Home telecare system using cable television plants-an experimental ...

IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 4, NO. 1, MARCH 2000

37

Home Telecare System Using Cable Television Plants—An Experimental Field Trial Ren-Guey Lee, Heng-Shuen Chen, Chung-Chih Lin, Kuang-Chiung Chang, and Jyh-Horng Chen

Abstract—To solve the inconvenience of routine transportation of chronically ill and handicapped patients, this paper proposes a platform based on a hybrid fiber coaxial (HFC) network in Taiwan designed to make a home telecare system feasible. The aim of this home telecare system is to combine biomedical data, including three-channel electrocardiogram (ECG) and blood pressure (BP), video, and audio into a National Television Standard Committee (NTSC) channel for communication between the patient and healthcare provider. Digitized biomedical data and output from medical devices can be further modulated to a second audio program (SAP) subchannel which can be used for second-language audio in NTSC television signals. For long-distance transmission, we translate the digital biomedical data into the frequency domain using frequency shift key (FSK) technology and insert this signal into an SAP band. The whole system has been implemented and tested. The results obtained using this system clearly demonstrated that real-time video, audio, and biomedical data transmission are very clear with a carrier-to-noise ratio up to 43 dB. Index Terms—CATV, home telecare, telemedicine.

I. INTRODUCTION

A

LARGE number of hospital beds are occupied by patients with chronic illnesses. This problem has led to the gradual development of home healthcare services [1]–[5]. The primary nursing healthcare model [6] of home healthcare consists of a primary nurse, physical therapists, and doctors. The primary nurse visits and cares for the patient at home. Consultation and further examination with therapists and physicians is initiated only if the primary nurse discovers problems which need further evaluation. However, this model is time-consuming and difficult to apply because of distance and commuting conditions. Consequently, other approaches have been proposed and implemented [7]–[9]. There are several technical requirements for a practicable home telecare service [10]. First, a wide-area network is needed to serve as a backbone to support multimedia transmissions to the home. Second, a high-speed transmission rate is required to transmit real-time video, audio, and biomedical signals. Third, interactive capability is needed between the patient and Manuscript received March 20, 1999; revised August 11, 1999. R.-G. Lee is with the Insitute of Electrical Engineering, National Taiwan University, Taipei, Taiwan. He is also with the Department of Electrical Engineering, Lunghwa Institute of Technology, Taiwan, R.O.C. H.-S. Chen is with the Insitute of Electrical Engineering and the Department of Medical Informatics, College of Medicine, National Taiwan University, Taipei, Taiwan. C.-C. Lin and J.-H. Chen are with the Insitute of Electrical Engineering, National Taiwan University, Taipei, Taiwan, R.O.C. K.-C. Chang is with the Department of Electrical Engineering, Lunghwa Institute of Technology, Taiwan, R.O.C. Publisher Item Identifier S 1089-7771(00)02121-X.

healthcare providers, and, finally, the patient’s end unit should be easy to install and be fairly simple to operate. Given these requirements, there are many combinations of technologies that could be used to serve as the home telecare system. Most wide-area networks are divided into switch-based networks and broadcast networks. Integrated service digital network (ISDN) and Asynchronous transfer mode (ATM) are the most popular switch-based networks. Broadcast networks contain wireless communications [11], [12] (satellite, microwave, , etc.), cable television (CATV) networks, and so forth. The transmission rate for ISDN is from basic rate interface (144 kb/s) to primary rate interface (1.92 Mb/s). Basic rate interfaces (BRI’s) are often combined to provide the necessary bandwidth for various applications [13], [14]. Nevertheless, the wiring area of ISDN is limited and the rental cost is relatively high in the Taiwan area. ATM is also suitable for high rate requirements because it offers very high bandwidths (up to 155 Mb/s) [15]. Unfortunately, the feasibility of ATM to the home is still immature at present. On the other hand, CATV networks are another option for several reasons. First, the CATV network combines optical fiber and coaxial cable into a two-way HFC infrastructure and, therefore, can support interactive service and transmit multimedia data to the home with high-bandwidth capability. Second, the CATV business is growing rapidly with an installation rate up to 80% in the Taiwan area, and it can be expanded to urban and rural regions. As a result, CATV plants appear to be a good choice for home telecare service. In the CATV services, the cable modem is a popular product that can be used for digital interactive services. Applying cable modems to home telecare applications, a computer and PC-base video conferencing systems can be used for dialogue between the patient and healthcare provider. Nevertheless, a cable modem is more expensive than a voice modem and the resolution of the video-conferencing system is too low (10 frames/s, 320 200 pixels) for medical services. In this paper, we propose a novel method to solve these problems. This paper is organized as follows. In Section II, an overview of the CATV system is described. In Section III, some existing systems in telemedicine are briefly discussed. Strategies for home telecare proposed in this paper are elaborated on in Section IV. The primary design and implementation are demonstrated in Section V. System assessments are summarized in Section VI. Finally, we conclude our report in Section VII. II. OVERVIEW OF THE CATV SYSTEMS Traditionally, CATV provides analog services by using 50–550-MHz frequency bandwidths (called the downstream path) and by using 5–42-MHz frequency bandwidths (called

