Signal processing laboratory
The laboratory was established in 1972 and is engaged in theoretical research and practical development of digital signal processing systems, including the development of specific techniques and applications in analog-to-digital signal conversion. The work of the laboratory during these years is reflected in more than 200 publications, conference presentations, and monographs.
Currently, 24 people are working in the laboratory, including 3 lead researchers, 4 researchers, 7 assistants.
Research and development areas:
- Virtual instruments based on advanced DSP technologies;
- Program-controlled radio devices, including those based on non-uniform sampling;
- Signal-dependent analysis of non-stationary signals, event-driven analog-to-digital conversions;
- Biometrics and brain signal processing;
- Microminiaturization of data acquisition and processing systems;
- Smart sensor and networked embedded system signal processing;
- Wireless sensor network systems, including sensor module hardware architecture, communication protocols, operating systems and application-oriented software;
- Applications of directional antenna arrays in wireless sensor networks;
- Transistor based UWB pulse generators and receivers.
Currently, 2 groups have been formed in the laboratory focusing on the development of wearable sensor systems and the development of ultra-wideband radar technology.
Wearable sensor group is working on wearable sensor system development with potential applications in medicine, sport and daily activities. Mainly systems are based on inertial sensors, but the group has also experience with bioelectric signals (ECG, EMG, EEG). Within group novel wired communication solution has been developed that allows data acquisition from several hundred sensors, using minimal wiring. The solution is further developed beyond the field of wearable sensor systems for monitoring the deformations of constructions.
Examples of developed technologies:
- 3D shape reconstruction fabric: https://www.youtube.com/watch?v=YDG0ERF2_d8
- human body motion model 3D reconstruction: https://www.youtube.com/watch?v=vAFCrMgJrmI
- human-computer interface development for people with disabilities: https://www.youtube.com/watch?v=tfiS01VfavU
Group competencies-expertise: sensor system development, inertial sensors, low power sensor system development, PCB design, Flexible PCB design, digital communication interfaces, Bluetooth and Bluetooth Low Energy communication in application level, inertial signal processing, bio-electric signal processing, machine learning algorithms, 3D visualization, simulations, software development for smart devices (Android OS smartphones, tablets) in wearable sensor context.
The Ultra wideband (UWB) radar team is working on research and development of equivalent time conversion radar systems, resulting in both different unique solutions to improve radar performance and efficiency and several patents and publications on UWB signal generation, reception, processing, etc. Also, the group has developed a UWB radar device, which is used to study various UWB radar applications, such as:
- through wall measurements;
- ice thickness measurements;
- observation of non-contact signs of life (breathing, heartbeat);
- time domain reflectometry;
- antenna time domain measurements;
- measurements of material parameters.
- Sensorial Clothes for Accurate Physical Exercise and Instant Feedback (SCAPE-IF) #ESIF
- Automated railway level crossing control system (PAKS) part 2 #ESIF
- Automated railway level crossing control system (PAKS) #ESIF
- Contactless ice thickness measurement device (EDI-ICE) part 2 #ESIF
- Contactless ice thickness measurement device (EDI-ICE) #ESIF
- AI-based analysis of multi-static UWB-IR radar signals for non-destructive estimation of materials and structure (MIRSA) #ESIF
- 3D shape sensing fabric (3D FABRIC) #ESIF
- Arrowhead-Tools for Engineering of Digitalisation Solutions (Arrowhead-Tools) #H2020
- Cyber-physical systems, ontologies and biophotonics for safe&smart city and society (GUDPILS) #SRP (VPP)
- DASP pielietojumu pētījumi konkurētspējīgu virtuālo instrumentu izstrādei #ESIF
- Integrated Components for Complexity Control in Affordable Electrified Cars (3Ccar) #H2020
- Intelligent Motion Control Platform for Smart Mechatronic Systems (I-MECH) #H2020
- Projekts Nr.3 „Oriģinālu signālu apstrādes paņēmienu izveide un izpēte konkurētspējīgu IT tehnoloģiju radīšanai” #SRP (VPP)
