Jagadeesh Kumar | IIT Madras (original) (raw)

Papers by Jagadeesh Kumar

2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), May 16, 2022

Studies in Skin Perfusion Dynamics, 2021

The method of photoplethysmography (PPG) detailed in Chapters 1 and 2 gained enormous prominence ... more The method of photoplethysmography (PPG) detailed in Chapters 1 and 2 gained enormous prominence due to the development of pulse oximetry. In pulse oximetry, the fact that hemoglobin bound with oxygen (called oxyhemoglobin) and hemoglobin without oxygen (deoxy-hemoglobin or reduced hemoglobin) absorb/reflect light differently is exploited in ascertaining, noninvasively, oxygen saturation in arterial blood. Most pulse oximeters that are in existence today use a couple of PPGs obtained using red and infrared wavelength light sources and calculate oxygen saturation in arterial blood using the red and IR PPGs and an empirical equation. This chapter details the development of pulse oximetry. It describes in detail a couple of novel methods of oxygen saturation calculation using the red and IR PPGs. The methods presented here do not need any calibration to be performed. 3.1 Physiological Signals for Diagnostics Dynamic and static measurements on the physical, electrical, chemical and acoustic signals of a human body will help ascertain its health [1-3]. Whenever a person is affected by a disease or gets injured, one or more of these physical, electrical, chemical and acoustic signals change. However, these physical, electrical, chemical and acoustic signals also change day to day due to natural variations in the life cycle. Moreover, the changes in these signals are a complex combination of different parameters. Hence it is very difficult to delineate the functioning or malfunctioning of the underlying biological parts or processes directly from these signals. The four traditional vital signs, namely, the pulse rate, the respiratory rhythm (and sound), the body temperature and the blood pressure are normally used by medical practitioners all over the globe to assess a patient's state of health. In the modern times, a fifth vital signal, namely, the oxygen saturation in blood has also gained importance. Today any patient with coronary or pulmonary problems must be evaluated for the oxygen

Engineering research express, May 13, 2022

Successive approximation type direct resistance to digital converter (SAR RDC) topology is presen... more Successive approximation type direct resistance to digital converter (SAR RDC) topology is presented here. The conventional SAR type ADC is augmented with an additional opamp inverting summer and a standard resistance such that the digital output of the SAR directly indicates the value of an unknown resistance connected between the output of the digital to analog converter of the SAR RDC and the inverting input of the added inverting summer. Analysis of the proposed technique presented here helps select proper components at the design stage itself to obtain minimal errors in the measurement of the unknown resistor. The major advantage of the proposed scheme is that it retains the basic architecture of an SAR ADC and hence can be implemented with all available SAR ADC architectures, including the ability to install ‘auto-ranging’. An added advantage is that the value of the unknown resistor is determined in terms of a standard resistor and hence good accuracy is easily obtained. Simulation studies and results obtained from a prototype SAR RDC built and tested, establish the efficacy of the proffered technique. The results indicate a worst-case error of < ±0.2 % and no missing codes.

International Conference on Power Electronics Machines and Drives, 2002

ABSTRACT This paper proposes a digital signal processor (DSP) based implementation of online air-... more ABSTRACT This paper proposes a digital signal processor (DSP) based implementation of online air-gap torque estimator for detection of squirrel cage rotor faults. Two noninvasive, computationally efficient methods for online air-gap torque monitoring are discussed. In both the methods, the air-gap torque is computed from two stator voltages and currents and is cost effective when compared with the use of a conventional torque transducer. The online air-gap torque monitor has been implemented using TMS320C31 and successfully tested on faulty cage rotors.

Power Electronics and …, 2001

Abstract-Identification of rotor faults in squirrel cage induction motors by estimation of air-ga... more Abstract-Identification of rotor faults in squirrel cage induction motors by estimation of air-gap torque spectra has gained considerable attention recently. This has the advantage that the signature spectrum generated by faults is in the low frequency region. But the torque computation ...

