Deploymen o Digi al Video and Audio
O e Elec ical SCADA Ne wo ks
J. I. Escude o, J. A. Rod íguez, M. C. Rome o, and S. Díaz
Abs ac —Wi h he a i al o new ha dwa e and so wa e ech-
nologies, supe iso y con ol and da a acquisi ion human-machine
in e aces (SCADA/HMI), usually ex -based, can now bene i
om he ad an ages he inclusion o mul imedia in o ma ion
b ings. Howe e , due o he special equi emen s imposed by
such sys ems, in eg a ing audio and ideo da a in o he SCADA
in e aces is no a i ial ask. In his documen we analyze hose
special cha ac e is ics and p opose solu ions so his in eg a ion is
possible in powe sys ems communica ion.
Index Te ms—Audio coding, digi al communica ion, mul imedia
communica ion, powe sys ems communica ion, supe iso y con-
ol and da a acquisi ion (SCADA) sys ems, ideo codecs.
I. INTRODUCTION
TRADITIONALLY, supe iso y con ol and da a acqui-
si ion/human-machine in e ace (SCADA/HMI) sys ems
ha e limi ed he display scope o s a us in o ma ion and ala ms
logs o simple ex cha ac e s.
This was mainly caused by he s a us o ha dwa e echnology
a ha ime:
— sys ems we e p op ie a y ones as he e we e no wide-
sp ead ha dwa e o so wa e pla o ms;
— he ea ly s age o de elopmen o he ne wo king
echnologies;
— ideo and audio comp ession echniques we e no
e icien enough o be used on sys ems o he han
scien i ic main ames.
P op ie a y sys ems mean he e was a s ong dependence be-
ween he so wa e and ha dwa e pa s, so only hose who buil
he ha dwa e sys ems had he knowledge o de elop so wa e
applica ions ha could be execu ed o e hose sys ems. Tha
leaded o expensi e and incompa ible pla o ms whe e he o ig-
inal manu ac u e could only do any imp o emen .
The ela i ely low p ocessing powe o hose sys ems, o-
ge he wi h he low bandwid h o e ed by he besides cus om
ne wo k echnologies, p e en ed SCADA/HMI sys ems om
using audio isual in o ma ion. Video and, o a lesse ex en ,
audio in o ma ion needed oo much bandwid h o be ansmi ed
o e he exis ing ne wo ks, and e en i ha was he case, i
would end up being oo expensi e o be used.
Th oughou he las wo decades, a a g ea e o lesse le el,
all hese echnologies (compu e ha dwa e and so wa e, ne -
This wo k was suppo ed in pa by he Minis e io de Ciencia y Tecnología o
Spain unde G an TIC2000-0367-P4-02. Pape no. TPWRD-00500-2003.
The au ho s a e wi h he Depa amen o de Tecnología Elec ónica, E.T.S.I.
In o má ica Uni e sidad de Se illa., A da., Reina Me cedes s/n 41012, Se illa,
Spain (e-mail: [email p o ec ed]).
wo king and audio isual p ocessing and analysis) ha e s eadily
been imp o ed, while he cos o acqui ing hem has dec eased.
1) The ha dwa e side has bene i ed om a aising le el
o semiconduc o s in eg a ion, which has lead, among
o he imp o emen s, o mo e powe ul p ocesso s and
as e and la ge memo y subsys ems. Now, hanks o
he new s anda d ha dwa e a chi ec u es ha ha e a isen,
and along wi h new cos -e ec i e widesp ead so wa e
pla o ms, we ha e a ou disposal in e ope able and
ha dwa e-independen sys ems.
2) Ne wo king has also e ol ed o e he yea s, and as a esul
om his, we can make use o many di e en ansmission
echnologies, bo h a o dable and powe ul.
3) Audio and ideo p ocessing has also been d ama ically
imp o ed. S anda d comp ession echnologies such as
MP3 and MPEG-4 allow comp ising a huge amoun o
in o ma ion in a ela i e small space.
