Hamming Window Function Research Articles

Electroretinogram Analysis Using a Short-Time Fourier Transform and Machine Learning Techniques.

Electroretinography (ERG) is a non-invasive method of assessing retinal function by recording the retina's response to a brief flash of light. This study focused on optimizing the ERG waveform signal classification by utilizing Short-Time Fourier Transform (STFT) spectrogram preprocessing with a machine learning (ML) decision system. Several window functions of different sizes and window overlaps were compared to enhance feature extraction concerning specific ML algorithms. The obtained spectrograms were employed to train deep learning models alongside manual feature extraction for more classical ML models. Our findings demonstrated the superiority of utilizing the Visual Transformer architecture with a Hamming window function, showcasing its advantage in ERG signal classification. Also, as a result, we recommend the RF algorithm for scenarios necessitating manual feature extraction, particularly with the Boxcar (rectangular) or Bartlett window functions. By elucidating the optimal methodologies for feature extraction and classification, this study contributes to advancing the diagnostic capabilities of ERG analysis in clinical settings.

A fast regularized CT reconstruction method based on a preconditioning matrix for limited-angle fan-beam CT

This paper proposes a fast regularized method for limited angle CT, the preconditioning matrix, which includes a weighting matrix and a filtering matrix, is utilized to improve the convergence speed. The projection and back-projection in the iteration process are replaced by the analytic operators to accelerate the computation speed. In addition, a Hamming window function is added to further suppress the noise and artifacts. Real data experiments show that the proposed method outperforms the other three methods in preserving the edge, convergence speed and computing speed.

Influence of electrode apodization weighted structure on the performance of SAW temperature sensors

In order to improve the comprehensive performance of the surface acoustic wave (SAW) temperature sensors and reduce clutter interference, the optimized Chebyshev window function, Blackman window function and Hamming window function are used to carry out the apodization weighting design for interdigital transducer (IDT) and reflective grating respectively. The influence of electrode apodization weighted structure on the performance of SAW temperature sensors is systematically studied through experiments. The results show that the apodization weighted design of IDT and reflective gate can effectively improve the resonance peak intensity and reduce the side lobe interference; the IDT and the reflection grating are designed with apodization weighting at the same time, compared with the single reflection grating weighting, the volatility of the side lobe of the Chebyshev window function and the Hamming window function increases, the volatility of the side lobe of the Blackman window function decreases; after electrode apodization optimization, the resonance frequency, Q value of the SAW sensor and the sensitivity to temperature increases; using a hamming window optimized electrode structure, the peak value of S11 is −36.73 dB and the Q value is 15 030. In order to ensure the signal processing ability and comprehensive performance of the sensor, an optimized Hamming window should be used for the electrode design of the SAW sensors.

Four window functions for simulation of vibration transmission effects in a planetary gear set

Analysis of vibration spectrum is one of the main investigation methods in the research filed for condition monitoring on planetary gear sets. However, such a gear set always exhibits complicated spectral structures in the vibration spectrum because of the planet carrier’s rotation, and the path distance from the fixed transducer to the moving meshing point will always be changed, which brings a modulation effect on the vibration signals received by a fixed transducer. Aiming to investigate the vibration transmission effects of planetary gear sets, four different window functions are introduced in this paper to simulate the transmission path changing with time i.e. the path between moving meshing position and a fixed transducer. Comparison results show that the Hamming window function may be a more suitable choice to model the transmission path changing with time in the planetary gear set.