2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

IEEE Transactions on Industrial Electronics, 2021

The basic principle of a noncontact method of measurement of conductivity of liquids, presented e... more The basic principle of a noncontact method of measurement of conductivity of liquids, presented earlier, is analysed to evolve design rules to have minimal error in the measurement. In this method, the current is sent through the liquid whose conductivity is to be measured by induction and the voltage across the liquid column is measured using capacitive coupled electrodes and the conductivity computed therefrom. Hence, problems that arise due to contamination or corrosion of contacting electrodes are eliminated. The signal conditioning circuit is developed such that the measurement of the voltage-drop across the column of the liquid and hence the determination of the conductivity of the liquids unaffected by the coupling capacitances of the potential electrodes. Thus, small deviations that can creep in during manufacturing of the probe (manufacturing tolerances) do not affect the performance. An error analysis of the proposed system was carried out and the practicality of the scheme verified by developing and testing a prototype. The test results showed a worst-case error of 0.82% in conductivity measurements. The facts that the proposed method is unaffected by the coupling capacitors and the presence of materials kept outside of the probe were also verified.

Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)

ABSTRACT The ECG segment is successively filtered in the discrete cosine transform (DCT) domain u... more ABSTRACT The ECG segment is successively filtered in the discrete cosine transform (DCT) domain using an eigen-filter with a selective spectral feature, to determine the J-point and the onset point of the ensuing T-wave. The slope and length of the ST-segment are read directly from the resultant filtered waveform

Proceedings of the 19th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. 'Magnificent Milestones and Emerging Opportunities in Medical Engineering' (Cat. No.97CH36136)

Page 1. Proceedings - 19th International Conference - IEEE/EMBS Oct. 30 - Nov. 2, 1997 Chicago, I... more Page 1. Proceedings - 19th International Conference - IEEE/EMBS Oct. 30 - Nov. 2, 1997 Chicago, IL. USA Automatic detection of PVC's using Autoregressive Models. Joseph S.Paul* MRSReddyt V. Jagadeesh Kumart Indian Institute of Technology ...

Captive model testing for ship motions, sea-keeping and dynamic effects has been always a challen... more Captive model testing for ship motions, sea-keeping and dynamic effects has been always a challenge due to the large amount of channels of data, the need for continuous data communication for effect feedback control, and in the case of extended studies relating to fleets, the methodology for group fleet control. For the first time a solution is offered by designing a free self-propulsion, self, on-board controlled, surface ship model. The design incorporates Wi-Fi enabled robust communication and control and protocols for data storage, exchange, multiple device control and communication to fleet sister surface ships for fleet control. The design is described in this paper with details of implementation on a demonstration oceanographic research vessel. It illustrates the excellent communication between shore station computer and the on-board system on a wire-free model with robust control and exhibiting all the motion behavior and dynamic effects.

Proceedings of the 17th Southern Biomedical Engineering Conference

Elimination of weak interfering components from electrocardiographic signals using linear predict... more Elimination of weak interfering components from electrocardiographic signals using linear prediction analysis. Joseph S Paul, MRS Reddy, V Jagadeesh Kumar The 1998 17 th Southern Biomedical Engineering Conference, 1998. ...

Clinical interventions in aging, 2017

Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 33.5 milli... more Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 33.5 million people worldwide. Aging is the main risk factor associated with AD. Drug discovery based on nutraceutical molecules for prevention and treatment of AD is a growing topic. In this sense, carotenoids are phytochemicals present mainly in fruits and vegetables with reported benefits for human health. In this research, the anti-amyloidogenic activity of three carotenoids, cryptocapsin, cryptocapsin-5,6-epoxide, and zeaxanthin, was assessed. Cryptocapsin showed the highest bioactivity, while cryptocapsin-5,6-epoxide and zeaxanthin exhibited similar activity on anti-aggregation assays. Molecular modeling analysis revealed that the evaluated carotenoids might follow two mechanisms for inhibiting Aβ aggregation: by preventing the formation of the fibril and through disruption of the Aβ aggregates. Our studies provided evidence that cryptocapsin, cryptocapsin-5,6-epoxide, and zeaxanthin have an...

Microprocessing and Microprogramming, 1992

Microprocessing and Mieroprogramming 33 (1991/92) 169-172 169 North-Holland A microprocessor-base... more Microprocessing and Mieroprogramming 33 (1991/92) 169-172 169 North-Holland A microprocessor-based scheme for deriving sampling frequency P. Sankaran and V. Jagadeesh Kumar Department of Electrical Engineering, Indian Institute of Technology, Madras, India ...

