12
-LEAD
ECG
MODULATOR
AND
DEMODULATOR
EQUIPMENT
FOR
TELEPHONY
TRANSMISSION
SL.
To a
l,
B.
La a
Az
n
al;
JM.
Que o
and
L.G.
F anquelo
Depa men
o Elec onic
Eng
inee ing,
Un
i
e si y
o
Se
ille
A da.
Camino
de
los
Descub
imien os, 41092, Se ille, Spain
E-ma
il: [email p o ec ed] T no: +34 954487371 Fax: +34 954487373
ABSTRA
CT
This
pape
desc ibes a
eleassis en
cy
sys em
ha
consis s
o a modula o
equipmen
o
he
acquisi ion.
s o age
and
FM ansmission o he ypic
al
12 lead ECG
signals
and
a demodulalO
equipmen
o
eco e ing
he
o iginal sig-
nals
in a medical
ceme
. Swi ched
elephone
ne wo k
and
GSM ne wo k can be used o
ansmi
he
audio e-
quency modula ed signal
ca ying
E
CG
In o ma ion.
This
p ojec h
as
been de eloped in collabo a ion
wi h
Teleasis-
cencia Ca dio es . S.L.
1.
INTRODUC
T
IO
N
Consume s
a e
dema
nding mo e access o
heal h
in o -
I
na ion
and
mo e con enien
hea
l
h
ca e
se ice.
Pa ic-
ula ly, people li ing in u al
o
emo e
a eas
la
ck
he
ac-
cess on u gen
and
special medical
ca e
.
In
hese
cases,
heal h
insu a
nce companies
mus
p o ide a medical as-
sis ance
wi hin
a minimum
dis ance
. Besides,
consume
sa is ac
ion in all
e
lemedicine
p og am
e alua ions
has
been e y high, Gi en
he
choice be ween con enience o
elemedicine
and
a eling o
see
he
consul an
in pe
-
son. hey o e whelmingly choose elemedicine.
I n
his
pape . we p opose a
modula o
and
demodula
-
o
equipmen
o ECG
ansmissIon
.
The
link
be ween
he
pa ien
and
he specialis
is
es ablished
using a e-
quency modula ed audiO
signal
ansmi ed
by
he
ele-
phone
ne wo k. Figu e I shows
he
basic now o in o ma-
ion.
The
emo e
po
i
n
(a
pa ien ,
a non specialis doc o )
ca
n connec wi h a medical
cen e
o
ansmi
he
p
e
i-
ously
s o ed
ECG signal
using
he
ECG modulalO .
The
ECG
demodula o
o
he
hos
cen e
can
eco e
he
o ig-
inal ECG signal
and
hen
a specialis can diagnose
any
hea
dis unc ion.
".
-a -
10
---::---:-10
...
-
REMOTE
POINT
MEDICAL
CENTER
Figu e
I:
Block
diag am
o ECG
sys em
The
12
-lead ECG
equipmen
is
ac ually
an
expansion
module o
he
basic equ
ipmen
desc ibed
in
{II. In nex
722
wo seClions. we explain
he
ha dwa e
and
so wa e
o
he
ECC modula o
and
demodula o . Sec ion III
shows
he
inal p olO ype
and
some
esu
l s,
and
inally conclusions
will be poin ed ou in sec ion
IV
2. 12·L
EA
D
MOD
U
LATOR
The
12
lead
modula o
eqUipmen
mus
op imize se e al
es i
c ions:
a ea
. powe consump ion
and
simul a
neous
acquisi ion.
I
mus
be
aken
in o a
cco
um
ha
ECG
signals
mus
be
sensed
and
ampli ied by a ac o o 1000. Elec oca dio-
g aphic
signals
ma
y
be
co up ed
by a ious kind o noise
(21
. Typical examples
a e
:
• Powe line In e e ence.
I
is
he
main
sou ce o
noise, because o
he
cables
a ached
o
he
10
elec-
odes.
• Elec ode co
n a
c noise.
I
is a
ansien
in e e
ence
cause
by he loss o con ac
be ween
he
elec ode
and
he
skin.
• Mo ion a i ac s.
I
consis s o
ansien
baseline
c
hanges
caused by
chang
es
in
he
elec ode-skin
impedance because o
mo emen s
o
h
e
pa ien
.
•
O he
noise sou ces.
The e
a e
se e al
o he
noise
sou ces
due
o muscle co
n a
c ion.
espi a ion
o a-
dio equency
in e e en
ces.
