
High Frequency Microwave

With the development trend of wireless and broadband in the communication link and even the whole information industry, the demand of high-frequency microwave bandwidth has been increasing. The RoF network system solves the problem of spectrum congestion in low-frequency band by providing an effective technology for the distribution of high-frequency microwave signals over optical fiber links. However, the traditional mm-wave generation technique is limited by the bandwidth of electronic devices. It is difficult to generate high-frequency and low-phase noise mm-wave signals with pure electrical components. The mm-wave communication technology based on photon assisted can overcome the bandwidth bottleneck of electronic devices and provide the potential for developing the low-cost infrastructure demand of broadband mobile services. This paper will briefly explain the characteristics of the RoF network system and the advantages of high-frequency mm-wave. Then we, respectively, introduce the modulation schemes of RoF mm-wave generation based on photon assisted including directly modulated laser (DML), external modulation, and optical heterodyne. The review mainly focuses on a variety of different mm-wave generation technologies including multifrequency vector mm-wave. Furthermore, we list several approaches to realize the large capacity data transmission techniques and describe the digital signal processing (DSP) algorithm flow in the receiver. In the end, we summarize the RoF network system and look forward to the future.

Wavelet-based Segmentation and Feature Extraction of Heart Sounds for Intelligent PDA-based Phonocardiography

2007 ◽  
Vol 46 (02) ◽  
pp. 135-141 ◽  
Author(s):  
H. Nazeran
Keyword(s):  
Feature Extraction ◽  
Spectral Analysis ◽  
Fourier Transform ◽  
Wavelet Transform ◽  
Digital Signal ◽  
Heart Sounds ◽  
Segmentation Algorithm ◽  
Frequency Resolution ◽  
Time Frequency ◽  
Frequency Information

Summary Objectives : Many pathological conditions of the cardiovascular system cause murmurs and aberrations in heart sounds. Phonocardiography provides the clinician with a complementary tool to record the heart sounds heard during auscultation. The advancement of intracardiac phonocardiography combined with modern digital signal processing techniques has strongly renewed researchers' interest in studying heart sounds and murmurs.The aim of this work is to investigate the applicability of different spectral analysis methods to heart sound signals and explore their suitability for PDA-based implementation. Methods : Fourier transform (FT), short-time Fourier transform (STFT) and wavelet transform (WT) are used to perform spectral analysis on heart sounds. A segmentation algorithm based on Shannon energy is used to differentiate between first and second heartsounds. Then wavelet transform is deployed again to extract 64 features of heart sounds. Results : The FT provides valuable frequency information but the timing information is lost during the transformation process. The STFT or spectrogram provides valuable time-frequency information but there is a trade-off between time and frequency resolution. Waveletanalysis, however, does not suffer from limitations of the STFT and provides adequate time and frequency resolution to accurately characterize the normal and pathological heartsounds. Conclusions : The results show that the wavelet-based segmentation algorithm is quite effective in localizing the important components of both normal and abnormal heart sounds. They also demonstrate that wavelet-based feature extraction provides suitable feature vectors which are clearly differentiable and useful for automatic classification of heart sounds.

scholarly journals Broadband Spectral Analysis Algorithm with High-Frequency Resolution for Elimination of Overlap Interference between Adjacent Channels

2021 ◽  
Vol 11 (21) ◽  
pp. 10262
Author(s):  
Xianhai Wang ◽  
Teng Wang ◽  
Chuan Yin ◽  
Jun Han ◽  
Qiao Meng ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
High Frequency ◽  
Filter Bank ◽  
Large Scale ◽  
Spectral Lines ◽  
Frequency Resolution ◽  
Output Data ◽  
Wideband Signals ◽  
Flexible Architecture ◽  
Adjacent Channels

Spectral lines can be analysed to determine the physical properties of molecular clouds and the astrochemical processes in the formation area of massive stars. To improve the observation technology of radio astronomy, this paper proposes and compares two spectral analysis algorithms (improved weighted overlap-add (IWOLA) + FFT and IWOLA + weighted overlap-add (WOLA)). The proposed algorithms can obtain an ultra-high-frequency resolution for real-valued wideband signals, eliminate the signal overlapping interference between adjacent channels, substantially decrease the required hardware resources, especially multipliers, adders, and memory resources, and reduce the system design complexity. The IWOLA + FFT algorithm consists of an improved weighted overlap-add (IWOLA) filter bank, fast Fourier transform (FFT), a specific decimation for the output data from the IWOLA filter bank, and a selection for part of the output data from the FFT. The IWOLA + WOLA algorithm consists of the same modules as the IWOLA + FFT algorithm, with the second-stage FFT replaced by the modules of the weighted overlap-add (WOLA) filter bank and the accumulation for each sub-band. Based on an analysis of the underlying principles and characteristics of both algorithms, the IWOLA + FFT algorithm demonstrated a spectrum with a high frequency resolution and a comparable performance to an ultra-large-scale FFT, based on two smaller FFTs and a flexible architecture instead of a ultra-large-scale FFT. The IWOLA + WOLA algorithm contains the same function as the IWOLA + FFT algorithm and demonstrates a higher performance. The proposed algorithms eliminated the interference between the adjacent channels within the entire Nyquist frequency bandwidth. The simulation results verify the accuracy and spectral analysis performances of the proposed algorithms.

scholarly journals Iterative FFT-algorithms with high frequency resolution

2021 ◽  
pp. 121-134
Author(s):  
О.В. Осипов
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Spectral Characteristic ◽  
High Frequency ◽  
Iterative Algorithms ◽  
Digital Signal ◽  
Frequency Resolution ◽  
Training Process ◽  
Source Signal ◽  
Fft Algorithms