IETE Journal of Research, 1997

ABSTRACT Measurement of current and voltage in high voltage systems employing optical fibre senso... more ABSTRACT Measurement of current and voltage in high voltage systems employing optical fibre sensors is becoming increasingly popular as the problem of insulation is practically eliminated. Vibrations, physical and acoustic, perturb the polarisation-preserving sensing fibre and cause added noise much in excess of the signal. The present paper discusses a method for reconstructing such a signal. The method, namely, signal-averaging digital phase sensitive detection (DPSD) recovers the signal of any arbitrary wave shape buried in noise. The only requirements are that the signal should be periodic and a local reference should be made available, conditions easily met in HV systems. The efficacy of the scheme is demonstrated by experimental results on a fibre optic current sensor with non-sinusoidal current.

2015 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2015

Resistive potentiometric type displacement sensors suffer wear and tear due to the sliding contac... more Resistive potentiometric type displacement sensors suffer wear and tear due to the sliding contact. The wear and tear can be reduced considerably by using a floating, contactless slide. The coupling capacitor that arises due to the use of a floating slide makes it difficult to obtain an output that linearly varies with the displacement. A signal conditioning circuit presented in this work operates on a resistive potentiometer type displacement sensor element with a floating slide and provides an output that is directly proportional to the displacement of the slide. Apart from the displacement, the output from the signal conditioning circuit depends only on a couple of dc reference voltages thus ensuring a good degree of accuracy and linearity. The results obtained from simulation studies and experimentation performed on a prototype unit built and tested establishes the efficacy of the proffered method.

OCEANS 96 MTS/IEEE Conference Proceedings. The Coastal Ocean - Prospects for the 21st Century

The wave energy group at the Indian Institute of Technology, Madras, India, in coordination with ... more The wave energy group at the Indian Institute of Technology, Madras, India, in coordination with the National Institute of Ocean Technology, Madras has successfully installed a pilot wave energy plant of the oscillating water column (OWC) type, at Vizhinjam, on the west coast of India. The wave energy plant (WEP) consists of a concrete caisson OWC pneumatically driving a Wells

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

Digital instrumentation systems are popular as they provide increased processing power and better... more Digital instrumentation systems are popular as they provide increased processing power and better user interface compared to their analog counterparts. To interface a transducer to a digital instrumentation system one needs a signal conditioner coupled to an analog to digital ...

2014 IEEE International Symposium on Medical Measurements and Applications (MeMeA), 2014

ABSTRACT Injury due to metal shrapnel is a major cause of death in victims of bomb blast, land mi... more ABSTRACT Injury due to metal shrapnel is a major cause of death in victims of bomb blast, land mines and gun fire. To recover these shrapnel surgically, surgeons use imaging systems for locating them inside the victim's body. Since these shrapnel are normally mobile, by the time the surgery starts, their positions would have changed making it very difficult for the surgeon to recover them. In certain cases, the shrapnel that are visible in the images can become untraceable during surgery. Giant Magneto Resistance (GMR) type sensor based tool to aid a surgeon to locate shrapnel was found to have poor depth response characteristics compared to inductive proximity sensor based tool. This paper presents the details of new schemes that were evaluated to improve the detection depths of the GMR sensor based shrapnel detectors. Results on prototype detectors built and tested establish the feasibility of the proffered schemes.

2014 Annual IEEE India Conference (INDICON), 2014

Direct Digital Converter (DDC) suitable for resistive sensor elements connected in the form of br... more Direct Digital Converter (DDC) suitable for resistive sensor elements connected in the form of bridge provides a digital output proportional to quantity being sensed. However, such a DDC requires that all the four sensor elements are to be identical. If there is a mismatch between the sensor elements (nominal values of the four resistances not equal) the error in the output of the DDC increases drastically. We now present a modified DDC that can tolerate mismatch between the four sensing elements of a bridge type resistive sensor. While the worst case error observed from the conventional DDC scheme rises from ± 0.07% to ± 1.32 % (simulation studies) for a very low mismatch of 0.03 %, the worst case error observed from the improved DDC scheme proposed here is only ± 0.24%.