In ew wo ds: we now ha e sys ems capable o p ocessing
huge amoun s o audio isual in o ma ion and ansmi ing i o
emo e loca ions [1], all a an a o dable cos .
In he case o SCADA sys ems, hey ha e p og essi ely
adop ed hese new echnologies, bu , due o hei special cha -
ac e is ics, a a slowe a e. SCADA sys ems a e ypically huge
sys ems, so he cos o upg ading hem is g ea e han o he
ypical sys ems.
They a e a ge ed o supe ise c i ical p ocesses. In such p o-
cesses, ails on he sys em could ha e ad e se side e ec s, so
only hose echnologies ha ha e been es ed enough a e aken
in o conside a ion.
II. PHYSICAL AND DATA LINK LAYERS ON SCADA SYSTEMS
Classic SCADA sys ems we e cen alized sys ems. Bu
mode n SCADA sys ems a e dis ibu ed ones, wha means
di e en nodes do he p ocessing, ins ead o pe o ming i in a
single, cen alized, machine.
Al hough he di ision o he exis ing buses on a SCADA
sys em di e s depending on he au ho , i is widely accep ed
he e a e a leas h ee di e en ypes o hem, in unc ion o
hei empo al equi emen s [2], (Fig. 1).
Da a ha comes om he senso s and is sen o ac ua o s, due
o he special empo al equi emen s needed, is ansmi ed o e
he so-called ield buses. These a e buses whe e ope a ion is
done in eal ime, and a e designed o suppo a high a ic o
limi ed messages in he o m o o de s and s a us da a. They a e
buses wi h low ansmission a e and cable leng h [3].
These buses a e ypically p op ie a y ones, bu in he las
yea s some open buses ha e been de eloped. The mos used a e
CAN Open, De iceNe and AS-i.
Fig. 1. Typical buses on SCADA sys ems.
The communica ion be ween p ocess con ol de ices and/o
be ween pe sonal compu e s wi h SCADA/HMI applica ions is
usually pe o med o e ano he ype o bus, known as con ol
bus [4].
Con ol buses ha e highe ansmission a es and mo e e-
laxed empo al es ic ions han ield buses; he ne wo k each
is also wide han on ield buses. In example, Con olNe eaches
5 Mb/s and allows links wi h a leng h o up o 30 Km i op ical
ibe is used. A segmen o a Modbus Plus bus has a maximum
leng h o 500 me e s while ansmi ing a up o 122 Mb/s.
The ise o pe sonal compu e s (PCs) in oduced he need o
in e connec ing a se o PCs in he same subne , so hey could
sha e in o ma ion. These sys ems wo k on en i onmen s less
ough han he o me ones, whils a he same ime hey need o
deal wi h a g ea e da a load. These buses a e known as in o -
ma ion buses.
In e ne and he TCP/IP p o ocol ha e imposed a ac s an-
da d, E he ne , which is widely used on his ype o buses.
We ha e ocused on s udying he opology o he elec ical
dis ibu ion ne wo ks. These ne wo ks a e usually wide han
hose used on indus ial applica ions.
F om his s udy, he ollowing conside a ions can be aken
in o accoun .
—Remo e s a ions can be loca ed a a dis ances om
he con ol cen e .
—T ansmission be ween emo e s a ions and he con ol
cen e (s) is pe o med o e medium ol age elec ical
lines o using adio signals, a slow a es.
—Only new s a ions use o ha e ano he ype o physical
links, usually ibe op ic.
—Equipmen wi hin he emo e s a ions a e exposed o
high in ensi y elec omagne ic dis o ions.
—The bandwid h o e ed by he ypical ield buses is no
enough o oom audio isual in o ma ion wi h a decen
quali y. I should no be o go en ha he in o ma ion
mus be de ailed enough o gi e ex a de ails ha could
no be ob ained wi h he usual ex displays.
Depending on he links a ailable on he con ol and in o ma-
ion buses (i exis ing), i will be mo e o less likely mul imedia
in o ma ion can be ansmi ed o e hem.