- Research of a new electronic sound processing equipment structure for professional active acoustic system with megaphone type sounds emitter using the multi-band high-precision digital FIR filters and D-class amps (SKANDA) #Contract research (Līgumpētījumi)
- Technology for development of nanopulse cyber-physical system for ground subsurface noninvasive inspection. (NanoKS) #ESIF
- Project Nr.2 “Innovative signal processing technologies for smart and effective electronic system development” (IMIS) #SRP (VPP)
- High sensitivity superwideband radar technology (LoTe) #ESIF
- Smart City Technologies for Human Lives Improvements (ViPTeh) #ESIF
- Research project No 1.10: (Implementation of the research Nr.1.10. „Research on the reconstruction technology of the volumetric three-dimensional images” with economic activity related, delegated industrial research part “Transformation of the DICOM standard image data for the 3D spatial image display (3DAtA) #Contract research (Līgumpētījumi)
- Pētījums par datorredzes paņēmienu attīstību industrijas procesu norises automatizācijai (DIPA) #ESIF
- Frictionless Energy Efficient Convergent Wearables For Healthcare and Lifestyle Applications (CONVERGENCE) #Chist-era / Flag-era
- Artificial Intelligence for Digitizing Industry (AI4DI) #H2020
- Vision, Identification, with Z-sensing Technology and key Applications (VIZTA) #H2020
- Ultra-wideband impulse radar Sensor (UPIRS) #ESIF
- Development of technologies for cyber physical systems with applications in medicine and smart transport (KiFiS) #SRP (VPP)
- Dynamic land use monitoring (NevKlas) #ESIF
- High precision synchronous timing in widely distributed scientific instrumentation (DaLaS) #ESIF
- Satellite remote sensing- based forest stock estimation technology (WoodStock) #ESIF
- Cyber-physical systems, ontologies and biophotonics for safe&smart city and society (VPP SOPHIS) #SRP (VPP)
- Innovative technologies for acquisition and processing of biomedical images (InBiT) #ESIF
- R&D Center for Smart Sensors and Networked Embedded Systems (VieSenTIS) #ESIF
- Aristov, V. (2020). Research of Indirect Method of Measuring the Pulse Generator Output Resistance by the Step Recovery Diode. 2020 24th International Conference Electronics. doi: 10.1109/IEEECONF49502.2020.9141617
- Aristov, V. (2020) Mathematical Analysis of the Nanosecond Pulse Generator on Two SRD Diodes Used in UWB Radars. Automatic Control and Computer Sciences, 54(3), 271-278. doi: 10.3103/S0146411620030013
- Shavelis, R., Ozols, K. (2020) Bluetooth Low Energy Wireless Sensor Network Library in MATLAB Simulink. Journal of Sensor and Actuator Network, 9 (3), 38. doi: 10.3390/jsan9030038
- R.Shavelis, K.Ozols, M.Greitans, V.Fescenko, "Performance of Adaptive Filters for Predicting the Future Values of the Vehicle Sideslip Angle", The 16th Biennial Baltic Electronics Conference BEC2018, Tallinn, Estonia, Oct. 8-10, 2018.
- Shavelis R., Ozols K., Greitans M., Amplitude Adaptive ASDM circuit, 2017 3rd International Conference on Event-Based Control, Communication and Signal Processing, Madeira, 2017
- OZOLS., K, SHAVELIS., R, Amplitude Adaptive ASDM without Envelope Encoding, The 2016 European Signal Processing Conference (EUSIPCO 2016), Budapest, Hungary, August 29 -September 2, 2016.
- HERMANIS, E., SHUPOLS, G., SHAVELIS, R., ARISTOV, V., 2015. Signal With Linear Distortions Restoration Experiments for Stroboscopic Comparator-Based Converters, Automatic Control and Computer Sciences, Vol. 49, No. 6, 2015, pp. 390-394.
- ARISTOV, V., SHAVELIS, R., SHUPOLS, G., and CIRULIS, R. 2015. An Investigation of Non-traditional Approach to Narrowing the GPR Pulses. 25th International Conference “Radioelektronika 2015”. Pardubice, Czech Republic, 21-22
- SHAVELIS, R., OZOLS, K., 2014. Design of FIR Decimation Filters with Low Group Delay for Audio Applications " The 14th Biennial Baltic Electronics Conference BEC2014, Tallinn, Estonia, Oct. 6-8
- SHAVELIS, R., OZOLS, K., GREITANS, M., 2014. Optimization of Filtering Scheme for Reduction of Loudspeaker Distortions, The 14th Biennial Baltic Electronics Conference BEC2014, Tallinn, Estonia, Oct. 6-8
- R.Shavelis and M.Greitans, "Extended Fourier Series Representation of Signals With Time-Varying Bandwidth", ICICS 2013, Tainan, Taiwan, 10 - 13 December, 2013.
- M.Greitans and R.Shavelis, “Extended Fourier series for time-varying filtering and reconstruction from level-crossing samples”, EUSIPCO 2013, Marrakech, Morocco, 9-13 September, 2013.
