MeMeA 2009 - International Workshop on Medical Measurements and Applications
Cetraro, Italy
May 29-30, 2009
Alternative Emergency Communication Channel
through Television Cable
C. Chandramouli* and Vivek Agarwal
Applied Power Electronics Laboratory, Department of Electrical Engineering,
Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India.
Abstract— This paper studies the feasibility of deploying an
alternative communication channel using domestic TeleVision
(TV) set with minor modification in hardware and software. The
remote control, video and audio circuits are modified while a new
component - Communication Transceiver (CT), is introduced
between the cable entry point and the TV set. With the proposed
system, the user can plug in a normal telephone to the CT to
make and receive calls. In addition to this, textual messaging is
also possible with the help of the remote control unit and the TV.
Due to the wide spread use of television sets in homes, this
alternative communication can be particularly effective during
medical or other emergencies for information transfer, broadcast
of announcements etc. It may also be useful for other applications
such as an ‘intercom’ is societies living in clusters. Similarly,
options for telemedicine are explored. All the details of this work
are presented.
(and the cable systems) to convert them into communication
equipment for transferring voice and textual data over TV
cable during emergency or normal conditions. A major
application of this alternative channel could be in
“Telemedicine”- for example a patient’s condition (e.g. ECG)
can be monitored remotely. Agarwal [4] and Lin [5] discuss
about the development of digital spirometer. Syzmanski [6]
and Lovell [7] discuss the web based device control and
biomedical data storage. Many researchers have worked on
converging the television and mobile networks for having an
interactive entertainment [8, 9]. The telephone can be used for
the voice data and the TV is used for textual and graphical
data (e.g. ECG) transfer. The communication can be
transmission of voice data and/or textual characters like the
Short Messaging Services (SMS) in mobile phones. The idea
is to develop an alternative communication channel with the
following objectives:
(i) A channel which can work when the telephone lines are
down, especially during emergency conditions.
(ii) Broadcast information during medical emergency or any
other dangerous situation.
(iii) Divert the local voice data traffic from the telephone lines
at a cheaper cost.
(iv) Transfer of medical data for remote monitoring and/or
treatment.
In the proposed system, the Communication Transceiver
(CT) converts the voice data from the telephone to a suitable
format for transmission through TV cable. The CT can
intelligently differentiate between the (i) Audio/Video data of
the TV program, (ii) Voice messages and (iii) Textual
messages. Suitable hierarchy is defined for utilizing the
channel effectively. A textual transceiver enmeshes with the
video circuits of the TV for displaying the messages. The
characters mask the video data on the TV screen for display.
Fig. 1 shows a typical TV cable network with proposed
modifications to convert it into a bi-directional communication
channel.
Keywords – Television networks, alternative mass communication
channel, Medical, Emergency reporting service, Telemedicine.
I.
INTRODUCTION
A TeleVision (TV) set in today’s world provides a means
of entertainment and information exchange. It also acts as a
public address system between the government and/or private
bodies and the people. Till the end of 1990s or so, it basically
remained a simplex broadband – a one way communication.
With the advancement of Mobile Networks’(MN) and internet
technology, however, the situation started to change. A need
was felt to merge the MN, the internet and the TV. This idea
got a further boost due to the advent of High Definition
TeleVision (HDTV) and associated TV technology with
provision for customizing.
Extensive research has been carried out for merging the
MN, the internet and the TV [1]. Kavassalis et al.,[2] have
described the impact of interactive television through Short
Messaging Service (SMS). Zahariadis et al., [3] have described
the internet as a mass media communication and proposed the
television network as a bidirectional communication channel.
This concept prompted the establishment of duplex
communication between the viewers and service providers
through television sets, cables and set-top boxes. It added value
to the service as the viewers could now give their feedback or
choice to the service provider (uplink), which enabled the
broadcast schedules of specific programs to be changed
dynamically.
Inventing alternative communication channels has always
remained on the minds of the researchers. Power Line Carrier
Communication (PLCC) is another example where power
cables have been used for voice data communication. Taking a
cue from the PLCC like communication channels and the
increasing uplink bandwidth from viewers to service providers,
in this paper a modification is proposed in the existing TV sets
N e w c o m p o n e n t - T r a n s m itte r f o r
u p w a r d lin k to th e o p e r a to r
B o o s te r /
D is tr ib u to r /
A m p lif ie r n o d e s
Set T op box
*Corresponding author. email: cmouli@iitb.ac.in
Fig. 1 Networked Television sets with the bi-directional data transmission
block.
