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Cooperative multi-user detection and ranging based on pseudo-random codes

ADVANCES IN RADIO SCIENCE 2009年 7卷 55-59页

作者： Morhart, C. Biebl, E. M. Tech Univ Munich Fachgebiet Hochstfrequenztech Munich Germany

We present an improved approach for a Round Trip Time of Flight distance measurement system. The system is intended for the usage in a cooperative localisation system for automotive applications. Therefore, it is designed to address a large number of communication partners per measurement cycle. By using coded signals in a time divison multiple access order, we can detect a large number of pedestrian sensors with just one car sensor. We achieve this by using very short transmit bursts in combination with a real time correlation algorithm. Futhermore, the correlation approach offers real time data, concerning the time of arrival, that can serve as a trigger impulse for other comunication systems. The distance accuracy of the correlation result was further increased by adding a fourier interpolation filter. The system performance was checked with a prototype at 2.4 GHz. We reached a distance measurement accuracy of 12 cm at a range up to 450 m.

关键词： .pedestrian ranging automotive applications distance measurement correlation algorithm Cooperative multi-user detection based on pseudo-random measurement cycle car sensor correlation result fourier interpolation

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SIGNAL PROCESSING METHOD OF AMBIENT TRACE-GAS MONITORING WITH TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY

SIGNAL PROCESSING METHOD OF AMBIENT TRACE-GAS MONITORING WIT...

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IEEE Youth Conference on Information, Computing and Telecommunication

作者： Xia, Hui Liu, Guoqiang Liu, Wenqing Zhang, Yujun Chinese Acad Sci Inst Elect Engn Beijing 100190 Peoples R China Chinese Acad Sci Anhui Inst Opt & Fine Mech Hefei 230031 Peoples R China

ISBN: (纸本)9781424450756

Tunable diode laser absorption spectroscopy (TDLAS) is a new method to detect trace-gas qualitatively or quantificationally based on the scan characteristic of the diode laser to obtain the absorption spectroscopy in the characteristic absorption region. It needs to combine with a long absorption path in the ambient trace-gas measurements. TDLAS has a significant advantage not only in sensitivity but also in rapidity of response. It has been widely used in many atmospheric trace-gases detection, ground trace-gas detection and gas leakage detection. On-line signal processing is necessary to most trace gas monitor. In this paper, data processing method for retrieval of gas concentration, as well as the wavelength alignment algorithm based on correlation detecting technique is described, realizing the aim of wavelength alignment between the standard signal spectral line and the measurement signal spectrum. So the precision of the retrieving system is improved satisfactorily.

关键词： Adaptive signal processing atmospheric measurements tunable diode laser absorption spectroscopy wavelength alignment correlation algorithm

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Real time phase-slopes calculations by correlations using FPGAs

Real time phase-slopes calculations by correlations using FP...

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Conference on Adaptive Optics Systems

作者： Trujillo Sevilla, J. Valido, M. R. Rodriguez Ramos, L. F. Boemo, E. Rosa, F. Rodriguez Ramos, J. M. Univ La Laguna Fac Ciencias Fis San Cristobal la Laguna 38202 Spain Inst Astrofis ES-38200 La Laguna Spain Univ Autonoma Madrid Spain

ISBN: (纸本)9780819472250

ELT laser guide star wavefront sensors are planned to handle an expected amount of data to be overwhelmingly large (1600 x 1600 pixels at 700 fps). According to the calculations involved, the Solutions Must consider to run on specialized hardware as Graphical Processing Units (GPUs) or Field Programmable Gate Arrays (FPGAs), among others. In the case of a Shack-Hartmann wavefront sensor is finally selected, the wavefront slopes can be computed using centroid or correlation algorithms. Most of the developments are designed using centroid algorithms, but precision ought to be taken in account too, and then correlation algorithms are really competitive. This paper presents an FPGA-based wavefront slope implementation, capable of handling the sensor Output stream in a massively parallel approach, using a correlation algorithm previously tested and compared to the centroid algorithm. Time processing results are shown, and they demonstrate the ability of the FPGA integer arithmetic in the resolution of AO problems. The selected architecture is based in today's commercially available FPGAs which have a very limited amount of internal memory. This limits the dimensions used in Our implementation, but this also means that there is a lot of margin to move real-time algorithms from the conventional processors to the future FPGAs, obtaining benefits from its flexibility, speed and intrinsically parallel architecture.