2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), May 16, 2022

Studies in Skin Perfusion Dynamics, 2021

The method of photoplethysmography (PPG) detailed in Chapters 1 and 2 gained enormous prominence ... more The method of photoplethysmography (PPG) detailed in Chapters 1 and 2 gained enormous prominence due to the development of pulse oximetry. In pulse oximetry, the fact that hemoglobin bound with oxygen (called oxyhemoglobin) and hemoglobin without oxygen (deoxy-hemoglobin or reduced hemoglobin) absorb/reflect light differently is exploited in ascertaining, noninvasively, oxygen saturation in arterial blood. Most pulse oximeters that are in existence today use a couple of PPGs obtained using red and infrared wavelength light sources and calculate oxygen saturation in arterial blood using the red and IR PPGs and an empirical equation. This chapter details the development of pulse oximetry. It describes in detail a couple of novel methods of oxygen saturation calculation using the red and IR PPGs. The methods presented here do not need any calibration to be performed. 3.1 Physiological Signals for Diagnostics Dynamic and static measurements on the physical, electrical, chemical and acoustic signals of a human body will help ascertain its health [1-3]. Whenever a person is affected by a disease or gets injured, one or more of these physical, electrical, chemical and acoustic signals change. However, these physical, electrical, chemical and acoustic signals also change day to day due to natural variations in the life cycle. Moreover, the changes in these signals are a complex combination of different parameters. Hence it is very difficult to delineate the functioning or malfunctioning of the underlying biological parts or processes directly from these signals. The four traditional vital signs, namely, the pulse rate, the respiratory rhythm (and sound), the body temperature and the blood pressure are normally used by medical practitioners all over the globe to assess a patient's state of health. In the modern times, a fifth vital signal, namely, the oxygen saturation in blood has also gained importance. Today any patient with coronary or pulmonary problems must be evaluated for the oxygen

Engineering research express, May 13, 2022

Successive approximation type direct resistance to digital converter (SAR RDC) topology is presen... more Successive approximation type direct resistance to digital converter (SAR RDC) topology is presented here. The conventional SAR type ADC is augmented with an additional opamp inverting summer and a standard resistance such that the digital output of the SAR directly indicates the value of an unknown resistance connected between the output of the digital to analog converter of the SAR RDC and the inverting input of the added inverting summer. Analysis of the proposed technique presented here helps select proper components at the design stage itself to obtain minimal errors in the measurement of the unknown resistor. The major advantage of the proposed scheme is that it retains the basic architecture of an SAR ADC and hence can be implemented with all available SAR ADC architectures, including the ability to install ‘auto-ranging’. An added advantage is that the value of the unknown resistor is determined in terms of a standard resistor and hence good accuracy is easily obtained. Simulation studies and results obtained from a prototype SAR RDC built and tested, establish the efficacy of the proffered technique. The results indicate a worst-case error of < ±0.2 % and no missing codes.

International Conference on Power Electronics Machines and Drives, 2002

ABSTRACT This paper proposes a digital signal processor (DSP) based implementation of online air-... more ABSTRACT This paper proposes a digital signal processor (DSP) based implementation of online air-gap torque estimator for detection of squirrel cage rotor faults. Two noninvasive, computationally efficient methods for online air-gap torque monitoring are discussed. In both the methods, the air-gap torque is computed from two stator voltages and currents and is cost effective when compared with the use of a conventional torque transducer. The online air-gap torque monitor has been implemented using TMS320C31 and successfully tested on faulty cage rotors.

Power Electronics and …, 2001

Abstract-Identification of rotor faults in squirrel cage induction motors by estimation of air-ga... more Abstract-Identification of rotor faults in squirrel cage induction motors by estimation of air-gap torque spectra has gained considerable attention recently. This has the advantage that the signature spectrum generated by faults is in the low frequency region. But the torque computation ...

