A DVB-T BASED SYSTEM FOR THE DIFFUSION OF

TELE-HOME CARE PRACTICE

Gianmarco Angius, Danilo Pani, Luigi Raffo, Stefano Seruis

DIEE - Dept. of Electrical and Electronic Engineering, University of Cagliari, Piazza d’Armi, 09123 Cagliari, Italy

Paolo Randaccio

Dept. of Physics, University of Cagliari, Cittadella Universitaria, Monserrato, Italy

Keywords:

Telemedicine, tele-home care, remote monitoring, ECG, DVB-T, MHP.

Abstract:

Typical telemedicine systems are usually PC based and in some cases they use expensive custom devices to

satisfy the system requirements. For tele-home care uses by elderly or untrained people, these type of solutions

are impracticable. As an example of user-friendly tele-home care system, in this paper we present the ﬁrst tele-

home care application of DVB-T technology over standard home entertainment equipments and a prototypal

low cost microcontroller-based acquisition unit for 1-lead ECG. The usability and low cost of the system show

the potentiality of the approach.

1 INTRODUCTION

In order to reduce the costs for both the patients and

the public administration, tele-home care systems are

today often used for clinical practice. They permit

to avoid the overcrowding of ambulatories for simple

routine examinations and, in the case of chronic pa-

tients that must be frequently monitored, to avoid the

costs and the waste of time of an ambulatory examina-

tion for simple physiological measurements that they

could easily perform at home, sending the recorded

data to the care staff in the appropriate department.

Howewer, these telemedicine systems are usually PC

based or use complex hardware and software prod-

ucts. Even if such technologies are quite popular to-

day, they are frequently used only by relatively young

people, which are not the primary tele-home care tar-

get.

The Digital Video Broadcast Terrestrial (DVB-T)

technology, under experimentation in Europe, will be

the only terrestrial television system after 2012. By

the use of a cheap set-top box, it is now possible to

adapt the new transmission tecnology to the old TV

equipments. The set-top box is actually a simple com-

puter, normally embedding a RS-232 compliant port

connector, a smart card reader and a modem for the

return channel link. In principle, it is then possible to

deﬁne tele-home care systems based on such technol-

ogy where the user interface is represented by the TV

screen (output) and the remote control (input). This

paper presents an example of a such system based

on DVB-T technology with a cheap microcontroller-

based acquisition unit and a very user-friendly inter-

face well exploitable even by elderly people.

The remainder of this paper is organized as fol-

lows. In Section 2 a brief analysis about related works

is presented. In Section 3 the whole proposed system

is introduced; Section 4 deals with some details on

the prototypal 1-lead ECG Base Station, whereas the

application on the set-top box is presented in Section

5. Section 6 concludes this work.

2 OTHER TELE-HOME CARE

PROJECTS IN LITERATURE

The primary activity of telemedicine systems was

the transmission of diagnostic medical images using

television for medical consultation from physician to

physician in remote places. Recently, telemedicine

systems through the Internet via satellite have be-

come a reality by means of high throughput mixed

satellite-web communication channels. This Section

presents some home-oriented telemedicine projects

making use of DVB and Internet, without the claim

to be exhaustive.

The Interactive Satellite Multimedia Information

System (ISIS) project (Pierucci and DelRe, 2000), re-

alized a telemedicine system based on satellite com-

Angius G., Pani D., Raffo L., Seruis S. and Randaccio P. (2008).

A DVB-T BASED SYSTEM FOR THE DIFFUSION OF TELE-HOME CARE PRACTICE.

In Proceedings of the First International Conference on Health Informatics, pages 31-36

 SciTePress

munication for furnishing interactive services for res-

idential users together with the traditional TV distri-

bution, porting tipical applications developed for ter-

restrial network (Internet) to the satellite digital video

broadcasting technology (DVB-S). By a dualband ter-

minal, connected in uplink via Eutelsat satellite and

in downlink via the Italsat satellite, the ISIS system

provides a small and low-cost transceiver for sites

not connected to the Internet or connected only in

dial-up low-speed mode. Through his Java applica-

tion for the DVB-S transceiver, called Medical Envi-

ronment for Diagnostic Images (MEDI), the project

can manage a medical image database for remote ex-

pert consultation and so it demonstrated the feasibil-

ity of satellite-based interactive multimedia services

for telemedicine purposes.