In o ma ion buses a e designed o suppo a high load o in-
o ma ion, bu con ol buses a e mo e sensi i e o such loods o
da a, as s a us and con ol messages a i al canno be delayed
oo much.
I is ecommended no o sha e he physical medium be ween
he audio isual in o ma ion and he SCADA eal- ime in o ma-
ion, bu in he e en i is, mul imedia da a should be ansmi ed
on di e en channels han hose used by supe ision in o ma-
ion so i does no in e e e wi h he la e .
A s udy o he di e en a ailable ansmission echnologies
has been made, analyzing hei ad an ages and d awbacks wi h
ega d o hei possible use as communica ion channels.
A. Elec ical Links
Powe line communica ion (PLC) e e s o he ansmission
o signals o e elec ical lines, a equencies o he han he
Hz o he al e na ing cu en . This echnology u ns any
elec ical plug in o a po en ial connec ion o all elecommunica-
ion se ices.
Al hough i has been widely used on SCADA sys ems om
he beginning, he bandwid h was qui e limi ed. In example,
he CENELEC EN 50065 s anda d speci ies 148.5 kHz as he
highes usable equency.
Ne e heless, u he esea ch done o e he las yea s has
b ough his echnology o he on . The use o coding me hods
such as ODFM allows he ansmission o in o ma ion o e low-
ension elec ical links a speeds o up o 45 Mb/s.
Wi h ega d o elec ic u ili ies, emo e s a ions a e usu-
ally linked o he medium ol age dis ibu ion sys ems, using
medium o low ol age ans o me s o eed he s a ions.
Tes s ha e been made o e medium ol age links showing u -
he imp o emen s mus be done in o de o ake p o i o hem
as a ansmission medium o mul imedia in o ma ion. The main
p oblem lies in he dis ibu ion ans o me s, which limi he e -
ec i e ansmission each o communica ion signals o a ew
hund ed o me e s. Anyway, al hough high speed PLC ansmis-
sion is s ill unde de elopmen , i is he ecommended solu ion
as i allows en e p ises o cu down on expenses in in as uc-
u es, and i is also an al e na i e o o he echnologies in case
hei use is no p o i able, o no possible.
B. Telephonic Lines
Can also be aken unde conside a ion when choosing om
he di e en a ailable op ions.
Tes s wi h 56-kb/s V.92 modems ha e showed he a e hey
each is no as enough o ansmi sui able audio and ideo
s eams. ADSL echnology could be a solu ion, bu ha dly any
elecom p o ide gi e suppo o hem ou side u ban a eas.
C. Op ic Fibe
One ideal solu ion as i bo h has a big bandwid h and is no
a ec ed by elec omagne ic pe u ba ions.
New cons uc ion acili ies end o use hem because o he
men ioned easons; in he case o elec ical companies, he op ic
ibe is usually laid along wi h he medium ol age elec ical
cables.
D. Non-Guided Links
The use o adio and mic owa e signals is also a good solu ion
o long dis ance ansmissions.
Solu ions based on he 802.11 s anda d o e each o up o
se e al kilome e s. The e exis s equipmen ha allows in e-
g a ing 802.11 sys ems in o 802.3 ne wo ks.
I mus be aken unde conside a ion ha he longe he
link is, he lowe is he e ec i e ansmission a e ha can be
ob ained. Also, an impo an in es men mus be done in he
an enna equipmen when ying o communica e wo dis an
poin s.
III. MULTIMEDIA SCADA NODES
A he ne wo k laye , IP p o ocol is p oposed as he so-
lu ion o in e connec he di e en subne s cons i u ing he
ull SCADA ne wo k, as nowadays ope a ing sys ems and
SCADA/HMI sui es o e ull suppo o his p o ocol. I no
only allows in e connec ing di e en lowe le el p o ocols, bu
i also allows making use o he ex ensi e anspo p o ocols
and applica ions ha make use o i .
The cen al co e o he sys em pe o ms basically he manage-
men o mul imedia in o ma ion [5]. In consequence, we need
o pe o m a de ailed analysis o all elemen s ha ake pa in
he p ocess and he echnologies a ailable o de elop hem.