- K.Ozols, M.Greitans, R.Shavelis. "Amplitude Adaptive Asynchronous Sigma-Delta Modulator", 8th International Symposium on Image and Signal Processing and Analysis (ISPA 2013), Trieste, Italy, September 4-6, 2013 Conference Proceedings pp.460-464
- K.Ozols, M.Greitans, R.Shavelis. "EEG Data Acquisition System Based on Asynchronous Sigma-Delta Modulator", The 13th Biennial Baltic Electronics Conference BEC2012, Tallinn, Estonia, Oct. 3-5, 2012.
- R. Shavelis, M. Greitans „Signal Sampling According to Time-Varying Bandwidth”, Proc. of the 20th European Signal Processing Conference EUSIPCO 2012, Bucharest, Romania, Aug., 2012., pp. 1164-1168.
- ARISTOV, V., KRUMINSH, K., PLOTSINSH, V., 2014. Assay of concurrent use of correlation and principal component analysis for tasks of UWB radar. Automatic Control and Computer Sciences, 48(5), pp. 296-302.
- GREITANS, M., HERMANIS E., ARISTOVS V., E. 2014. Research an Indirect Method of Calculating Complex Antenna Impedance. Automatic Control and Computer Sciences, Vol. 48, No. 6, pp. 375–380.
- ARISTOV, V. 2016. Optimization of the transmitter pulse duration by the criterion of the radiation spectrum maximization at a given frequency. Automatic Control and Computer Sciences. 50(4), 220-225.
- V. Aristov, "Distance localization of the moving object by applying the karhunen–loeve transform to ultra-wideband impulse signals". ISSN 0146-4116, Automatic Control and Computer Sciences, 2017, Vol. 51, No. 5, pp. 294–300. © Allerton Press, Inc., 2017.
- M. Greitans, V. Aristov, and T. Laimina “Application of the Karhunen–Loeve Transformation in Bio_Radiolocation: Breath Simulation”. ISSN 0146_4116, Automatic Control and Computer Sciences, 2012, Vol. 46, No. 1, pp. 18–24. © Allerton Press, Inc., 2012.
- V. Aristov. T.Laimina “ The Use Of The Karhunen Loeve Transformation To Form The Speech Data For Their Subsequent Wiring To Sound By Probing Sound Source By An Ultra-Wideband Pulse Locator” , Žurnāls Austria-science, № 17/ 2018, pp.22-28. The possibility of applying the first principal component of the Karunen-Loeve transformation is developed to form the speech data for their subsequent wiring to sound when a sound source (speaking person) is probed with an ultrawideband pulse locator.
- V. Aristov. Mathematical Description of the Operation of a Step-Recovery-Diode-Based Pulse Generator Circuit. Automatic Control and Computer Sciences, 2018, No. 6. The paper describes the operation of a classic step-recovery-diode-based pulse generator circuit using differential equations. The circuit has parasitic inductances and capacitors for both circuit elements and the diode in addition to standard discrete elements necessary for pumping the diode and generating a sharp edge. The results are compared with experimental data.
- Karhunen-Loeve transform as a tool to eliminate signal’s redundancy, when small targets detection
- Retrieval information from the UWB pulse signal using the Karhunen Loeve transform
- V. Aristov. Influence of Nonlinearity of Fast Sawtooth Voltage on Stroboscopic Transformation of Signals in Receivers of Sensors Locators. Automatic Control and Computer Sciences, 2019, Vol.53, No. 4, pp. 291-297.
- A. Hermanis, K. Nesenbergs, R. Cacurs, and M. Greitans, "Wearable Posture Monitoring System with Biofeedback via Smartphone", Journal of Medical and Bioengineering, (ISSN: 2301-3796), March 2013, Vol. 2, no. 1, pp.40-44, 2013
- HERMANIS, A., CACURS, R. and GREITANS, M., 2016. Acceleration and Magnetic Sensor Network for Shape Sensing. IEEE Sensors Journal, 16(5), pp. 1271-1280.