Toward a cylinder pressure signals-based active synthesis algorithm for engine sound

The active sound design (ASD) technology is one of the most flexible methods to achieve the diverse design of automobile sound, in which the active sound synthesis algorithm is essential. However, in previous works, the discontinuity phenomena always appear in the synthesized sound. Thus, a new method of active engine sound synthesis based on cylinder pressure signals is proposed in this paper for the sound synthesis algorithm of ASD technique. Firstly, the index matrix of sound grains is constructed based on the periodicity of engine cylinder pressure signal. Then the frame length and frame shift are defined by tracing the time step of Revolutions Per Minute (RPM) of engine, and the hamming window function is constructed to extract sound grains. Subsequently, the overlap-and-add (OLA) method is used to realize the synthesis of engine sounds with different durations. In addition, the code program of proposed algorithm is written and the ASD prototype system is built respectively to synthesize the engine sounds. Finally, a similarity evaluation metric is defined to verify the effectiveness of proposed algorithm. The results show that our algorithm not only restitutes the main features of original sound, but also satisfies both the real-time feedback on the driving status and the continuity of synthesized sound. It contributes to the development of real-time ASD engineering for automobiles.

The phase-only Tribonacci photon sieve

In this paper, a kind of diffractive optical elements (DOEs), i.e., the phase-only Tribonacci photon sieve (TriPS), is proposed. The TriPS constructed with the Tribonacci sequence can produce two equal-intensity axial foci and the ratio of the focal lengths is related to the 3-golden mean. In the design of the TriPS, the Hamming window function was utilized to modulate the distribution of the pinholes. It was found that the TriPS generates smaller foci than the corresponding Tribonacci zone plate (TriZP). The simulation and experimental results verified the performance of the proposed DOE. Moreover, a TriPS with an optimum order was found to possess smaller focal spots, which would be useful in high resolution optical imaging.

A Design of a low-pass FIR filter using Hamming Window Functions in Matlab

The reduction and filtering of the input components of an original signal in one or more frequency bands using a finite impulse response, better known as FIR, is designed using a function of the Hamming window. Although there are various window functions such as the Blackman window function, the Hanning window function and the rectangular window functions that can be used as digital filters, the Hamming window function was used in this study for the reason of its minimum damping/decibel of the stopband with a reduced transition bandwidth. Among the other three widow functions that can be used, the Blackman window function is closest to the Hamming window function in terms of minimum bandstop attenuation/decibel, since both have a dB value greater than -50. However, in terms of transition bandwidth (Δω), the Hamming window has a narrower bandwidth than the Blackman window, making it more appropriate to use in this FIR filter design. This type of filter is important for analyzing the different types of signals that are essential in a world where digital filters play a major role in DSP applications. This research paper offers a Matlab-based low-pass FIR digital filter that uses Hamming window functions. Keywords: FIR filters, Hamming window, Blackman window Hanning window, Matlab. DOI: 10.7176/CEIS/11-2-04 Publication date: February 29 th 2020

A New Sidelobe Cancellation Method for LFM Radars

Pulse Compression technique is a vital tool commonly used in radar to increase range resolution and signal to noise ratio. Pulse compression allows achieving the performance of a shorter pulse using a longer pulse and hence gain of a large spectral bandwidth. Unwanted signals from sidelobes returns affect the detection capability of any radar. Different sidelobe reduction/cancellation techniques based on pulse compression for Linear Frequency Modulated (LFM) radars have been deployed and addressed before. In this paper, a new optimum filter for enhancing radar detection capabilities of LFM radars is introduced. The proposed filter response is compared with the windowed classical matched filter response associated with Hamming window function. The filter is implemented using Software Defined Radio (SDR). A practical test has been carried to investigate its performance. Results show superior performance of our proposed matched filter compared to that of classical versions

Signal acquisition and processing system based on zynq dual core

In order to speed up the acquisition and processing of signal, this paper has developed a signal acquisition and processing system based on zynq platform. Based on the ARM Cortex-A9 dual-core and editable logic unit architecture of Zynq AP SoC platform, this paper implements a fully functional signal acquisition and processing system by software and hardware collaborative design. ARM0 is the main processor that controls system and shared resources. ARM1 is the slave processor. ARM1 is responsible for receiving the data converted by the AD7606 analog-to-digital chip. The data is sent to the Hamming window function IP core created under vivado HLS through the AXI bus. After the data is processed by Hamming window function, it is sent to ARM1 again through AXI bus. OCM acts as the shared memory for ARM0 and ARM1 communication. The Linux system runs on ARM0. The processed data is sent to the upper computer through ethernet through UDP protocol. Utilizing the architecture of the Zynq platform, the system efficiency is improved, and the stability of the system is ensured, so that the FPGA can enter the field of embedded systems.