In 2001, a multipurpose health care telemedicine

system with a base unit and a mobile unit was de-

veloped in Greece too (Kyriacou et al., 2001). At

patient’s home, the mobile unit allows the transmis-

sion of vital bio-signals and static images of the pa-

tient to the base unit at the physician site (ofﬁce or

hospital). The mobile unit device is compliant with

some of the commercial main vital signs monitor and

it is able to transmit ECGs, non-invasive blood pres-

sure (NIBP), body temperature, percentage of arterial

oxygen saturation (SpO

) and heart rate. Based on the

TCP/IP protocol, the communication between the two

parts ensures safe data transmission and the possibil-

ity to use different telecommunication means (GSM

or satellite links).

Launched in January 2001, the Universal Remote

Signal Acquisition For hEalth (U-R-Safe) tele-home

care project (Mailhes et al., 2003), created a mo-

bile telemedicine system for home monitoring to be

used by elderly peaple and disabled patients in Eu-

rope. Via short range Wireless Personal Area Net-

work (WPAN), wearable ECG and SpO

sensors are

connected to a portable electronic device, able to

send the recorded data to a remote central through

the TCP/IP protocol and the wireless public network

(GPRS, UMTS and GEO satellites). The portable unit

is also capable of sending an alarm when patient fells

sick, falls or pushes a button.

The Standard and Interoperable Satellite Solution

to Deploy Health Care Services Over Wide Area

(HEALTHWARE) project (Loghelongue, 2007), is

an integrated project of the Aeronautics and Space

thematic priority of the 6th Framework Program

(FP6) for satellite telecommunications systems and

telemedicine applications. Thanks to the digital

video broadcasting - return channel by satellite (DVB-

RCS) technology, that offers satellite reception and

transmission capabilities from anywhere, the project

aims at developing and validating DVB-RCS based

telemedicine solutions. It will focus on the areas

of chronic respiratory disease, cardiology and oncol-

ogy, through four main applications: medical train-

ing, tele-consultation, second opinions and monitor-

ing and remote assistance at home.

Even if these systems are very interesting, none

of them owns the characteristics presented in Section

1, primarily the possibility to be used by untrained

people to perform single exams rather then continu-

ous monitoring, with an immediate visual conﬁrma-

tion of the quality of the signal measurement. None

of them could be used by the patient to control his/her

health state through simple measurements even with-

out sending the exam to a remote care center.

3 THE PROPOSED DVB-T

TELE-HOME CARE SYSTEM

Digital Television (DTV) uses digital encoding tech-

niques to broadcast video, audio and data contents to

a receiver in the consumer’s home (set-top box). In

order to add multimedia information to the normal

television program, the Multimedia Home Platform

(MHP) allows the user to actively interact with the TV

(Interactive TV) obtaining useful services and infor-

mation. Based on the JavaTV platform, an extension

and standardization of existing Java APIs in the con-

text of DTV, MHP enables the interaction between the

interactive applications and the set-top box by a soft-

ware interface (middleware). Over a Virtual Machine,

JavaTV applications (called Xlets) run in the set-top

box with the support of a real-time Operating System

(OS), which provides all the functionalities required

including hardware resources access.

3.1 System Overview

The proposed system is depicted in Figure 1. The pa-

tient must own a TV, a DVB-T set-top box (with its

remote control) connected in uplink to the telephone

line, a personal smart card and a simple Base Sta-

tion unit for bio-signals acquisition. The Remote Care

Center (RCC) instead, has only a simple PC acting as

TCP/IP server,since the patient’s set-top box can send

through the Internet the result of the exams.

The Base Station is a simple microcontroller-

based acquisition unit to perform the digital biosig-

nals acquisition. It is connected to the set-top box

for data visualization and transmission, and it is con-

trolled by it and then indirectly by the user only

through the set-top box remote control, then simpli-

fying the overall procedure.

internet

Application broadcast

Remote Care Center

TV & set-top box

RS-232

IR-coupler

Base Station

personal smart card

mhp Homecare

patients home

set-top box

remote control

Figure 1: A schematic representation of the proposed DVB-

T system for tele-home care.

