Embedded Systems
The contemporary solutions of measurement and
instrumentation are based on dedicated computer
systems, and offer a wide variety of autonomous
services. These services include primarily data
acquisition, information processing, and control, but
there are several other additional mechanisms to
achieve high-quality overall performance. The
majority of such applications can be considered as
embedded systems due to the fact, that in addition to
the sensors and the actuators, also the dedicated
computer system components are invisibly
embedded into the hosting environment. The role of
these embedded systems is to measure or identify
the behaviour of their environment, which is
followed by some real-time computations to provide
proper characterization, influence and control.
The Department of Measurement and Information
Systems operates seven smaller laboratories working
on problems related to various kinds of embedded
systems, and hosts the Embedded Information
Technology Research Group of the Hungarian
Academy of Sciences and the Budapest University
of Technology and Economics.
Calibration Instruments Laboratory
Research interest: current, voltage, impedance
measurement,
self-calibrating
instruments,
calibration of instrument transformers, artificial
impedances.
Staff: István Zoltán, associate professor, Zoltán
Benesóczky, András Görgényi, Balázs Vargha,
senior lecturers, József Dudás, engineer, Zoltán
Román, and Zsolt Szepessy as PhD students.
Resources and infrastructure: DC-Calibrator, ACCalibrator, CT-Calibrator, VT-Calibrator, Standard
CTs, Impedance Analyzer.
Major research and development projects:
The Department has a great tradition in research and
development of precision electrical measurements
and metrology including the complete innovation
process.
The main fields of the research activity:
 Current, voltage, impedance and power
measurement
 Self-calibrating, self-correcting instruments
 Calibration of instrument transformers
 Artificial impedances
Since the appropriate reference standards did not
exist, or were not available, the high precision
instruments developed between 1980 and 1990
served mainly calibration purposes.
From the beginning of the 90's, the rapid
development of the analogue, digital and mixed
signal processing opened new possibilities in
instrumentation. Thanks to this advancing hardware
and software tools, the calibration functions of the
devices could be integrated into the measuring
instruments, and even the automatic self-correction
of the errors measured during the self-calibration
process became possible.
Based on these methods the following typical errors
became manageable:
 the errors of approximation
 calculable errors
 measurable errors
 errors caused by influence quantities
 thermal drift
Thanks to this approach the overall accuracy of the
instruments can be even 1000-times better than that
of the built-in components. This possibility basically
changes the principles of development of measuring
instruments.
From the beginning of the 90's, more and more PhD
students became involved in the research of selfcalibrating
and
self-correcting
measuring
instruments in the following topics:
 Artificial impedances
 Self-calibrating amplifiers
 Correction of thermal dynamic errors
 Impedance analysis
 Calibration Algorithm for Current-Output
R-2R Ladders
 Calibration of power measuring instruments
The self-calibrating and self-correcting measuring
instruments provide the possibility of low-cost and
efficient remote calibration via Internet, foreseeing
already the technology of the third millennium in
precision measurement and metrology.
The growing development-, manufacturing-,
marketing-, and after sales service requirements
related to the new, advanced calibration instruments
required a more appropriate organisation, thus in
1997 the CALIN Electronics Ltd. was established.
Parallel to this, the co-operation with the
Department was successfully continued by CALIN
Electronics Ltd. As a result of the common efforts,
in 1998 a new advanced generation of self-
calibrating
and
self-correcting
measuring
instruments has been introduced to the international
market. These instruments are used as national
standards and also for automatic calibration in
manufacturing of current and voltage transformers in
Austria, Brazil, England, Germany, Hungary,
Romania, and Taiwan.
Some recent products:
Figure 4. Standard Current Transformer for
calibration of watthour meters
Figure 1. Instrument Transformer Analyzer
composed of 1 ppm calibrator and programmable
high-power artificial impedance with 101442
settings
Acknowledgement: The staff of the laboratory
wishes to express his appreciation to the former
contributors: László Schnell, Endre Tóth, Péter
Osváth, Gyula Korányi, Péter Pataki, Ferenc Nagy,
Zoltán Reguly, László Naszádos, László Gyöngy,
Erik Bohus.
