| 1. |
- Adalbjörnsson, Stefan Ingi, et al.
(författare)
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Sparse Localization of Harmonic Audio Sources
- 2016
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Ingår i: IEEE/ACM Transactions on Audio, Speech, and Language Processing. - 2329-9290. ; 24:1, s. 117-129
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a novel method for estimating the locations of near- and/or far-field harmonic audio sources impinging on an arbitrary, but calibrated, sensor array. Using a joint pitch and location estimation formed in two steps, we first estimate the fundamental frequencies and complex amplitudes under a sinusoidal model assumption, whereafter the location of each source is found by utilizing both the difference in phase and the relative attenuation of the magnitude estimates. As audio recordings often consist of multi-pitch signals exhibiting some degree of reverberation, where both the number of pitches and the source locations are unknown, we propose to use sparse heuristics to avoid the necessity of detailed a priori assumptions on the spectral and spatial model orders. The method’s performance is evaluated using both simulated and measured audio data, with the former showing that the proposed method achieves near-optimal performance, whereas the latter confirms the method’s feasibility when used with real recordings.
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| 2. |
- Ask, Erik, et al.
(författare)
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Minimal Structure and Motion Problems for TOA and TDOA Measurements with Collinearity Constraints
- 2013
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Ingår i: 2nd International Conference on Pattern Recognition Applications and Methods, Proceedings of. - 9789898565419 ; , s. 425-429
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Konferensbidrag (refereegranskat)abstract
- Structure from sound can be phrased as the problem of determining the position of a number of microphones and a number of sound sources given only the recorded sounds. In this paper we study minimal structure from sound problems in both TOA (time of arrival) and TDOA (time difference of arrival) settings with collinear constraints on e.g. the microphone positions. Three such minimal cases are analyzed and solved with efficient and numerically stable techniques. An experimental validation of the solvers are performed on both simulated and real data. In the paper we also show how such solvers can be utilized in a RANSAC framework to perform robust matching of sound features and then used as initial estimates in a robust non-linear leastsquares optimization.
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| 3. |
- Burgess, Simon, et al.
(författare)
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Indoor Localization Using Smartphones in Multi Floor Environments Without Prior Calibration or Added Infrastructure
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Indoor positioning for smart phone users has received a lot of attention in recent years. While many solutions have been developed, most rely on extra sensors, a need for predeployment of infrastructure or collecting ground truth data to train on. In this paper we see what can be done using only existing WiFi-infrastructure and Received Signal Strength from these, not using any extra sensors or calibration of the signal environment. We expand on previous work by using a multi floor model taking into account dampening between floors, and optimize a target function consisting of least squares residuals, to find positions for WiFis and the smartphone measurement locations. Experiments indicate that floor detection needs to be semi-supervised or in need of additional sensors. The method was tested inside two buildings, with tree stories each, with mean errors of smartphone positions of 15.2 m and 13.5 m respectively.
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| 4. |
- Burgess, Simon, et al.
(författare)
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Minimal Solvers for Unsynchronized TDOA Sensor Network Calibration
- 2014
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Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783642453465 ; , s. 95-110
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Konferensbidrag (refereegranskat)abstract
- Calibration of network nodes using only time differences of arrival (TDOA) measurements opens up for interesting applications in wireless ad-hoc sensor networks, e.g. finding the positions of cell phones by only ambient sounds or radio. We present two novel approaches for the problem of self-calibration of network nodes using only TDOA when both receivers and transmitters are unsynchronized. We consider the previously unsolved minimum problem of far field localization in three dimensions, which is to locate four receivers by the signals of nine unknown transmitters, for which we assume that they originate from far away. The first approach, the Ellipsoid TDOA method, is a geometric representation based on the fact that the time differences between four receivers characterize an ellipsoid. We calculate by linear least-squares regression the ellipsoid from the observed measurements of nine or more transmitters, by which the constellation of receivers is characterized. In the second approach we propose using linear algebra techniques on the matrix of unsynchronized TDOA measurements, enabling us to solve a set of linear equations for a parametrization of the unknowns. This approach is extended to more than four receivers and nine transmitters in a straightforward manner. In extensive experiments we evaluate and compare both approaches and analyze specific failure modes of the algorithms. Here, we demonstrate that the algorithms are robust to moderate Gaussian measurement noise and that the far field assumption is reasonable if the distance between transmitters and receivers is at least four times the distance between the receivers. In an indoor experiment using sound we reconstruct the microphone positions up to a mean error of 5 cm.
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| 5. |
- Burgess, Simon, et al.
(författare)
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Node Localization in Unsynchronized Time of Arrival Sensor Networks
- 2012
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Ingår i: 21st International Conference on Pattern Recognition (ICPR 2012), Proceedings of. - 9784990644116 ; , s. 2042-2046
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Konferensbidrag (refereegranskat)abstract
- We present a method for solving the previously unstudied problem of localizing a set of receivers and directions from transmitters placed far from the receivers, measuring unsynchronized time of arrival data. The same problem is present in node localization of microphone and antenna arrays. The solution algorithm using 5 receivers and 9 transmitters is extended to the overdetermined case in a straightforward manner. Degenerate cases are shown to be when i) the measurement matrix has rank 4 or less or ii) the directions from the transmitters to the receivers lie on an intersection between the unit sphere and another quadric surface. In simulated experiments we explore how sensitive the solution is with respect to different degrees of far field approximations of the transmitters and with respect to noise in the data. Using real data we get a reconstruction of the receivers with a relative error of 14%.
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| 6. |
- Burgess, Simon, et al.
