A Real Time Embedded set up Based on Digital Signal Controller for ...

Sensors & Transducers Volume 105, Issue 6 June 2009

www.sensorsportal.com

ISSN 1726-5479

Editor-in-Chief: professor Sergey Y. Yurish, phone: +34 696067716, fax: +34 93 4011989, e-mail: [email protected] Editors for Western Europe Meijer, Gerard C.M., Delft University of Technology, The Netherlands Ferrari, Vittorio, Universitá di Brescia, Italy Editor South America Costa-Felix, Rodrigo, Inmetro, Brazil

Editors for North America Datskos, Panos G., Oak Ridge National Laboratory, USA Fabien, J. Josse, Marquette University, USA Katz, Evgeny, Clarkson University, USA Editor for Asia Ohyama, Shinji, Tokyo Institute of Technology, Japan

Editor for Eastern Europe Sachenko, Anatoly, Ternopil State Economic University, Ukraine

Editor for Asia-Pacific Mukhopadhyay, Subhas, Massey University, New Zealand

Editorial Advisory Board Abdul Rahim, Ruzairi, Universiti Teknologi, Malaysia Ahmad, Mohd Noor, Nothern University of Engineering, Malaysia Annamalai, Karthigeyan, National Institute of Advanced Industrial Science and Technology, Japan Arcega, Francisco, University of Zaragoza, Spain Arguel, Philippe, CNRS, France Ahn, Jae-Pyoung, Korea Institute of Science and Technology, Korea Arndt, Michael, Robert Bosch GmbH, Germany Ascoli, Giorgio, George Mason University, USA Atalay, Selcuk, Inonu University, Turkey Atghiaee, Ahmad, University of Tehran, Iran Augutis, Vygantas, Kaunas University of Technology, Lithuania Avachit, Patil Lalchand, North Maharashtra University, India Ayesh, Aladdin, De Montfort University, UK Bahreyni, Behraad, University of Manitoba, Canada Baliga, Shankar, B., General Monitors Transnational, USA Baoxian, Ye, Zhengzhou University, China Barford, Lee, Agilent Laboratories, USA Barlingay, Ravindra, RF Arrays Systems, India Basu, Sukumar, Jadavpur University, India Beck, Stephen, University of Sheffield, UK Ben Bouzid, Sihem, Institut National de Recherche Scientifique, Tunisia Benachaiba, Chellali, Universitaire de Bechar, Algeria Binnie, T. David, Napier University, UK Bischoff, Gerlinde, Inst. Analytical Chemistry, Germany Bodas, Dhananjay, IMTEK, Germany Borges Carval, Nuno, Universidade de Aveiro, Portugal Bousbia-Salah, Mounir, University of Annaba, Algeria Bouvet, Marcel, CNRS – UPMC, France Brudzewski, Kazimierz, Warsaw University of Technology, Poland Cai, Chenxin, Nanjing Normal University, China Cai, Qingyun, Hunan University, China Campanella, Luigi, University La Sapienza, Italy Carvalho, Vitor, Minho University, Portugal Cecelja, Franjo, Brunel University, London, UK Cerda Belmonte, Judith, Imperial College London, UK Chakrabarty, Chandan Kumar, Universiti Tenaga Nasional, Malaysia Chakravorty, Dipankar, Association for the Cultivation of Science, India Changhai, Ru, Harbin Engineering University, China Chaudhari, Gajanan, Shri Shivaji Science College, India Chavali, Murthy, VIT University, Tamil Nadu, India Chen, Jiming, Zhejiang University, China Chen, Rongshun, National Tsing Hua University, Taiwan Cheng, Kuo-Sheng, National Cheng Kung University, Taiwan Chiang, Jeffrey (Cheng-Ta), Industrial Technol. Research Institute, Taiwan Chiriac, Horia, National Institute of Research and Development, Romania Chowdhuri, Arijit, University of Delhi, India Chung, Wen-Yaw, Chung Yuan Christian University, Taiwan Corres, Jesus, Universidad Publica de Navarra, Spain Cortes, Camilo A., Universidad Nacional de Colombia, Colombia Courtois, Christian, Universite de Valenciennes, France Cusano, Andrea, University of Sannio, Italy D'Amico, Arnaldo, Università di Tor Vergata, Italy De Stefano, Luca, Institute for Microelectronics and Microsystem, Italy Deshmukh, Kiran, Shri Shivaji Mahavidyalaya, Barshi, India Dickert, Franz L., Vienna University, Austria Dieguez, Angel, University of Barcelona, Spain Dimitropoulos, Panos, University of Thessaly, Greece Ding, Jianning, Jiangsu Polytechnic University, China