Contact person:
István Zoltán
izoltan@mit.bme.hu
www.mit.bme.hu/~izoltan/
Figure 2. 1 ppm Standard Current Transformer used
in the 0.5….10000 A current range
Selected publications:
Figure 3. Standard Additional Burden for voltage
transformer calibration
1. Zoltán, I., “A Multi-Function Standard
Instrument
for
Current
Transformer
Calibration,” OIML, Bulletin, Vol. XXXVI, No.
4, October 1995, pp. 28-32.
2. Zoltán, I., “Impedanzsynthese,” Technisches
Messen 68 (2001) 4, Oldenbourg Verlag,
Munich, Germany, pp. 179-181.
3. Vargha, B. and I. Zoltán, “Calibration
Algorithm for Current-Output R-2R Ladders,”
IEEE
Trans.
on
Instrumentation
and
Measurement, Vol. 50, No. 5, October 2001, pp.
1216-1220.
4. Szepessy, Zs. and I. Zoltán, “Thermal Dynamic
Model of Precision Wire-Wound Resistors,”
IEEE
Trans.
on
Instrumentation
and
Measurement, Vol. 51, No. 5, October 2002, pp.
930-934.
Biomedical Engineering Laboratory
Research
interest:
electronic
biomedical
instruments, biosignal processing, marker-based
movement analysis, home health monitoring.
www.mit.bme.hu/~jobbagy/biomed
Staff: Ákos Jobbágy, associate professor, András
Görgényi, senior lecturers, Károly Bretz jr., PhD
student.
Education: Biomedical Instrumentation, Electronic
Measuring Equipment, Project Laboratory and
Thesis work for Biomedical Instrumentation.
Resources and infrastructure: passive markerbased motion analysers: PRIMAS (precision 3D)
and PAM (simple 2D), electronic biomedical
instruments: (ECG, PPG, blood-pressure monitors,
pulmonary analyser), battery operated (scope
meters, hand-held DMMs) and bench-top electrical
instruments.
Major research and development projects:
Movement analysis: “Development of signal
processing algorithms to compensate the non-ideal
projection of passive marker-based motion
analysers,” financed by NWO and OTKA. (See:
www.mit.bme.hu/
~jobbagy/parkinson/parkinson.htm,
~jobbagy/cdreklam/Markerbasedma.html)
Diagnosis and staging of patients with neural
diseases is challenging, especially in the early phase.
Passive marker-based motion analysis helps the
objective assessment providing information about
the movement of body segments during well-defined
hand- and finger movements.
We developed different feature extraction methods
to evaluate the movement and thus the actual
performance of the tested persons. These tests help
in the early diagnosis of Parkinson's disease as well
as in setting the appropriate medication of patients.
Our tests confirmed that Parkinson's disease
manifests itself uniquely in the movement disorders
of a patient. A simple and cheap image-based
motion analyser (PAM) has been developed at the
Department that is affordable for routine clinical
use. We offer also the programs that evaluate the
performance of tested persons, taking into account
the regularity and the speed of the movements.
Partners: E. Hans Furnée, TU Delft, Péter Harcos,
Szt. Imre Hospital, Emil Monos, Semmelweis
University, Gábor Fazekas, Szt. János Hospital,
OORI.
Figure 5. Marker trajectories during the fingertapping test. Performance of the right and left hand
of a healthy subject (above) and a newly diagnosed
Parkinsonian (below).
Home health monitoring: “Artificial patient and
model in medical informatics,” financed by FKFP,
and “Home health monitoring,” financed by OTKA.
World life expectancy more than doubled over the
past two centuries, a further increase is estimated.
National health care systems should be
accommodated; the prevalence rates of many
diseases substantially change over age. The average
medical expenditure per person is significantly
higher for the elderly than for younger people.
Keeping the healthiness of the population can be
helped by home health monitoring. Many diseases
can be treated more effectively and at a lower cost if
early signs are detected.
In Hungary cardiovascular diseases are the leading
cause of death, being responsible for about half of
the deaths [www.bel2.sote.hu/hipertonia]. It is
estimated that 30% of the Hungarian population has
hypertonia, above age 65 this ratio increases to
approximately 65%. Diagnosis in the early stage
would make it possible to start medication and
treatment to prevent the deterioration of the patients.