关键词： Adaptive optics. wavefront phase slopes correlation algorithm centroid algorithm Sack-Hartmann sensor FPGA real-time processing

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Effect of image structure on the accuracy of correlation algorithm for measuring the displacement of image

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Guangxue Jishu/Optical Technique 2005年第SUPPL.期31卷 130-132页

作者： Shi, Hai-Feng Hu, Xin-Qi Department of Photo-electronic Engineering Beijing Institute of Technology Beijing 100081 China

The correlation algorithm for calculation of the displacement of images was presented, and the effect of image structure on the accuracy of the algorithm was focused on. In computer simulation, images with different structure are obtained by using low pass filter, and a method of using high resolution images is used to produce low resolution images with sub-pixel movements.

关键词： correlation algorithm Image matching Structure of image Wave-front sensor

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Stress intensity factor gauging by digital image correlation: Application in cyclic fatigue

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STRAIN 2007年第3期43卷 181-192页

作者： Hamam, R. Hild, F. Roux, S. Univ Paris 06 CNRS ENS Cachan LMT CachanUMR 8535 F-94235 Cachan France CNRS UMR 125 Lab surface Verre & Interfaces F-93303 Aubervilliers France

A fatigue crack in steel (CCT geometry) is studied via digital image correlation. The measurement of the stress intensity factor (SIF) change during one cycle is performed using a decomposition of the displacement field onto a tailored set of elastic fields. The same analysis is performed using two different routes, namely, the first one consists in computing the displacement field using a general correlation technique providing the displacement field projected onto finite element shape functions, and then analysing this displacement field in terms of the selected mechanically relevant fields. The second strategy, called integrated approach, directly estimates the amplitude of these elastic fields from the correlation of successive images. Both procedures give consistent results, and offer very good performances in the evaluation of the crack tip position (uncertainty of about 20 mu m for a 14.5-mm crack), SlFs (uncertainty < 1 MPav root m) and opening properties.

关键词： correlation algorithm crock opening identification technique integrated approach photomechanics

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Stress intensity factor gauging by digital image correlation: Application in cyclic fatigue

Stress intensity factor gauging by digital image correlation...

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International Conference on Photomechanics

作者： Hamam, R. Hild, F. Roux, S. Univ Paris 06 CNRS ENS Cachan LMT CachanUMR 8535 F-94235 Cachan France CNRS UMR 125 Lab surface Verre & Interfaces F-93303 Aubervilliers France

关键词： correlation algorithm crock opening identification technique integrated approach photomechanics

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Digital image correlation: from displacement measurement to identification of elastic properties - a review

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STRAIN 2006年第2期42卷 69-80页

作者： Hild, F Roux, S Univ Paris 06 LMT Cachan CNRS ENS CachanUMR 8535 F-94235 Cachan France CNRS Lab Surface Verre Interfaces UMR 125 F-93303 Aubervilliers France

The current state of the art of digital image correlation, where displacements can be determined for values less than one pixel, enables one to better characterise the behaviour of materials and the response of structures to external loads. A general presentation of the extraction of displacement fields from pictures taken at different instants during an experiment is given. Different strategies can be followed to determine subpixel displacements. New identification procedures are then devised making use of full-field measurements. A priori or a posteriori routes can be followed. They are illustrated on the analysis of a Brazilian disk test.