To
eco d
an
ECG
an
elec ic ci cui be ween
he
hea
and
he
elec oca diog aph
mus
be comple ed. Fo his
pu pose, elec odes
a e
placed on di e en
pa s
o
he
body su ace. Ten elec odes
a e
connec ed o
he
mod-
u
la o
equipmen
by
means
o cables: nine
o
hem
a e
Mexplo ing-
elec
odes while
he
las
one is
he
e e ence
placed
on
he
igh
leg.
Depending
on
he
posi ion o
elec odes
and
he
measu ed
ec o s, we
can
di
s inguish
h ee
g oups o ECG
signals
131.
• Bipola
s anda d
leads. Elec odes placed on
he
igh
a m
(RA), le
a m
(LA)
and
l
e
leg
(LL)
a e
used o
pi
ck up
he
po en ial
a ia ions
on
hese
ex-
emiCies. Bipola leads
named
dl. dIl
and
dIl
l
a e
ob ained by eco ding espec i ely he po en ial di -
e ences be ween
LA
and
RA.
LL
and
RA,
and
LL
and
LA.
• Unipola
ex emi y
leads. Unipola
ex emi y
leads
a e
ob ained
by eco ding
he
di e ences be ween
RA.
LA
a
nd
LL a
nd
a poin n
amed
Wilson's cen
al
e minal.
This poin is g
i
en by
he
s
um
o he po-
en ials om
RA.
LA
and
LL.
These leads a e known
as
aVR. a
VL
and
aVF.
• Unipo
la
p e
co dial leads.
The
unip
ola
p
eco dial
ECG is ob ained by placing
he
explo ing el
ec
ode
on
hl::
classical six loca ions o
he
an
e i
o
and
le
po ions o
he
ches . U
nipola
p eco dial l
eads
a e
ob ained
a~
h
e di e ence be ween
h
ese six posi-
ions and
h
e Wllson's cen al
e minal.
They
a e
p e ixed
by
he
le e
~V~
o
ll
owed by
numbe s
1
h
ough
6.
which indica e he co espo
ndin
g
ches
si es
.
The
acquisi ion
s age
is pel o med by a low powe in-
s
um
e
n a ion
ampli ie w
i h
a
p og ammab
le gain ac-
O
.
ECG in e e ences
a e
e
a ed
in
h
e ollowing way:
,Jowe line
in
e
e en
ces
a e
a enua ed
ha
nk
s o com-
mon mode ejec ion a io (CMRR) o
he
ampli ie ; be-
sides. a 50 Hz no ch
il
e
is di
gi a
ll
y
jmplemen ed
in
he
mi
c op ocesso c
hip
.
Inpu
signals
a e
high
pass
il
e ed
o elimin
a e
ba
se
line c
han
ges. Finally, elec odes
co
n
sis s
o pa ch
es
wi h a conduc o gel
ha
gua an ees
a good
c
on a
c wj h
he
body su ace.
I
is a
eq
ui
em
en
o
h
e
p
ojec
ha
h
e
12
l
eads
mus
be
acqui ed
simul aneousl
y
in en seconds.
Tha
m
ea
ns
ha
he
inpu
signals
mu
s
be mul iplexed o
he
8-bi
analog
o digi al con e e o
he
mic
o-co
m
olle .
Fi
gu e
2 shows a
bl
oc
k
diag
am
o
h
e
modula o
equip-
men . Using
he
ypical
10
elec
odes,
he
1
2-
l
ead
ECG
signals
a e
acqui ed
in
pa allel
and
hem
mul iplexed o
h
e analog o digi al con e sion.
Sa
mpling
equency is
100
Hz
.
The
mic o-con olle (MC6
8L
II
om Mo o ola
141)
s o es
h
e ECG signals
usin
g
h
e
analog
o dig
i
al
co
n-
e e
(10
seconds
o
each lead)
In
he
R
EG
po
si ion o
h
e
eqU
ipmen
and
sends
h
e
modula ed
ECG
sig
nals o
he
speake
in
he
PLAY
posi ion, showing
he
co espo
nding
ECG l
ea
d in a o
u
digi s
alphanume ic
dis
pl
ay
.
~
~-.
-
-,
~
~
'--
--'
"-
u
Figu e
2:
Block di
ag a
m o
he
12
-lead ECG modul
a o
3.
DEMODULATOR
Figu e 3
Is
a block
diag am
o
h
e
demodula o
equi
p-
men .