The presently existing blood-pressure meters either
require trained operator or do not assure accurate
measurement. Automatic and semi-automatic bloodpressure meters are simple-to-use thus widespread in
home health monitoring. However, their results are
not accurate and reproducible enough, the reliability
of self-assessment is not satisfactory, medical
doctors have reservations for the results. The best
grade (A) in the British Hypertension Society
standard allows 40% of the results deviate from the
reference by more than 5 Hgmm, 15% of the results
by more than 10 Hgmm and 5% of the results by
more than 15 Hgmm. The aim of our research work
has been to increase the accuracy and
reproducibility of the indirect, cuff-based blood
pressure measurement with the help of the
photoplethysmographic (PPG) signal. A method has
been developed to measure the systolic and diastolic
pressure and not the mean pressure as it is done
while using the oscillometric method. A patient
monitoring device is being developed that is able to
store daily physiological measurement results (blood
pressure, 10-s ECG recording) for 2 months. The
device is also able to analyse the recorded data and
request help if needed via mobile phone.
Partners: Gábor Halász (BUTE, Faculty of
Mechanical Eng.), Márk Kollai (Semmelweis
University).
Contact person:
Ákos Jobbágy
jobbagy@mit.bme.hu
www.mit.bme.hu/~jobbagy/
Selected publications:
1. Jobbágy, Á., L. Gyöngy, E. Monos,
“Quantitative evaluation of long-term locomotor
activity of rats,” IEEE Trans. on Instrumentation
and Measurement, Vol. 51, No. 2, Apr. 2002,
pp. 393-397.
2. Jobbágy, Á, E.H. Furnée, P. Harcos, M. Tárczy.,
“Early detection of Parkinson's disease through
automatic movement evaluation,” IEEE
Engineering in Medicine and Biology Magazine,
Vol. 17, No. 2, March-Apr. 1998, pp. 81-88.
3. Jobbágy, Á, “Photoplethysmographic Signal
Aids Indirect Blood-Pressure Measurement,”
Proc. of MEDICON 2001, IX. Mediterranean
Conf. on Medical and Biological Engineering
and Computing, 12-15 June 2001, Pula, Croatia,
pp. 262-264.
Computer Networks Laboratory
Research interest: communication of embedded
systems, sensor networking, real-time and
distributed communications, quality of service,
wireless networking.
http://www.mit.bme.hu/projects/iiensor
Staff: Csaba Tóth, senior lecturer, Tamás
Kovácsházy lecturer, László Kádár and Balázs
Scherer research assistants.
Education: Multimedia Networking, Informatics,
Project Laboratory and Thesis works for Embedded
Systems.
Resources and infrastructure: two laboratories,
PC-based development systems for PIC (8 bit) and
ARM (32 bit) micro-controllers, a sample network
of voice over IP telephony (made by Siemens),
IEEE 802.11bg wireless network, Gigabit Ethernet
Cluster, 10/100Base-T networking components
including switches, routers, firewalls etc.
Major research and development projects:
Gigabit Ethernet Cluster: Workpackage of NEXT
TTA – High Confidence Architecture for Distributed
Control
Applications,
EU
IST-2001-32111
Programme.
http://www.mit.bme.hu/projects/isensor/NEXT
The Gigabit workpackage explored the achievable
performance and the limitations and bottlenecks of a
TTA network composed of commercial off-the-shelf
high-end state-of-the-art hardware components. In
The objective of NEXT TTA project was to develop,
Figure 6. Network Laboratory I.
(NEXT TTA Gigabit Ethernet Cluster)
and implement novel algorithms, tools, and
components to provide a generic architecture for
safety-critical applications in different application
domains (e.g., aerospace, automotive, and railway
applications). NEXT TTA project was an integration
of many different problem solutions that have been
explored independently over many years in different
research institutions.
The Gigabit workpackage explored the achievable
performance and the limitations and bottlenecks of a
TTA network composed of commercial off-the-shelf
high-end state-of-the-art hardware components. In
particular, the workpackage set-up a TTA cluster
consisting of ordinary PCs, which are the nodes of
the cluster, and a Gigabit Ethernet serving as the
interconnection network. All the components could
be purchased at the " next door computer shop".