1089–7771/00$10.00 © 2000 IEEE

Authorized licensed use limited to: National Taiwan University. Downloaded on March 3, 2009 at 22:27 from IEEE Xplore. Restrictions apply.

38


Fig. 1. Spectrum location of MTS signals in NTSC type of television signals.

Fig. 2. Home telecare system architecture.

the upstream path) to support two-way services. Since each analog channel has a 6-MHz bandwidth, about 78 channels can be accommodated in the downstream path and 6 channels in the upstream path. For a good carrier-to-noise ratio (CNR) and efficient expenditure, a CATV center constructs transmissions routine with the HFC network. The head-end is the center of the program broadcast. The program is transmitted from the trunk line to the feeder line. The feeder line broadcasts to subscribers via a drop line. For program quality, an amplifier is used to replenish signal loss. Return modules must be installed in all amplifiers for interactive services. Multichannel television sound (MTS), as accepted by the FCC and shown in Fig. 1, provides monaural and stereo sound, as well as a second audio program (SAP) subchannel for possible second-language audio, and a private communication channel (PRO) in place of the NTSC 4.5-MHz audio subcarrier band. There is 25 kHz of bandwidth in the SAP subchannel, which is generally not used in CATV systems [16]. III. AN OVERVIEW

OF

SOME EXISTING TELEMEDICINE SYSTEMS

In most of the literature [1]–[5], telecommunication technology used in medical applications, such as in distance education, telemedicine, picture achieving and communication system (PACS), and teleradiology, uses twist-pair phone

Fig. 3. The packet format for biosignal transmission.

lines [17], ISDN [13], [14], or ATM [15]. In telemedicine applications, high-speed networks are needed to transmit multimedia data. Some research has focused on hospital-to-hospital telemedicine. In these cases, expensive and high-speed networks can be constructed. In Stewart’s research [18], which presented an ultrafast network, the signaling rate was 12.5 Mb/s for radiologic images by Ethernet1 and fiber distributed data interface (FDDI) networks. VISTAnet and MICA also provide high-speed networks between 155 and 622 Mb/s for medical applications [15]. However, these applications are too expensive to expand into the home. One community application of telemedicine is home telecare service [5], [7], [8]. To support this service with digital telecommunication techniques, the bandwidth requirement of the system is at least 1.8 Mb/s. It should include real-time video information with a protocol of MPEG-1 (1.5 Mb/s) and a digital audio signal protocol of MPEG-1 layer 2 audio (32–256 kb/s), equivalent to CD quality. The existing system for home telecare, which uses a phone line, can transmit biomedical signals 1Sun

Microsystems, Inc., Mountain View, CA.


LEE et al.: HOME TELECARE SYSTEM USING CABLE TELEVISION PLANTS

Fig. 4.

39

Format for biphase coding.