A. Mul imedia Da a Acquisi ion
Fi s , i is essen ial o analyze which ha dwa e elemen s allow
cap u ing ideo and audio in o ma ion.
Mul imedia signals mus be in digi al o m so compu e s can
p ocess hem, so in case hey a e analog hey ha e o be p e i-
ously digi ized.
This is he case o analog came as; as hey need addi ional
cap u e ha dwa e o pe o m he analog o digi al con e sion
o he inpu signal. On he con a y, digi al came as (i.e., web
cams) al eady o e a digi al lux; a wo s hey would need ad-
di ional ha dwa e so hey can be connec ed o he compu e .
This digi al da a use o be coded on he aw RGB24 o he
spa ially comp essed YUV colo spaces, al hough some ca ds
o e he possibili y o comp essing he da a wi h codecs such
as MPEG. In he case o digi al came as, some use colo -com-
p essing me hods (usually YUV a ian s) o each highe pixel
esolu ions o ame a es.
The use o comp ession is highly unwished in his i s phase,
as i equi es addi ional use o p ocesso ime because i da a is
acqui ed in a comp essed o ma and an analysis o he da a is
needed. I would be necessa y o decomp ess i be o e being able
o pe o m any p ocessing on he images/sounds. Also, i on a
la e phase we need o comp ess he in o ma ion using ano he
decomp ession echnique, a p e ious decomp ession o he da a
would also be needed.
Once acqui ed, bo h he ideo and audio in o ma ion a e man-
aged he same way, so om now on we will concen a e on he
ideo side, knowing ha he same is applied o audio da a.
The main di e ence when dealing wi h ideo and audio p o-
cessing consis s on ideo da a needing mo e esou ces (band-
wid h, p ocesso ime, e c.) han audio o each he same le el
o pe cep ual quali y.
B. Signal Analysis
This module analyzes he inpu da a, so abno mal si ua ions
can be de ec ed, and wa nings o ala ms gi en on consequence.
This is a p ocess ha needs a lo o sys em esou ces, so his
module could be loca ed on a di e en compu e o ca d.
In case a di e en compu e is used, i would be needed o
ne wo k i wi h he cap u e sys em, ob aining he mul imedia
da a h ough a high-speed leased link.
C. Signal Comp ession
A e he ini ial signal acquisi ion s age, i would be desi able
o pe o m he comp ession o he cap u ed da a, so i needs less
bandwid h o be ansmi ed [6].
The e a e wo comp ession me hods: lossy and lossless. Wi h
a lossless o ma , la e decomp essing/comp essing ope a ions
will no al e he quali y o he gene a ed da a, while when using
a lossy o ma , hose ope a ions will mean p og essi e signal
de e io a ion, and wi h he consequences i ca ies o he image
ideli y.
Howe e , he comp ession a ios eached by he lossy
me hods widely su pass hose eached when using loss less
algo i hms. The o me can each up o 50:1 comp ession a ios
whils he la e ha dly each 2:1 a ios.
Because i is only needed o comp ess he da a once, and
decomp ession is a ask ha needs a ela i ely low amoun o
sys em esou ces, lossy o ma s a e he ecommended ones.
The e a e many lossy codec echnologies a ailable (wa ele ,
ac al, DCT, e c.). Those based on DCT a e by a he mos
widely suppo ed and hey also o e a g ea quali y/comp es-
sion powe ela ion, so i we had o choose we would use DCT
based codecs.
D. Semi-Tempo al S o age
As i is being gene a ed, he mul imedia s eam can be s o ed
so i is a ailable o la e use.
In such a case, only a limi ed pe iod o ime is usually s o ed,
making necessa y a s eam imming s a egy, as he inpu
s eam is a con inuous one. No e ha he close, c ea ion and
dele ion o he in ol ed iles can cause he loss o in o ma ion
du ing he p ocess.
The s o ed da a may also need o be sen o hose s a ions ha
ask o i , meaning he encode so wa e/ha dwa e mus be able
o gene a ing mul iple ou pu s eams.