Our workpackage implemented a Windows-based
host for this TTA cluster, and analysed the whole
system by measuring its performance and attributes.
Industrial
application of
modern infocommunications technology (IKTA 164/2000 –
Sponsored by the Hungarian Ministry of Education.)
Co-operation with VERTESZ Kft.
http://www.mit.bme.hu/projects/isensor/IKTA2000
During the last five years a remarkable spreading of
high-level communication technologies, principally
the Ethernet and internet, was noticeable in the
embedded system market. As a result, most of the
leading embedded system manufacturers have
started offering solutions to connect their devices
into TCP/IP protocol based computer networks,
unfortunately, using non-standard protocols in the
application layer.
The goal of this project was to review the applicable
internet protocols and system architectures, to
describe a solution for developing network capable
smart sensors and actuators, with good system
integration ability.
Figure 7. Network Laboratory II.
http://rten.mit.bme.hu/projects/isensor/ICCC2003
We have developed an SNMP-based pseudo NCAP
(based on IEEE 1451) providing a transducer
independent network accessible interface, useable to
formalise the control of devices with different
functions.
http://rten.mit.bme.hu/projects/isensor/IMTC2003
Contact person:
Csaba Tóth
toth@mit.bme.hu
http://www.mit.bme.hu/~toth/
Selected publications:
1. Cs. Tóth, B. Scherer, L. Kádár, T. Bakó:
Implementation possibilities of networked smart
transducers,
ICCC
2003,
International
Carpathian Control Conference, Tatranska
Lomnica, Slovak Republic, 26-29 May 2003,
pp. 198-201.
2. B. Scherer, Cs. Tóth, T. Kovácsházy., B.
Vargha: SNMP-Based Approach to Scalable
Smart Transducer Networks, IMTC 2003, IEEE
Instrumentation and Measurement Technology
Conference, Vail, Colorado, USA, 20-22 May
2003, pp. 721-725.
3. Tamás Kovácsházy, Róbert Szabó, Performance
Measurement Tool for Packet Forwarding
Devices, 2001 IEEE Instrumentation and
Measurement Technology Conference IMTC
2001, Budapest, Hungary, 2001, Vol. 2., pp.
860-863,
4. T. Péter, Cs. Tóth, Quality of System
Monitoring in a Complex Internet Service
Provider - Case study. IEEE International
Conference on Intelligent Engineering Systems
(INES’99), Slovakia, Nov. 1-3, 1999, pp. 629633.
Logic Design Laboratory
Research interest: digital system design, high level
synthesis, advanced signal and image processing
architectures, embedded microprocessor systems,
dynamically reconfigurable computers, and system
on a programmable chip implementations.
Staff: Béla Fehér, Gábor Horváth, associate
professors, Lőrinc Antoni, research assistant, Péter
Szántó PhD student.
Education: The laboratory has a central role in the
practical education of the students of the Embedded
Systems Branch. Our open laboratory policy makes
the lab to a familiar working place not only for the
curricula lectures, but also for the elaboration of the
particular student ideas as well. Subjects related to
the laboratory are Digital Technique, Logic Design,
Microprocessor Systems, Design of SoPCs by
FPGAs, student project and thesis works.
Resources and infrastructure: The laboratory is
equipped with 12 PCs, configured as W2000
workstations. All important design software’s are
available in the laboratory, including the Xilinx ISE
and EDK FPGA development system, the Matlab
Environment, the Mentor Graphics ModelSim,
FPGA Advantage, SystemVision, Seamless and
Celoxica Handel-C tools. Tektronix TPA 700 LA or
ARM MultiICE IDE development boards from
Digilent and XESS are also available.
Major research and development projects: The
Logic Design laboratory is the centre of the
department’s research work for the design of
complex digital systems, with emphasis on the
application of FPGAs and exploitation of the reconfigurability. Significant results were achieved
with the application of FPGAs in the field of digital
signal processing. Different basic linear FIR and IIR
filter structures, DSP core generators, and efficient
finite word and distributed arithmetic building
blocks were developed [1]. Based on special
recursive algorithm, high performance 1D and 2D
linear transform modules (WHT, DCT) were
implemented in an area optimized way [2]. Similar
methods were used later to implement nonlinear
median filters as well, for high speed video signal
processing. Current research is focused on FPGA
implementation of advanced 3D rendering
algorithms for portable applications with
reconfigurable computing architectures [3].