Fig. 5. A block diagram of the part of the RF modem for the healthcare provider-end and the patient-end.

between the patient and healthcare provider but cannot transmit good quality video and audio signals together. In Rodriguez’s work [5], 12-lead electrocardiogram (ECG) and blood pressure (BP) data can be monitored and sent to hospitals. A specialist diagnoses those biomedical signals and advises the patient with off-line analysis. In addition, some commercial products provide the “video visits” capability to selected home telecare patients. This allows two-way video interaction up to 10 frames/s [19] at a lower resolution than that used for medical services. Taking a global view of the telemedicine system, hospital-tohospital applications and home telecare services have different criteria for cost, speed, and network distribution. IV. A STRATEGY FOR THE HOME TELECARE SYSTEM To solve the inconvenience of routine transportation of chronically ill and handicapped patients, a strategy for a home telecare system is proposed in this system. The system architecture, as shown in Fig. 2, can support face-to-face interactive dialogue between the patient and healthcare provider. We allocate a prescribed downstream and upstream channel in a CATV system. The downstream channel transmits the healthcare provider video and audio signals to the patient-end. Similarly, the upstream channel uses the return path. This system consists of three parts: the patient-end, the healthcare provider-end, and the CATV center. At the patient-end, equipment such as a television, charge coupling device (CCD), microphone, analog RF modulator, and, if necessary, a bedside monitor or portable ECG and BP devices can be used for physiological checks and transmitted via an SAP subchannel in the NTSC format by an RF modem. A stethoscope is installed at the patient-end to listen to heart and breath sounds which are transmitted to the healthcare provider-end

Fig. 6. The circuit board in the RF modem for the patient-end and the healthcare provider-end.

via a monaural audio band in the NTSC format. The television receives NTSC signals including video and audio from the healthcare provider-end. The analog RF modulator modulates the CCD video and microphone signal into the NTSC format and shifts the NTSC signal to an upstream frequency allocation. On the healthcare provider-end, the television is replaced by a computer and embedded TV-card. Furthermore, this computer retrieves the patient’s medical records from the hospital information system (HIS) and radiological information system (RIS) [20], [21]. A patient information packet (PIP) database that can store the medical record is applied in the home telecare service in this system [22]. The CATV center contains a frequency switch box that transfers upstream and downstream frequency allocations. Two channels were chosen, T7, from 5.75 to 11.75 MHz, for the upstream channel and A6, from 84 to 90 MHz, for the downstream channel. During a teleconsultation, the healthcare provider and patient have a face-to-face meeting via the CCD camera, television,


40

Fig. 7.


A block diagram of part of the RF modem for the CATV center.

and microphone. If necessary, the provider can guide the patient in the use of medical devices and transmission of data to the provider-end. V. SYSTEM DESIGN AND IMPLEMENTATION In this section, full details of the system design are discussed. Fig. 3 presents a packet format for transmission of biomedical signals. The length of the format is variable to match ECG and BP data for a duration of one second. A packet length, which depends on the sample rate, is set by the software. The cyclic redundancy check (CRC) method is adopted for error control. For real-time monitoring of patient data, a time scale has to be recorded in each packet. This system provides the transmission of three-channel ECG and BP data between the healthcare provider-end and the patient-end. The bit rate of each ECG channel is 8 bit/sample and 200 samples/s. The total bit rate equals 4800 bit/s. For BP, the sampling rate is one per minute and the data length is equal to 16 bit. The ECG and BP are combined into the biomedical data stream and the stream is translated into RS232C format under 9.6 kbit/s baud rate. The policy of error control is presented by a nonauto repeat query (ARQ) scheme [23]. If a transmission error occurs, the computer at the healthcare provider-end will show an error point and the data should be ignored. The ECG data can be real-time. This system provides an RF modem interface, which inserts biomedical signals into the HFC network. The RF modem puts biomedical signals into the SAP subchannel in a prescribed upstream channel. The primary transmission data include three-channel ECG, BP, calling signals, and an emergency alarm, which is generated when the patient presses a button, by using a 9.6 kb/s baud-rate at the patient-end. In the CATV center, an RF modem is used to send a control signal between the patient and healthcare provider ends. Also, the RF modem is a transceiver to receive data from the patient-end and to send a control signal to the patient-end. One of the design issues in the RF modem provides a commonly recommended format for various medical devices. The interface of an RF modem with an RS232C format is an international standard usually used for medical devices. For reduction of carrier drift, RS232C is translated into biphase code in the RF modem. Biphase code, shown in Fig. 4, avoids the influence of the dc level in a voltage-control oscillation (VCO)

Fig. 8. The circuit board in the RF modem for the CATV center.

