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Björklund, Svante
Alternative names
Publications (10 of 15) Show all publications
Björklund, S. & Rydell, J. (2017). Micro-doppler classification with boosting in perimeter protection. In: IET Conference Publications: . Paper presented at 2017 International Conference on Radar Systems, Radar 2017, Belfast. Institution of Engineering and Technology (CP728)
Open this publication in new window or tab >>Micro-doppler classification with boosting in perimeter protection
2017 (English)In: IET Conference Publications, Institution of Engineering and Technology , 2017, no CP728Conference paper, Published paper (Refereed)
Abstract [en]

In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar. From time-velocity diagrams of the data, physical features have been extracted and used in a Boosting classifier to distinguish between the classes "human", "animal" and "man-made object". This type of classifier has received much attention lately, but not in radar micro-Doppler classification. The classification result on the current data reaches 90% correct classification with this classifier. The ability to distinguish between humans and animals is good on this data. This classifier type gives insight into the classifier and the utilized features, and is easy to use. A comparison with a SVM (Support Vector Machine) classifier, which is common for micro-Doppler, has also been performed. © 2017 Institution of Engineering and Technology. All rights reserved.

Place, publisher, year, edition, pages
Institution of Engineering and Technology, 2017
Keywords
Boosting, Classification, Micro-doppler, Radar, Airport security, Animals, Object detection, Radar systems, Support vector machines, Boosting classifiers, Classification results, Perimeter protection, Physical features, Security surveillance, SVM(support vector machine), Classification (of information)
National Category
Signal Processing Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-16646 (URN)2-s2.0-85048690177 (Scopus ID)
Conference
2017 International Conference on Radar Systems, Radar 2017, Belfast
Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2018-06-29Bibliographically approved
Björklund, S. (2017). Signal Processing for Radar with Array Antennas and for Radar with Micro-Doppler Measurements. (Doctoral dissertation). Karlskrona: Blekinge Tekniska Högskola
Open this publication in new window or tab >>Signal Processing for Radar with Array Antennas and for Radar with Micro-Doppler Measurements
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radar (RAdio Detection And Ranging) uses radio waves to detect the presence of a target and measure its position and other properties. This sensor has found many civilian and military applications due to advantages such as possible large surveillance areas and operation day and night and in all weather. The contributions of this thesis are within applied signal processing for radar in two somewhat separate research areas: 1) radar with array antennas and 2) radar with micro-Doppler measurements.

Radar with array antennas: An array antenna consists of several small antennas in the same space as a single large antenna. Compared to a traditional single-antenna radar, an array antenna radar gives higher flexibility, higher capacity, several radar functions simultaneously and increased reliability, and makes new types of signal processing possible which give new functions and higher performance.

The contributions on array antenna radar in this thesis are in three different problem areas. The first is High Resolution DOA (Direction Of Arrival) Estimation (HRDE) as applied to radar and using real measurement data. HRDE is useful in several applications, including radar applications, to give new functions and improve the performance. The second problem area is suppression of interference (clutter, direct path jamming and scattered jamming) which often is necessary in order to detect and localize the target. The thesis presents various results on interference signal properties, antenna geometry and subarray design, and on interference suppression methods. The third problem area is measurement techniques for which the thesis suggests two measurement designs, one for radar-like measurements and one for scattered signal measurements.

Radar with micro-Doppler measurements: There is an increasing interest and need for safety, security and military surveillance at short distances. Tasks include detecting targets, such as humans, animals, cars, boats, small aircraft and consumer drones; classifying the target type and target activity; distinguishing between target individuals; and also predicting target intention. An approach is to employ micro-Doppler radar to perform these tasks. Micro-Doppler is created by the movement of internal parts of the target, like arms and legs of humans and animals, wheels of cars and rotors of drones.