Djordjevich, Alexandar, City University of Hong Kong, Hong Kong Donato, Nicola, University of Messina, Italy Donato, Patricio, Universidad de Mar del Plata, Argentina Dong, Feng, Tianjin University, China Drljaca, Predrag, Instersema Sensoric SA, Switzerland Dubey, Venketesh, Bournemouth University, UK Enderle, Stefan, Univ.of Ulm and KTB Mechatronics GmbH, Germany Erdem, Gursan K. Arzum, Ege University, Turkey Erkmen, Aydan M., Middle East Technical University, Turkey Estelle, Patrice, Insa Rennes, France Estrada, Horacio, University of North Carolina, USA Faiz, Adil, INSA Lyon, France Fericean, Sorin, Balluff GmbH, Germany Fernandes, Joana M., University of Porto, Portugal Francioso, Luca, CNR-IMM Institute for Microelectronics and Microsystems, Italy Francis, Laurent, University Catholique de Louvain, Belgium Fu, Weiling, South-Western Hospital, Chongqing, China Gaura, Elena, Coventry University, UK Geng, Yanfeng, China University of Petroleum, China Gole, James, Georgia Institute of Technology, USA Gong, Hao, National University of Singapore, Singapore Gonzalez de la Rosa, Juan Jose, University of Cadiz, Spain Granel, Annette, Goteborg University, Sweden Graff, Mason, The University of Texas at Arlington, USA Guan, Shan, Eastman Kodak, USA Guillet, Bruno, University of Caen, France Guo, Zhen, New Jersey Institute of Technology, USA Gupta, Narendra Kumar, Napier University, UK Hadjiloucas, Sillas, The University of Reading, UK Haider, Mohammad R., Sonoma State University, USA Hashsham, Syed, Michigan State University, USA Hasni, Abdelhafid, Bechar University, Algeria Hernandez, Alvaro, University of Alcala, Spain Hernandez, Wilmar, Universidad Politecnica de Madrid, Spain Homentcovschi, Dorel, SUNY Binghamton, USA Horstman, Tom, U.S. Automation Group, LLC, USA Hsiai, Tzung (John), University of Southern California, USA Huang, Jeng-Sheng, Chung Yuan Christian University, Taiwan Huang, Star, National Tsing Hua University, Taiwan Huang, Wei, PSG Design Center, USA Hui, David, University of New Orleans, USA Jaffrezic-Renault, Nicole, Ecole Centrale de Lyon, France Jaime Calvo-Galleg, Jaime, Universidad de Salamanca, Spain James, Daniel, Griffith University, Australia Janting, Jakob, DELTA Danish Electronics, Denmark Jiang, Liudi, University of Southampton, UK Jiang, Wei, University of Virginia, USA Jiao, Zheng, Shanghai University, China John, Joachim, IMEC, Belgium Kalach, Andrew, Voronezh Institute of Ministry of Interior, Russia Kang, Moonho, Sunmoon University, Korea South Kaniusas, Eugenijus, Vienna University of Technology, Austria Katake, Anup, Texas A&M University, USA Kausel, Wilfried, University of Music, Vienna, Austria Kavasoglu, Nese, Mugla University, Turkey Ke, Cathy, Tyndall National Institute, Ireland Khan, Asif, Aligarh Muslim University, Aligarh, India Sapozhnikova, Ksenia, D.I.Mendeleyev Institute for Metrology, Russia