Fig. 9. The provider-end interface to retrieve HIS data for the home telecare service.

circuit, which generates the RF central carrier for the frequency shift key (FSK) method. The average dc level is approximately equal to zero with a long period of biphase signal. For emission control, the frequencies of the RF modem for the upstream and downstream subchannels were assigned to 8 and 89 MHz, respectively. For the 89-MHz radio frequency channel, there is little leakage from the CATV network and the use of the channel is temporary because home telecare services are prescheduled. Interference will be slight. Fig. 5 shows a part of the RF modem for user-end data paths that includes the healthcare provider-end and the patient-end. In this block diagram, the 8-MHz modulator encodes upstream data input to a biphase signal that modulates the VCO circuit



Fig. 10.

41

The GUI of the DICOM format MIR image at the provider-end.

TABLE I SUBJECTIVE QUALITY OF DIFFERENT CNR’S

Fig. 11.

An experimental test-bed for the home telecare system.

to generate an 8.02-MHz FM signal. The biphase CODEC (encoder and decoder) is implemented by a PIC-16C54 microprocessor with a 20-MHz oscillator. The baseband refiner removes the RF transient component and rectifies the waveform to a kHz freVCO circuit for generating the FSK signal in quency offset. The 8.02-MHz bandpass filter (BPF) limits the output bandwidth to meet the channel spectrum of the CATV system. To avoid interference with active RF modems, an on/off control module attenuates the output of an idle RF modem to less than 70 dB. The downstream module, an 89-MHz demodulator, is shown in the lower half of Fig. 5. The mixer extracts the FM signal and modulates it to the 8.02-MHz bandwidth which corresponds to the upstream module for filter design. The orthogonal FM demodulator and slicer separate the signal from the carrier, and the digital signal is regenerated by a biphase decoder. Fig. 6 shows the implementation of a part of an RF modem for the patient-end and healthcare provider-end. In the CATV center, the RF modem consists of an 89-MHz modulator and 8-MHz demodulator, as shown in Fig. 7. For design flexibility, the forepart of the 89-MHz modulator is similar to that of the patient-end. The output of the VCO circuit is connected to the 8.02-MHz BPF for bandwidth limit. The mixer compounds an 81-MHz oscillator and 8-MHz filter output into an 89-MHz FM signal and inserts it into the CATV network. The upstream demodulator is shown in the lower half of Fig. 7. The mixer shifts an 8-MHz FM signal to 10.7 MHz

Fig. 12.

The test-bed in the CATV center for the home telecare system.

by the 18.72-MHz oscillator. The 10.7-MHz signal was used because it is inexpensive and easily available because it is usually used in televisions. The orthogonal FM demodulator, slicer, and biphase decoder are similar to that of the patient-end. The circuit board is shown in Fig. 8. The healthcare provider-end interface is shown in Fig. 9. Through a Web-browser, the physician can retrieve the patient’s medical records from a PIP database. For radiological image representation, a medical image tool is designed and embedded in this system. In Fig. 10, we show an example of MRI in the DICOM format. The contrast of the MRI can be modified if necessary.


42

Fig. 13.


The spectrum allocation of (a) the 89-MHz modulator, (b) the 89-MHz demodulator, (c) the 8-MHz modulator, and (d) the 8-MHz demodulator.

VI. SYSTEM ASSESSMENT Figs. 11 and 12 show an experimental test-bed for the home telecare system using CATV plants. There are 13 analog channels in a 19-in rack to measure co-channel interference, complex triple beat (CTB), and complex second order (CSO), which are important factors in assessing CATV quality [24]–[27]. A distributed network is combined by two trunk amplifiers taps. Some attenuators are used to test the video, and two audio, and biosignal quality in different CNR’s. The system assessment is divided into video and biomedical data parts. For video estimation, the subjective quality, defined by the Television Allocations Study Organization (TASO), is shown in Table I. A practical test shows that the described experimental test-bed obtains a CNR up to 43 dB without any attenuators. CTB and CSO are less than 63 dB, which is lower than 53 dB, the criterion of CATV law in the Taiwan area. We can provide clear video for the patient and healthcare provider. The stability of the RF modem is measured by a spectrum analyzer. The 89-MHz modulator has two harmonics that can be removed by filter. The frequency spectrum is shown in Fig. 13(a)–(d). All signal levels are higher than 41 dB in all spectra. In Taiwan’s CATV system, the CNR is supposed to be maintained higher than 43 dB. However, in real CATV systems, problems might lead to a lower CNR. For the reliability of the home telecare system, we therefore lowered the CNR with attenuators to measure the bit-error rate (BER) of the biomedical signals transmission. To measure the BER, biomedical signals were sent

