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Design a system for monitoring human health VIA power line based on basic embedded system.

Introduction

Powerline systems use the standard electrical power lines to transmit data [1],[2]. The electrical power distribution grid offers, due to its omnipresence, a tremendous potential for extended fast and reliable communication services [1]. For many years, power lines have been used for low speed (<30kbps) data communication in application like power distribution automation and remote meter reading [3,4].The objective of patient remote monitoring is to have a quantitative assessment of the important physiological variables of the patients during critical periods of their biological functions from a distance [1].the distance may be realized within a hospital and more specific from ICU room to nursing or monitoring room. An Intensive Care unit (ICU) may be designed and equipped to provide care to patients with a range of conditions, or it may be designed and equipped to provide specialized care to patients with specific conditions. For example, a neuron medical ICU would care for patients with acute conditions involving the nervous system or for patients who have just had neurosurgical procedures and would require equipment for monitoring and assessing the brain and spinal cord. A neonatal ICU is designed and equipped to care for infants who are ill, born prematurely, or have a condition requiring constant monitoring [5]. Patient monitoring equipment includes; acute care physiologic monitoring system continuously measures and displays data on vital signs, such as heart rate, blood pressure, cardiac output, and blood oxygen levels. Pulse oxmeter monitors the oxygen saturation in the blood. Intracranial pressure monitoring measures the pressure of fluid in the brain in patients with head trauma or other conditions affecting the brain (such as tumors, edema, or hemorrhaging). Apnea monitor continuously monitors breathing to detect cessation in infants and adults at risk of respiration failure [6].In this work system consists of embedded systems and communication channel has been designed for transmitting real data mentioned above. Two main topologies have been implemented; Firstly two wires has been used as a channel for basic embedded system and secondly power line was used as a transmission channel for the same purpose; the second system was considered as an improved system because interfacing circuits have been adapted to the embedded systems.

System Description

The system consists firstly of a master board using AT89C51 microcontroller which has been interfaced to LCD display and ADC 0809 equipped with 8 input channels. Each channel can be used as transducer link. Obviously RS232 has been introduced for establishing serial communication with various baud rates for timer1 (TH1) for Microcontroller AT89C51. As baud rate of 9600bps has been used for serial communication along with PC for testing purposes and to synchronous with UART chip in PC, while microcontroller has it built-in UART, Figure1 shows a system designed for monitoring human health in intensive care unite.

[FIGURE 1 OMITTED]

C code was used for programming microcontrollers. It was possible to generate data with different baud rates according to the necessity may be imposed. Signal conditioning has been used in order to increase the flexibility of an ADC as shown in Figure2. Data has been collected from human body as actual data transformed to voltage or current by means of sensors. Data collected has been conditioned in this system to fit with ADC usage. The 8 channels of ADC have been used and interfaced to microcontroller AT89C51 for controlling and display the different values obtained. An improved system has been designed to accomplish the aim of this work; it was by using the same cores of the previous basic system that using RS232, two wires and serial data transmission has been changed by removing the RS232 and using the new protocol that has been established. Therefore it consists of designing a special circuit for AC power line interfacing, this circuit designed to be the main gate to entering power line media.

[FIGURE 2 OMITTED]

Design Concepts

Basic System Design

A system for serial communication as a simplex transmission null modem connection has been designed referring to [7]; in this work data have been generated from the transmitter and received by the receiver in stead of PC. The cores have been used were 89c51 for the transmitter and receiver see Figure 3.

[FIGURE 3 OMITTED]

Improved Design

The previous system has been mentioned above improved by applying a new protocol for convenient communication through power line. RS232 has been replaced by interfacing circuit and modulator in the transmitter and regarding receiver interfacing circuit, demodulator and high pass filter have been introduced as shown in Figure4.

[FIGURE 4 OMITTED]

Systems Functionality

The main system consists of two circuits of embedded system (for transmitter and receiver); one situates in the transmitter part and second circuit presents in the receiver part; furthermore these two embedded systems consist of a system for realizing proper functions regarding human health monitoring because the transmitter was designed to pickup data by means of transducers and sensors attached to human body which have been interfaced to system through the 8 channel of an ADC. Parameters have been extracted from human body like: temperature, blood pressure, respiration status, heart rate.... etc. The controllers of these systems were microcontrollers AT89C51 in both transmitter and receiver. Embedded system of the transmitter consists of microcontroller 89C51, ADC 0809 which provides eight selected channels and LCD for display. ADC has been designed to pickup real variation of data in the form of voltage within certain delay (by means of program), while the receiver consists of only microcontroller 89C51 and LCD for display. This system has been tested; it has been found that it's highly reliable for null modem connection by using two external extra wires through RS 232. Now the same system has been modified to meet the aim of using power line as transmission media, this can be done only by replacing the RS232's from the transmitter and the receiver by two different interfacing circuits. Interfacing circuits have been deigned previously to remote control appliances through power line and it was a good opportunity to use this circuit for designing new systems. The circuit consist of basic modulator (Driver and Injection Circuit), high pass filter and driver, a coupling filter consists of isolation transformer and two capacitors which have been designed for realizing firstly an isolation from AC power line (230V 50Hz) and secondly for injection digital data (with high frequency) through power line as shown in Figure 5 and Figure 6 for the transmitter and the receiver respectively.