The
audio signal is ac
qui ed
and p eampli ied.
Figu e
3:
Block
diag am
o
he
ECG
demodula o
Then
a equency- ol age
con e e
eco e
he
o iginal
SignaL A e a il e s
a
ge.
he
ECG signal is digi ally
co
n-
ened
using
he
analog
o digi al
co
n
e e
o
h
e mlc o-
co
n olle c
i
c
ui
. Finally.
h
e digi al signal is
ansmi ed
o a hos PC using a
se
ial RS-232 link
o
a
in a
ed
link
(l DA). The equipmen can
wo
k
w
i h
ba e i
es o a DC
powe s
up
pl
y.
4.
PROTOTYPE
AND
R
ESULTS
The
modula o
equip
men
h
as
been di ided in an
analog
boa d and a digi al boa d.
Figu e
4 is a pic u e o
h
e
anal
og
boa d (
op
iew).
I
includes he acquisi ion o he
12-1
ea
d Signals. SMT
co
mp
one
n
s allow o achie e size
es ic ions.
The e
is a
po en iome e
o
eac
h Signal o
se
h
e ze
o
alu
e.
Figu e 4: Modula o :
analog
boa d
Figu e 5 shows
he
digi al boa d.
I
is
based
on
h
e
mic o-con olle ci cui
ha
con ols
he
analog
mul i
-
plexe s.
he
ou digi
alphanume ic
display
and
a low
ba e y
ci cui de ec o .
Figu e
5:
Modula o
: digi al boa d
Finally. igu e 6 is a
pic u
e o
he
demodula o
equip-
men
.
The
boa d includes a DC powe supply (on
he
igh
bo om
pa
o
he
pic u e)
he
p eampli ie
and
he
e-
quency o ol age
con e e
(on
he
le
bo om)
and
he
se ial
connec o
and
he
I DA Jed on
he
op o
h
e
piC-
u e.
The
mic o-con olle
and
he
d i e
o
he
se ial
link
a e
placed on
he
o he
la
ye
o
he
boa d.
Figu e
6:
Demodula o boa d
An
example
he
demodula ed signals
a e
shown in ig.
u es
7
and
8.
Pa Ucuia iy.
ig.
7 shows
he
bipola
and
unipola
ex emi ies
leads,
and
ig.
8 shows
unipola
p e-
co dJal leads. Ve ical axis is
he
cap u ed
digi al
alue
ansmi ed
o
he
PC.
5.
CONCLUSIONS
A el
easis ency
sys em
o
ECG
signals
has
been de el-
oped in collabo a ion
wi h
a medical cen e .
The
sys em
co
nsis s
o
a po able
12
l
ead
modula o
equipmen ,
used
by
he
pa ien
o a non specialis doc o ,
and
a demodula-
o loca ed in
his
medical
cen e
. The main es ic ions
a e
ela ed
w
i h
he
modula o
because i will
be
used
by
he
pa ien .
I
mus
be
o educed size. wi h
he
maximum
au onomy
and
use
iendly.
This
equipmen
can
be
use ul in emo e
a eas
wi hou
a
ca diology specialis
and
in
manda o y
mecl caJ e isions
in ac o ies
whe e
hund eds
o
ECC
mus
be
done. Simul-
aneous
acquisi ion
o
he
12
lead allows a eco d
ime
o
en
seconds o
each
e ision.
6.
REFERENCES
111
S.L. To aI. J.M. Que o.
M.
Ele
na
P ez
. L.G. F anquelo.
Sl T
Bo
a d
o
Ac
quisi ion
o
El
ec
oca diog aph
Sig
-
nals
and
CSM
T
ansmission. P oc. DCIS·2000
..
Mon pellie . pp. 805- 814. No . 2000.
121
G.M.
F iesen
. T.C.
Janne .
M.A.
Jadallah.
S.L. Ya es.
S.R.
Quin
and
H.T. Nagle. A Compa ison
o
Noise
Sensi iey
o
Nine
QRS Decec ion Algo i hms.
IEEE
T ans
. Biomed.
Eng
..
ol. 37.
no.
I.
pp. 85-98. Aug.
1990.
131
J.
W.
Hu s
and
RC.
Schlan .
The
Hea . McG aw-
Hill.
Heal h
P o esions Di ision. 71h edi ion. 1990.
141
Mo o ola In
c..
MC68HCll
Re e ence
Manual
. Mo·
o ola. Re .
3.
199
1.
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bipola and unipola ex emi ies leads
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