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In order to avoid eavesdropping, beamforming can be used not only to induce artificial noise or jamming signal to an eavesdropper, but also transmit desired signals to a legitimate user (or sensor) from an access point (AP) equipped with an antenna array. In this paper, with proper power allocation, we show that beamforming under a rich scattering environment can guarantee a certain secrecy rate with...
Most existing source enumeration methods provide a satisfactory performance in high or middle signal-to-noise ratio (SNR), but almost lose effectiveness at low SNR. This paper proposed a source enumeration method based on squared Euclidean norm of the vector, the multiplication of the steering matrix and the left singular value vector of Hankel matrices for low SNR, which introduces the construction...
We propose a Wiener filter design method for collecting target sources on a noisy sports field. Because the noise on a sports field, e.g., cheering from the audience, arrives from the same direction as that of the targeted source, it is difficult to accurately design a Wiener filter by simply using spatial cues. This study focused on a combination of spatial cues and acoustic feature modeling. The...
An RF Phased array can steer the direction of the beam electronically and it brings about benefits in terms of signal to noise ratio (SNR) and directivity. However, testing the phased array generally requires expensive and high performance RF equipment. This increases production test cost and hampers in-field calibration. We present a low-cost, self-compensating Built-In Self-test (BIST) and calibration...
In this paper we propose a novel Track Before Detect (TBD) filter aimed at tracking multiple extended targets from phased-array observations. For extended targets, the source signal is angularly distributed, and hence we track the centroid Direction Of Arrival (DOA) of the target generated signal — called target signal. In this work we suppose known the shape and extent of the target-signal angular...
The proposed method realizes adaptive reduced-dimension processing based on joint optimization of both reduced-dimension matrix and beam-forming weight vector. Meanwhile, the spatial spectrum reconstruction technology is used to update the covariance matrix of array data online. The simulation results show that the proposed method is robust to the dimension of the reduced-dimension matrix and significantly...
We discuss the application of the sparse processing techniques in the differential breast-cancer imaging. We derive the sparse model by assuming that the parameters of the inhomogeneous breast model are known from the previous measurements. In the linear model, we use the numerically computed three-dimensional Green's functions. We investigate the role of the regularization parameter and the number...
Conformal arrays, distributed processors and bistatic architectures allow us to develop more and more effective phased array multifunction radars. In particular, conical (as well as cylindrical) arrays permit to avoid scan angle losses, and multiple sub-arrays with digital beamforming enhance the time-energy efficiency by executing in parallel the various radar tasks. A system architecture, now under...
The small degrees of freedom (DOFs) and low SNR of incoming signal lead to direction of arrival (DOA) estimation performance degradation. A spacetime signal processing method for DOA estimation is presented. This method takes advantage of the spatial and temporal statistics of the incoming signal, expanding the dimensions of covariance matrix by increasing the time delay taps which can reduces the...
Giant Ukrainian Radio Telescope (GURT) is a low-frequency one with active phased antenna array, which is being built in Ukraine in addition to the existing UTR-2 radio telescope. In this paper we consider the signal-to-noise ratio in active antenna, which is used as an element of GURT radio telescope antenna array. The sensitivity of the element mainly determines the sensitivity of not only the entire...
A low complexity frequency domain bearing estimation technique is described in this paper. The technique presented makes use of a pair of orthogonal dipoles or differential sensors along with an omni directional pressure sensor for the bearing estimation. The paper describes the theory from first principles with an overview of the simulation results and also covers the proof of concept experimental...
In this paper, a compression technique for ECG signal using low-rank matrix approximation based on inter and intra beat correlation, is presented. Here, singular value decomposition (SVD) has been exploited to explore the low rank representation using truncation process that stores most significant data with few singular values. In this method, two dimensional (2-D) array of ECG signal is constructed...
The ASKAP radio telescope in Australia is the first synthesis imaging array to use phased-array feeds (PAFs). These permit wider fields of view and new modalities for radio-frequency interference (RFI) mitigation. Previous work on imaging-array RFI cancellation has assumed that processing bandwidths are very narrow, and correlator integration times are short. However, these assumptions do not necessarily...
Directional antennas shape transmission patterns to provide greater coverage distance and reduced coverage angle. When used in an ad-hoc network, this reduces interference among transmitting nodes and thereby increases throughput. A problem that has not been addressed is how to compute individual beam patterns that maximize some measure of global network performance. Historically, the focus has been...
In this paper a robust Audio steganography technique is proposed by randomizing and dynamically changing the embedding sequence. Advance Encryption standards is used for providing additional security and robustness to the algorithm and tested for the 30 speech files. The addition of cryptography in steganography increases the robustness and introduces a higher level of security since the key is required...
Direction Of Arrival (DOA) estimation is a well known problem that has been studied through a wide range of different approaches and methods. Most of these methods make use of several snapshots in the array to provide an accurate result but their performance is commonly degraded when only a single snapshot is available. An improved ESPRIT algorithm to the problem of direction of arrival (DOA) estimation...
A method for electromagnetic radiation source identification is proposed. The spatial characteristic of a radiation source is taken as the unique parameter for support vector machines (SVMs) to identify. First, the location of radiation source is determined by the triangulation method, and then its spatial characteristic is collected by a band receiver array with simulation, which removes the limit...
For an antenna array input mixture of m point source signals in K-distributed noise, we compare DOA estimation delivered by Maximum Likelihood and the recently introduced Robust G-MUSIC (RG-MUSIC) technique. We demonstrate that similar to the Gaussian case, MLE is still superior to RG-MUSIC, especially within the so-called threshold region. This makes it possible to use the Expected Likelihood (EL)...
The relative transfer function (RTF), i.e. the ratio of acoustic transfer functions between two sensors, can be used for sound' source localization / beamforming based on a microphone array. The RTF is usually defined with respect to a unique reference sensor. Choosing the reference sensor may be a difficult task, especially for dynamic acoustic environment and setup. In this paper we propose to use...
This work presents a cost-effective low-rank technique for designing robust adaptive beamforming (RAB) algorithms. The proposed technique is based on low-rank modelling of the mismatch and exploitation of the cross-correlation between the received data and the output of the beamformer. We construct a linear system of equations which computes the steering vector mismatch based on prior information...
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