Kim, Min Young, Kyungpook National University, Korea South Ko, Sang Choon, Electronics and Telecommunications Research Institute, Korea South Kockar, Hakan, Balikesir University, Turkey Kotulska, Malgorzata, Wroclaw University of Technology, Poland Kratz, Henrik, Uppsala University, Sweden Kumar, Arun, University of South Florida, USA Kumar, Subodh, National Physical Laboratory, India Kung, Chih-Hsien, Chang-Jung Christian University, Taiwan Lacnjevac, Caslav, University of Belgrade, Serbia Lay-Ekuakille, Aime, University of Lecce, Italy Lee, Jang Myung, Pusan National University, Korea South Lee, Jun Su, Amkor Technology, Inc. South Korea Lei, Hua, National Starch and Chemical Company, USA Li, Genxi, Nanjing University, China Li, Hui, Shanghai Jiaotong University, China Li, Xian-Fang, Central South University, China Liang, Yuanchang, University of Washington, USA Liawruangrath, Saisunee, Chiang Mai University, Thailand Liew, Kim Meow, City University of Hong Kong, Hong Kong Lin, Hermann, National Kaohsiung University, Taiwan Lin, Paul, Cleveland State University, USA Linderholm, Pontus, EPFL - Microsystems Laboratory, Switzerland Liu, Aihua, University of Oklahoma, USA Liu Changgeng, Louisiana State University, USA Liu, Cheng-Hsien, National Tsing Hua University, Taiwan Liu, Songqin, Southeast University, China Lodeiro, Carlos, Universidade NOVA de Lisboa, Portugal Lorenzo, Maria Encarnacio, Universidad Autonoma de Madrid, Spain Lukaszewicz, Jerzy Pawel, Nicholas Copernicus University, Poland Ma, Zhanfang, Northeast Normal University, China Majstorovic, Vidosav, University of Belgrade, Serbia Marquez, Alfredo, Centro de Investigacion en Materiales Avanzados, Mexico Matay, Ladislav, Slovak Academy of Sciences, Slovakia Mathur, Prafull, National Physical Laboratory, India Maurya, D.K., Institute of Materials Research and Engineering, Singapore Mekid, Samir, University of Manchester, UK Melnyk, Ivan, Photon Control Inc., Canada Mendes, Paulo, University of Minho, Portugal Mennell, Julie, Northumbria University, UK Mi, Bin, Boston Scientific Corporation, USA Minas, Graca, University of Minho, Portugal Moghavvemi, Mahmoud, University of Malaya, Malaysia Mohammadi, Mohammad-Reza, University of Cambridge, UK Molina Flores, Esteban, Benemérita Universidad Autónoma de Puebla, Mexico Moradi, Majid, University of Kerman, Iran Morello, Rosario, University "Mediterranea" of Reggio Calabria, Italy Mounir, Ben Ali, University of Sousse, Tunisia Mulla, Imtiaz Sirajuddin, National Chemical Laboratory, Pune, India Neelamegam, Periasamy, Sastra Deemed University, India Neshkova, Milka, Bulgarian Academy of Sciences, Bulgaria Oberhammer, Joachim, Royal Institute of Technology, Sweden Ould Lahoucine, Cherif, University of Guelma, Algeria Pamidighanta, Sayanu, Bharat Electronics Limited (BEL), India Pan, Jisheng, Institute of Materials Research & Engineering, Singapore Park, Joon-Shik, Korea Electronics Technology Institute, Korea South Penza, Michele, ENEA C.R., Italy Pereira, Jose Miguel, Instituto Politecnico de Setebal, Portugal Petsev, Dimiter, University of New Mexico, USA Pogacnik, Lea, University of Ljubljana, Slovenia Post, Michael, National Research Council, Canada Prance, Robert, University of Sussex, UK Prasad, Ambika, Gulbarga University, India Prateepasen, Asa, Kingmoungut's University of Technology, Thailand Pullini, Daniele, Centro Ricerche FIAT, Italy Pumera, Martin, National Institute for Materials Science, Japan Radhakrishnan, S. National Chemical Laboratory, Pune, India Rajanna, K., Indian Institute of Science, India Ramadan, Qasem, Institute of Microelectronics, Singapore Rao, Basuthkar, Tata Inst. of Fundamental Research, India Raoof, Kosai, Joseph Fourier University of Grenoble, France Reig, Candid, University of Valencia, Spain Restivo, Maria Teresa, University of Porto, Portugal Robert, Michel, University Henri Poincare, France Rezazadeh, Ghader, Urmia University, Iran Royo, Santiago, Universitat Politecnica de Catalunya, Spain Rodriguez, Angel, Universidad Politecnica de Cataluna, Spain Rothberg, Steve, Loughborough University, UK Sadana, Ajit, University of Mississippi, USA Sadeghian Marnani, Hamed, TU Delft, The Netherlands

Sandacci, Serghei, Sensor Technology Ltd., UK Saxena, Vibha, Bhbha Atomic Research Centre, Mumbai, India Schneider, John K., Ultra-Scan Corporation, USA Seif, Selemani, Alabama A & M University, USA Seifter, Achim, Los Alamos National Laboratory, USA Sengupta, Deepak, Advance Bio-Photonics, India Shearwood, Christopher, Nanyang Technological University, Singapore Shin, Kyuho, Samsung Advanced Institute of Technology, Korea Shmaliy, Yuriy, Kharkiv National Univ. of Radio Electronics, Ukraine Silva Girao, Pedro, Technical University of Lisbon, Portugal Singh, V. R., National Physical Laboratory, India Slomovitz, Daniel, UTE, Uruguay Smith, Martin, Open University, UK Soleymanpour, Ahmad, Damghan Basic Science University, Iran Somani, Prakash R., Centre for Materials for Electronics Technol., India Srinivas, Talabattula, Indian Institute of Science, Bangalore, India Srivastava, Arvind K., Northwestern University, USA Stefan-van Staden, Raluca-Ioana, University of Pretoria, South Africa Sumriddetchka, Sarun, National Electronics and Computer Technology Center, Thailand Sun, Chengliang, Polytechnic University, Hong-Kong Sun, Dongming, Jilin University, China Sun, Junhua, Beijing University of Aeronautics and Astronautics, China Sun, Zhiqiang, Central South University, China Suri, C. Raman, Institute of Microbial Technology, India Sysoev, Victor, Saratov State Technical University, Russia Szewczyk, Roman, Industrial Research Inst. for Automation and Measurement, Poland Tan, Ooi Kiang, Nanyang Technological University, Singapore, Tang, Dianping, Southwest University, China Tang, Jaw-Luen, National Chung Cheng University, Taiwan Teker, Kasif, Frostburg State University, USA Thumbavanam Pad, Kartik, Carnegie Mellon University, USA Tian, Gui Yun, University of Newcastle, UK Tsiantos, Vassilios, Technological Educational Institute of Kaval, Greece Tsigara, Anna, National Hellenic Research Foundation, Greece Twomey, Karen, University College Cork, Ireland Valente, Antonio, University, Vila Real, - U.T.A.D., Portugal Vaseashta, Ashok, Marshall University, USA Vazquez, Carmen, Carlos III University in Madrid, Spain Vieira, Manuela, Instituto Superior de Engenharia de Lisboa, Portugal Vigna, Benedetto, STMicroelectronics, Italy Vrba, Radimir, Brno University of Technology, Czech Republic Wandelt, Barbara, Technical University of Lodz, Poland Wang, Jiangping, Xi'an Shiyou University, China Wang, Kedong, Beihang University, China Wang, Liang, Advanced Micro Devices, USA Wang, Mi, University of Leeds, UK Wang, Shinn-Fwu, Ching Yun University, Taiwan Wang, Wei-Chih, University of Washington, USA Wang, Wensheng, University of Pennsylvania, USA Watson, Steven, Center for NanoSpace Technologies Inc., USA Weiping, Yan, Dalian University of Technology, China Wells, Stephen, Southern Company Services, USA Wolkenberg, Andrzej, Institute of Electron Technology, Poland Woods, R. Clive, Louisiana State University, USA Wu, DerHo, National Pingtung Univ. of Science and Technology, Taiwan Wu, Zhaoyang, Hunan University, China Xiu Tao, Ge, Chuzhou University, China Xu, Lisheng, The Chinese University of Hong Kong, Hong Kong Xu, Tao, University of California, Irvine, USA Yang, Dongfang, National Research Council, Canada Yang, Wuqiang, The University of Manchester, UK Yang, Xiaoling, University of Georgia, Athens, GA, USA Yaping Dan, Harvard University, USA Ymeti, Aurel, University of Twente, Netherland Yong Zhao, Northeastern University, China Yu, Haihu, Wuhan University of Technology, China Yuan, Yong, Massey University, New Zealand Yufera Garcia, Alberto, Seville University, Spain Zagnoni, Michele, University of Southampton, UK Zamani, Cyrus, Universitat de Barcelona, Spain Zeni, Luigi, Second University of Naples, Italy Zhang, Minglong, Shanghai University, China Zhang, Qintao, University of California at Berkeley, USA Zhang, Weiping, Shanghai Jiao Tong University, China Zhang, Wenming, Shanghai Jiao Tong University, China Zhang, Xueji, World Precision Instruments, Inc., USA Zhong, Haoxiang, Henan Normal University, China Zhu, Qing, Fujifilm Dimatix, Inc., USA Zorzano, Luis, Universidad de La Rioja, Spain Zourob, Mohammed, University of Cambridge, UK