Phone: 91-22-25767422
978-1-4244-3599-9/09/$25.00 ©2009 IEEE
257
Apart from dealing with medical or other emergency
situations, such a system also has other applications, some of
which are:
(i) In an urban environment, the proposed system can form an
effective local communication link due to societies living in
populated clusters.
(ii) It can be used for ‘intra-communication’ between the wards
in hospitals in case the telephone lines are down or busy.
(iii) It can be used as a public announcement system especially
at places like railway stations and airports.
The email ids or other kind of transmitter address details
may be maintained by an authority so that spamming and
related abusive usage can be avoided. Additional services to
support this Voice Over Television Cable (VOTC) and
Message Over Television Cable (MOTC) can be explored.
II.
raster scan. A black rectangular background is added for every
‘keyed-in’ character for creating a contrast for better
readability. The keyed character immediately appears on the
TV screen. Fig. 3 shows the communication link between the
keyboard and TV.
Due to the advancement in LCD and Thin Film
Transistor Technology (TFT), the recent digital television sets
or Non-Cathode Ray Tube displays have a video buffer area.
This buffer is a static RAM with each byte(s) of data mapped
on to a particular pixel on the display. The contents of the
SRAM are refreshed, based on the frame rate requirement
whether it is NTSC or PAL.
New component – The textual characters go
along with the Identity codes
PROPOSED HARDWARE MODIFICATION
Set Top box
As the system is built over a TV, the hardware involved is a
customization of existing discrete blocks of circuits. The
hardware system is spread in three parts (i) Alpha-numeric
Infra-Red (IR) remote unit, (ii) Transmitter for upward link in
the booster/distributor, and a (iii) Communication Transceiver
(CT).
Data flow
To local operator
A. Alpha-numeric infra-red keyboard
It is a normal IR TV remote with additional
alphanumeric keys and an ergonomic case for better grip and
ease of operation. Each character key on the remote control
sends a unique set of bits through infra red waves. Fig. 2
depicts the modified alpha numeric remote control unit with
special functions. To minimize the power consumption, the
TV screen is used as the display unit. Pressing the message
button pops up a black window on the TV screen. The typed
characters immediately appear on the TV screen. The
character keys represent a typical PC keyboard. Pressing the
send button pops a window in which address of the sender is
typed. The address must have been registered with the service
provider. At the receiving end, a pop up window will open for
the receiver to read the message. However, more options can
be provided or considered for future work. For instance the
address storage, message storage and communication when
the TV is switched off and alert when a message is received.
IR Link
To Satellite
Remote control with alpha
numeric keypad and display
Fig. 3 Communication between remote control and the television set.
C. Textual Transceiver(TT)
This block exists between the cable entry point and
the television set. It literally hooks on the signal cable after
amplification to detect the uplink and downlink textual
messages. The data is framed in such a way that every
transmission forms a separate frame. The subsequent frame
data is masked at the ‘character content area’ of the display.
Fig. 4 depicts the position of the textual transceiver block
inside the television set.
A unique Start of Frame (SOF) and End of Frame
(EOF) data and the address of the sender is introduced in the
character data frame. This block holds the address of the
television set and stores the textual content.
IR Transmitter
Optional Display
View
message
Communication
Transceiver
Send Message
Alphanumeric
Keys
Picture Tube
Function Keys
Fig. 2 Remote control with alpha numeric keys.
New component
B. IR Receiver and Decoder
The IR receiver is mounted on the front panel of the
TV such that a ‘line-of-sight’ exists with the hand-held remote
control unit. Each character’s code is recognized using a lookup table, stored in a memory device. In an analog TV set, the
decoder converts the character(s) received in the form of a
Text (Encoder & Decoder )+
Address (Decoder) + Mixer
Data path for Visual representation
Fig. 4 Textual transceiver between the cable entry point and the television
circuit.
258
displayed in a pop up window which partially masks a portion
of the video data in the back ground.
It can be made to work without the TV turning ON. For
sending or reading the message, the user has to turn ON the
PC. For every transaction of communication, one frame of
video data is replaced by the TT. The data is framed in such a
way that every transmission forms a separate frame. The
subsequent frames of data are masked at the ‘character content
area’ of the display.