2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

IEEE Transactions on Industrial Electronics, 2021

The basic principle of a noncontact method of measurement of conductivity of liquids, presented e... more The basic principle of a noncontact method of measurement of conductivity of liquids, presented earlier, is analysed to evolve design rules to have minimal error in the measurement. In this method, the current is sent through the liquid whose conductivity is to be measured by induction and the voltage across the liquid column is measured using capacitive coupled electrodes and the conductivity computed therefrom. Hence, problems that arise due to contamination or corrosion of contacting electrodes are eliminated. The signal conditioning circuit is developed such that the measurement of the voltage-drop across the column of the liquid and hence the determination of the conductivity of the liquids unaffected by the coupling capacitances of the potential electrodes. Thus, small deviations that can creep in during manufacturing of the probe (manufacturing tolerances) do not affect the performance. An error analysis of the proposed system was carried out and the practicality of the scheme verified by developing and testing a prototype. The test results showed a worst-case error of 0.82% in conductivity measurements. The facts that the proposed method is unaffected by the coupling capacitors and the presence of materials kept outside of the probe were also verified.

Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)

ABSTRACT The ECG segment is successively filtered in the discrete cosine transform (DCT) domain u... more ABSTRACT The ECG segment is successively filtered in the discrete cosine transform (DCT) domain using an eigen-filter with a selective spectral feature, to determine the J-point and the onset point of the ensuing T-wave. The slope and length of the ST-segment are read directly from the resultant filtered waveform

Proceedings of the 19th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. 'Magnificent Milestones and Emerging Opportunities in Medical Engineering' (Cat. No.97CH36136)

Page 1. Proceedings - 19th International Conference - IEEE/EMBS Oct. 30 - Nov. 2, 1997 Chicago, I... more Page 1. Proceedings - 19th International Conference - IEEE/EMBS Oct. 30 - Nov. 2, 1997 Chicago, IL. USA Automatic detection of PVC's using Autoregressive Models. Joseph S.Paul* MRSReddyt V. Jagadeesh Kumart Indian Institute of Technology ...

Captive model testing for ship motions, sea-keeping and dynamic effects has been always a challen... more Captive model testing for ship motions, sea-keeping and dynamic effects has been always a challenge due to the large amount of channels of data, the need for continuous data communication for effect feedback control, and in the case of extended studies relating to fleets, the methodology for group fleet control. For the first time a solution is offered by designing a free self-propulsion, self, on-board controlled, surface ship model. The design incorporates Wi-Fi enabled robust communication and control and protocols for data storage, exchange, multiple device control and communication to fleet sister surface ships for fleet control. The design is described in this paper with details of implementation on a demonstration oceanographic research vessel. It illustrates the excellent communication between shore station computer and the on-board system on a wire-free model with robust control and exhibiting all the motion behavior and dynamic effects.

Proceedings of the 17th Southern Biomedical Engineering Conference

Elimination of weak interfering components from electrocardiographic signals using linear predict... more Elimination of weak interfering components from electrocardiographic signals using linear prediction analysis. Joseph S Paul, MRS Reddy, V Jagadeesh Kumar The 1998 17 th Southern Biomedical Engineering Conference, 1998. ...

Clinical interventions in aging, 2017

Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 33.5 milli... more Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 33.5 million people worldwide. Aging is the main risk factor associated with AD. Drug discovery based on nutraceutical molecules for prevention and treatment of AD is a growing topic. In this sense, carotenoids are phytochemicals present mainly in fruits and vegetables with reported benefits for human health. In this research, the anti-amyloidogenic activity of three carotenoids, cryptocapsin, cryptocapsin-5,6-epoxide, and zeaxanthin, was assessed. Cryptocapsin showed the highest bioactivity, while cryptocapsin-5,6-epoxide and zeaxanthin exhibited similar activity on anti-aggregation assays. Molecular modeling analysis revealed that the evaluated carotenoids might follow two mechanisms for inhibiting Aβ aggregation: by preventing the formation of the fibril and through disruption of the Aβ aggregates. Our studies provided evidence that cryptocapsin, cryptocapsin-5,6-epoxide, and zeaxanthin have an...

Microprocessing and Microprogramming, 1992

Microprocessing and Mieroprogramming 33 (1991/92) 169-172 169 North-Holland A microprocessor-base... more Microprocessing and Mieroprogramming 33 (1991/92) 169-172 169 North-Holland A microprocessor-based scheme for deriving sampling frequency P. Sankaran and V. Jagadeesh Kumar Department of Electrical Engineering, Indian Institute of Technology, Madras, India ...

