scholarly journals RESEARCH OF RELATION OF SAMPLERS FREQUENCY CHARACTERISTICS / STROBAVIMO ĮTAISO DAŽNINIŲ CHARAKTERISTIKŲ SĄRYŠIO TYRIMAS

2016 ◽  
Vol 8 (3) ◽  
pp. 282-288 ◽  
Author(s):  
Tomaš Tankeliun
Keyword(s):  
Sine Wave ◽  
Frequency Characteristics ◽  
Time Base ◽  
Wave Method ◽  
Magnitude Response ◽  
Wave Measurement ◽  
Measurement Algorithm ◽  
Width Measurements ◽  
Minimal Phase ◽  
Sync Pulse

This paper proposes an algorithm to reduce limitations in band-width measurements of sampling oscilloscopes then using a swept sine-wave measurement method. The traditional swept sine-wave method allow measure only magnitude response. Phase response can be computed only if a sampler is a minimal phase circuit. In this paper alternative bandwidth measurement algorithm using the nose-to-nose method with measurements corrections for the non-idle properties of oscilloscope is de-scribed. Algorithm includes for noise, time base distortions and jitter in measurement signals corrections methods. Proposed algorithm allows to measure phase and magnitude responses when only two similar oscilloscopes and the source of sync pulse are used. Algorithm performs as well as the swept sine-wave method in case when both samplers have the same frequency characteristics. Stroboskopiniai osciloskopai skirti matuoti sparčius periodinius signalus naudojant sąlyginai nesparčius didelio skiltiškumo analoginius-skaitmeninius keitiklius. Vienas iš pagrindinių stroboskopinio osciloskopo mazgų, užtikrinančių, kad osciloskopo charakteristikos atitiktų metrologinius reikalavimus, ir kuriame vyksta matuojamo aukštadažnio signalo spektro transformacija į žemų dažnių sritį, yra strobavimo įtaisas. Šiame darbe pateikiamas strobavimo įtaiso veikimo principas, nagrinėjami įtaiso dažninių charakteristikų matavimo būdai taikant pastovios amplitudės, kintančio dažnio harmoninio virpesio ir priešpriešiais sujungtų strobavimo grandinių metodus. Gauti rezultatai rodo, kad nagrinėjamas strobavimo įtaisas nepriklauso minimalios fazės grandinių klasei ir apskaičiuoti įtaiso dažninę fazės charakteristiką (DFCh) iš dažninės amplitudės charakteristikos (DACh) neįmanoma, tačiau taikant priešpriešiais sujungtų strobavimo grandinių matavimo metodą galima gauti įtaiso DACh ir DFCh nenaudojant papildomos aukštadažnės matavimo įrangos ir mažinant matavimo proceso trukmę.

A Simple Method for Measuring Stiffness during Running

2005 ◽  
Vol 21 (2) ◽  
pp. 167-180 ◽  
Author(s):  
Jean-Benoît Morin ◽  
Georges Dalleau ◽  
Heikki Kyröläinen ◽  
Thibault Jeannin ◽  
Alain Belli
Keyword(s):  
High Speed ◽  
Sine Wave ◽  
Force Platform ◽  
Mechanical Parameters ◽  
Wave Method ◽  
Leg Length ◽  
Mass Model ◽  
Time Curve ◽  
Simple Method ◽  
Vertical Stiffness

The spring-mass model, representing a runner as a point mass supported by a single linear leg spring, has been a widely used concept in studies on running and bouncing mechanics. However, the measurement of leg and vertical stiffness has previously required force platforms and high-speed kinematic measurement systems that are costly and difficult to handle in field conditions. We propose a new “sine-wave” method for measuring stiffness during running. Based on the modeling of the force-time curve by a sine function, this method allows leg and vertical stiffness to be estimated from just a few simple mechanical parameters: body mass, forward velocity, leg length, flight time, and contact time. We compared this method to force-platform-derived stiffness measurements for treadmill dynamometer and overground running conditions, at velocities ranging from 3.33 m·s–1to maximal running velocity in both recreational and highly trained runners. Stiffness values calculated with the proposed method ranged from 0.67% to 6.93% less than the force platform method, and thus were judged to be acceptable. Furthermore, significant linear regressions (p< 0.01) close to the identity line were obtained between force platform and sine-wave model values of stiffness. Given the limits inherent in the use of the spring-mass model, it was concluded that this sine-wave method allows leg and stiffness estimates in running on the basis of a few mechanical parameters, and could be useful in further field measurements.

Visual Evoked Potentials to Gratings and Noise

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 355-355
Author(s):  
Y E Shelepin ◽  
A K Harauzov ◽  
N N Krasilnikov ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Evoked Potentials ◽  
White Noise ◽  
Visual Evoked Potentials ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Frequency Characteristics ◽  
Visual Evoked

Visual evoked potentials were recorded in a study of the spatial-frequency characteristics of the human visual system. Stimuli were gratings with and without superposition of white noise. Evoked potentials were recorded in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes, according to the ‘ten-twenty’ electrode system. A set of black-and-white sine-wave gratings was used with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1. The gratings were presented with binary quasi-white noise or with a uniform grey field with mean luminance equal to that of the noise. The amplitudes of the N1, P1, N2, and P2 response components were compared under the two stimulation conditions. Changes in the form of responses as well as changes in spatial-frequency characteristics were found when white noise was superimposed. The results obtained are discussed in terms of the presence and location of matched filtering in the visual system.