Low-Complexity Adaptive Sonar Imaging

We have studied the low-complexity adaptive (LCA) beamformer in active sonar imaging. LCA can be viewed as either a simplification of the minimum variance distortionless response (MVDR) beamformer, or as an adaptive extension to the delay-and-sum (DAS) beamformer. While both LCA and MVDR attempt to minimize the power of noise and interference in the image, MVDR achieves this by computing optimal array weights from the spatial statistics of the wavefield, while LCA selects the best performing weights out of a predefined set. To build confidence in the LCA method, we show that a robust MVDR implementation typically creates weight sets with shapes spanning between a rectangular and Hamming window function. We let LCA select from a set of Kaiser windows with responses in this span, and add some steered variations of each. We limit the steering to roughly half the − $3$ -dB width of the window's amplitude response. Using experimental data from the Kongsberg Maritime HISAS1030 sonar we find that LCA and MVDR produce nearly identical images of large scenes, both being superior to DAS. On point targets LCA is able to double the resolution compared to DAS, or provide half that of MVDR. This performance is achieved with a total of six windows: the rectangular window and the Kaiser window with $\beta =5$ , in an unsteered version, and versions that are left and right steered to the steering limit. Slightly smoother images are produced if the window count is increased to 15, but past this we observe minimal difference. Finally, we show that LCA works just as well if Kaiser windows are substituted with trigonometric ones. All our observations and experiences point to LCA being very easy to understand and manage. It simply works, and is surprisingly insensitive to the exact type of window function, steering amount, or number of windows. It can be efficiently implemented on parallel hardware, and handles any scene without the need for parameter adjustments.

Sparse Channel Estimation using Hybrid Approach for OFDM Transceiver

Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to frequency offsets that is use to demolish the orthogonality among number of subcarriers. The OFDM introduced the inter-carrier interference and it is also capable of degrading the error performance. The channel estimation plays an important role to make OFDM more efficient. Proposed approach uses hybrid technique for Sparse Channel Offset (SCO) estimation in orthogonal frequency division multiplexing (OFDM) over frequency selective fading channel by using pilot tone and Hamming window filtering approach. Proposed approach uses hamming windows function in order to optimize Fast Fourier Transform channel estimation algorithms. Common window functions are: Rectangular window, Hanning window and Hamming window. Hamming window function as the main lobe has a good width and side-lobe decay rate. The result of the proposed approach is better than the previous approaches.

Designing a Low- Pass Fir Digital Filter by Using Hamming Window and Blackman Window Technique

In this paper is simulated the time- domain unit sample response of sine function and frequency- domain response of sine function. Digital filter plays an important role in today’s world of communication and computation. Without digital filter we cannot think about proper communication because noise occurs in channel. For removing noise or cancellation of noise we use various type of digital filter. In signal processing, there are mainly two types of filters exist .they are the Finite Impulse Response (FIR) filter and Infinite Impulse Response (IIR) filter. Finite Impulse Response (FIR) filter can be designed form Infinite Impulse Response (IIR) filter by various techniques. The widely used technique is the window technique. This paper low-pass FIR filter is implemented using an efficient adjustable window function based on Hamming window and Blackman window function. The output of the FIR design by Blackman window and the Blackman window are shown in this paper by simulating the code in Matlab. The Matlab program returns with a satisfactory result with proper magnitude plotting.

An Excellent 2D Window Function

In the aid of sinc sum function and matrix equation a new 2D window function is obtained. It is as simple as a 2D cosine window function. Comparison shows that the new 2D window function can provide much better 2D FIR filters than 2D Hamming window function. Maximum passband ripples are about 2.5-3.5 times smaller and maximum stopband ripples are about 1.5 times smaller with equal or very small different passband and stopband edge frequencies.