IETE Journal of Research, 1997

ABSTRACT Measurement of current and voltage in high voltage systems employing optical fibre senso... more ABSTRACT Measurement of current and voltage in high voltage systems employing optical fibre sensors is becoming increasingly popular as the problem of insulation is practically eliminated. Vibrations, physical and acoustic, perturb the polarisation-preserving sensing fibre and cause added noise much in excess of the signal. The present paper discusses a method for reconstructing such a signal. The method, namely, signal-averaging digital phase sensitive detection (DPSD) recovers the signal of any arbitrary wave shape buried in noise. The only requirements are that the signal should be periodic and a local reference should be made available, conditions easily met in HV systems. The efficacy of the scheme is demonstrated by experimental results on a fibre optic current sensor with non-sinusoidal current.

2015 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2015

Resistive potentiometric type displacement sensors suffer wear and tear due to the sliding contac... more Resistive potentiometric type displacement sensors suffer wear and tear due to the sliding contact. The wear and tear can be reduced considerably by using a floating, contactless slide. The coupling capacitor that arises due to the use of a floating slide makes it difficult to obtain an output that linearly varies with the displacement. A signal conditioning circuit presented in this work operates on a resistive potentiometer type displacement sensor element with a floating slide and provides an output that is directly proportional to the displacement of the slide. Apart from the displacement, the output from the signal conditioning circuit depends only on a couple of dc reference voltages thus ensuring a good degree of accuracy and linearity. The results obtained from simulation studies and experimentation performed on a prototype unit built and tested establishes the efficacy of the proffered method.

OCEANS 96 MTS/IEEE Conference Proceedings. The Coastal Ocean - Prospects for the 21st Century

The wave energy group at the Indian Institute of Technology, Madras, India, in coordination with ... more The wave energy group at the Indian Institute of Technology, Madras, India, in coordination with the National Institute of Ocean Technology, Madras has successfully installed a pilot wave energy plant of the oscillating water column (OWC) type, at Vizhinjam, on the west coast of India. The wave energy plant (WEP) consists of a concrete caisson OWC pneumatically driving a Wells

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

Digital instrumentation systems are popular as they provide increased processing power and better... more Digital instrumentation systems are popular as they provide increased processing power and better user interface compared to their analog counterparts. To interface a transducer to a digital instrumentation system one needs a signal conditioner coupled to an analog to digital ...

2014 IEEE International Symposium on Medical Measurements and Applications (MeMeA), 2014

ABSTRACT Injury due to metal shrapnel is a major cause of death in victims of bomb blast, land mi... more ABSTRACT Injury due to metal shrapnel is a major cause of death in victims of bomb blast, land mines and gun fire. To recover these shrapnel surgically, surgeons use imaging systems for locating them inside the victim's body. Since these shrapnel are normally mobile, by the time the surgery starts, their positions would have changed making it very difficult for the surgeon to recover them. In certain cases, the shrapnel that are visible in the images can become untraceable during surgery. Giant Magneto Resistance (GMR) type sensor based tool to aid a surgeon to locate shrapnel was found to have poor depth response characteristics compared to inductive proximity sensor based tool. This paper presents the details of new schemes that were evaluated to improve the detection depths of the GMR sensor based shrapnel detectors. Results on prototype detectors built and tested establish the feasibility of the proffered schemes.

2014 Annual IEEE India Conference (INDICON), 2014

Direct Digital Converter (DDC) suitable for resistive sensor elements connected in the form of br... more Direct Digital Converter (DDC) suitable for resistive sensor elements connected in the form of bridge provides a digital output proportional to quantity being sensed. However, such a DDC requires that all the four sensor elements are to be identical. If there is a mismatch between the sensor elements (nominal values of the four resistances not equal) the error in the output of the DDC increases drastically. We now present a modified DDC that can tolerate mismatch between the four sensing elements of a bridge type resistive sensor. While the worst case error observed from the conventional DDC scheme rises from ± 0.07% to ± 1.32 % (simulation studies) for a very low mismatch of 0.03 %, the worst case error observed from the improved DDC scheme proposed here is only ± 0.24%.