Sensors & Transducers Journal (ISSN 1726-5479) is a peer review international journal published monthly online by International Frequency Sensor Association (IFSA). Available in electronic and on CD. Copyright © 2009 by International Frequency Sensor Association. All rights reserved.

Sensors & Transducers Journal

Contents Volume 105 Issue 6 June 2009

www.sensorsportal.com

ISSN 1726-5479

Editorial Sensors Systems Need Smart Sensors: SENSOR+TEST 2009 at a Glance Sergey Y. Yurish…………………………………………………………………………………………….

I

Research Articles Development of an Intelligent Capacitive Mass Sensor Based on Co-axial Cylindrical Capacitor Amir Abu_Al_Aish, Mahfoozur Rehman, Anwar Hasni Abu Hassan and Mohd Rizal Arshad...........

1

Accurate Measurement of ‘Q’ Factor of An Inductive Coil Using a Modified Maxwell Wein Bridge Network Subrata Chattopadhyay, Bijnan. R. Maity and Sagarika Pal..............................................................

10

New Type Small-angle Sensor Based on the TIR and SPR Theories in Heterodyne Interferomery Shinn-Fwu Wang, Jyh-Shyan Chiu, Lung-Hsiang Lee, Cheng-Min Lee, Rong-Moo Hong ................

18

A Real Time Embedded set up Based on Digital Signal Controller for Detection of BioSignals Using Sensors Dipali Bansal, Munna Khan, Ashok K. Salhan ...................................................................................

26

Development of Hardware Dual Modality Tomography System R. M. Zain, R. Abdul Rahim................................................................................................................

33

Designing of Water Quality Detector Using pH Sensor Pavika Sharma, Prerna Garg, and P. A. Alvi......................................................................................

42

Design and Modeling a New Optical Modulator Mohammad Mezaael ..........................................................................................................................

50

Study of a Modified Design of a Potential Transformer S. C. Bera and D. N. Kole...................................................................................................................

56

Simulation Study of IMC and Fuzzy Controller for HVAC System Umamaheshwari and P. Sivashanmugam .........................................................................................

66

Digital Position Control System of a Motorized Valve in a Process Plant Using Hybrid Stepper Motor as Actuator Subrata Chattopadhyay, Utpal Chakraborty, Arindam Bhakta and Sagarika Pal ..............................

73

Modeling and Analysis of a Bimorph PZT Cantilever Beam Based Micropower Generator Jyoti Ajitsaria, Song-Yul Choe, Phil Ozmun, Dongna Shen and Dong-Joo Kim. ...............................

81

PPY-PVA Blend Thin Films as a Ammines Gas Sensor D. B. Dupare, M. D. Shirsat and A. S. Aswar .....................................................................................

94

Sanguinarine and its Electropolymerization onto Indium Tin Oxide as a Mediator for Biosensing Ravindra P. Singh, Byung-Keun Oh and Jeong-Woo Choi................................................................