It performs the following functions.
(i) Sending textual messages – compiling the textual message
includes the process of receiving characters from alphanumeric keypad, forming a frame of data, superimpose the
message frame over the video data and send it to the TV video
port. The IR signals sent by the alphanumeric keypad are
processed by the CT, the characters that are decoded are
converted and superimposed on the current frame of video
data.
The message will be displayed till the remote keypad
sends a command to shut off. Contrast back ground is added
for every character for better readability. Fig. 5 shows the
textual data frame which will be inserted between the video
data. A temporary buffer is provided to store the text. An
intermittent power shut down or interruption upon received
messages will not lead to loss of the composed message.
D. Communication Transceiver(CT)
The communication transceiver (CT) is connected between the
TV antenna port and the cable input as shown in Fig. 7. It
literally hooks on to the signal cable after amplification to
detect the uplink and downlink textual messages. The prime
component of the prototype is the development of CT. The CT
schedules the message prompts like message composing,
reading received messages and other user interaction related
messages.
Message on the screen
To Telephone line
1
2
Switch
Please send ambulance to
12/13,…. Street,.. Opp to
XYZ school
Communication
Transceiver
Television set
To Cable network
Fig. 7 Communication Transceiver connected between the TV cable and the
telephone.
(i) Bidirectional transfer of voice data.
The CT handles the voice data transfer through the
television cable. The voice data will be through a conventional
telephone set. The incoming and outgoing voice data is
modulated appropriately not to interfere with the visual data
being delivered to the television set. Tests have been
performed to analyze the existing audio-video signals and
telephone voice data. While both are differential voltage
signals, suitable interface to mix these varied signals is
required. The telephone line input from the exchange is not
going to interfere with the TV signal. The objective is focused
on reducing the component /module count and/or using the
existing appliances to establish the alternative communication
channel. Fig .7 shows the setup of measuring the waveform at
specific points in the video amplification circuit. Fig.8 shows
the horizontal sync pulses.
F ra m e n + 3
F ra m e n
F ra m e n + 1
P le a s e s e n d
a m b u la n c e to … ..
F ra m e n + 2
Fig. 5 Text data frame inserted between the video data frame.
(ii) Receiving textual messages
Any textual message received (either broadcast or
peer to peer) will prompt the user with a message on the
screen. The user can choose to or not to display/read the
textual messages. Once accepted the received messages are
converted to a frame of data. The received message sent
through the proposed system typically looks like the one
shown in Fig. 6.
S cope show ing the scan
line syncro nisation p ulse
Please send ambulance to 12/13,….
Street,.. Opp to XYZ school
Fig. 6 Textual messaging appears on the TV screen on the foreground while
the video data is playing in the background.
TV
This will be superimposed on the current video data and
displayed on the TV screen. The message will be displayed till
a command is sent to shut off. The received textual data is
Fig. 7 Scan line being measured using a scope and hooking on the amplifier
input.
259
This application may be particularly useful inside hospital
wards of the monitoring the patient condition.
(ii) Spirometer
A brief description and the development of low cost
spirometer is included in this section. Spirometer is used for
medical diagnosis that is designed to identify and quantify
defects and abnormalities of various lung conditions in human
respiratory system. They help in monitoring the response of
lungs to medical treatment. It can be used to detect Chronic
Obstructive Pulmonary Disease (COPD) and asthma.
Monitoring cough and wheezing may not provide an accurate
assessment of the severity of asthma in a patient. With the
results of the breathing tests conducted using a spirometer, the
response and improvement in an asthma patient’s condition
during the treatment can be monitored accurately. Spirometer
measures the flow and volume of gas (air) moving into and out
of the lungs during a breathing maneuver.
The measured flow and volume values are plotted as
graphs called the spirograms. These spirograms comprise of
flow-time, volume-time, and flow-volume graphs. The
spirograms obtained for a healthy person and an unhealthy
person can be compared to determine how much the patient is
suffering. The spirometric data can be obtained by measuring
either the flow rate or the volume of the gas moving into and
out of the lungs. It is possible to determine either the volume
or the flow rate of the gas, by knowing one of them as they are
interrelated. The spirometers are based on the measurement of
either the flow rate or the volume of gas.
Every biomedical system comprises of two parts.
