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Phased array radio telescopes allow for the filtering of Radio Frequency Interference (RFI) in the spatial domain. Spatial filters are advantageous in radio astronomy when the separation between RFI and astronomical sources cannot be made in the time or frequency domains. Consequently, the mitigation of the RFI relies on the quality of its spatial signature vector (SSV) estimation. The latter depends...
This paper presents a weighted version of shooting method for high-resolution Direction Of Arrival (DOA) estimation based on Sparse Spectrum Fitting (SpSF). SpSF is one of the sparse DOA estimation methods based on ℓ1-regularization which uses the penalty term in optimization. The regularization process often takes long time and is very sensitive to the penalty term, but it is difficult to know its...
Failed elements will destroy the array performance, therefore methods to compensate for array element failures are important. Generally, there are two different lines to address this problem, reconstructing missing array element signals and reoptimize the weights of the remaining array elements according to a desired performance criterion. In this paper, a novel way termed Doubly Weighted Average...
The paper presents a method of echo azimuth angle estimation for ultrasonic range finders. The method is based on phase shift determination. Because of size of applied transducers it is not possible to determine the shift in a direct way. This problem is discussed and error analysis is presented as well as some experimental results.
Beamforming is a famed signal processing technique which boosts the signal power received from the desired direction. The threedimensional (3D) beamforming technique has obtained a growing attention due to its potential that enables several strategies like user specific elevation beamforming and vertical sectorization compared to conventional horizontal beamforming. In this paper, a new 3D multi-band...
In this paper, we propose a 2-dimension bearing estimation method based on spatial time-frequency analysis. We generalize spatial power spectrum based on wavelet transform (SPS-WT) to 3-dimension space. By analyzing the relationship between the wavelet transform of the frequency invariant beam's output and the array's beampattern, we derived SPS-WT in 3-dimension space. The method has good performance...
In order to remove desired signal component from the sample covariance matrix, a novel robust adaptive beamformer is proposed based on desired signal covariance matrix estimation. The desired signal direction is first calculated based on the first-order Taylor series approximation, and then the desired signal's steering vector and power are estimated by using iterative robust minimum variance beamforming,...
The increasing spectrum occupancy is a serious threat for highly sensitive astronomical measurement at radio frequencies. The deployment of array radio telescopes allows the exploitation of spatial information regarding sources of radio frequency interference (RFI) in order to filter them out of astronomical data and theoretical recover uncorrupted time and frequency data. This paper introduces the...
A method is proposed for reducing the effect of white noise in wideband uniform linear arrays via a combination of a judiciously designed transformation followed by highpass filters. The reduced noise level leads to a higher signal to noise ratio for the system, which can have a significant effect on the performance of various direction of arrival (DOA) estimation methods. As a representative example,...
A coprime sensor array (CSA) estimates the spatial power spectral density (PSD) of the observed signal by multiplying one conventionally beamformed subarray scanned response with the complex conjugate of the other. This product processor removes the CSA subarray spatial aliasing ambiguities, but has a peak sidelobe higher than the peak sidelobe of a fully populated uniform linear array (ULA). Moreover,...
The paper presents an improved multiple signal classification algorithm based on coherent signals sources to estimate the direction of the arrival coherent signals. In the process of implement the algorithm, data eigen values are first decomposed from the received signal sources, and then using the relationship between the signal subspace corresponding to big eigen value and the signal steering vector...
Systems based on Synthetic Aperture Radar Tomography at low frequencies offer 3D imaging capabilities, appropriate for forest monitoring. However the extraction of an ecologically meaningful measure of forest structure from the 3D reflectivity is not straightforward and several considerations need to be carefully taken into account, in order to avoid misinterpretations of the nature of the information...
The aim of this work is to design a direction finding system that uses arbitrarily oriented and spaced, short dipole antenna array, and examine the array elements orientation and position perturbation effects on the accuracy of the estimated angle of arrival (AoA). The Min-Norm Angle of Arrival estimation method is modified through the standard Lagrange Optimization Method to accommodate variations...
This paper introduces the Array-based Compressed sensing Receiver Architecture (ACRA). ACRA allows digital receiver arrays to operate at dramatically larger instantaneous bandwidths by sampling the signals from different array elements at different sub-Nyquist sampling rates. Signal processing inspired by the sparse fast Fourier transform allows for signal detection, estimation, and angle-of-arrival...
In order to reduce the computation complexity during the multi-dimension iterative search of the MUSIC algorithm used to estimate the polarization and DOA of incident signal, an improved algorithm for estimating the polarization and DOA is proposed based on a polarization sensitive uniform array. Firstly, the polarization and DOA of the incident signal are coarsely estimated by a beam forming method...
The main purpose of synthetic aperture radar tomography (T-SAR) is to retrieve the vertical distribution of the backscattered power within a range-azimuth resolution cell, allowing three dimensional (3-D) imaging of volumetric targets. The achievable resolution of conventional spectral estimators, used to tackle with the T-SAR vertical distribution estimation problem, highly depends on the span of...
When the femtocell base station has perfect channel state information, it can adopt beamforming to avoid interference. However, the perfect channel assumption may not be practicable due to the channel-state information delay, channel estimator error, and bandwidth wastage while reporting channel parameters. In this paper, we proposed an angle of arrival (AOA) based beamforming structure for orthogonal...
LTE License-Assisted Access (LTE-LAA) in unlicensed spectrum has drawn a lot of attention due to its appealing data traffic offloading potential. However, the coexistence of LTE and WiFi technologies in the same unlicensed bands needs careful design to avoid severe interference between them. In this paper, we propose a coexistence scheme to create opportunities for LTE-LAA small cells and WiFi devices...
In this paper we propose for comparative analysis of wideband direction of arrival (DOA) estimation methods with nested array. Previously developed methods, Incoherent method, Coherent signal subspace processing (CSSM) and Weighted average of signal subspace (WAVES) could not perform satisfactory DOA estimation due to the single dimensionality and associated with lesser degree of freedom. In nested...
Direction of Arrival (DOA) estimation implies estimating the direction concerning angles of arrival of the received signals by an array of elements. This paper presents a review to a comparative analysis of several DOA estimation algorithms broadly classified into Beamforming (Classical & Capon's) and Subspace-based techniques (Multiple Signal Classification (MUSIC), Minimum Norm and Root-MUSIC)...
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