104

Effect of Dilution and Model Analysis of Distillery Effluent Using Dissolved Oxygen as Parameter J. Sumathi, S. Sundaram....................................................................................................................

113

Growth and Characterization of Nanocrystalline ZnO Thin Films by Spray Pyrolysis: Effect of Molarity of Precursor Solution Dharmendra Mishra, K. C. Dubey, R. K. Shukla, Anchal Srivastava and Atul Srivastava .................

119

pH Homeostasis of a Biosensor in Renal Function Regulation Linked with UTI T. K. Basak, T. Ramanujam, V. Cyrilraj, G. Gunshekharan Asha Khanna, Deepali Garg, Poonam Goyal, Arpita Gupta..............................................................................................................

127

Micro-Flow Based Differential Pressure Sensor Microbridge Technologies, White Paper ............................................................................................

135

Authors are encouraged to submit article in MS Word (doc) and Acrobat (pdf) formats by e-mail: [email protected] Please visit journal’s webpage with preparation instructions: http://www.sensorsportal.com/HTML/DIGEST/Submition.htm International Frequency Sensor Association (IFSA).

Sensors & Transducers Journal, Vol. 105, Issue 6, June 2009, pp. 26-32

Sensors & Transducers ISSN 1726-5479 © 2009 by IFSA http://www.sensorsportal.com

A Real Time Embedded Set Up Based on Digital Signal Controller for Detection of Bio-Signals Using Sensors 1

Dipali BANSAL, 2Munna KHAN, 3Ashok K. SALHAN 1

Apeejay College of Engineering, Sohna, Haryana, India 2 Jamia Millia Islamia, New Delhi, India 3 D.I.P.A.S, D.R.D.O, Delhi, India E-mail: [email protected], [email protected], [email protected]

Received: 29 March 2009 /Accepted: 22 June 2009 /Published: 30 June 2009 Abstract: Real time embedded systems created using digital signal processors have a significant progressive role in processing of multi-parametric bio-signals. The decreasing cost of this technology has resulted in its commercial availability and provides high speed, accuracy, noise immunity, low power consumption, programmability and size reduction. The analysis however is done generally on stored data and there is a need of a data acquisition unit that makes the system expensive. This paper proposes the design of an intelligent dsPIC digital signal controller DM330011 based system for continuous monitoring and automatic analysis of bio-signals. This kit has on board analog to digital converters and programming circuitry. The front end hardware includes biosensors and self developed tested cascaded amplifiers, right leg drive circuits and active filters. Verified Zero phase band pass filter algorithm in MATLAB shall be tested in the software tool by dsPIC. The final system would result in an inexpensive stand alone solution to real time implementation of medical monitors. Copyright © 2009 IFSA. Keywords: Digital signal processors, Embedded system, Medical monitors, Real time system

1. Introduction Digital signal processors (DSP) have enabled an automated approach to analysis of complex human biological signals, enhanced computational speeds, easy data acquisition and ability to handle huge amount of data. Digital Signal controller (DSC) is a hybrid solution that combines the processing power of a DSP and the utility of a Microcontroller which includes fast interrupt times, control of peripherals, general purpose I/O and can run compact code. Digital signal controllers developed by 26

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Texas Instruments (T.I) have been widely explored to give a system on chip solution to real time implementation and feature extraction of ECG signals. Digital heart rate monitors have been implemented by T.I using MSP430FG439 micro controllers and the results are displayed on a LCD. The RS232 port is utilized to interface data to the computer [1]. Digital signal processor TMS 320F206 along with the microcontroller 89C55 is also used to develop a 12-lead automatic ECG analysis system. The arrangement allows high speed sampling with precision and quantifies the heart rate, P-R interval and Q-T interval in the ECG [2]. A 300 MHz floating point DSP TMS320C6713 is used in a yet another application to give a solution to real time fetal ECG extraction. This scheme is simulated using code composer studio v3.1 including all its peripherals [3]. DSP based enhanced data acquisition system is also developed using TMS320C25 [4]. Further work is done to localize Q-T interval in an ECG waveform using wavelets and TMS320C25 add on card to a host IBM computer. The acquired bio-signal is digitized at 250 samples per sec and a 16 bit analog to digital converters (ADC) [5]. Texas digital signal processing chip TMSC5402 is again used along with a Pentium PC, HP arbitrary waveform generator model 33120A and Tektronix oscilloscope TDS 410A to locate the QRS complex in an ECG. Template matching method is then used for real time signal analysis [6]. MSP430F149 along with a fast 12 bit ADC provides a solution to remote home health care where the data is sent to a computer using RS232 interface. The ECG signal is acquired using custom designed amplifier, filter and protection circuits [7]. High speed low power DSP TMS320VC5509A is embedded using algorithm based on wavelet transform to develop a portable monitor to continuously examine the ECG for 10 hours [8]. Holter monitoring of bio-signals in real time has been made possible using TMS320C542 and Del Mar PWA amplifier Digicorder [9]. The same arrangement is further explored to provide spectral and statistical heart rate variability analysis and filtering [10]. MIT BIH Arrhythmia data base is also validated for online QRS detection using TMS320C6701 [11]. Low cost DSP TMS320C31 is used in certain applications to build up a real R-R interval detection scheme using correlation technique [12]. Digital signal processors developed by other manufacturers also allow the fast execution of algorithm for bio-signal processing. Hyperstone’s RISC DSP developer board along with 3 channel ECG Holter amplifier, 12 bit Dallas semiconductor’s ADC and USB interface to PC is used to develop an embedded prototype for patient monitoring [13]. Floating point DSP 96002 from Motorola, IBM computer and ADC is used to provide an ECG processing system. The arrangement is connected to the host PC using on chip Emulator [14]. ARM 922T macro-cell having 32 bit RISC processor along with general purpose input/output (GPIO) and ADC allows a system on chip solution to QRS detection in ECG signal [15]. STMicroelectronics based DSP ST220 is used to design a versatile integrated system for analyzing bio-signals [16]. Work done earlier mainly involves the DSC developed by Texas Instruments. Also, for acquiring the bio-signal ADC and commercial amplifiers are utilized which make the entire arrangement expensive. This paper proposes the design to develop a Microchip dsPIC digital signal controller based cost effective real time embedded system for acquisition and analysis of physiological signals, mainly ECG and Carotid pulse waveform. The project work includes self developed amplifier and filter system also.