- A. Hermanis, R. Cacurs, K. Nesenbergs un M. Greitans. "Efficient Real-Time Data Acquisition of Wired Sensor Network with Line Topology", 2013 IEEE Conference on Open Systems, 2-4 dec., 6lpp. doi: 10.1109/ICOS.2013.6735062
- HERMANIS, A., CACURS, R., GREITANS, M., 2015. Shape sensing based on acceleration and magnetic sensor system, 2015 IEEE International Symposium on Inertial Sensors and Systems (ISISS), 23-26
- HERMANIS, A., GREITANE, A., GEIDĀNE, S., ANCĀNS, A., CACURS, R., GREITĀNS, M., 2015. Wearable Head and Back Posture Feedback System For Children With Cerebral Palsy, Abstract: Journal of Rehabilitation Medicine (ISSN 1650-1977).
- SUDARS, K., CACURS, R., HOMJAKOVS, I., JUDVAITIS, J., 2015. LEDs based video camera pose estimation, Bulletin of the Polish Academy of Sciences, Technical Sciences, Col. 64 No 4 2015, pp 897-905. Impact factor: 0.91.
- Bluetooth Low Energy Throughput in Densely Deployed Radio Environment
- Atis Hermanis, Krisjanis Nesenbergs, "Grid shaped accelerometer network for surface shape recognition", Electronics Conference (BEC), 2012 13th Biennial Baltic, pp.203-206, 2012. DOI: 10.1109/BEC.2012.6376852
- Jānis Ārents, Ričards Cacurs, Modris Greitans, "Integration of Computervision and Artificial Intelligence Subsystems with Robot Operating System Based Motion Planning for Industrial Robots", Automatic Control and Computer Sciences Journal, Volume 52, Issue 5, 2018
- A. Ancans, A. Rozentals, K. Nesenbergs, M. Greitans. “Inertial sensors and muscle electrical signals in human-computer interaction”, 6th International Conference on Information and Communication Technology and Accessibility ICTA 2017
- Vaviļina, E., G. Gaigals. "Highly Reconfigurable Beamformer Stimulus Generator." Latvian Journal of Physics and Technical Sciences 55.1, 53-63, 2018.
- G. Gaigals, E. Vavilina. "Simulation of compressed sensing based passive radar for drone detection." 2017 5th IEEE Workshop on Advances in Information, Electronic and Electrical Engineering (AIEEE). IEEE, 2017.
- Gaigals, G., M. Donerblics, and G. Dreifogels. "Development of Mathematical Models for Detecting Micron Scale Volumetric Defects in Thin Film Coatings." Latvian Journal of Physics and Technical Sciences 53.2, 38-47, 2016.
- E. Vavilina, G. Gaigals. "Improved LabVIEW Code Generation" Baltic J. Modern Computing, Vol. 4, No. 1, 89-97, 2016.
- G. Gaigals, M. Greitans and A. Andziulis, "Compressive Sensing: Analysis of Signals in Radio Astronomy", Baltic Astronomy, vol.22, pp. 347-361, 2013
- Ruibys, K., A. Andziulis, T. Eglynas, M. Jusis, D. Drungilas, and G. Gaigals. Development of distributed real time data aquisition system for radio telescope monitoring. Space Research Review: 34.
- J. Trokss, A. Lesins, G. Gaigals, M. Nechaeva, Vl. Bezrukovs. Receiving system for ionospheric research. Latvian Journal of Physics and Technical Sciences, december 2012., N6 (Scopus, Tompson Reuter Web of Science, EBSCO).
- Gaigals G., Lībiete I., Bezrukovs D., Jēkabsons N. Radio-Telescope RT-16 control system. Journal of International Scientific Publications: Materials, Methods & Technologies, Volume 6. 2012.
- LR patent Nr. 15529 A "ANTENNA SYSTEM FOR UNDERGROUND RADAR WITH LOCATION OF THE ANTENNAS OPPOSITE EACH OTHER"
- Patent No. EP2695297 (B1) “Ultra-wideband sharpener for excitation a symmeric antenna”
- European Patent No. EP3093992 A1 "An input clocked comparator circuit of an equivalent time sampling converter"
- Latvian Patent No. 14641 “Equivalent time sampling convertor of comparator type"
- LR patents Nr. 14622 “Zigzag antena, kas konstruktīvi ir sajūgta ar koaksiālo kabeli”
- Latvian Patent No.14730. "Stroboscopic comparator"
- LR patents Nr. 14767 “Simetriskas ultra-platjoslas (UWB) antenas triecienierosmes impulsa formētājs”
- LR patents Nr. 14803. “Strobējams komparators ar aizkaves līniju”
- LR patents Nr.15068. “Stroboskopiskais pārveidotājs ultraplatjoslas radiolokācijas signālu atklāšanai”
- LR patents Nr.15273. "Ierīce attālināta kustībā esoša objekta lokalizēšanai"