Figure 8. 48 tap, 16 bit FIR filter in a 5k gates
FPGA
Figure 9. LOGSYS-BLOXES FPGA Educational
Board
Significant work has been done to offer a modular
FPGA/PLD development board family for the
students, called LOGSYS-BLOXES. Three levels of
boards has been made, supporting the different
needs of the education in the basic, entry level logic
design, and later on the implementation of more
complex DSP and communication units and system
on a chip development and verification. A simple,
standardized USB-based debugger, control and
power interface is also provided with a rich set of
interesting peripheral interface modules.
Unique property of dynamic reconfiguration (DRC)
capability of some SRAM technology based FPGAs
makes possible very special applications, for
example the dependability and fault tolerance
analyses of complex digital systems. DRC is used to
inject Single Event Upset (SEU) or stuck-at-1 (or 0)
like errors into the logic and evaluate the behaviour
in real time [4]. This research was done in
cooperation with Prof. Régis Leveugle, TIMA,
France. Efficient arithmetic modules were also
developed exploiting the DRC, in frame of the
national FKFP project Re-configurable Computing
Architectures (0413/1997). Partners were University
of Veszprém and University of Miskolc. The Logic
Design Laboratory also serves as a Technology
Expertise Center (TEC) in different national and EC
projects. It offers consultation
and design services for SMEs
interested
in
advanced
embedded
system
design
methodologies. The EC funded
FP5 technology transfer project JENET (Joint
European Network of Embedded Internet
Technologies, IST IST-2000-28422) is a good
example of these activity. JENET is promoting the
use of the new communication capabilities in
industrial applications, specifically the embedded
Digital Signal Processing Laboratory
Figure 10. JENET presentation,
Magyar Regula, 2003.
internet technology in products and systems
developed by European enterprises. JENETis carried
out by a network of 7 TECs and 27 User Companies
(UCs) from Belgium, Germany, Hungary, Italy,
Poland, Romania and United Kingdom. Local
partner SMEs are Infoware Co., Meldetechnik Ltd.,
Silex Ltd., and the project coordinator is CRR, Italy.
More information: http://www.eurojenet.com.
Contact Person:
Béla Fehér
feher@mit.bme.hu
http://www.mit.bme.hu/~feher/
Selected publications:
1. Fehér, B., “Efficient Synthesis of Distributed
Vector Multipliers,” Journal of Microprocessors
and Microprogramming, Vol. 38. No. 1-5. 1993.
2. Fehér, B., “ New Inner Product Algorithm of the
2D DCT,” Digital Video Compression:
Algorithm and Technologies, Proc. SPIE, Vol.
2419. ISBN 0-8194-1766-1.
3. Szantó, P. and B. Fehér, “3D Rendering using
FPGAs,” IFIP International Conference on
VLSI SOC, December 1-3, 2003 Darmstadt,
Germany.
4. Antoni, L., R. Leveugle, B. Fehér, “Using runtime reconfiguration for fault injection
applications,” IEEE Trans. on Instrumentation
and Measurement, Vol. 52, No. 5, October 2003.
Research interest: Signal modelling, adaptive
signal processing, digital filter structures, transformdomain signal processing. Signal processing in
complex measurement systems.
Staff: László Sujbert, László Naszádos senior
lecturers, Balázs Bank, research assistant, Károly
Molnár PhD. student. Part-time contributors: Gábor
Péceli, professor, Tamás Dabóczi, associate
professor, Gyula Simon, senior lecturer.
Education:
Embedded
systems
laboratory,
Information systems laboratory, Project laboratory.
Resources and infrastructure:
 DSP development boards (Analog Devices,
Motorola, Texas Instruments)
 Vibro-acoustic
transducers,
signal
conditioners (Brüel&Kjaer)
 Digital storage scopes, spectrum analyzers,
special generators (LeCroy, HP)
Major research and development projects:
Active noise control is an old idea for acoustic
noise suppression, but it could be implemented only
since the advent of digital signal processors. The
solution is based on the destructive interference
phenomenon. We have developed a dedicated
method for suppressing periodic noise components.