The smart card, which must be programmed by

the RCC, is used to identify the patient providing all

the information needed to carry out the proper ex-

ams sending them to that RCC. The adoption of the

smart-card for user authentication and to provide to

the Xlet the required information about internet con-

nection and RCC server IP address, avoids the patient

to keep in mind or annotated elsewhere such informa-

tion, improving the system usability. It also enables

the personalization of the Xlet for the single user,

since the exams that can be performed are only those

programmed in the smart-card by the care staff. Since

the largest part of DVB-T set-top boxes has a smart

card reader (normally used for the pay-per-view ser-

vices), no hardware on the base station is required to

add this functionality.

The DVB-T MHP set-top box is like a computer,

characterized by an input channel from user (the re-

mote control), an output channel for the user (TV

screen) and some ports to allow its interfacing with

other devices, namely a serial port (RS-232) and an

RJ-11 connector for the telephone line (since the set-

top box has an internal modem), beyond the tradi-

tional audio/video connectors. The application pre-

sented in this paper has been tested on a Telesystem

TS7.4DT set-top box, with the version 21p1 of the

producer’s software, and implementing the MHP 1.02

proﬁle with some enhancements, primarily the addi-

tion of java packages for both the smart card and the

serial RS-232 port management. The real-time OS is

Osmosys. To interact with the base station, the set-top

box uses the RS-232, whereas to send data to the RCC

the integrated modem is used. In the proposed system

the connection is in dial-up, so that it is surely simpler

to have this facility in every home compared to broad-

band connections. The Xlet application is loaded into

the set-top box by means of a broadcast transmission

provided by a broadcaster, so that successive releases

of it can be updated without the user’s intervention.

3.2 Patient’s User Interface

The graphic user interface (GUI) of the Xlet (hereafter

called MHPHomecare) is user-friendly and intuitive,

so that the patient can easily control the application by

means of the remote control. The user can explore the

application moving through the different full-screen

frames (hereafter called FSFs), choosing among the

possible options and functions by means of the remote

control keys, as if it would be a PC keyboard. Three

of the full-screen frames are generic whilst there is

another FSF for each exam. The three generic FSFs

are:

• the primary FSF, the ﬁrst FSF shown when the

application is started. It waits for the smart card

insertion in the set-top box for user authentication

and then it shows the patient’s name (storing the

other authentication data only for the transmission

purposes), waiting for patient’s commands. It is

possible to close the application only from the pri-

mary FSF.

• the about FSF, that shows the application credits

and can be launched only from the primary one;

• the reduced FSF, that corresponds to the window

minimization to allow the patient to watch a TV

program while the application is running in back-

ground. It can be launched from every FSF.

Figure 2: The ECG exam screen of the MHPHomecare ap-

plication (ECG Exam FSF). The image has been acquired

by means of a frame grabber from the set-top box video

output, resulting in a poor quality and in altered colors.

In this application we used a simple 1-lead ECG to

test the whole system, so there is only another FSF (a

screenshot of this FSF is shown in Fig. 2), ECG exam.

It enables the ECG acquisition and shows in real-time

the samples acquired from the Base Station and all the

other information sent by it about the current exam,

such as the hearth rate (in bpm) and a warning mes-

sage in case of poor quality signal. Once the exam has

been saved, from the same FSF it is possible to send

it to the server of the RCC, to review it on the TV

(with zoom and scroll functions), to save a new exam

or to return to the primary FSF. The patient can inter-

act with the application moving through the different

FSFs as depicted in Fig. 3.

primary FSF

Smart card

not recognized

or not inserted

valid smart card insertion

User authenticated.

Waiting exam

selection

Waiting

acquisition start

or back command

ECG exam FSF

Start application

Real time plot of the

ECG signal. Signal

memorization

Sending data to the

remote care center.

Signal review, scroll

and zoom

Exit application

valid smart card extraction ECG exam selection

start acquistion

back

redo

send exam

Figure 3: The interaction scheme between the patient and

the set-top box application.

4 A PROTOTYPAL 1-LEAD ECG

BASE STATION

In order to test our system we realized a simple

microcontroller-based Base Station to acquire the pa-

tient’s bio-signals. The Base Station is a black-box

for the patient, and he cannot interact with it beyond

the on/off power supply switch. The Base Station is

battery powered, for simpler use and improved patient

safety, and can include a different number of sensors

and acquisition circuitry to serve different remote ex-

amination needs.