Energy Landscapes and Catalysis in Nitric-oxide Synthase

Nitric oxide (NO) plays diverse roles in mammalian physiology. It is involved in blood pressure regulation, neurotransmission, and immune response, and is generated through complex electron transfer reactions catalyzed by NO synthases (NOS). In neuronal NOS (nNOS), protein domain dynamics and calmodulin binding are implicated in regulating electron flow from NADPH, through the FAD and FMN cofactors, to the heme oxygenase domain, the site of NO generation. Simple models based on crystal structures of nNOS reductase have invoked a role for large scale motions of the FMN-binding domain in shuttling electrons from the FAD-binding domain to the heme oxygenase domain. However, molecular level insight of the dynamic structural transitions in NOS enzymes during enzyme catalysis is lacking. We use pulsed electron-electron double resonance spectroscopy to derive inter-domain distance relationships in multiple conformational states of nNOS. These distance relationships are correlated with enzymatic activity through variable pressure kinetic studies of electron transfer and turnover. The binding of NADPH and calmodulin are shown to influence interdomain distance relationships as well as reaction chemistry. An important effect of calmodulin binding is to suppress adventitious electron transfer from nNOS to molecular oxygen and thereby preventing accumulation of reactive oxygen species. A complex landscape of conformations is required for nNOS catalysis beyond the simple models derived from static crystal structures of nNOS reductase. Detailed understanding of this landscape advances our understanding of nNOS catalysis/electron transfer, and could provide new opportunities for the discovery of small molecule inhibitors that bind at dynamic protein interfaces of this multidimensional energy landscape.

Faithful reconstruction of digital holograms captured by FINCH using a Hamming window function in the Fresnel propagation

Recent advances in Fresnel incoherent correlation holography (FINCH) increase the signal-to-noise ratio in hologram recording by interference of images from two diffractive lenses with focal lengths close to the image plane. Holograms requiring short reconstruction distances are created that reconstruct poorly with existing Fresnel propagation methods. Here we show a dramatic improvement in reconstructed fluorescent images when a 2D Hamming window function substituted for the disk window typically used to bound the impulse response in the Fresnel propagation. Greatly improved image contrast and quality are shown for simulated and experimentally determined FINCH holograms using a 2D Hamming window without significant loss in lateral or axial resolution.

The Application Research of Six-Axis Force Sensor Used by Trans-Femoral Prosthesis

Intelligent bionic leg (IBL) is an advanced trans-femoral prosthesis. First, the conception and structure component of IBL are introduced. Then, working principle of six-axis force sensor is analyzed in detail. The type selection and design of filter are discussed. In the end, the data filtering of low pass filter based on hamming window function is established and simulation is done. The simulation indicates that force and torque signal has a significant improvement after filtering and the filter designed in the paper is reasonable.

뇌전기파 분석용 FFT 프로세서 설계

본 논문에서는 의료 서비스를 위한 뇌전기파(EEG: electroencephalogram) 신호 분석용 FFT(Fast Fourier Transform) 프로세서를 구현하였다. 실시간으로 발생하는 EEG 신호를 블록으로 나누어 short-time FFT 처리하기 위해 Hamming 창 함수를 사용하였으며, 이로 인해 감소되는 양끝의 값은 1/2 오버랩 시켜 보완하였다. 0~100 [Hz] 사이의 주파수 특성을 갖는 뇌전기파의 효율적인 대역 분석을 위해 256-point FFF 프로세서를 radix-4 알고리듬을 적용하여 구현하였으며, 단일 메모리 뱅크 구조를 사용하여 집적도를 높였다. 설계된 FFT 프로세서는 FPGA 구현을 통해 가능을 검증하였으며, 연산오차가 2% 이내로 높은 연산 정밀도를 갖는다. This paper describes a design of fast Fourier transform(FFT) processor for EEG(electroencephalogram) signal analysis for health care services. Hamming window function with 1/2 overlapping is adopted to perform short-time FFT(ST-FFT) of a long period EEG signal occurred in real-time. In order to analyze efficiently EEG signals which have frequency characteristics in the range of 0 Hz to 100 Hz, a 256-point FFT processor is designed, which is based on a single-memory bank architecture and the radix-4 algorithm. The designed FFT processor has been verified by FPGA implementation, and has high accuracy with arithmetic error less than 2%.