Using micro-Doppler, this thesis presents results on feature extraction for classification; on classification of targets types (humans, animals and man-made objects) and human gaits; and on information in micro-Doppler signatures for re-identification of the same human individual. It also demonstrates the ability to use different kinds of radars for micro-Doppler measurements. The main conclusion about micro-Doppler radar is that it should be possible to use for safety, security and military surveillance applications.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2017. p. 180
Series
Blekinge Institute of Technology Doctoral Dissertation Series, ISSN 1653-2090 ; 2
Keywords
radar, signal processing, array antenna, subarray, clutter, jamming, interference, direction of arrival estimation, security, micro-Doppler, feature extraction, classification
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-13639 (URN)978-91-7295-335-2 (ISBN)
Public defence
2017-03-31, Karlskrona, 00:00 (English)
Opponent
Supervisors
Available from: 2017-01-16 Created: 2016-12-18 Last updated: 2017-03-08Bibliographically approved
Björklund, S., Grahn, P., Nelander, A. & Pettersson, M. (2016). Measurement of Rank and Other Properties of Direct and Scattered Signals. International Journal of Antennas and Propagation, 2016, Article ID 5483547.
Open this publication in new window or tab >>Measurement of Rank and Other Properties of Direct and Scattered Signals
2016 (English)In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2016, article id 5483547Article in journal (Refereed) Published
Abstract [en]

We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival) estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments. © Copyright 2016 Svante Björklund et al.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2016
Keywords
Antenna arrays, Antennas, Covariance matrix, Eigenvalues and eigenfunctions, Electronic warfare, Interference suppression, Radar, Radar measurement, Signal processing, Transmitters, Wireless telecommunication systems, Controlled experiment, Covariance matrix estimation, DOA (direction of arrival) estimations, Indoor measurement, Location of transmitters, Measured properties, Radar applications, Wireless communications, Direction of arrival
National Category
Communication Systems Signal Processing Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-13495 (URN)10.1155/2016/5483547 (DOI)000386827700001 ()2-s2.0-84994314235 (Scopus ID)
Funder
Knowledge FoundationA multiscale, cross‐disciplinary approach to the study of climate change effect on ecosystem services and biodiversity
Note

open access

Funders: Swedish Armed Forces   Swedish Defence Materiel Administration

Available from: 2016-11-24 Created: 2016-11-23 Last updated: 2017-11-29Bibliographically approved
Bjorklund, S., Johansson, T. & Petersson, H. (2016). Target Classification in Perimeter Protection with a Micro-Doppler Radar. In: 2016 17TH INTERNATIONAL RADAR SYMPOSIUM (IRS): . Paper presented at 17th International Radar Symposium (IRS), MAY 10-12, 2016, Krakow, POLAND.
Open this publication in new window or tab >>Target Classification in Perimeter Protection with a Micro-Doppler Radar
2016 (English)In: 2016 17TH INTERNATIONAL RADAR SYMPOSIUM (IRS), 2016Conference paper, Published paper (Refereed)
Abstract [en]

In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar of a low complexity and cost-effective type. From time-velocity diagrams of the data, some physical features have been extracted and used in a support vector machine classifier to distinguish between the classes "human", "animal" and "man-made object". Both the type of radar and the classes are suitable for perimeter protection. The classification result are rather good, 77% correct classification. Particularly interesting is the surprisingly good ability to distinguish between humans and animals. This also indicates that we can choose to have limitations in the radar and still solve the classification task.

Series
International Radar Symposium Proceedings, ISSN 2155-5745
National Category
Communication Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-13059 (URN)000381801100095 ()978-1-5090-2518-3 (ISBN)
Conference
17th International Radar Symposium (IRS), MAY 10-12, 2016, Krakow, POLAND
Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-01-16Bibliographically approved
Björklund, S. (2015). Clutter Properties for a Side-Looking Radar with Planar Regular and Irregular Subarrays. In: 2015 16TH INTERNATIONAL RADAR SYMPOSIUM (IRS): . Paper presented at 16th International Radar Symposium (IRS), JUN 24-26, 2015, Dresden, GERMANY (pp. 730-735).
Open this publication in new window or tab >>Clutter Properties for a Side-Looking Radar with Planar Regular and Irregular Subarrays
2015 (English)In: 2015 16TH INTERNATIONAL RADAR SYMPOSIUM (IRS), 2015, p. 730-735Conference paper, Published paper (Refereed)
Abstract [en]

The effect of the subarray design in a side-looking moving radar with a planar antenna on some clutter properties which are important for suppressing the clutter with STAP (Space-Time Adaptive Processing) is investigated by simulations. These properties are interference DOA Doppler Spectrum (DDS) and clutter rank. The conclusions from the work is that irregular antennas give less clutter in the DDS and that larger subarrays give lower clutter rank.

