Showing papers by "V. Jagadeesh Kumar published in 2008"
TL;DR: Analysis of the proposed technique indicates that the effects of nonidealities and variations in circuit parameters on the performance of the CDC is either in the form of a gain error and/or an offset, both of which can be easily compensated.
Abstract: A digital converter that directly translates variations in the capacitances of a differential-type capacitive sensor to a proportional digital value is described in this paper. A conventional dual-slope, analog-to-digital converter is suitably modified to obtain direct capacitance-to-digital conversion (CDC). Analysis of the proposed technique indicates that the effects of nonidealities and variations in circuit parameters on the performance of the CDC is either in the form of a gain error and/or an offset, both of which can be easily compensated. Simulation studies and experimental results obtained from a prototype built and tested prove the efficacy of the proposed scheme.
33 citations
TL;DR: A linear variable differential capacitive transducer for the measurement of planar angles from 0deg to 360deg and test results obtained from a prototype indicated that the worst-case error was less than 0.1 %.
Abstract: A linear variable differential capacitive transducer for the measurement of planar angles (from 0deg to 360deg) is presented in this paper. The sensor part of the transducer is made of parallel plates of standard and easy-to-fabricate shapes, and the signal-conditioning electronics are realized, employing a couple of simple relaxation oscillators. The output of the transducer is only dictated by a pair of dc reference voltages, and hence, high accuracy and linearity over the entire range (from 0deg to 360deg) are easily obtained by the use of precision dc reference voltages. Detailed analysis indicates that the sensitivity of the transducer is minimal for variations in different parameters. Experimental results obtained on a prototype transducer that has been built and tested establish the efficacy of the proposed transducer. The worst-case error of the prototype transducer is found to be less than 0.1%.
19 citations
12 May 2008
TL;DR: In this paper, a noninvasive method of estimation of oxygen saturation in arterial blood (SpO 2 ), employing the popular photoelectric plethysmographic (PPG) principle, is presented.
Abstract: A novel and noninvasive method of estimation of oxygen saturation in arterial blood (SpO 2 ), employing the popular photoelectric plethysmographic (PPG) principle, is presented here. Based on a refined model for the attenuation of light in a PPG sensor, a simple method of computation of SpO 2 that is not influenced by interfering parameters of a patient such as skin colour and quantum of intervening tissue between the source and the detector in a PPG sensor as well as sensor dependent parameters such as source intensity and detector sensitivity is identified. Preliminary results obtained on a prototype pulse oximeter, built and tested, demonstrate the practicality of the proposed method.
16 citations
12 May 2008
TL;DR: A variation of the accepted PPG technique is described, to provide a contact-less and non-invasive method of characterizing dermal perfusion, which employs a 3-CCD, multi-spectral camera, to image the selected area.
Abstract: Photoplethysmography (PPG) has come to be accepted as a common, non-invasive method for measuring the level of oxygen saturation in arterial blood. This paper describes a variation of the accepted PPG technique, to provide a contact-less and non-invasive method of characterizing dermal perfusion. It employs a 3-CCD, multi-spectral camera, to image the selected area. The acquired images are analysed by making use of the fact that the absorption co-efficient of oxygenated blood is more in the infra-red (IR) region of the spectrum, when compared to the red region. This fact is utilised to characterize the extent of dermal perfusion in the selected area of the skin.
15 citations
12 May 2008
TL;DR: In this article, an approach for the use of Wigner-Ville distribution (WVD), a time frequency analysis method, for the detection of winding deformation during short circuit test of a transformer is presented.
Abstract: An approach for the use of Wigner-Ville Distribution (WVD), a time frequency analysis method, for the detection of winding deformation during short circuit test of a transformer is presented. The method is validated through experiments conducted on a specially designed 6.6 kV voltage transformer. The results of time frequency analysis approach using WVD and time scale analysis using Wavelet Transform (WT) are compared to the results obtained with the frequency response analysis method to identify an optimal signal analysis tool possessing improved sensitivity for the detection of winding deformation in transformers during short circuit tests.
5 citations