On the Clustering of Head-Related Transfer Functions Used for 3-D Sound Localization

Head-related transfer functions (HRTFs) serve the increasingly dominant role of implementation 3-D audio systems, which have been realized in some commercial applications. However, the cost of a 3-D audio system cannot be brought down because the efficiency of computation, the size of memory, and the synthesis of unmeasured HRTFs remain to be made better. This paper presents a way to moderate the memory requirement and computational complexity in order to reduce the cost of a 3-D audio system. We employ the library of HRTF measurements called Knowles Electronics Mannequin for Acoustic Research (KEMAR) as the original data [8]. First of all, each HRTF measurement has to be approximated in the minimum phase, and the length of the HRTF is limited by use of a modified Hamming window function, if necessary. Second, we propose an improved LBG-based clustering algorithm to lower the huge number of HRTFs. During the clustering, each HRTF is represented by its power cepstrum. Only portions of the HRTFs are reserved, and the others are neglected on condition that the minimal average mismatch distance between measured and synthesized HRTFs is achieved. Before applying localization of 3-D sounds, both unmeasured and removed HRTFs can be synthesized by linear interpolation and interaural time difference insertion. Experimental results reveal that the average and the maximum mismatch distances deriving from our improved LBG-based clustering method are less than those from the uniform clustering and LBG-based clustering methods [13].

A new method of multibeamforming for a swath bathymetry sonar system and its MIMD parallel architecture

In a swath bathymetry sonar system, real-time multibeamforming is required in order to increase the coverage and the efficiency. To determine the direction of seafloor echo accurately, traditional beamforming must work at a high sample rate, the interpolation is used to reduce computing amounts, but when there are tens of receiving channels and beams, the interpolation filter algorithm will rapidly increase computing amounts to result in the real-time multibeamforming, this is very difficult. Combining with a swath bathymetry sonar system, a new method of quadrature beamforming is described in this paper. It combines time domain beamforming with phase shifting beamforming to process the available bandpass signal. To reduce sample rate, a mixing frequency technique is used. A quadrature component is obtained from a single-channel A/D converter utilizing Hilbert transformation and its coefficient is weighted with Hamming window function, therefore, amplitude and phase is highly accurate. Comparing with the traditional beamforming method, the method presented in the paper is characterized by high accuracy, less sample rate, and less computation complexity, easily realized with a high speed DSP device. The parallel pipeline architecture is given based on TMS320C30. Simulating and lake trial results show that the method is right and efficient. The method is universal for active sonar.

Myoelectric signal characteristics in lumbar back muscles during fatigue

The present study examines the possible differences in electrophysiological manifestations of low back muscle fatigue between symptomatic (CON) and symptomatic (LB) persons by means of EMG frequency power spectral analysis during fatiguing back extension for a period of 60s. Two sets of maniature electrodes were attached at the level of L3 paravertebrally and the recorded myoelectric signals were digitized and processed with the Hamming window function and 512-point fast Fourier transform to calculate mean power frequency (MPF). Results indicate that LB group ( n = 9) showed a significantly higher rate of MPF decline than that of CON group (n = 9) (37.2±1.9 Hz/min, <0.05) . When the degree of asymmetry (fatiguable vs. less fatiguable sides) was tested, LB group showed a highly significant differences (37.4±3.8 vs 25.8±4.9, p<0.05) which was more than 2.5 times the corresponding values in CON group (difference being 4.5 Hz, p > 0.05). These data suggest that EMG frequency power spectral analysis can be successfully employed in objective assessment of low back muscle fatiguability and the degree of asymmetry in the rate of fatigue development.