Series
International Radar Symposium Proceedings, ISSN 2155-5745
Keywords
ARRAYS; RANK
National Category
Telecommunications Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-12963 (URN)000380372600159 ()978-3-9540-4853-3 (ISBN)
Conference
16th International Radar Symposium (IRS), JUN 24-26, 2015, Dresden, GERMANY
Available from: 2016-08-31 Created: 2016-08-30 Last updated: 2017-03-14Bibliographically approved
Björklund, S., Nelander, A. & Pettersson, M. (2015). Fast-Time and Slow-Time Space-Time Adaptive Processing for Bistatic Radar Interference Suppression. In: 2015 IEEE INTERNATIONAL RADAR CONFERENCE (RADARCON): . Paper presented at IEEE International Radar Conference (RadarCon), MAY 10-15, 2015, Arlington, VA (pp. 674-678). IEEE Communications Society
Open this publication in new window or tab >>Fast-Time and Slow-Time Space-Time Adaptive Processing for Bistatic Radar Interference Suppression
2015 (English)In: 2015 IEEE INTERNATIONAL RADAR CONFERENCE (RADARCON), IEEE Communications Society, 2015, p. 674-678Conference paper, Published paper (Refereed)
Abstract [en]

In bistatic radar with transmitter and receiver geographically separated the interference from ground clutter and the direct path signal transmitter-receiver will be strong and must be suppressed in order to detect the target. We apply FT-STAP (Fast-Time Space Time Adaptive Processing) to the suppression, which is unusual, and compare with conventional ST-STAP (Slow-Time STAP) by simulations in order to see whether FT-STAP is an alternative to ST-STAP. The performance of FT-STAP is much worse than of ST-STAP. We give an explanation for this, which also may be the basis for large improvements of FT-STAP. Moreover, we suggest two new performance measures.

Place, publisher, year, edition, pages
IEEE Communications Society, 2015
Series
IEEE Radar Conference, ISSN 1097-5764
Keywords
bistatic radar, clutter, rank, STAP, slow-time, fast-time
National Category
Signal Processing Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-11784 (URN)000370972900122 ()978-1-4799-8232-5 (ISBN)
Conference
IEEE International Radar Conference (RadarCon), MAY 10-15, 2015, Arlington, VA
Available from: 2016-04-01 Created: 2016-04-01 Last updated: 2017-03-06Bibliographically approved
Bjorklund, S., Petersson, H. & Hendeby, G. (2015). Features for micro-Doppler based activity classification. IET radar, sonar & navigation, 9(9), 1181-1187
Open this publication in new window or tab >>Features for micro-Doppler based activity classification
2015 (English)In: IET radar, sonar & navigation, ISSN 1751-8784, E-ISSN 1751-8792, Vol. 9, no 9, p. 1181-1187Article in journal (Refereed) Published
Abstract [en]

Safety and security applications benefit from better situational awareness. Radar micro-Doppler signatures from an observed target carry information about the target's activity, and have potential to improve situational awareness. This article describes, compares, and discusses two methods to classify human activity based on radar micro-Doppler data. The first method extracts physically interpretable features from the time-velocity domain such as the main cycle time and properties of the envelope of the micro-Doppler spectra and use these in the classification. The second method derives its features based on the components with the most energy in the cadence-velocity domain (obtained as the Fourier transform of the time-velocity domain). Measurements from a field trial show that the two methods have similar activity classification performance. It is suggested that target base velocity and main limb cadence frequency are indirect features of both methods, and that they do often alone suffice to discriminate between the studied activities. This is corroborated by experiments with a reduced feature set. This opens up for designing new more compact feature sets. Moreover, weaknesses of the methods and the impact of non-radial motion are discussed.

Keywords
Doppler radar, Fourier transforms, feature extraction, micro-Doppler based activity classification, radar micro-Doppler signatures, physically interpretable feature extraction, time-velocity domain, cadence-velocity domain, Fourier transform
National Category
Communication Systems
Identifiers
urn:nbn:se:bth-11346 (URN)10.1049/iet-rsn.2015.0084 (DOI)000365855500007 ()
Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2017-12-01Bibliographically approved
Björklund, S. (2015). Three-Dimensional DPCA with Rotating Antenna for Clutter Cancellation. In: 2015 IEEE Radar Conference (RadarCon): . Paper presented at IEEE International Radar Conference, Arlington, Virginia, USA (pp. 1579-1583). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Three-Dimensional DPCA with Rotating Antenna for Clutter Cancellation
2015 (English)In: 2015 IEEE Radar Conference (RadarCon), Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 1579-1583Conference paper, Published paper (Refereed)
Abstract [en]