(a)The patient terminal, (b) Physician/medical specialist
Terminal. They are explained with respect to portable
spirometer.
(a) Patient Terminal
The patient terminal comprises of the spirometer
interfaced with the communication receiver. Any other
biomedical device developed for telemonitoring purpose
should adopt the same protocol for data compatibility with the
CT. Fig. 10 shows the spirometer with the communication
transceiver.
The unit comprises of a
(i) Blow tube: through which the patient inhales and
exhales,
(ii) A pressure sensor: this is used for measuring the rate
of air flow and the air volume,
(iii) A microcontroller: The microcontroller senses the
pressure and computes the air volume and pressure during
the breathing process.
Fig 8. Horizontal scan line syncronisation pulses
III.
TELEMDEICINE – AN APPLICATION
The communication transceiver can be coupled with
a biomedical system to enable tele-monitoring of a patient.
The emergency communication channel is intended to alert the
patient’s neighborhood about his/her critical condition. Hence
the primary objective of the biomedical system is to detect the
abnormality and automatically send the alarm as a text
message to a specific receiver or as a broadcast to a group of
receivers. The other objective is to transfer diagnosis data over
the television cable. This section describes two of the
biomedical applications.
(i) ECG measurement system
Some of the vital parameters representing the
stability of the human body are of low frequency (e.g. ECG
signals lie in 0.01 - 2 kHz range). These can be transmitted as
uplink data. Thus, the proposed system can be used for
remotely monitoring the ECG of a patient. The ECG signal is
sampled and packed as a frame of data. The receiver terminal
blocks the video feed from the cable network and allows only
the ECG signal to be seen on the TV. Fig. 9 shows the
functional blocks which will be required to transfer data over
the TV cable network. The textual data, medical data and
other applications will have an identity code for the receiver
TV set to recognize it. This application may be particularly
useful inside hospital wards for monitoring the patient’s
condition.
T o T elep h o n e lin e
1
2
T o T e lep h o n e lin e
S w itch
T o C ab le n etw o rk
TV
C o m m u n icatio n
T ran sceiv er
1
2
S w itch
T elev isio n set
T o C a b le n e tw o rk
TV
C o m m u n ica tio n
T ran s ce iv e r
E C G E q u ip m en t
w ith d ata lo g g in g
T e le v is io n s e t
E lectro d es
w ith lead s
S eria l L in k
B lo w T u b e
F lo w
of
a ir
(w h ile in h a la tio n
a n d ex h ala tio n )
Fig. 10 Spirometer unit interfaced with the communication transceiver and the
cable network.
S p iro m e te r
Fig. 9 ECG unit interfaced with the communication transceiver and the cable
network.
260
IV. CONCLUSIONS
The data is serially transmitted to the communication
transceiver using the RS-232 port. Fig 11 shows the
spirometer section of the telemetry system. The push buttons
and LCD are used for input and output operations. The display
shows the instructions provided by a remote physician to the
patient.
Power supply
A feasibility study on implementing the system has been
conducted. It is observed that the TV cable can be used as an
alternative channel during an emergency medical condition or
otherwise. Biomedical systems for heart and lungs have been
investigated. In the development of spirometer, the results
(spirogram) are found to be consistent and satisfactory. An
abnormality detection circuit in spirometer is tested and
satisfactory results are observed. These results will be
transmitted through the CT. The work is being carried out to
explore the potential of the system with an optimized design
and more features.
Serial data line for the
communication transceiver
Microcontroller
REFERENCES
[1]
[2]
[3]
Keypad
Blow Tube
[4]
Fig. 11 Spirometer prototype
(b) Physician Terminal
A medical specialist’s terminal is like any other
patient terminal. The communication receiver communicates
directly with the PC through its USB port. The communication
transceiver packs the received data and sends the data serially.
Fig 12 shows the medical specialists terminal. The waveform
displayed in the PC monitor is the spirogram.
[5]
[6]
[7]
T o Telep hone line
[8]
1
[9]
2
Sw itch
TV
To C able n etw ork
C o m m unication
T ransceiver
Television set
Serial L ink
1
51
0
5llit
1 0. 0. 0. 1. 1. 1.
0s
er
-- 25 50 75 00 25 50
s
51
0
PC
Fig. 12 Medical specialist terminal (CT with PC)
261
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