Fig. 14. The BER of the RF modem at different CNR’s.

from the patient-end to the healthcare provider-end up to 10 000 times from the RF modem. The results are shown in Fig. 14. The BER is still lower than 0.1% even when the CNR is 40 dB, which is better than what we need. By doing this, we proved that the RF modem could be used satisfactorily for home telecare service over CATV plants. When ECG data is changed into RS232C format for the RF modem, some truncation errors will occur. Therefore, the percent rms difference (PRD) is used to assess ECG data [27]. The formula of the PRD is shown


%

(1)


Fig. 15. (a) Original ECG data acquired from a 16-bit A/D converter. (b) The reconstructed ECG digital data.

where and are samples of the original and reconstructed data sequences. We sent original data, as shown in Fig. 15(a), from an RF modem on the patient-end and reconstructed the data on the healthcare provider-end, as shown in Fig. 15(b). In this case, the PRD was 0.02%, which is better than some popular ECG data compression techniques such as AZTEC, DPCM linear predict coding, and Fourier descriptor [27].

43

stability and simplicity of the FSK method are important issues in this system [30]. Because the transmission data is a little less than 19.2 kbit/s, some complex modulating technologies such as orthogonal frequency division multiplexing (OFDM)2 and quadrant amplitude modulation (QAM) [31] could not be used in the telecare system. Cable modems and asymmetric digital subscriber line (ADSL)3 which have a wider bandwidth could be used for telecare depending on the CATV infrastructure and an upgraded PBX system. However, the asymmetric transmission rate protocol in cable modems and ADSL will limit the number and quality of bidirectional video transmissions. Raw ECG data can be transmitted from the patient-end and reconstructed at the healthcare provider-end for telediagnosis applications. In this study, the ECG data transmission had a 0.02% PRD. This is acceptable from the doctor’s point of view, and this quality is better than some popular ECG data compression techniques such as AZTEC, DPCM linear predict coding, and Fourier descriptor [27]. CATV companies provide some channels which can be rented out. Scrambling techniques are provided to ensure privacy and security for the patient. Therefore, a home telecare system using an HFC network would be feasible. Anticipated future development is the integration of home care records from different clinics and hospitals. We are now installing this system between the palliative medicine ward at National Taiwan University Hospital and the households of their discharged patients. The results of this evaluation will be presented after one year of study. Nonetheless, digital video and audio are the current trend in telemedicine. Home telecare will be digitized if broadband networks become popular nationwide. An analog RF modulator will be replaced with a supporting quality of service (QoS) broadband modem in this system. ACKNOWLEDGMENT The authors would like to thank Dr. S.-M. Huo, Vice Superintendent of National Taiwan University Hospital, Dr. C.-Y. Chen, and Dr. F.-R. Guo for their recommendations in this research. REFERENCES

VII. DISCUSSIONS AND CONCLUSIONS This paper presents a novel method for home telecare service. This service provides real-time and high-quality video and audio that supports interactive communication between the healthcare provider and patient at a distance by using the CATV network. The proposed system has the following features. First, the experimental HFC network communication between the healthcare provider and patient had a CNR of 43 dB and a speed of 30 frames/s. This quality is better than a video-conferencing system in telemedicine applications [29]. Second, a specially designed RF modem for transmitting alarms, emergency calls and biomedical data such as ECG and BP was designed and thoroughly tested in this network. The RF modem translates all data into FM signals by FSK technology and inserts those signals into a second audio band in the prescribed channel. The