The method is the extension of the resonator-based
observer developed also at the department. The
advantages of the resonator-based noise controller
are its fast convergence (compared to other
methods) and its low computational burden. Based
on the experiences with the resonator-based periodic
noise controller, we have developed a modification
of the well-known filtered-X LMS algorithm
Figure 11. Typical performance of an active noise
control system
allowing faster convergence for broadband noise
control, as well. Grants, international relations:
 OTKA: Acoustic applications of digital
signal processing, F 035060
 TPD-TNO Delft, the Netherlands
http://www.tpd.tno.nl
Digital sound synthesis of musical instruments has
been acclaimed at the department in the last years. It
needs very precise measurements and poses serious
signal processing problems. The results achieved in
this field can be utilized generally, e.g. in system
identification or in filter design. We have
successfully synthesized the sound of organ, violin
and piano. Most of research results were achieved
for piano sound synthesis, where the digital
waveguide model has been improved. Grants,
international relations:
 OTKA: Acoustic applications of digital signal
processing, F 035060
 MOSART IHP (Improving Human Potential)
Training Network, HPRN-CT-2000-00115
http://www.diku.dk/forskning/musinf/mosart

Helsinki University of Technology, Laboratory
of Acoustics and Audio Signal Processing
http://www.acoustics.hut.fi

University of Padua, Department of Information
Engineering http://www.dei.unipd.it
One of our latest industrial projects is development
of a DSP-based system for in-motion weighing of
railway carriages. It is a two-level system that
comprises of 16 or 24 DSP-based Measurement
Units (MU) and a powerful HOST PC. The MUs
store the deformation signals of the rail caused by
Figure 12. Transfer function measurement of a
violin body
the wheels of an in-motion train. The deformation is
measured by strain gauges. AD converters sample
the signal of the strain gauge bridge, and this signal
is processed at the DSP. The HOST collects the
stored data, and a large database is built for each
train.
Contact person:
László Sujbert
sujbert@mit.bme.hu
www.mit-bme/~sujbert/
Selected publications:
1. Sujbert, L., and G. Péceli, “Signal model based
periodic noise controller design,” Measurement
- the Journal of the IMEKO, vol. 20, No. 2, pp.
135-141.
2. L. Sujbert, “A new filtered LMS algorithm for
active noise control,” Proc. of the Active '99 The International EAA Symposium on Active
Control of Sound and Vibration, Dec. 2-4, 1999,
Fort Lauderdale, Florida, USA, pp. 1101-1110.
3. Bank, B., and Vesa Välimäki, "Lobust Loss
Filter Design for Digital Waveguide Synthesis
of String Tones," IEEE Signal Processing
Letters, vol. 10, No. 1, pp. 18-20, Jan. 2003.
Chaotic Signals and Systems
Laboratory
Research interest: Chaotic communication
systems, analysis and computer simulation of data
communication systems, frequency synthesis, phaselocked loop. http://www.mit.bme.hu/research/chaos/
Staff: Géza Kolumbán, associate professor, Gábor
Kis, Zoltán Jákó, research assistants, Zoltán Szabó,
Béla Frigyik, PhD students.
Education: Electronics I and II, Theory and
Applications of Nonlinear Theory and Chaos (PhD
course), System Level Design and Analysis. Project
Laboratory works and MS Theses.
Resources and infrastructure: Linux-based PCs.
Major research and development projects:
Development and analysis of novel signal
processing architectures for system-on-a-chip
(SoC) integrated circuits, T038083, financed by
OTKA (2002-2005).
The project has been launched to find new
transceiver and frequency synthesizer configurations
for communication and measurement purposes.
Partners: Prof. G. Chen (City University of Hong
Kong; Profs. C.M. Lau and C.K. Tse, The Hong
Kong Polytechnic University.
Innovative signal processing exploiting chaotic
dynamics (INSPECT), Esprit Project 31103, Open
LTR – 2nd phase, Financed by European
Commission, 1998-2001.
http://www.cordis.lu/esprit/src/31103.htm,
http://www.mit.bme.hu/research/chaos/inspect/
Chaotic signals are inherently wideband signals that
can be generated with high power efficiency using
simple nonlinear circuits in any frequency band and
at arbitrary power level. In chaotic communications,
the digital information to be transmitted is mapped
directly into a wideband chaotic waveform. Chaotic
communication offers a low cost alternative solution
to conventional spread spectrum communication.