В работе представлены три итерационных алгоритма быстрого преобразования Фурье с прореживанием по времени, имеющие алгоритмическую сложность O (N·R·log2N), где R — частотное разрешение спектральной характеристики (отношение длины набора частот к длине N набора отсчетов исходного сигнала). Алгоритмы отличаются способами организации вычислений: некоторые используют обратную перестановку битов, другие — дополнительные массивы. Приведены подробные вычислительные графы, а также блок-схемы разработанных алгоритмов. Полученные результаты можно использовать для улучшения отечественной электроники и программного обеспечения, а также включать в учебный процесс при подготовке инженеров в области цифровой обработки сигналов. This paper presents three iterative algorithms for fast Fourier transform with decimation in time; these algorithms have the algorithmic complexity O (N·R·log2N), where R is the frequency resolution of the spectral characteristic (the ratio of the length of the frequency set to the length of the N set of samples of the source signal). The algorithms differ in the way they organize calculations: some use reverse bit permutation, while the others use additional arrays. Detailed computational graphs and flowcharts of the developed algorithms are provided. The results obtained can be used to improve domestic electronics and software as well as may be included in the training process for engineers in the field of digital signal processing.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

scholarly journals Spectral Analysis of Stationary Signals Based on Two Simplified Arrangements of Chirp Transform Spectrometer

Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 65
Author(s):  
Quan Zhao ◽  
Ling Tong ◽  
Bo Gao
Keyword(s):  
Spectral Analysis ◽  
Frequency Conversion ◽  
Frequency Resolution ◽  
Matching Problem ◽  
System Sensitivity ◽  
Deep Space Exploration ◽  
Spectrum Measurement ◽  
Stationary Signals ◽  
Simulation And Experiment ◽  
Remote Sensing Systems

The classical two-channel push-pull chirp transform spectrometer (CTS) has been widely applied in satellite-borne remote sensing systems for earth observation and deep space exploration. In this paper, we present two simplified structures with single M(l)-C(s) CTS arrangements for the spectral analysis of stationary signals. A simplified CTS system with a single M(l)-C(s) arrangement and a time delay line was firstly developed. Another simplified structure of CTS with a M(l)-C(s) arrangement and a frequency conversion channel was also developed for spectral analysis of stationary signals. Simulation and experiment results demonstrate that the two simplified arrangements can both realize spectrum measurement for the stationary signals and obtain the same frequency resolution, amplitude accuracy and system sensitivity as that of the classical two-channel push–pull CTS system. Compared to the classical CTS structure, the two simplified arrangements require fewer devices, save power consumption and have reduced mass. The matching problem between the two channels can be avoided in the two simplified arrangements. The simplified CTS arrangements may have potential application in the spectrum measurement of stationary signals in the field of aviation and spaceflight.

scholarly journals Evaluation of working memory in relation to cochlear implant consonant speech discrimination

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Mai M. El Ghazaly ◽  
Mona I. Mourad ◽  
Nesrine H. Hamouda ◽  
Mohamed A. Talaat
Keyword(s):  
Working Memory ◽  
Speech Perception ◽  
High Frequency ◽  
Word List ◽  
Frequency Discrimination ◽  
Frequency Resolution ◽  
Speech Discrimination ◽  
Place Of Articulation ◽  
Strong Positive Relationship ◽  
Speech And Language Development

Abstract Background Speech perception in cochlear implants (CI) is affected by frequency resolution, exposure time, and working memory. Frequency discrimination is especially difficult in CI. Working memory is important for speech and language development and is expected to contribute to the vast variability in CI speech reception and expression outcome. The aim of this study is to evaluate CI patients’ consonants discrimination that varies in voicing, manner, and place of articulation imparting differences in pitch, time, and intensity, and also to evaluate working memory status and its possible effect on consonant discrimination. Results Fifty-five CI patients were included in this study. Their aided thresholds were less than 40 dBHL. Consonant speech discrimination was assessed using Arabic consonant discrimination words. Working memory was assessed using Test of Memory and Learning-2 (TOMAL-2). Subjects were divided according to the onset of hearing loss into prelingual children and postlingual adults and teenagers. Consonant classes studied were fricatives, stops, nasals, and laterals. Performance on the high frequency CVC words was 64.23% ± 17.41 for prelinguals and 61.70% ± 14.47 for postlinguals. These scores were significantly lower than scores on phonetically balanced word list (PBWL) of 79.94% ± 12.69 for prelinguals and 80.80% ± 11.36 for postlinguals. The lowest scores were for the fricatives. Working memory scores were strongly and positively correlated with speech discrimination scores. Conclusions Consonant discrimination using high frequency weighted words can provide a realistic tool for assessment of CI speech perception. Working memory skills showed a strong positive relationship with speech discrimination abilities in CI.

scholarly journals Sexual Assault: Social and Stranger Rape

1987 ◽  
Vol 6 (1) ◽  
pp. 49-56 ◽  
Author(s):  
K. Edward Renner ◽  
Carol Wackett
Keyword(s):  
Social Context ◽  
Sexual Assault ◽  
Cultural Values ◽  
High Frequency ◽  
Relative Frequency ◽  
Medical Attention ◽  
Physical Injury ◽  
Sexual Assaults ◽  
Assault Victims ◽  
To Receive

The Service for Sexual Assault Victims in Halifax reviewed 474 cases of sexual assault handled over a three-year period to determine the nature and relative frequency of social and stranger sexual assault. Women are most likely to be sexually assaulted by a man who is known to and often trusted by them. Women who are raped in a social context are less willing than those raped by a stranger to seek help at the time of the assault, to receive medical attention, or to report the rape to the police. They are also less likely to be threatened with physical harm or to receive physical injury. The cultural values which are responsible for the high frequency of sexual assaults by men who are known to their victims, and for the reluctance of the women to disclose the assault, are discussed.

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