As he signal analysis module, i can be loca ed on o he com-
pu e han he one whe e he cap u ing p ocess is done. Unless
a high-speed leased connec ion exis s be ween he s o ing and
he emi ing s a ions, he use o high pe o mance, big capaci y,
ha d disk uni s is he ecommended solu ion.
E. Mul imedia Da a S eaming
This module is dedica ed o he dis ibu ion o he mul imedia
in o ma ion so i is a ailable o emo e s a ions.
Basically, he s eaming p ocess consis s in imming he con-
inuous inpu da a and dis ibu es i o e he ne wo k. This job
is mainly done a anspo le el whe e he usual anspo p o-
ocols used when s eaming a e as ollows.
1) UDP (Use Da ag am P o ocol): I is a connec ionless
anspo p o ocol, pe ec o he dis ibu ion o eal- ime in-
o ma ion, as i does no gua an ee he deli e y.
I may seem, as a d awback ins ead o being an ad an age,
bu i is pa icula ly bene icial when doing eal- ime s eaming.
Unlike da a as iles o e-mails, which need o be en i ely de-
li e ed wi hou ega d o he ime aken in ansmi ing hem,
he alue o eal- ime mul imedia da a dec eases as ime goes.
So, i a ame is los in i s way, i is no wo h he e o o
e-sending i , as i is mo e han p obable la e ames a e al eady
being played. The e ansmission o los ames would suppose
a was e o bandwid h.
I mus be no ed mul imedia s eams mus ha e addi ional
synch oniza ion in o ma ion in o de o be able o play he da a.
The los o he sync in o ma ion will p obably lead o a los o
he synch ony du ing he playback, wha supposes a p oblem
when using only UDP o ansmi he da a.
Ano he d awback o UDP is ha , due o secu i y easons, i
is possible UDP packe s canno pass h ough i ewalls.
2) TCP (T ansmission Con ol P o ocol): This is a connec-
ion-o ien ed p o ocol, and he dominan one in In e ne .
The d awback o TCP when dealing wi h eal- ime da a is
i e ansmi s he nondeli e ed da a, so i supposes a was e o
bandwid h. Anyway, i he need o keeping he in eg i y o he
mul imedia da a exis s, i is he ecommended p o ocol. I sol es
he p oblems ela ed o he los o synch oniza ion da a.
As wi h UDP, i can also happen TCP packe s canno pass
h ough ce ain i ewalls.
3) RTP (Real-Time T anspo P o ocol): I has been de-
signed o be used on eal- ime applica ions.
Usually placed on op o UDP, i may be used along wi h o he
anspo , o e en ne wo k laye , p o ocols.
Occasionally, packe s can be los o hey may be ecei ed
diso de ed a he des ina ion, wha can be e y ha m ul o he
s eam sync. To sol e hose de iciencies, he RTP heade holds
empo al in o ma ion and a sequence numbe ha allows he
ecei e side o ebuild he media in o ma ion.
Addi ionally, and based on he p e iously desc ibed anspo
p o ocols, some solu ions a applica ion le el a e commonly
used o he deli e y o mul imedia in o ma ion:
a) HTTP (Hype -Tex T ans e P o ocol): Based on TCP,
and no speci ically designed o deal wi h eal- ime da a, he
ad an age o using HTTP is da a sen using his p o ocol is able
o pass h ough i ewalls on mos occasions.
E en hough i in oduces ex a da a and addi ional delays
when ansmi ing mul imedia in o ma ion, i is a alid solu ion
on mos occasions.
b) RTSP (Real-Time S eaming P o ocol): Taken di ec ly
om he p o ocol memo [7]: “The Real Time S eaming P o-
ocol, o RTSP, is an applica ion-le el p o ocol o con ol o e
he deli e y o da a wi h eal- ime p ope ies. RTSP p o ides an
ex ensible amewo k o enable con olled, on-demand deli e y
o eal- ime da a, such as audio and ideo.”
I can be used o e any anspo p o ocol, usually RTP.
