Recently, the authors proposed a miniaturized microphone array not utilizing the phase difference but utilizing the directivity of each microphone, namely aggregated microphones. We have already showed that the phased...
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ISBN:
(纸本)1424403081
Recently, the authors proposed a miniaturized microphone array not utilizing the phase difference but utilizing the directivity of each microphone, namely aggregated microphones. We have already showed that the phased microphone array and the aggregated microphones can be described within the same framework. We have also showed that it is possible to apply the aggregated microphones to the various methods of the phased microphone array. However, the difference of the performance between the phased array and the aggregated microphones has not been evaluated yet. The effect of the directivity and the posture of each microphone on the performance of the aggregated microphones has not also been evaluated yet. In this paper, we evaluate the performance of DCMP (Directionally Constrained Minimization of Power) adaptive array utilizing aggregated microphones.
Local processing on the nodes of a distributed sensing andprocessing system has the benefits of reducing the data volume transferred from the nodes to the fusion center, reducing both transmission power requirements ...
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ISBN:
(纸本)1424403081
Local processing on the nodes of a distributed sensing andprocessing system has the benefits of reducing the data volume transferred from the nodes to the fusion center, reducing both transmission power requirements and the computational burden on the fusion center. The individual nodes obtain measurements from the environment and transmit a quantized detection statistic to the fusion center. Quantization threshold levels need to be found for each sensor that maximize the performance of the system. We propose a global optimization method, the particle filtering optimization method, that uses particle filtering to propagate the values of the thresholds of a distributed detection system to sensor threshold values that are optimal with respect to some measure of system performance. We demonstrate, through simulations, the effectiveness of the particle filtering optimization method in finding the threshold of each of the sensors used in detection scenario.
Wireless sensor networks have been applied successfully in real-time distributed and collaborative sensing. In these situations, each sensor is responsible for extracting pertinent information from the surrounding env...
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ISBN:
(纸本)1424403081
Wireless sensor networks have been applied successfully in real-time distributed and collaborative sensing. In these situations, each sensor is responsible for extracting pertinent information from the surrounding environment and transmitting it to other sensors and/or to the main processing station. This is done while operating under several constraints, such as low computational capabilities, limited arithmetic precision, and the need to conserve power. In this paper, we present a low-complexity voice activity detector and a gender classifier for implementation on the Crossbow sensor motes. In addition, a decision fusion algorithm that resides at the base station is also implemented. A series of experiments that characterize the performance of the algorithms under varying conditions and in different environments are presented and several of the challenges we faced in developing this real-time implementation are discussed.
For low frequency observations (< 300 MHz) the radio astronomical community is currently developing a number of new instruments such as the low frequency array (LOFAR), the Mileura wide field array (MWA) and the pr...
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ISBN:
(纸本)1424403081
For low frequency observations (< 300 MHz) the radio astronomical community is currently developing a number of new instruments such as the low frequency array (LOFAR), the Mileura wide field array (MWA) and the primeval structure telescope (PaST). These telescopes require new calibration algorithms since phased arrays require an all-sky approach to imaging and calibration. This implies that the calibration will generally have to deal with a multitude of sources. In this paper we will discuss a muldsource calibration method to estimate the gains and phases of the receiving elements without having to solve for the receiver noise powers at the same time. Our method is able to handle arbitrary known source models. We will show that the proposed algorithm is asymptotically efficient by comparing the results from Monte Carlo simulations with the Craimer-Rao bound for the underlying data model.
On small platforms, angle-of-arrival (AOA) estimation of an E-M signal can be accomplished with colocated antennas measuring multiple components of the propagating wave. An electrically small Vector sensor (VS) Antenn...
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ISBN:
(纸本)1424403081
On small platforms, angle-of-arrival (AOA) estimation of an E-M signal can be accomplished with colocated antennas measuring multiple components of the propagating wave. An electrically small Vector sensor (VS) Antenna constructed above and below the wing of a small UAV measures three components of the propagating wave. Determining the AOA involves fitting known "calibration" AOAs and corresponding antenna response to a modeled response. The least-squares calibration approach described here determines the azimuth and elevation AOAs for sources located at typical elevation angles to within a few degrees, agreeing with the Cramer-Rao Lower Bound (CRLB). These results justify the use of small VS antennas to do direction finding (DF) in high SNR environments.