In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. In a previous paper we saw that it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrived at a theoretical condition for this. In this new paper we extend the condition with rotating array antennas. We also formulate an optimization problem for, besides the clutter cancellation, also maximizing the target signal.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2015
Series
IEEE Radar Conference (RadarCon), ISSN 1097-5659
Keywords
Clutter, Radar antennas, Optimization, Radar clutter, Airborne radar
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-13637 (URN)10.1109/RADAR.2015.7131249 (DOI)978-1-4799-8232-5 (ISBN)
Conference
IEEE International Radar Conference, Arlington, Virginia, USA
Available from: 2016-12-18 Created: 2016-12-18 Last updated: 2017-01-16Bibliographically approved
Björklund, S., Nelander, A. & Pettersson, M. (2013). Auxiliary beam terrain-scattered interference suppression: reflection system and radar performance. IET Radar, Sonar & Navigation, 7(8), 836-847
Open this publication in new window or tab >>Auxiliary beam terrain-scattered interference suppression: reflection system and radar performance
2013 (English)In: IET Radar, Sonar & Navigation, ISSN 1751-8784, Vol. 7, no 8, p. 836-847Article in journal (Refereed) Published
Abstract [en]

Terrain-scattered interference (TSI), that is, jammer signals reflected on the earth's surface, is a significant problem to military airborne radar. In auxiliary beam TSI suppression, the TSI in the main radar beam is estimated by a single or several auxiliary beams and is subtracted from the main beam channel. The signal to subtract is the auxiliary beam signals fed through an estimate of the ‘reflection system’, which describes scattering on the surface. The authors first present results on the structure of this TSI suppression, on the estimation of the reflection system and on the quality of the estimate. Then the authors derive theoretical expressions for the signal-to-interference plus noise ratio (SINR) and the remaining TSI power for a single auxiliary beam. Since the SINR is directly connected to the radar performance, it can be seen what factors affect the performance and how. It was noted that when the estimated reflection system is missing one or more delays of the true system, the TSI filter cannot suppress the TSI signal completely. This phenomenon, which is called ‘TSI leakage’, has a very large impact on the performance. The SINR cannot be kept constant. Instead, an ‘SINR improvement’ can be defined.

Place, publisher, year, edition, pages
The Institution of Engineering and Technology (IET), 2013
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-6818 (URN)10.1049/iet-rsn.2011.0407 (DOI)000326459400002 ()oai:bth.se:forskinfo223552380FFF7A9DC1257C120071C02F (Local ID)oai:bth.se:forskinfo223552380FFF7A9DC1257C120071C02F (Archive number)oai:bth.se:forskinfo223552380FFF7A9DC1257C120071C02F (OAI)
Available from: 2013-12-17 Created: 2013-10-28 Last updated: 2017-01-16Bibliographically approved
Björklund, S., Henrik, P. & Gustaf, H. (2013). On Distinguishing between Human Individuals in Micro-Doppler Signatures. In: 14th International Radar Symposium (IRS), 2013: . Paper presented at International Radar Symposium (IRS), Dresden, Germany,. Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>On Distinguishing between Human Individuals in Micro-Doppler Signatures
2013 (English)In: 14th International Radar Symposium (IRS), 2013, Institute of Electrical and Electronics Engineers (IEEE), 2013Conference paper, Published paper (Refereed)
Abstract [en]

Radar micro-Doppler signatures (MDS) of humans are created by movements of body parts, such as legs and arms. MDSs can be used in security applications to detect humans and classify their type and activity. Target association and tracking, which can facilitate the classification, become easier if it is possible to distinguish between human individuals by their MDSs. By this we mean to recognize the same individual in a short time frame but not to establish the identity of the individual. In this paper we perform a statistical experiment in which six test persons are able to distinguish between walking human individuals from their MDSs. From this we conclude that there is information in the MDSs of the humans to distinguish between different individuals, which also can be used by a machine. Based on the results of the best test persons we also discuss features in the MDSs that could be utilized to make this processing possible.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2013
Keywords
Target tracking, Legged locomotion, Radar tracking, Doppler radar, Principal component analysis
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-13638 (URN)978-1-4673-4821-8 (ISBN)
Conference
International Radar Symposium (IRS), Dresden, Germany,
Available from: 2016-12-18 Created: 2016-12-18 Last updated: 2017-01-16Bibliographically approved
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