F. Remo e Con ol o De ices
In case i is equi ed o ha e ad anced con ol unc ions o e
he cap u ing de ice, a module implemen ing a con ol in e ace
will be needed.
This is especially use ul when wo king wi h came as; wi h a
emo e con ol module, hei posi ion, zoom and ocus s a e can
be managed. The bandwid h equi emen s o such ope a ions a e
minimal.
I is only le o say ha , o his pu pose, i is ecommended
o use a s anda d p o ocol o send he commands o he came as
and ecei e hei s a us. Sony’s VISCA, a de ice-and pla o m-
independen p o ocol o synch onized con ol o mul iple ideo
de ices, is widely used on hese applica ions.
IV. INTEGRATING THE MULTIMEDIA SYSTEM WITH
SCADA/HMI SUITES
The in eg a ion o hi d-pa ies applica ions on SCADA so -
wa e sys ems has his o ically been a di icul ask.
O e he las yea s he e o o he de elope s o he mos
known SCADA/HMI sui es (In ellu ion’s iFIX, Wonde Wa e’s
Fac o y Sui e, e c.,) ha e ocused on adop ing he la es so wa e
echnologies.
Mode n sui es un o e mass ope a ing sys ems, such as Win-
dows (usually only on p o essional, mo e s able e sions such as
Windows NT o 2000) and, o a lesse ex en , Linux. In ou e-
sea ch p ojec , we ha e selec ed In ellu ion’s iFIX as ou es ing
pla o m, a SCADA/HMI sui e ha wo ks on Windows 2000
and Windows XP P o essional ope a ing sys ems.
iFIX, as mos la es SCADA sui es, suppo he la es ech-
nologies de eloped by Mic oso . Apa om suppo ing Vi-
sual Basic o Applica ions, which allows he use o VB inside
he HMI applica ion, i is being buil as an Ac i eX con aine .
This allows in eg a ing hi d-pa ies applica ions designed as
Ac i eX con ols.
As Ac i eX con ols can be buil using mos impo an p o-
g amming languages, his opens he doo o he use o many
ex e nal APIs.
The e o e, we’ e designed he mul imedia sys em as an Ac-
i eX con ol ha uses he Windows Media [8] mul imedia sui e
o deal wi h mul imedia da a. This sui e o e s APIs o C++ and
VisualBasic languages.
Windows Media Encode API allows cap u ing image/audio
om nea ly any Di ec X compa ible de ice, comp essing he
cap u ed da a and s eaming i o e HTTP.
Using HTTP p o ocol should be enough in mos occasions,
as SCADA ne wo ks a e usually s a ic ones and do no ha e he
high a ic peaks In e ne has. In case i he use o RTP o UDP
is equi ed, he Windows Media Se ices componen is a good
solu ion.
Fig. 2. Example o mul imedia enabled SCADA/HMI sys em.
To play he mul imedia con en , he Windows Media Playe
componen can be used. Apa om ha ing an API, i has been
implemen ed as an Ac i eX con ol.
Remo e access o he mul imedia sys em is needed in o de
o con igu e i . The DCOM echnology deals wi h he secu i y
issues ela ed o emo e accesses.
Fig. 2 shows an SCADA/HMI sys em using he p e iously
commen ed echnologies. No e he PDB, SAC, and DIT pa s
can di e i using ano he SCADA/HMI sys em o he han iFIX
[9].
V. CONCLUSIONS
Now, in eg a ion o mul imedia in o ma ion in SCADA sys-
ems is close o eali y. Mo e and mo e equen ly, elec ic u il-
i ies a e equipped wi h an unde lying da a ne wo k (usually one
o op ic ibe ) whose bandwid h is sui able o ideo, audio and
da a anspo . Also inno a ions on communica ions echnolo-
gies like powe -line communica ions and wi eless ne wo ks a e
impo an ac o s o ake in o accoun o his in eg a ion.