[1] L. W. Kaye, “Telemedicine: Extension to home care,” Telemedicine J., vol. 3, no. 3, pp. 243–246, 1997. [2] J. D. Bronzino and J. Gover, “Medical technology: A solution to the health care cost problem,” IEEE Eng. Med. Biol. Mag., pp. 313–315, July 1994. [3] C. Ruggiero, M. Giacomini, and R. Sacile, “A multimedial environment for elderly health care: A local experience at the Savona,”, IEEE 0-78032050-6/94, 1994. [4] G. Au, C. K. Kwok, and K. Higa, “The development of telework in the health care industries,” in Proc. 28th Annu. Hawaii Int. Conf. System Sciences, 1995, pp. 456–465. [5] M. J. Rodriguez, M. T. Arredondo, F. del Pozo , E. J. Gomez, A. Martinez, and A. Dopico, “A home tele-care management system,” Computers in Cardiology, pp. 433–436, 1994. [6] T. Y. Chiu, “Terminal care,” National Taiwan University Hospital, research proposal, 1996. 2Wireless solution for global communications Web site. [Online]. Available: http://www.ofdm.com 3[Online]. Available: http://www.adsl.com


44


[7] M. Y. Kim, “A multimedia information system for home health-care support,” IEEE Multimedia Mag., pp. 83–87, Winter 1995. [8] L. Tetzlaff, M. Y. Kim, and R. Schloss, “Home health care support system,” in CHI95, New York, 1995. [9] M. T. Arredondo, F. del Pozo , E. Gomez, T. Barranquero, M. Lallana, and M. J. Rodriguez, “A Telemedicine approach for hypertension care,” in Proc. Computers in Cardiology, 1991, pp. 595–598. [10] J. E. Cabral and Y. Kim, “Multimedia systems for telemedicine and their communications requirements,” IEEE Commun. Mag., pp. 20–27, July 1996. [11] H. Murakami, K. Shimizu, K. Yamamoto , T. Mikami, N. Hoshimaya, and K. Kondo, “Telemedicine using mobile satellite communication,” IEEE Trans. Biomed Eng., vol. 41, pp. 488–497, May 1994. [12] B. Bruegge and B. Bennington, “Applications of mobile computing and communication,” IEEE Personal Commun., pp. 64–71, Feb. 1996. [13] S. Akselsen, A. K. Eidsvik, and T. Folkow, “Telemedicine and ISDN,” IEEE Commun. Mag., pp. 46–51, Jan. 1993. [14] K. Chipman, P. Holzworth, J. Loop , N. Ransom, D. Spears, and B. Thompson, “Medical applications in a B-ISDN field trial,” IEEE Trans. Select. Areas Commun., vol. 10, pp. 1173–1186, Sept. 1992. [15] W. A. Bruwer, J. D. Loop, J. A. Symon, and B. G. Thompson, “VISTAnet and MICA: Medical applications leading to the NCH,” IEEE Networking, pp. 24–31, Nov./Dec. 1994. [16] E. R. Bartlett, Cable Television Technology & Operations—HDTV and NTSC System. New York: McGraw-Hill, 1990. [17] S. J. Dwyer, III, A. W. Templeton, W. H. Anderson , K. S. Hensley, M. A. McFadden, B. K. Stewart, J. S. Honeymoon, L. T. Cook, K. G. Baxter, R. Y. Wingard, and C. L. Hall, “Teleradiology using switched dialup networks,” IEEE J. Selected Areas Commun., vol. 10, pp. 1161–1172, Sept. 1992. [18] B. K. Stewart, S. L. Lou, W. K. Wong, and H. K. Huang, “An ultrafast network for communication of radiologic images,” AJR, vol. 156, pp. 835–839, Apr. 1991. [19] (1998) Products list. Telemed-Care Company. [Online]Available: http://www.telemed-care.com [20] G. R. Thoma, L. R. Long, and L. E. Berman, “A client/server system for internet access to biomedical text/image databanks,” Computerized Medical Imaging and Graphics, vol. 20, no. 4, pp. 259–268, 1996. [21] A. Hutchison, M. Kaiserswerth, M. Moser, and A. Schade, “Electronic data interchange for health care,” IEEE Commun. Mag., pp. 28–34, July 1996. [22] C. C. Lin, J. R. Duann, C. T. Liu, H. S. Chen, J. L. Su, and J. H. Chen, “A unified multimedia database system to support tele-medicine,” IEEE Trans. Inform. Technol. Biomed., vol. 2, pp. 183–192, Sept. 1998. [23] H. Bruneel and M. Moeneclaey, “On the throughput performance of some continuous ARQ strategies with repeated transmission,” IEEE Trans. Commun., vol. COM-34, Mar. 1986. [24] Q. Zhang and R. Ward, “Automatic monitoring of the quality of cable television pictures,”, IEEE 0-7803-0532-9/92, 1992. [25] R. P. C. Wolters, “Characteristics of upstream channel noise in CATVnetworks,” IEEE Trans. Broadcasting, vol. 42, pp. 328–332, Dec. 1996. [26] C. A. Eldering, N. Himayat, and F. M. Gardner, “CATV return path characterization for reliable communications,” IEEE Commun. Mag., pp. 62–69, Aug. 1995. [27] K. J. Kerpez, T. E. Chapuran, R. C. Menendez, and S. S. Wagner, “Digital transmission over in-home coaxial wiring,” IEEE Trans. Broadcasting, vol. 43, pp. 136–144, June 1997. [28] S. M. S. Jalaleddine, C. G. Hutchens, R. D. Strattan, and W. A. Coberly, “ECG data compression techniques—A unified approach,” IEEE Trans. Biomed. Eng., vol. 37, pp. 329–343, Apr. 1990. [29] I. E. G. Richardson, M. J. Riley, W. Haston, and I. Armstrong, “Telemedicine and teleconferencing: The SAVIOUR project,” Computing & Control Eng. J., pp. 21–26, Feb. 1996. [30] Y. L. C. de Jong, R. P. C. Wolters, and H. P. A. van den Boom, “A CDMA based bidirectional communication system for hybrid fiber-coax CATV networks,” IEEE Trans. Broadcasting, vol. 43, pp. 127–135, June 1997. [31] K. J. Kerpez, “A comparison of QAM and VSB for hybrid fiber/coax digital transmission,” IEEE Trans. Broadcasting, vol. 41, pp. 9–16, Mar. 1995.