In the prototypal version presented in this work, it

implements a single channel electrocardiogram (lead

I) and consists in a classical ECG ampliﬁer coupled

with a very simple and low cost Digital Signal Con-

troller (DSC), i.e. the Microchip

dsPIC30F4013.

This is a 16-bit 30MIPS DSC enhanced with DSP

hardware, such as a 17-bit x 17-bit multiplier, a 40-bit

ALU, two 40-bit saturating accumulators and a 40-

bit bidirectional barrel shifter. It also provides several

embedded peripherals such as a 12-bit successive ap-

proximation analog to digital converter, and an US-

ART, both of them employed in this prototype. The

Base Station scheme is depicted in Fig. 4

Figure 4: A schematic representation of the prototipal 1-

lead ECG base station.

The fundamental characteristics of the Base Sta-

tion (frequency bandwidth, sampling frequency and

the number of bits of the A/D converter) are chosen

according to the recommendations of American Heart

Association for standardization and speciﬁcations in

automated electrocardiography (Bailey et al., 1990).

The ECG ampliﬁer is a low-pass system with a vari-

able gain up to 2000 and a cutoff frequency of 100

Hz. It consists of an optically isolated instrumentation

ampliﬁer with high CMRR connected to the wrists of

the patient and a simple inverting operational ampli-

ﬁer connected to the right ankle for electromagnetic

coupling noise rejection purpose, so that only 3 dis-

posable (or reusable) electrodes are needed. The DSC

is programmed to sample the ECG signal at 250 Hz,

and it is interfaced through its internal USART to the

DVB-T set-top box.

According to the international recommendations

about the patient’s safety, the physical connection be-

tween the Base Station and the set-top box is repre-

sented by an infrared (IR) link. The Base Station em-

beds a module for the IR transmission of the serial

stream, whereas the set-top box exploits an external

IR coupler connected to the RS-232 serial port.

In order to reduce both the residual 50/60 Hz en-

vironmental electrical noise we have implemented a

digital notch ﬁlter, whereas a high-pass digital FIR

ﬁlter (cutoff frequency 0.05 Hz) was added for the

baseline drift elimination. All these computations are

performed in real-time on the Base Station, since the

set-top box is quite slow in processing due to the Java

VM and to the applications running on it. On the Base

Station has been also implemented a simple QRS de-

tector for heart rate calculation and visualization on

the TV screen (Friesen et al., 1990). The RR interval

measurement is performed sample by sample, and if

it is too far from the standards a warning code is sent

to the set-top box to ask the user to control the correct

connection of the electrodes. The average heart rate is

sent when the acquisition stops and is referred to the

average RR during the acquisition window.

5 THE INTERACTIVE

APPLICATION: THE

MHPHOMECARE XLET

MHPHomecare is a standalone application composed

of several threads. It enables the non-simultaneous

acquisition from the Base Station of an ECG exam,

its visualization on the TV screen, and its sending via

modem to the RCC where a server receives and stores

the exam.

5.1 Graphic User Interface Thread

Taking into account the differences between PC and

TV graphical applications, beyond the Java Abstract

Window Toolkit (AWT), also the HAVi (Home Au-

dio/Video Interoperability) API for graphic interfaces

have been used (Java, 2007). We used Tiresias as de-

fault font, which has been created speciﬁcally for the

TV screen, providing high readability and basing on

the Western European ISO- 8859-1 fonts set.

A speciﬁc thread is in charge to create the objects

related to the graphic elements composing the differ-

ent FSFs of the application, and it shows/hides them

depending on the current FSF.

5.2 Smart Card Management for User

Identiﬁcation

The smart card is read by means of the SATSA (Se-

curity and Trust Services API) classes (Satsa, 2007),

that represent the new standard for smart card access

in Java. To access the smart card, we used the meth-

ods based on the APDU (ISO7816-4) protocol, but

the byte constituting the APDU strings are relative to

the ACOS2 microprocessor card by Advanced Card

Systems Ltd. To read the information stored into the

memory of the card it is necessary to provide the CXS

code to the method that opens the APDU connection,

since the smart card is not a JavaCard (Dvt, 2006). A

User Data File on the smart card stores the patient’s

name and its Personal Identiﬁcation Code, the treat-

ing physician’s name and its Identiﬁcation Number,

a permission exam code, some information about the

ISP (user ID, password, telephone number) and the

server IP address.

