PARALLEL SUBSPACE PROJECTION BEAMFORMING FOR AUTONOMOUS, PASSIVE SONAR SIGNAL PROCESSING

2003 ◽  
Vol 11 (01) ◽  
pp. 55-74
Author(s):  
KEONWOOK KIM ◽  
ALAN D. GEORGE
Keyword(s):  
Signal Processing ◽  
Distributed System ◽  
Wide Band ◽  
Subspace Projection ◽  
Adaptive Beamformer ◽  
Cluttered Environment ◽  
Execution Speed ◽  
Sonar Signal Processing ◽  
Performance Results

Adaptive techniques can be applied to improve performance of a beamformer in a cluttered environment. The sequential implementation of an adaptive beamformer, for many sensors and over a wide band of frequencies, presents a serious computational challenge. By coupling each transducer node with a microprocessor, in-situ parallel processing applied to an adaptive beamformer on a distributed system can glean advantages in execution speed, fault tolerance, scalability, and cost. In this paper, parallel algorithms for Subspace Projection Beamforming (SPB), using QR decomposition on distributed systems, are introduced for in-situ signal processing. Performance results from parallel and sequential algorithms are presented using a distributed system testbed comprised of a cluster of computers connected by a network. The execution times, parallel efficiencies, and memory requirements of each parallel algorithm are presented and analyzed. The results of these analyses demonstrate that parallel in-situ processing holds the potential to meet the needs of future advanced beamforming algorithms in a scalable fashion.

PARALLEL ALGORITHMS FOR SPLIT-APERTURE CONVENTIONAL BEAMFORMING

1999 ◽  
Vol 07 (04) ◽  
pp. 225-244 ◽  
Author(s):  
ALAN D. GEORGE ◽  
KEONWOOK KIM
Keyword(s):  
Parallel Algorithms ◽  
Distributed System ◽  
High Speed ◽  
Coarse Grained ◽  
Autonomous Operation ◽  
High Speed Network ◽  
Bearing Estimation ◽  
Execution Speed ◽  
Single Aperture ◽  
Performance Results

Quiet submarine threats and high clutter in the littoral undersea environment increase the processing demands on beamforming arrays, particularly for applications which require in-array autonomous operation. Whereas traditional single-aperture beamforming approaches may falter, the Split-Aperture Conventional Beamforming (SA-CBF) algorithm can be used to meet stringent requirements for more precise bearing estimation. Moreover, by coupling each transducer node with a microprocessor, parallel processing of the split-aperture beamformer on a distributed system can glean advantages in execution speed, fault tolerance, scalability, and cost. In this paper, parallel algorithms for SA-CBF are introduced using coarse-grained and medium-grained forms of decomposition. Performance results from parallel and sequential algorithms are presented using a distributed system testbed comprised of a cluster of workstations connected by a high-speed network. The execution times, parallel efficiencies, and memory requirements of each parallel algorithm are presented and analyzed. The results of these analyses demonstrate that parallel in-array processing holds the potential to meet the needs of future advanced sonar beamforming algorithms in a scalable fashion.

scholarly journals Location of agate geodes in Permian deposits of Simota gully using the GPR

2021 ◽  
Author(s):  
Michał Mierczak ◽  
Jerzy Karczewski
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Electromagnetic Energy ◽  
Reflection Coefficients ◽  
Electric Permittivity ◽  
Pyroclastic Deposits ◽  
High Attenuation ◽  
Subsurface Geology ◽  
Study Test

AbstractThe article describes the establishment of the location of agate geodes using the GPR method in the area of the Simota gully (Lesser Poland Voivodeship). Agates (a multicolored variety of gemstone of chalcedony group) have multifaceted values that informed their study. Traditional methods of geode location are less reliable, hence the attempt to use the GPR method. Measurements were taken at two study test sites with subsurface geology of weathered melaphyre and pyroclastic deposits using a GPR system (ProEx). A high-frequency antenna (1.6 GHz) was used along with the pre-established profiles of lengths of 6-m and 10-cm intervals. Furthermore, simple soil tests using the soil sampler tool were made prior to the GPR measurement. The GPR results show significant high attenuation of the electromagnetic energy interpreted to be due to clay components of the regolith. Advanced signal processing procedures (such as the attribute of the signal) were used on the data for better enhancement that aided interpretation. Other anomalies depicted on the radargrams were thought to be the presence of roots, pieces of melaphyres-targeted agates. Furtherance to ascertain the reflection coefficients as recorded on the GPR data, in situ samples (root pieces, melaphyres, agates) taken were tested in the laboratory for electric permittivity property. Based on the interpretation results, several agate geodes were dug out from the ground.

scholarly journals Application of Biphase Complete Complementary Code for Ionospheric Sounding

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2811 ◽  
Author(s):  
Guobin Yang ◽  
Peng Duan ◽  
Chunhua Jiang ◽  
Tongxin Liu ◽  
Ting Lan ◽  
...  
Keyword(s):  
Signal Processing ◽  
Cross Correlation ◽  
Technical Feasibility ◽  
Performance Results ◽  
Ionospheric Sounding

This paper illustrates the processes carried out for the application of biphase complete complementary code (CCC) for ionospheric sounding to address the coherent interference problem in multi-station ionospheric sounding. An algorithm to generate the biphase CCC is described, and the detailed process of waveform construction and signal processing is presented. Characteristics of the autocorrelation and cross-correlation are analyzed through simulations, and the technical feasibility of the application of CCC is explored. Experiments of ionospheric sounding with the CCC are also implemented to verify performance. Results demonstrate that the CCC performs well in multi-station ionospheric sounding, and is capable of eliminating the coherent interference in the network of ionosondes, compared to the conventional complementary code.

Structural Quality And Electrical Behavior Of Epitaxial High-κ Y2O3 / Si(001)

2002 ◽  
Vol 745 ◽  
Author(s):  
G. Vellianitis ◽  
G. Apostolopoulos ◽  
A. Dimoulas ◽  
K. Argyropoulos ◽  
B. Mereu ◽  
...  
Keyword(s):  
Leakage Current ◽  
Wide Band ◽  
Amorphous Layer ◽  
Ex Situ ◽  
Structural Quality ◽  
Wide Band Gap ◽  
Annealing Temperatures ◽  
Grown Sample ◽  
Transistor Fabrication

ABSTRACTY2O3 thin films were grown directly on Si (001) by MBE and annealed in-situ under UHV at various annealing temperatures. The samples were investigated in-situ by RHEED and ex-situ by HRTEM. A 7 to 15 Å thick non-uniform interfacial amorphous layer is observed in the as-grown sample. After annealing at 490°C under UHV for 30 minutes the amorphous layer is reduced and a sharp Y2O3/Si interface is obtained. At higher annealing temperatures, YSi2 islands start to form at the Y2O3/Si interface. I-V measurements performed on generic MIS structures show that the annealed samples exhibit higher leakage current density than the as-grown sample, due to reduction of the wide band gap interfacial layer. Leakage current densities in annealed samples remain below 1A/cm2, which is acceptable for future high-κ transistor fabrication.

Smart pixel-based wavelet transformation for wideband radar and sonar signal processing

1997 ◽  
Author(s):  
Barry L. Shoop ◽  
Andre H. Sayles ◽  
Glen P. Dudevoir ◽  
Dirk A. Hall ◽  
Daniel M. Litynski ◽  
...  
Keyword(s):  
Signal Processing ◽  
Wavelet Transformation ◽  
Sonar Signal Processing ◽  
Smart Pixel ◽  
Wideband Radar
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