The use of multi-dimensional wave extraction algorithm for a multi-receivers axial transmission ultrasound device used in bone evaluation is proposed. As far as we know, multidimensional signalprocessing techniques h...
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ISBN:
(纸本)1424403081
The use of multi-dimensional wave extraction algorithm for a multi-receivers axial transmission ultrasound device used in bone evaluation is proposed. As far as we know, multidimensional signalprocessing techniques have never been implemented in this configuration. A SVD-based wave-front extraction is implemented for the characterization of an energetic low frequency contribution. Velocity accuracy is estimated on a synthetic dataset. Furthermore, the energetic low frequency removal is illustrated on in vivo signals. Results are promising as for the application of multidimensional techniques in medical ultrasound used in transmission.
Mobile satellite terminals especially with high-gain antenna require fast and accurate beam tracking algorithms for communication. The main topic of this paper is the extension of a tracking algorithm to mobile satell...
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ISBN:
(纸本)1424403081
Mobile satellite terminals especially with high-gain antenna require fast and accurate beam tracking algorithms for communication. The main topic of this paper is the extension of a tracking algorithm to mobile satellite communications, its implementation and performance. The presented considerations and simulation results concern low SNR condition and narrow antenna beam configuration as existing in satellite communications. The assumed satellite is geostationary. The work is presented in context of SANTANA-2 project, (Smart Antenna Terminal), founded and supported by the German DLR on behalf of BMBF. The realized terminal uses an antenna array in Ka-band and fully implements Digital BeamForming (DBF) to control the beam pointing direction and the antenna beam shape.
Secondary Surveillance Radar (SSR) based on multilateration principle and omni-directional antennae are operational today [1, 2]. We proposed new algorithms to separate a mixture of overlapping SSR replies on a M-elem...
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ISBN:
(纸本)1424403081
Secondary Surveillance Radar (SSR) based on multilateration principle and omni-directional antennae are operational today [1, 2]. We proposed new algorithms to separate a mixture of overlapping SSR replies on a M-elements antenna in previous works [3, 4], other solutions were also proposed in the literature [5, 6, 7]. Unfortunately, all have either some shortcomings, or an expensive computational cost, or no simple practical implementation. Therefore, there is a need for reliable, simple, effective algorithms to separate multiple SSR signals. Real recorded signals in a live environment are used to demonstrate the effectiveness of the proposed techniques.
It is known that blind timing synchronization of OFDM systems can be realized for AWGN channels using the redundant information of cyclic prefix. In this paper, we extend the blind method to the case of array receiver...
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ISBN:
(纸本)1424403081
It is known that blind timing synchronization of OFDM systems can be realized for AWGN channels using the redundant information of cyclic prefix. In this paper, we extend the blind method to the case of array receivers via adaptive beamforming, and a new approach is proposed to improve the synchronization accuracy for high data rate OFDM systems, where rich multipath rays are present. The extended method is to coherently combine the desired signals of array receivers and suppress the undesired signals using adaptive beamforming. And the approach is to reduce the effect of multipath rays on synchronization. Simulation results show that in rich multipath scenarios the approach works effectively both in the absence and the presence of carrier frequency offset.
Synthetic Aperture Radar (SAR) imaging technology has continued to evolve over the last few decades and the future holds promise. Beam raster scanning for 2D flyover SAR is yet another milestone in the evolutionary pa...
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ISBN:
(纸本)1424403081
Synthetic Aperture Radar (SAR) imaging technology has continued to evolve over the last few decades and the future holds promise. Beam raster scanning for 2D flyover SAR is yet another milestone in the evolutionary path of SAR imaging. This SAR imaging technique may have application in areas like passive unmanned aerial vehicle SAR. This paper builds on the 2D aperture synthesis concepts based upon rigorous analytical results presented by the authors earlier and elucidates the characteristics of sombrero point spread function and reconstruction in comparison to sine point spread function and reconstruction. This paper also explains the concept of 2D target area data collection scheme called flyover beam raster scanning.
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