Ren-Guey Lee was born in 1965. He received the M.S. degree from the Department of Electrical Engineering, National Chen Kung University, Taiwan, in 1989. He is currently working toward the Ph.D. degree at the Department of Electrical Engineering, National Taiwan University, Taipei. Since 1991, he has been with the Department of Electrical Engineering, Lunghwa Institute of Technology, where he is currently an Associate Professor. His research interests include medical informatics, worldwide web applications, home telecare, data mining, man–machine interface, and applications to CATV.

Heng-Shuen Chen received the M.D. degree from National Taiwan University, Taipei, in 1985. He is currently working toward the Ph.D. degree at the Department of Electrical Engineering at the same university. He received Residency and Fellowship training from 1987 to 1992 and became a Faculty Member in 1992 with the Family Medical Department, National Taiwan University Hospital. Currently he is also a Senior Lecturer and Director of the Medical Informatics Program in the Department of Medical Informatics, College of Medicine, National Taiwan University. His research interests include, but are not limited to: computer-assisted learning, telemedicine, distance education, preventive medicine, and computerized medical records.

Chung-Chih Lin received the B.S. and M.S. degrees in biomedical engineering from Chung Yuan University in 1992 and 1994, respectively, and the Ph.D. degree in electrical engineering from National Taiwan University, Taipei, in 1999. His research interests include medical informatics, worldwide web application, multimedia, database, artificial neural networks for biomedical applications, and data compression.

Kuang-Chiung Chang was born in Taiwan on July 23, 1956. He received the B.S. and M.S. degrees in electrical engineering from Tatung Institute of Technology, Taipei, Taiwan, in 1979 and 1987, respectively, and the Ph.D. degree in electrical engineering from National Taiwan University, Taipei, in 1993. Since 1987, he has been with the Department of Electrical Engineering, Lunghwa Institute of Technology, where he is currently an Associate Professor. His research interests include robust control theory, digital signal processing methods, power electronics, and applications in CATV.

Jyh-Horng Chen was born in 1960. He received the B.S. degree from the Department of Electrical Engineering, National Taiwan University (NTU), Taipei, in 1982, the M.S. degree in biomedical engineering from National Yang Ming Medical College, and the Ph.D. degree from the Universities of California at Berkeley/San Francisco Joint Bioengineering Program. He joined the faculty of the Department of Electrical Engineering, NTU, as an Associate Professor in 1991. His research interests include medical informatics, magnetic resonance imaging, and man–machine interface for disables. Dr. Chen is a member of SMRM and AAPM.