Seven European universities collaborated in the
INSPECT Esprit Project to find applications for
chaotic signals in communication and watermarking
of digital pictures. The Chaotic Systems Team
coordinated the research and implementation of a
working prototype of frequency-modulated chaosshift keying (FM-DCSK) communication system.
We have invented FM-DCSK (the most robust
chaotic modulation scheme), derived exact
expressions for the noise performance of correlatorbased chaotic modulation schemes, developed an
ultra fast computer simulator to evaluate the system
performance of digital communication systems
under various channel conditions, elaborated the
system proposal and determined the system level
parameters for the INSPECT FM-DCSK chaotic
data communications system.
The INSPECT FM-DCSK radio shown in Fig 13
operates in the 2.4-GHz ISM band and was
successfully tested in 2001. To illustrate its excellent
multipath performance, the bit error rate (BER)
curves of conventional differential phase-shift
keying (DPSK) and chaotic FM-DCSK are
compared in Fig. 14. Although the single-ray
performance of FM-DCSK is worse than that of
DPSK, in the indoor multi-path channels the DPSK
fails completely (see dash-dotted curve) while FMDCSK has only a 4-dB loss in the system
performance (see dashed and dotted curves).
Our direct partner in the INSPECT Project was Prof.
M.P. Kennedy, University College Dublin.
Spread spectrum communication exploiting
chaos, Office of Naval Research (ONR), USA,
1995-1996.
Figure 14. BER curves of conventional DPSK and
chaotic FM-DCSK in a single-ray additive white
Gaussian noise (AWGN) channel (solid and dashed,
respectively) and in an indoor multi-path channel
(dash-dotted and dotted, respectively.
The goal of this project was to propose an
underwater chaotic communication scheme for the
submarines of US Navy. In the project we have
elaborated a comprehensive theory for chaotic
waveform communications.
Partners: Prof. L.O. Chua, University of California,
Berkeley, and Prof. M.P. Kennedy, University
College Dublin.
Contact person:
Géza Kolumbán,
kolumban@mit.bme.hu
www.mit.bme.hu/~kolumban/
Selected publications:
1. Kolumbán, G., M.P. Kennedy, Z. Jákó and G.
Kis, “Chaotic communications with correlator
receiver: Theory and performance limits,”
invited paper in Proceedings of the IEEE, vol.
90, pp. 711-732, May 2002.
2. Kennedy M.P., and G. Kolumbán, guest editors,
Special Issue on “Noncoherent Chaotic
Communications,” IEEE Trans. Circuits and
Syst. I, vol. 47, pp. 1661-1732, December 2000.
3. Kolumbán, G., M.P. Kennedy and L.O. Chua,
“The role of synchronization in digital
communications using chaos,” IEEE Trans.
Circuits and Syst. I, Part I: “Fundamentals of
digital communications,” 44(10): 927-936,
October 1997; Part II: “Chaotic modulation and
chaotic synchronization,” 45(11): 1129-1140,
November 1998; Part III: “Performance
bounds,” 47(12): 1673-1683, December 2000.
4. G. Kolumbán, “Theoretical noise performance
of correlator-based chaotic communications
schemes,” IEEE Trans. Circuits and Syst. I, vol.
47, pp. 1702-1711, December 2000.
5. G. Kolumbán, “The theory and implementation
of a robust chaotic digital communications
system,” invited talk at 2003 Microwave
Symposium Workshop, IEEE International
Microwave Symposium, Philadelphia, USA,
June 2003.
www.ims2003.org/technical/workshop/
WMA.htm
Figure 13. Picture of the 2.4-GHz FM-DCSK prototype receiver built in the framework of INSPECT Esprit
Project.
System Identification Laboratory
Research interest: identification of linear systems,
parameter estimation, SISO/MIMO modelling,
effect of nonlinear disturbances, signal reconstructtion using known measurement system models
(inverse filtering).