2. Design Considerations Basic design of real time portable medical monitors incorporates the following sub systems: • • • • •

Selection of proper sensor for picking the bio-signal Amplifier circuit Analog active filters Analog to digital conversion of acquired signal for interface to computer Power management 27

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• Display unit • Data control and processing • Algorithm for data analysis Major innovations and up gradations are feasible in the key areas such as compaction of sizes, low power consumption, enhanced efficiency and reliability, additional memory, quick response and lengthened battery performance. Data control management was primarily handled through micro controllers which has gradually being substituted by DSP based controls. DSP Kit portfolio provides a perfect environment and tool box for developing portable medical applications. To start with the development the first task is to review the vast range of processor and identify the right kind of DSP that provides flexibility, programmability, and quality. Table 1 compares and highlights features of various commercial DSP processors from vendors like Texas Instruments, Analog Devices, FreeScale (Motorola) and MicroChip [17]. Table 1. Comparison of Digital Signal Processing chips by various manufacturers. Family

Format

Texas Instruments TMS 320C Fixed 24x/F24x TMS 320F 2833x

Floating

TMS 320C 55x

Fixed

TMS 320DM 6446

Fixed

TMS 320C 67x

Floating

Data Size Clock

On Chip Memory Unit (Bytes) price

16 bits

40 MHz 150 MHz

6.5k-34.5k

300 MHz 594 MHz 300 MHz

80k-376k

72k-264k

$ 12-28 Floating Version of C62x, low power, high precision

160 MHz 32 / 40 bits 400 MHz 16 bits 750 MHz 8/16/ 600 32/40 bits MHz

16k-128k

$ 12-29 Enhanced Version ADSP 218x

384k-1024k

$ 8-40 High speed Version of Sharc 2126x

52k-328k

$ 5-31 Dual MAC DSP with variable speed

512k-3M

$ 131- 4 way VLIW, SIMD 205

24 bits

275 MHz 120 MHz 300 MHz 1 GHz

24k-648k

$ 4-43 -

20k-612k

$ 3-20 Contains micro controller, Enhanced 568xx $ 32-38 Based on SC 1400

10.1 M

$ 150- Based on SC 3400, quad core chip 181

40 MHz

6.2k-287k

$ 2-8

32 bits 16 bits 8/16 bits 32 bits

182k-582k

232k

Remarks

$ 2-9

Hybrid micro-controller & DSP. Speed 100 MIPS $ 3-20 Addition to C28x features $ 4-15 Power efficient, suits long battery life applications $ 33 ARM 9, C64x, high performance

Analog Devices ADSP 219x ADSP 213xx Sharc ADSP BF5xx Blackfin

Fixed Floating Fixed

Fixed & Floating FreeScale (Motorola) ADSP TS 20x

DSP 563xx

Fixed

DSP 5685x (56800E)

Fixed

MSC 71xx

Fixed

MSC 81xx

Fixed

16 bits

16 bits 16 bits 16 bits

408k-472k

MicroChip dsPIC 3x F

Fixed

16 bits

Hybrid micro controller & DSP. Has on board ADC. Speed 40 MIPS

28

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The next step is to explore the availability and feature of add on development tools of DSP starter kits required to simulate and test run the project. The starter kits come packed with a range of peripherals and interfaces that provide a doorway to DSP projects and applications. Primary development procedure includes an IDE (integrated development environment) that contains a vast collection of inbuilt functions along with user friendly GUI (graphical user interfaces) thus enabling fast project design implementation. Debugger is an integrated part of these IDE that help to quickly and easily track down and fix software problems. Once the DSC is finalized an appropriate sensor would be selected to pick the biological data. A hardware system then needs to be developed to amplify and filter the biological signal picked. The analog output of this amplifier system is then converted into a digital output using ADC so that it can be interfaced with the host computer that acts as the output display device. Designs however now make it possible to interface analog data directly to the computer. Data control and signal processing algorithms are then explored on the acquired signal. Portable medical monitors are generally corrupted by disturbances like baseline wandering up to 0.5 Hz due to electronic circuits, 50 Hz (in India) power line interference, muscle activity noise up to 20 Hz because sensor-body interface is not stationary in time, changing electrode resistance due to drying of gel etc. All these interferences lead to decreased system performance and reliability. Digital signal processing (DSP) algorithms for noise reduction therefore needs to be used in many biomedical engineering applications. Initially DSP was used for off-line processing of stored data with computer as the display device. Now however online solutions are possible and shall be explored in this work using DSP processors. Detailed materials required and method to be used in this work is explained in the subsequent section.