(författare)
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Pose Estimation from Minimal Dual-Receiver Configurations
- 2012
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Ingår i: 21st International Conference on Pattern Recognition (ICPR 2012), Proceedings of. - 9784990644116 ; , s. 2553-2556
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Konferensbidrag (refereegranskat)abstract
- Using multiple receivers (microphones or antennas) in a rigid configuration, such as on a smartphone, it is possible to measure time difference of arrival to the receivers. This in turn can be used to determine the direction to the transmissions, if there are at least three receivers. When using two receivers it can be used to determine the angle to the transmissions relative to the line through the two receivers. In this paper we study three minimal problems for pose using such data: (i) determine position and orientation using five transmissions, (ii) determine position and orientation using four transmissions and known ’down’ direction and (iii) determine position using three transmissions and known orientation. Numerically stable solvers are implemented. An experimental validation of the solvers are performed on simulated data
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| 7. |
- Burgess, Simon, et al.
(författare)
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Smartphone Positioning in Multi-Floor Environments Without Calibration or Added Infrastructure
- 2016
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Ingår i: 2016 International Conference on Indoor Positioning and Indoor Navigation (IPIN). - 9781509024254
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Konferensbidrag (refereegranskat)abstract
- Indoor positioning for smartphone usershas received a lot of attention in recent years. Whilemany solutions have been developed, most rely on aneed for pre-deployment of infrastructure or collectingground truth data to train on. In this paper we see whatcan be done using existing WiFi-infrastructure andReceived Signal Strength from these to smartphones,not using any calibration of the signal environment ormanually set WiFi positions. We expand on previouswork by using a multi-floor model taking into ac-count dampening between floors, and optimize a targetfunction consisting of least squares residuals, to findpositions for WiFis and the smartphone measurementlocations simultaneously. Pressure sensors are used todo floor estimation. The method was tested inside twomulti-story buildings, with 5 stories each, with medianerrors of smartphone positions of 12.5m and 16.4m andwith WiFi median position errors of 7.16m and 19.4mrespectively. Correct floor detection was achieved for96% of all smartphone positions.
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| 8. |
- Burgess, Simon, et al.
(författare)
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TOA Sensor Network Calibration for Receiver and Transmitter Spaces with Difference in Dimension
- 2013
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Ingår i: 21st European Signal Processing Conference (EUSIPCO 2013).
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Konferensbidrag (refereegranskat)abstract
- We study and solve the previously unstudied problem of finding both sender and receiver positions from time of arrival (TOA) measurements when there is a difference in dimensionality between the affine subspaces spanned by receivers and senders. Anchor-free TOA network calibration has uses both in sound, radio and radio strength applications. Using linear techniques and requiring only a minimal number of receivers and senders, an algorithm is constructed for general dimension p for the lower dimensional subspace. Degenerate cases are determined and partially characterized as when receivers or senders inhabits a lower dimensional affine subspace than was given as input. The algorithm is further extended to the overdetermined case in a straightforward manner. Simulated experiments show good accuracy for the minimal solver and good performance under noisy measurements. An indoor environment experiment using microphones and speakers gives a RMSE of 2.35cm on receiver and sender positions compared to computer vision reconstruction.
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| 9. |
- Burgess, Simon, et al.
(författare)
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TOA sensor network self-calibration for receiver and transmitter spaces with difference in dimension
- 2015
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Ingår i: Signal Processing. - : Elsevier BV. - 0165-1684. ; 107:Online 11 June 2014, s. 33-42
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Tidskriftsartikel (refereegranskat)abstract
- We study and solve the previously unstudied problem of finding both transmitter and receiver positions using only time of arrival (TOA) measurements when there is a difference in dimensionality between the affine subspaces spanned by receivers and transmitters. Anchor-free TOA network calibration has uses both in radio, radio strength and sound applications, such as calibrating ad hoc microphone arrays. Using linear techniques and requiring only minimal number of receivers and transmitters, an algorithm is constructed for general dimension p for the lower dimensional subspace. Degenerate cases are determined and partially characterized as when receivers or transmitters inhabit a lower dimensional affine subspace than was given as input. The algorithm is further extended to overdetermined cases in a straightforward manner. Utilizing the minimal solver, an algorithm using the Random Sample Consensus (RANSAC) paradigm has been constructed to simultaneously solve the calibration problem and remove severe outliers, a common problem in TOA applications. Simulated experiments show good performance for the minimal solver and the RANSAC-like algorithm under noisy measurements. Two indoor environment experiments using microphones and speakers give a RMSE of 2.35 cm and 3.95 cm on receiver and transmitter positions compared to computer vision reconstructions.
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| 10. |
- Kuang, Yubin, et al.
(författare)
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A Complete Characterization and Solution to the Microphone Position Self-Calibration Problem
- 2013
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Ingår i: A. - 1520-6149. ; , s. 3875-3879
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Konferensbidrag (refereegranskat)abstract
- This paper presents a complete characterization and solution to microphone position self-calibration problem for time-of-arrival (TOA) measurements. This is the problem of determining the positions of receivers and transmitters given all receiver-transmitter distances. Such calibration problems arise in application such as calibration of radio antenna networks, audio or ultra-sound arrays and WiFi transmitter arrays. We show for what cases such calibration problems are well-defined and derive efficient and numerically stable algorithms for the minimal TOA calibration problems. The proposed algorithms are non-iterative and require no assumptions on the sensor positions. Experiments on synthetic data show that the proposed minimal solvers are numerically stable and perform well on noisy data. The solvers are also tested on two real datasets with good results.
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