Staff: István Kollár, professor, Tamás Dabóczi,
associate professor, Gyula Simon, senior lecturer,
József Németh, research assistant, László Balogh,
János Márkus, Balázs Vödrös, PhD students, Zoltán
Bilau, graduate student.
Education: Digital signal processing, System
identification,
Embedded
systems,
Project
Laboratory, and Diploma thesis design.
Major research and development projects:
Identification in the Frequency Domain
The close cooperation between our department, and
the Department ELEC at the Vrije Universiteit
Brussel, Belgium (http://wwwtw.vub.ac.be/elec/), is
continuous since 1989. One of the major results of
this cooperation is the Frequency Domain System
Identification Toolbox for MATLAB. The
peculiarity of the frequency domain methods is that
they solve the maximum likelihood equations in the
frequency domain, making it possible to fully
exploit the advantages of harmonic excitations.
An important step in identification is the validation
of the results. We always have to check whether the
result really satisfies our requirements, is in no
contradiction with the preliminary assumptions, and
corresponds to the data. A program can only offer
tools for this purpose: the validation itself is the task
of the person who performs the identification.
The toolbox effectively uses the following advanced
MATLAB tools:



graphical user interface,
automatic procedures, and
data structures.
The investigated system can be anything from
electrical systems (filters, machines) to mechanical
systems (airplanes, cars, robot arm) and acoustical
systems (airplane cabin, loudspeaker), etc.
The toolbox is now in use throughout the world.
Linear modelling is currently being extended to
characterize slight nonlinear distortions, and to
model multiple input – multiple output systems.
Inverse filtering
The accuracy of time domain waveform
measurements is limited by the finite bandwidth of
the measurement instrument. This means that high
frequency components of the signal will be
suppressed and the phase of the different frequency
components will be modified. The result is a
Figure 15. Compare and Evaluate Models
window of the GUI of the fdident toolbox
distorted waveform; the fast changes of the signal
are rounded, rapid transitions are stretched out.
Digital post-processing of the measured data can
improve the result. This is called inverse filtering.
This problem is usually ill-posed, that is, small
changes in the measured output signal cause large
fluctuations in the estimation of the input signal.
Different inverse filtering techniques provide
different approaches to suppress the amplified noise
without significantly distorting the useful signal.
Successful applications of inverse filtering:

High voltage lightning measurements:
compensating the distortion of high voltage
dividers. Cooperating party: Swiss Federal
Institute of Technology, Zürich, Switzerland,
High Voltage Laboratory

Calibration of ultra high-speed oscilloscopes.
Cooperating party: National Institute of
Standards and Technology, NIST, USA

Restoration the sound of old movies, kept on
film
Figure 16. Measured and reconstructed high voltage
lightning impulses
Figure 16. High voltage lightning impulse
measurement setup
High voltage generator, chopping gap and high
voltage dividers – HV laboratory of the ETH Zürich
Recent Research Grants:
OTKA (Hungarian Scientific Research Fund), NIST
(National Institute of Standards and Technology,
USA), Hungarian Ministry of Education.
Contact persons:
István Kollár
Tamás Dabóczi
kollar@mit.bme.hu
daboczi@mit.bme.hu
www.mit.bme.hu/~kollar/
.../~daboczi/
Selected publications:
1. FDIDENT (1999-2003), Frequency Domain
System Identification Toolbox Developers’
Page. http://elec.vub.ac.be/fdident/
2. Kollár, I., R. Pintelon, Y. Rolain, J. Schoukens,
and Gy. Simon, “Frequency Domain System
Identification
Toolbox
For
MATLAB:
Automatic Processing – From Data To Models.”
IFAC Symposium on System Identification,
SYSID 2003, Aug. 2003, Rotterdam.
3. Dabóczi, T., I. Kollár, Gy. Simon, and T.
Megyeri, “How to Test Graphical User
Interfaces?”
IEEE
Instrumentation
and
Measurement Magazine, Vol. 6, No. 3, pp. 2733, Sep. 2003.
4. Deyst, J. P., N. G. Paulter, T. Dabóczi, G. N.
Stenbacken, T. M. Souders, "A Fast Pulse
Oscilloscope Calibration System," IEEE Trans.
on Instrumentation and Measurement, Vol. 47,
No. 5, pp. 1037-1041, 1998.