F om a echnical app oach, his in eg a ion is easible, such
as we ha e desc ibed in his pape , and we a e s ill wo king on
he implemen a ion o a speci ic sys em and esea ching abou
ansmission o mul imedia and elecon ol in o ma ion. F om
a unc ional app oach, his in eg a ion g ea ly ex ends he unc-
ionali y o SCADA sys em, so i en iches exis ing elecon ol
unc ions adding new ope a ion, main enance suppo , and op-
e a o s aining unc ions.
REFERENCES
[1] J. I. Escude o, F. Gonzalo, M. Mejías, M. Pa ada, and J. Luque, “Mul i-
media in he ope a ion o la ge indus ial ne wo ks,”in P oc. IEEE In .
Symp. Indus ial Elec onics, 1997, pp. 1281–1285.
[2] J. Aiza and R. Sa on , “Buses y disposi i os pa a comunicaciones indus-
iales,”Au omá ica e Ins umen ación, pp. 93–129, Jun. 2000.
[3] S. A. Nasa , Schaum’s Ou line o Elec ical Powe Sys ems. NY: Mc-
G aw-Hill T ade, 1989.
[4] S. A. Boye , SCADA: Supe iso y Con ol and Da a Acquisi ion, 2nd
ed. New Yo k, NY, Uni ed S a es: ISA—The Ins umen a ion, Sys ems
and Au oma ion Socie y, 1999.
[5] F. Halsall, Mul imedia Communica ions: Applica ions, Ne wo ks, P o-
ocols and S anda ds, Ha low, U.K.: Addison-Wesley, 2001.
[6] A. H. Sadka, Comp essed Video Communica ions, Chiches e , England:
Wiley, 2002.
[7] H. Schulz inne e al.,“Real Time S eaming P o ocol (RTSP),”IETF,
RFC 2326, Ap . 1998. S a us: P oposed s anda d.
[8] Windows Media SDK (2003). [Online]. A ailable: h p://msdn.mi-
c oso .com/lib a y/de aul .asp?u l=/lib a y/en-us/dnwm /h ml/
wmsdk.asp.
[9] iFIX 2.5—Elec onic Books, MA, Uni ed S a es: In ellu ion Dynamics,
Feb. 2001. In ellu ion Dynamics.
J. I. Escude o ecei ed he physics deg ee in 1979
and he Doc o a e in physics in 1995 om he Uni-
e si y o Se ille, Se ille, Spain.
He has held se e al eaching posi ions. He has been
P o esso o Elec onic Enginee ing a he Uni e si y
o Se ille since 1989. D . Escude o has ocused his
esea ch ac i i y on he s udy o compu e ne wo k
pe o mance, powe sys ems elecon ol, and he use
o mul imedia in powe sys ems con ol.
J. A. Rod íguez ecei ed he deg ee in compu e
enginee ing in 2003 om he Uni e si y o Se ille,
Se ille, Spain. A p esen he is wo king in se e al
p ojec s abou mul imedia in he ope a ion o la ge
indus ial ne wo ks.
His p incipal s udy is ocused on he use o
mul imedia in powe sys ems elecommunica ion
ne wo ks.
M. C. Rome o ecei ed he compu e enginee ing
deg ee om he Uni e si y o Se ille, Se ille, Spain,
in 1999. A p esen she is wo king on he Ph.D. hesis
in mul imedia con ol o powe sys ems.
Since 1999 she has wo ked on se e al esea ch
p ojec s ocused on elecommunica ions ne wo k
managemen and powe sys ems elecon ol a he
Uni e si y o Se ille. In 2001 she became Associa e
P o esso and began he eaching wo k in he School
o Compu e Enginee ing, Uni e si y o Se ille.
S. Díaz ecei ed he deg ee in compu e enginee ing
in 1999 om he Uni e si y o Se ille, Se ille, Spain.
A p esen he is wo king on his Ph.D. hesis in Powe
Sys em Con ol.
Since 1999 he has wo ked in se e al esea ch
p ojec s ocused on compu e ne wo k managemen
a he Uni e si y o Se ille. In 2000 he became
Associa e P o esso and began his eaching wo k in
he School o Compu e Enginee ing, Uni e si y o
Se ille.