FACILITY FOR CALIBRATION OF PHOTOMETERS FOR TEMPORAL LIGHT MODULATION

Mapping Intimacies ◽

10.25039/x48.2021.op27 ◽

2021 ◽

Author(s):

P.R. Dekker ◽

A.L. van Bloois

Keyword(s):

Frequency Response ◽

Root Mean Square ◽

Contrast Ratio ◽

Standard Uncertainty ◽

Reference Source ◽

Mean Square ◽

Light Modulation ◽

Digital Converter ◽

Analog To Digital ◽

Acousto Optic Modulator

We developed a facility for calibration of TLM (temporal light modulation) photometers. The facility is based on a laser-fed reference source, of which the radiance can be modulated with an acousto-optic modulator (AOM). A system of photodiodes, amplifiers, and an analog-to-digital converter (ADC) is used to sample the temporally modulated radiance of the source. With the facility a TLM photometer was calibrated for display contrast ratio RMS (root mean square) with an absolute combined standard uncertainty of 0,037 %. In addition, the facility has been characterised with the aim of measuring flicker and stroboscopic effect, considering the Ecodesign ‘Single Lighting Regulation’. The frequency response of the facility shows to be sufficient to accommodate measurements of flicker and the stroboscopic effect.

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Characterization of an analog-to-digital converter frequency response by a Josephson arbitrary waveform synthesizer

Measurement Science and Technology ◽

10.1088/1361-6501/aafb27 ◽

2019 ◽

Vol 30 (3) ◽

pp. 035006 ◽

Cited By ~ 2

Author(s):

Javier Díaz de Aguilar ◽

J R Salinas ◽

Oliver Kieler ◽

Raúl Caballero ◽

Ralf Behr ◽

...

Keyword(s):

Frequency Response ◽

Analog To Digital Converter ◽

Digital Converter ◽

Analog To Digital ◽

Arbitrary Waveform

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Analysis and Development of Hybrid Earphone Combining Balanced-Armature and Dynamic Receivers

Applied Sciences ◽

10.3390/app9235047 ◽

2019 ◽

Vol 9 (23) ◽

pp. 5047

Author(s):

Yuan-Wu Jiang ◽

Dan-Ping Xu ◽

Zhi-Xiong Jiang ◽

Jun-Hyung Kim ◽

Sang-Moon Hwang

Keyword(s):

Frequency Response ◽

Root Mean Square ◽

Sound Pressure Level ◽

Sound Pressure ◽

Sound Quality ◽

Pressure Level ◽

Analysis Tool ◽

Mean Square ◽

Rapid Progress ◽

Audio Output

With the rapid progress in the development of multimedia devices, earphones have become increasingly important as audio output tools. Hybrid earphones combining balanced-armature (BA) and dynamic receivers can produce better performance over a wider range when compared to the earphones with BA receiver alone (BA earphones) or dynamic receiver alone (dynamic earphones). BA and dynamic earphones are multi-physics products that exhibit coupling between the electromagnetic, mechanical, and acoustic domains. In this study, an analysis tool is developed to design a hybrid earphone based on the conventional BA and dynamic earphones. Using the developed analysis tool, an acoustic tube is optimized to match the earphone target curve and obtain improved sound quality. A prototype is manufactured and tested, and the experimental results verify the feasibility and effectiveness of the developed analysis tool. The root-mean-square value of the sound pressure level (SPL) deviation of the hybrid earphone with the optimized acoustic tube is 4.60, whereas those for the dynamic and BA earphones are 8.94 and 6.04, respectively. Thus, it is verified that the frequency response is improved using the hybrid earphone developed herein.

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Method for filtering proportional valve-frequency-response test data containing impulsive noise

Advances in Mechanical Engineering ◽

10.1177/1687814019836298 ◽

2019 ◽

Vol 11 (3) ◽

pp. 168781401983629

Author(s):

Yan Qiang ◽

Yingzhou Wang ◽

Lan Luo ◽

Gang Wang ◽

Yuyang Zhao ◽

...

Keyword(s):

Root Mean Square Error ◽

Frequency Response ◽

Mean Square Error ◽

Root Mean Square ◽

Frequency Characteristic ◽

Impulsive Noise ◽

Mean Square ◽

Characteristic Curves ◽

Amplitude Frequency Characteristic ◽

Proportional Directional Valve

Impulsive noise, generated by inverters and other equipment used in the field, tends to easily enter test channels in scenarios where continuous frequency conversion signals are employed to test the frequency response of electrohydraulic proportional valves. Interference caused by such noise reduces the signal-to-response ratio of response signals, thereby influencing the accuracy of the frequency response of proportional valves. To address this concern, in this article, an integrated filtering method that combines ensemble empirical mode decomposition with median filtering is proposed. The proposed method first preprocesses the response signals of the systems and subsequently obtains frequency-response diagrams using fast Fourier transforms. Simulation results demonstrate that the proposed method reduces the root mean square error associated with the amplitude–frequency characteristic curves of the proportional directional valve considered from 2.1 to 0.3, whereas that associated with phase–frequency characteristic curves is reduced from 78.0 to 1.4 with signal-to-noise ratios in the high-frequency band being of the order of –20 dB. Experimental results also reveal that the proposed method reduces the root mean square error of the amplitude–frequency characteristic curves of the proportional directional valve by 52.5% and that of the phase–frequency characteristic curves by 71.2%.

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An Improved Analytical Model of a Spectrometer for Optical Coherence Tomography

Photonics ◽

10.3390/photonics8120534 ◽

2021 ◽

Vol 8 (12) ◽

pp. 534

Author(s):

Evgeny P. Sherstnev ◽

Pavel A. Shilyagin ◽

Dmitry A. Terpelov ◽

Valentin M. Gelikonov ◽

Grigory V. Gelikonov

Keyword(s):

Experimental Data ◽

Optical Coherence Tomography ◽

Frequency Response ◽

Analytical Model ◽

Spectral Resolution ◽

Electrical Circuit ◽

Optical Coherence ◽

Digital Converter ◽

Analog To Digital ◽

Depth Sensitivity

We present an improved analytical model of a spectrometer for optical coherence tomography (OCT), which more accurately describes the OCT in-depth sensitivity fall-off. The model considers the intrinsic spectral resolution of the dispersive element and the influence of additional components (inequidistance-correcting prism). The model is validated by experimental data obtained both from other studies and our own experiments. The influence of the frequency response of the CCD electrical circuit and the analog-to-digital converter to the OCT signal fall-off was also detected and was shown to be significant in some cases.

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