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Due to waveguide dispersion and array shape distortion, target's energy spreads in the vicinity of direction of arrival in spatial orientation spectrum. To solve this problem, a spatial spectrum estimation method using beam signal spectral decomposition is proposed. Utilizing correlation between signals which spread in multiple beams, beam signal spectrum is decomposed using singular value decomposition...
This paper introduces the basic theory and method of compressed sensing, and its application in DOA estimation. The theory uses a new sampling method through sparse sampling and reconstruction of the signal to break through the limitation of the Nyquist sampling theorem, effectively solving the inherent shortcomings of classic spatial spectrum estimation algorithms.
The first modular 4-channel frontend for exploring phased array communications at a carrier frequency of 300 GHz was developed. A metamorphic HEMT process with a gate length of 35 nm was the key enabling technology for the integration of each transmit and receive channel. All channels implemented the quadrature direct conversion architecture. The measured RF bandwidth exceeded 55 GHz for the receive...
Future communication links will require higher data rates, multiple beams, and higher transmit/receive gains, in addition to smaller weight, cost, and power. With the growing interest for reduced size platforms and the requirement for ultra-wideband (UWB) performance to address multifunctionality, there is a strong need for UWB apertures to enable increased spectral efficiency, multifunctionality...
This work explores integrating sparse recovery methods into the ray space transform. Sparse recovery methods have proven useful in microphone array analysis of sound fields. In particular, they can provide extremely accurate estimates of source direction in the presences of multiple, simultaneous sources and noise. The ray space transform has recently emerged as a useful tool to analyse sound fields,...
Synthetic aperture sonar has the characteristics of high resolution imaging which is not limited by the detection range. It can be used for imaging and mapping of the seafloor. However, the product value of detection range and speed of navigation is limited by the physical length of the array in the traditional synthetic aperture sonar. When the speed of navigation is improved on condition that the...
In this paper, it is illustrated how to carry out adaptive processing simultaneously at multiple frequencies using the same antenna array consisting of dissimilar antenna elements nonuniformly spaced and deployed above an imperfect ground plane. First, an electromagnetic transformation technique is described which can compensate for all non-ideal effects of an antenna array deployed in a real environment,...
With the advent of the new class of radio telescopes as for example the LOw Frequency ARray (LOFAR) and the Square Kilometer Array (SKA) the necessity of using data mining procedures to handle the huge amount of data collected during their observations became crucial. Software design has resulted in a complete shift of methods by which information is collected in the radio frequency domain. Pointing...
As the medical ultrasound signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape. Thus, their reconstruction using adaptive beamformer (BF) become indispensable in order to improve the quality of the image. Generalized Side Lobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
An ultrasonic array system is designed for wirelessly powering and communicating with implantable medical devices. A flexible hardware interface is used to drive a 32-element linear phased array with emphasis on programmability and efficiency rather than bandwidth or peak power. Various beam patterns and data modulation schemes are verified at a depth of 6 cm in a tissue phantom with more than sufficient...
Ultrasound (US) therapy is, for a large panel of application, a promising technique which still requires an accurate monitoring system. Therefore, the passive acoustic mapping (PAM) beamforming technique is outlined. It reconstructs cavitation activity maps by beamforming acoustic signals passively recorded by an array. This method has already been explored in 2D with optimizations as phase coherence...
In the past, members of our group developed a model based beamforming method called aperture domain model image reconstruction (ADMIRE). They tuned ADMIRE to improve ultrasound image quality by suppressing sources of image degradation such as off-axis scattering, reverberation, and phase aberration. In addition, the development of ADMIRE demonstrated that beamforming could be posed as a regularized...
As medical ultrasound (MU) signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape; thus, their reconstruction using Adaptive Beamformers (BF) becomes indispensable in order to improve the quality of the imaging system. Generalized Sidelobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
A novel multi-dimensional noise-shaping method is proposed to extend Δ-Σ modulation to the two-dimensional (2-D) (space, time) case. It uses spatial oversampling to provide another degree of freedom for ADC designers to shape quantization noise when temporal oversampling is limited. The method uses lossless discrete integrators (LDIs) to implement spatial integrators and is suitable for use in microwave...
The performance of superdirective beamforming of a practical circular hydrophone array is investigated. The received signal of a 16-element circular hydrophone array with radius of 0.25m are measured in the anechoic water tank. The array manifold at the frequency of 1.11kHz is obtained. The superdirective beamforming of the circular array is designed and realized. The correctness and effectiveness...
In this paper, we present a greedy sensor selection algorithm for minimum variance distortionless response (MVDR) beamforming under a modular budget constraint. In particular, we propose a submodular set-function that can be maximized using a linear-time greedy heuristic that is near optimal. Different from the convex formulation that is typically used to solve the sensor selection problem, the method...
Radio frequency interference (RFI) has becoming a seriously limitation in the retrieval of geophysical parameters from the measurements of microwave radiometers. In this work, a novel RFI localization approach is presented here to improve the computationally complexity by using virtual arrays and direction of arrival (DOA) estimations techniques. The proposed RFI localization method utilizes the underlying...
The security of public places has been greatly concerned by the government and organizations in recent decades. Detecting the crowd flow in public places can help alerting the congestion of the channel immediately and making an immediate evacuation policy to prevent the occurrence of extrusion stampede. However, the common detection techniques require special additional hardware components that suffer...
In this paper, a beamforming system for LTE- Advanced based on Array sampling technology is proposed. Antenna Array that has been designed covers LTE mid and high bands. RF multiplexer 8x1 switch has been designed and simulated. The system is composed of agile RF frontend and FPGA digital signal processing unit.
This paper tests and demonstrates the ability of a twin set of passive radar systems to monitor real time an area of interest and track medium size targets. The results are based on a real data acquisition campaign performed using two eleven element array antenna based passive radars in the Oslo fjord area in September 2016.
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