Design of Frequency and Amplitude of Sine Wave Measurement Circuit Based on MSP430

2014 ◽  
Vol 536-537 ◽  
pp. 356-359
Author(s):  
Shou Gang Sui ◽  
Jing Ye Xu ◽  
Jia Xu Zhang
Keyword(s):  
Human Computer Interaction ◽  
Sine Wave ◽  
Peak Detection ◽  
Measurement Circuit ◽  
Electronic Technology ◽  
Wave Signal ◽  
Wave Measurement ◽  
Measurement Results ◽  
Detection Circuit ◽  
Measuring Frequency

Sine wave signal is a kind of typical electronic technology signal waveform, and frequency, amplitude and phase are three elements of the sine wave respectively. In order to measure the elements more accurately, scientific research methods is adopt in the design. Based on high precision of peak detection circuit combined with MSP430 MCU, the circuit for measuring frequency and amplitude of sine wave signal is implemented, and the results could be shown in the display circuit at the same time. The circuit can work within the 1kHz - 20kHz and 240mV - 5V sine wave signal, and has display circuit, which can display accurate measurement results, to achieve human-computer interaction.

Spatial-Frequency Characteristics of Different Areas of Human Cortex

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 167-167
Author(s):  
A K Harauzov ◽  
Y E Shelepin ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Electrode System ◽  
Frequency Characteristics ◽  
Spatial Frequencies

We recorded visual evoked potentials in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes according to the ‘ten - twenty’ electrode system. Stimuli were black-and-white sine-wave gratings with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1, presented at four different temporal frequencies (1, 2, 4, 8 Hz). Stimulation was either contrast-reversal or onset. VEPs were analysed both by component analysis and by Fourier transformation. Spatial characteristics were measured from the dependence of the amplitudes and latencies of the main response components (N1, P1, N2, P2) on the contrast and spatial frequency of the gratings. The characteristics obtained in the occipital lobe are in accordance with earlier experimental data [Regan, 1989 Human Electrophysiology (Amsterdam: Elsevier)]. When the temporal frequency of stimulation was increased, the maximum of the spatial-frequency curves shifted to lower spatial frequencies. However, we found differences in the spatial-frequency characteristics of different cortical areas. The results are discussed in terms of differences in the spatial and temporal tuning of the receptive fields of neurons in these areas.

scholarly journals Calibration of DAC Mismatch Errors in $\Sigma\Delta$ ADCs Based on a Sine-Wave Measurement

2013 ◽  
Vol 60 (9) ◽  
pp. 567-571 ◽  
Author(s):  
Maarten De Bock ◽  
Xinpeng Xing ◽  
Ludo Weyten ◽  
Georges Gielen ◽  
Pieter Rombouts
Keyword(s):  
Sine Wave ◽  
Sigma Delta ◽  
Wave Measurement

Reliability of Leg and Vertical Stiffness During High Speed Treadmill Running

2017 ◽  
Vol 33 (2) ◽  
pp. 160-165 ◽  
Author(s):  
Panagiotis Pappas ◽  
Giorgos Dallas ◽  
Giorgos Paradisis
Keyword(s):  
High Speed ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Sine Wave ◽  
Treadmill Running ◽  
Repeated Measure ◽  
Wave Method ◽  
Vertical Stiffness ◽  
Measure Analysis ◽  
Repeated Measure Analysis

In research, the accurate and reliable measurement of leg and vertical stiffness could contribute to valid interpretations. The current study aimed at determining the intraparticipant variability (ie, intraday and interday reliabilities) of leg and vertical stiffness, as well as related parameters, during high speed treadmill running, using the “sine-wave” method. Thirty-one males ran on a treadmill at 6.67 m∙s−1, and the contact and flight times were measured. To determine the intraday reliability, three 10-s running bouts with 10-min recovery were performed. In addition, to examine the interday reliability, three 10-s running bouts on 3 separate days with 48-h interbout intervals were performed. The reliability statistics included repeated-measure analysis of variance, average intertrial correlations, intraclass correlation coefficients (ICCs), Cronbach’s α reliability coefficient, and the coefficient of variation (CV%). Both intraday and interday reliabilities were high for leg and vertical stiffness (ICC > 0.939 and CV < 4.3%), as well as related variables (ICC > 0.934 and CV < 3.9%). It was thus inferred that the measurements of leg and vertical stiffness, as well as the related parameters obtained using the “sine-wave” method during treadmill running at 6.67 m∙s−1, were highly reliable, both within and across days.

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

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