3. Materials and Methods Block diagram of the Digital Signal Processor based real time embedded system for acquisition of Human Physiological Signals is sketched in Fig 1. The measurement system consists of a transducer to pick the human physiological signal, amplifier system, hardware band-pass filter, fifty hertz notch filter, Digital signal controller and a personal computer as the output display device.

Fig. 1. Block diagram of DSP based Real Time Embedded System for acquisition of Bio-Signals.

The design is based on an intelligent MPLAB starter kit dsPIC digital signal controller DM 330011 board for continuous monitoring and automatic analysis of human physiological parameters. The kit is purchased from microchipDIRECT for $59.98. Fig. 2 is the experimental set up for dsPIC DSC based real time embedded system for acquisition of bio-signals. The front end hardware required for the data acquisition includes Ag-Ag-Cl or Piezoelectric sensors, self developed cascaded amplifiers, right leg drive circuits, active band-pass filters and 50 Hz notch filters. The amplifier and filter system is designed and already tested using TL-084C differential amplifiers [18]. The starter kit demonstrates features of dsPIC 33FJ 256 GP 506 and is a general purpose fixed point Digital Signal Controller 29

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(DSC) with compatible interface options to PIC24 MCUs and dsPIC30F DSCs. The controller has 256 KB Flash and 16 KB RAM. It is a 16/24/32 bit Digital signal controller with a maximum frequency of 48 kHz and a CPU speed of 40 MIPS. The operating temperature range is -40 to 850 C and the operating voltage range is 3 to 3.6 V. The available Digital Communication Peripherals are 2-UART, 2-SPI and 2-I2C. The Analog Peripherals include one ADC 18x12-bit @ 500 kbps. Other peripherals are 16-bit PWM resolutions, 16 Timers, Parallel Port- GPIO and 8 DMA. It also has an on board in circuit debugging and programming circuitry with C compiler and IDE and connects directly to the USB port on a computer. Programming shall be done using MPLAB IDE. Analog output signal obtained from the front end amplifier system shall be routed to the 12 bit analog to digital converter (ADC) module in the on board kit for software processing. This rules out the need of an extra ADC, thus reducing the size and the cost involved. The Zero phase band pass filter algorithm tested and implemented in MATLAB shall now be verified in the development software tool provided by dsPIC.

Fig. 2. Experimental set up for dsPIC DSC based Embedded System for acquisition of Bio-Signals.

4. Discussions Real time medical monitors that allow continuous monitoring need to be designed carefully. A compromise is made between efficiency and reliability to cost, size, hardware potential and power requirements by the system. Earlier used microcontroller system for the purpose lacked the complicated processing power requirements but the DSP kits used these days for medical monitoring have sufficient power for long-lasting use [19]. The design proposed in this work shall ensure sophisticated real time processing of bio-signals using MicroChip’s DSP kits that requires less power, is compact in size and is cost effective. Another advantage of using DSC over conventional microcontrollers is that DSC uses Harvard architecture whereas others use the Von Neumann architecture. The Von Neumann architecture uses a single memory to hold both data and instructions. In comparison, the Harvard architecture uses separate memories for data and instructions and hence can be fetched at the same time, thus providing higher speed [20]. The format used by DSP processors is categorized as fixed point and floating point, both having their own merits and demerits. Fixed point DSPs usually represent each number with a minimum of 16 bits. In comparison, floating point DSPs typically use a minimum of 32 bits to store each value. The 30

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ADSP TS 20x developed by analog devices are optimized for both floating point and fixed point operations, and executes them with equal efficiency as is indicated in Table 1. Because of their lower cost and power, fixed-point processors are best suited for high volume, heavily embedded silicon implementations and shall therefore be used in this project. Floating-point processors are best for custom applications where even faster development is required at an extra cost [20]. The tools available with the DSP kits also play an important role in designing medical monitoring systems. Development tool by Texas is the Code Composer Studio which is a complete code development environment that runs on Windows and offers high-level C-callable functions to speed up the progress. In embedded applications, the most common OS is Wind River’s VxWorks and work is also done on Linux. Micro chip DSP kits also provide a complete user friendly IDE and works on windows platform [20]. For acquiring the bio-signal especially ECG, commercially available amplifiers and ADC are utilized which make the entire system cumbersome and expensive. MPLAB’s dsPIC digital signal controller DM 330011 kit that will be used in this project has on-board ADC which shall enable reduction in the complexity of the medical monitors. The amplifier system required are custom made, have already been tested on a MATLAB based GUI and are very cost effective.