A thread, that is active in the primary FSF, ver-

iﬁes the correct insertion of the smart card into the

reader, hence reading the User Data File. If the card

is not properly inserted and recognized, the Xlet re-

mains blocked on the primary FSF. Once the card has

been recognized, the permission exam code is used to

allow the user to perform only some speciﬁc exams

among those available, hence disabling all the other

ones.

5.3 Serial Port Management for Exam

Acquisition

The serial port control is possible by means of the

it.dtt.comm

package, available on the set-top box

used in this application. The communication fol-

lows analogue principles we can ﬁnd in

javax.comm

and the serial port behaves according with the RS-

232 standard. A thread manages the communication

through it.

The set-top box sends to the Base Station the com-

mands to start the acquisition and to stop it. Both

such commands are simply 1-byte words. The “start”

command word is logically divided in two parts, i.e.

the actual command to enable the serial port trans-

mission, and a code that identiﬁes the exam the user

chose by means of the Xlet application. The set-top

box receives from the serial port the samples of the

current exam in frames composed of N samples each,

where N changes from exam to exam as a function of

the sample rate. The application deals with 8 or 16-

bit signals (the data are stored in arrays of short). In

the current implementation only the ECG is available

on the Base Station, and it is acquired at 250 sam-

ple/sec, 16 bit/sample. With such sample rate and data

width, the maximum re-painting rate of the graphic

area where the signal is plotted is 200ms, which in

turn means that a frame of input samples must consist

of minimum N = 50 samples.

After the exam stops with a “stop” command

word, the Base Station sends to the set-top box a last

word with the value of the heart rate expressed in

bpm so that the Xlet updates with this information the

proper FSF.

5.4 Modem Management for Exam

Transmission

A speciﬁc thread is in charge to manage the modem,

and it operates by means of the

org.dvb.net.rc

package (Java, 2007), jointly with the

java.net

and

java.io

packages. The operations performed by

means of these packages are: ISP number dialing, ISP

authentication and TCP/IP data transfer towards the

server by means of a socket opening.

The user can start the transmission to the RCC

from the exam FSF simply pressing a key on its re-

mote control. In response to this action, the thread

establishes the connection with the ISP using the in-

formation previously read from the smart card. Once

the connection with the ISP has been established, the

thread opens a client socket specifying the IP address

of the server of the RCC. This IP address is read from

the smart card too, since different users need to send

their exams to different RCCs. At this point, the

thread sends a stream composed of two main parts:

the patient’s data and the exam data (collected during

the acquisition phase). Once the whole data stream

has been sent, the connection is closed and another

exam can be acquired.

6 CONCLUSIONS

In this paper, a DVB-T framework for tele-home care

was presented along with its prototype implementa-

tion.

Thanks to the DVB-T set-top box, which is very

similar to a computer with the possibility to be pro-

grammed, the system can interact with external cus-

tom peripherals and can be connected to the web.

Easy to use by people not skilled in digital electron-

ics, and since tele-home care is mainly used to mon-

itor elderly people which eventually falls in the pre-

vious category, pushed by the imminent deadline de

ﬁned by the UE for the switch-off of the old ana-

log broadcasting transmission system, such tele-home

care framework could represent the best solution in

terms of quality and costs. Compared to traditional

systems, the presence of a visual environment on the

TV screen allows a more friendly use providing also

more detailed information and feedbacks about the

signal quality, and guiding the user through all the

exam procedure without any required printed manual.

Experimental results show the high potentiality of

the proposed solution and deserve further improve-

ments such as the development of a more powerful

base station (or a set of different base station models),

the realization of a digital broadcasting system, and

the extension to the ofﬁcial sanitary card, currently

under trial in some Italian regions and in other Eu-

ropean countries. It is actually under test a complete

Visual application to read and analyze the exams on

the Remote Care Center.

ACKNOWLEDGEMENTS

This work is part of the Personal e-Care project,

which has been partially founded by INFN, the Nu-

clear Physics Italian Institute.

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