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

Observation

Observation has been noted when testing both systems according to baud rates variation these variations were between 75 to 9600 bps. The basic system using RS232 functioned properly up to 9600 bps. The basic system was tested for two values of baud rate (9600 and 4800) it shows a good functionality, while the improved system suffering from improper transmission because of the unpredictable environments existing in power line channel. Therefore the system was provided by low rate transmitting circuit that using a relay for this purpose ( basic modulator) the baud rate has been decreased in the embedded system to a value 75 bps (-384 decimal) loaded to TH1 register. This low baud rate has been tested for the relay functionality and it shows a good reaction of the system. Therefore the same values of baud rate used for the basic system have been used for testing the improved system but the system shows incorrect transmission because the delay imposes it limitations due to mechanical functionality. Therefore for too low baud rate (75bps) the system shows a good functionality as shown in observation table1.

Systems Limitations

Practical limitations have been noted that interfacing circuits used as data injectors to power line designed to transmit low data rate; it has been designed to remote control switching appliances (ON and OFF). High rates will impose serious problem because the main part of this system was stable multi-vibrator; where 555 IC considered as a heart of these circuits and a relay. If Switching Mode Power Supply (SMPS) used for supplying embedded systems; probability of transmission failure increases and data will change the destination and be picked up by SMPS due to the design properties of these power supplies. Certain type of Multi-socket has been provided by noise filter circuit when it's used for connecting the transmitter and the receiver, but due to high pass filter in built in these sockets data has been blocked. It is very possible that data will be affected by an inverter (battery backup) which has been installed in the same phase where the systems connected to power line. The major limitation appears when the transmitter and receiver connected to two different phases there for it's recommended to function the hall system in single phases otherwise non matching phasing deviates the data to improper phase. Therefore it is highly recommended to tack into considerations and avoid this improper functionality.

Conclusion and future work

Both systems can be used for monitoring human health successfully under specific conditions noting that basic system used for the improved system. The basic system adds extra coast for communication channel wiring and affects the infrastructure wiring of a building. Improved system used just the existing power line as a communication channel. Basic system immune counter noises while the improved system subjected to various noises which have been overcame. As Future work the improved system can provided by a more sophisticated modem using FSK modulation, it seems to be one of the more simple and robust modulation method for power line communication [7],[8],[9]. Instead of this band it seems that only spread spectrum methods are possible [10]. Overcome the limitations mentioned in the system limitations section can be as assignment for major future works.

References

[1] Anindya Majumder, James Caffery, Jr., October/November 2004, "Power line communication: an overview", IEEE Potentials.

[2] D. Clarke, February 1998, IEEE Internet Computing, "POWERLINE COMMUNICATIONS: Finally Ready for Prime Time?", Pages 10-11

[3] R.S. Khandpur, 2003 "Handbook of Biomedical instrumentation", Second Edition.

[4] Hudson AG, Beuerle DR, Fiedler HJ. 1976, "SSB carrier for utility control and communication", Proceedings of IEEE national Telecommunication conference, 2.1.1-2.1.7.

[5] Lokken G, Jagoda N, D'Auteuil RJ. 1976, "The proposed Wisconsin electric company load management system using power line over distribution line". Proceedings of the IEEE National Telecommunication conference, 2.2.1-2.2.3.

[6] Savino, Josef S., C. William Hanson III, and Timothy J. Gardner. October 2000, "Cardiothoracic intensive Care: Operation and Administration." Seminars in Thoracic and Cardiovascular Surgery 12: 362-70.

[7] Adnan S. Obeed, Nitin M. Kulkarni, Arvind D. Shaligram, 2008, "Design of Embedded System for Simplex Transmission to a PC through Power line", ICEVD.

[8] Matthias Karl, Klaus Dostert, 1996 "Selection of an Optimal Modulation Scheme for Digital Communications Over Low Voltage Power Lines", Spread Spectrum Techniques and Applications Proceedings.

[9] Hakki Cavdar, January 2004, "Performance Analysis of FSK Power Line Communications Systems over the Time-Varying Channels: Measurements and Modeling", IEEE Transactions on Power Delivery, Vol. 19, No. 1.

[10] Petra Cuntic, Alen Baiant, 2003--June 11-13, "Analysis of Modulation Methods for Data Communications over the Low-voltage Grid", Proceeding of the 7th International Conference on Telecommunication--ConTEL Zagreb, Croatia.

Adnan S. Obeed *, Nitin M. Kulkarni * and Arvind D. Shaligram **

* Department of Electronic science, Fergusson College, Pune FC Road, Pune, Maharashtra, 411004, India, E-mail: adnan_101_saadon@yahoo.com, nmkulkarni@yahoo.com

** Department of Electronic science, University of Pune, Pune Ganeshkhind Road, Pune, Maharashtra, 411007 India 25699841, E-mail:ads@electronics.unipune.ernet.in
Table 1: Evaluation of the two systems for different cases.

S.N.   Type of     Baud   Inverter   Using   Using    Transmission
       channel     Rate   Presence   SMPS    Filter   Status
                   kbps

1.     RS 232      9600   yes        yes     yes      Transmitted
2.     RS 232      4800   yes        yes     yes      Transmitted
3.     Powerline   9600   yes        yes     yes      Failure
4.     Powerline   4800   NO         NO      NO       Failure
5.     Powerline   75     yes        yes     yes      Transmitted
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Article Details
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Author:Obeed, Adnan S.; Kulkarni, Nitin M.; Shaligram, Arvind D.
Publication:International Journal of Applied Engineering Research
Article Type:Report
Geographic Code:1USA
Date:Apr 1, 2009
Words:1977
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