5. Conclusions Portable medical monitors are devices capable of saving human life, but their costs limit wider use. A low-cost, single-chip solution can help overcome this obstacle. The cost of a personal medical monitor can be reduced through use of new technologies which incorporate microcontroller and digital signal processing as an integrated system. The arrangement discussed in this paper would result in an inexpensive stand alone established solution to real time implementation of medical monitors for acquiring and analyzing parameters like ECG and Carotid pulse waveform. The embedded system can be further programmed to calculate the heart rate, heart rate variability and cardiac output.

References [1] Murugavel Raju, Heart-Rate and EKG Monitor Using the MSP430FG439, Texas Instruments Application Report, SLAA280A–Revised September 2007. [2] Yang Y., Yin D., Freyer R., Development of a digital signal processor-based new 12-lead synchronization electrocardiogram automatic analysis system, Comput Methods Programs Biomed, 69, 1, 2002, pp. 57-63. [3] D Pani, S Argiolas, L Raffo, A DSP Algorithm and System for Real-Time Fetal ECG Extraction, Computers in Cardiology, 2008, 35, pp. 1065−1068. [4] Sahambi J. S., Tandon S. N., Batt R. K., DSP based enhanced data acquisition system, Biomed Sci Instrum., 1995, 31, pp. 247-250. [5] J. S. Sahambi, S. N. Tandon, R. K. P. Bhatt, An Automated Approach to Beat by Beat QT- Interval Analysis, IEEE Engineering in Medicine and Biology, May/June 2000, pp. 97-101. [6] S. Mohammad, Z. Lim, Y. Lin, A. Sani, K. Zanjani, M. Paracha, J. Jenkins, Real-Time ECG Analysis Using a TI TMSC54x Digital Signal Processing Chip, Computers in Cardiology, 2003, 30, pp. 541−544. [7] C. S. Ho, H. T. Wu, D. M. Lu, C. H. Lin, S. H. Ho and K. H. Chou, Development of a Measurement System for Electrocardiograms and Its Application to Remote Home Care, Proceedings of 2005 CACS Automatic Control Conference, Tainan, Nov 18-19, 2005. [8] Lin Qi, Yonghong Zhang, Jing Bai, Development of Portable ECG Monitor On Low-cost DSP, IFMBE Proceedings, Vol. 14/6, JC 27, pp. 4058-62. [9] Emil Jovanov, Pedro Gelabert, Reza Adhami, Bryan Wheelock, Robert Adams, Real Time Holter Monitoring of Biomedical Signals, DSP Technology and Education Conference DSPS’99, August 4-6, 1999, Houston, Texas. 31

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[10] Dejan Raskovic, Emil Jovanov, Thomas Martin, Shuaib Hanief, Pedro Gelabert, Energy Profiling of DSP Applications, A Case Study of an Intelligent ECG Monitor, Proc. of DSPS fest 2000, Houston, Texas, Aug. 2-4, 2000. [11] S. Hoferichter, B. U. Köhler, C. Hennig and R. Orglmeister, On-Line QRS-Detection Using the TMS320C6701, Proc. of 3rd European DSP Education & Research Conference, Paris, 2000. [12] Buttfield A. C., Bolton M. P., Real time measurement of RR intervals using a digital signal processor, J. Med. Eng. Technol., 29, 1, 2005, pp. 8-13. [13] Shripad Kondra, Chong Yew, Farhan Ahmad, Ulrich G. Hofmann, Prototype of a Patient Monitoring Device based on an embedded RISC/DSP system, ICMP 2005/BMT Conference, Nuremberg, Germany, September 2005. [14] Francisc Iacob, Cornel Popescu, A DSP based processing system for Electrocardiographic signals, http://www.ee.bilkent.edu.tr/~signal/BCSP [15] Meng-Chou Chang, Zong-Xin Lin, Che-Wei C hang, Hsiao-Lung Chan, and Wu-Shiung Feng, Design of a System-on-Chip for ECG signal processing, 2004 IEEE Asia-Pacific Conference on Circuits and Systems, December 6-9, 2004, pp. 441-444. [16] Iyad Al Khatib, Francesco Poletti, Davide Bertozzi, Luca Benini et al, A Multiprocessor System-on-Chip for Real-Time Biomedical Monitoring and Analysis: Architectural Design Space Exploration, 43rd Design Automation Conference (DAC 06). [17] BDTI’s Pocket Guide to Processing Engines for Embedded Applications. http://www.BDTI.com/benchmarks.html [18] Dipali Bansal, Munna Khan, Ashok K. Salhan, A computer based wireless system for online acquisition, monitoring and digital processing of ECG waveforms, Journal of Computers in Biology & Medicine, 39, 4, Jan 2009, pp. 361-367. [19] Dejan Raskovic, Emil Jovanov, and Krishna Kavi, Hierarchical Digital Signal Processing, ISPACS 2001, Nashville, TN, Nov. 20-23, 2001. [20] Processor Comparison: Texas Instruments C6000 DSP and Motorola G4 PowerPC, www.pentek.com

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