关键词： Brazilian disk test correlation algorithm integrated approach kinematic measurements photomechanics

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Young's Modulus extraction methods for soft tissue from ultrasound measurement system

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INSTRUMENTATION SCIENCE & TECHNOLOGY 2006年第4期34卷 393-404页

作者： Li, XF Wang, GL Huang, LH Zhang, GX Tianjin Univ State Key Lab Precise Measurement Technol & Instr Tianjin 300072 Peoples R China

Young's Modulus of soft tissue is a key index to evaluate the biomechanical features of the soft tissue;it has a close relationship to the force and deformation of the soft tissue. In order to measure the force and the deformation of soft tissue, a specially designed device is used to link ultrasound and force transducers by mounting them in series. The combined transducers can simultaneously sense the compressive force and the deformation of the soft tissue. The measurement system is calibrated, before it is used, to collect the data. Based on the measured force and the measured deformation of the soft tissue, the analytics biomechanical model of the soft tissue can be obtained by data fitting. In this paper, the biomechanical model of the soft tissue is assumed to be linear and possess viscous elasticity;when the model of the soft tissue is a linear model, the derived Young's Modulus of the soft tissue is a constant;when the model of the soft tissue is a viscoelastic model, the derived Young's Modulus is a function of the deformation of the tissue. Calibration data show that the maximal error of the measurement system is less than 1.9 mu m, non-linearity error gamma(T) is +/- 0.06%, and the static error band g is +/- 0.07%. The measurement system can be used to diagnose the pathology of soft tissue.

关键词： soft tissue ultrasound deformation correlation algorithm Young's Modulus force

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Performance comparison of algorithms for estimating the strain of soft tissue from ultrasound

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INSTRUMENTATION SCIENCE & TECHNOLOGY 2005年第6期33卷 673-689页

作者： Li, XF Huang, LH Zhang, GX Freiheit, T Tianjin Univ State Key Lab Precise Measurement Technol & Instr Tianjin 300072 Peoples R China Univ Calgary Dept Mech & Mfg Engn Calgary AB Canada

A specially designed device is used to link ultrasound and force transducers by mounting them in series. The combined transducers can simultaneously sense the deformation and compression force in the soft tissue. In this system, the method for obtaining the exact strain of the soft tissue during compression is very important. In this paper, six different algorithms to estimate the strain of the tissue are compared: Normalized correlation (NC), Direct correlation (DC), Sum Absolute Differences (SAD), Sum Squared Differences (SSD), Hybrid-sign correlation (HC), and Maximum algorithm. In order to evaluate the results of the six algorithms, a calibration system is setup in which the grating transducer and ultrasound sensor are connected in series. The strain of the soft tissue analyzed by six methods is compared. The results show that the estimating accuracy of tissue strain by the NC, DC, and SSD algorithms are completely the same, and there is no distinct difference in estimating accuracy between the SAD and NC (or DC and SSD) algorithms(alpha = 0.05). The standard deviation and maximal deviation of the delay time obtained by the HC and Maximum algorithms is unstable, and the delay time estimated by these two algorithms also shows false peaks. The time to run the SAD algorithm is more than the time to run the DC and SSD algorithms (alpha = 0.05), while there is no distinct difference in the time to run the DC and SSD algorithms. For systems with limited hardware resources, the DC and SSD algorithms are suitable.

关键词： soft tissue ultrasound strain correlation algorithm

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A new class of adaptive algorithm based on correlation functions for double-talk acoustic echo cancelling

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MATHEMATICS AND COMPUTERS IN SIMULATION 2004年第6期65卷 599-605页

作者： Asharif, MR Chen, R Yamashita, K Univ Ryukyus Fac Engn Dept Informat Engn Okinawa Japan Univ Tehran Fac Engn Dept Elect & Comp Engn Tehran Iran Osaka Prefecture Univ Grad Sch Engn Dept Elect & Elect Syst Osaka Japan

Echo path estimation in echo cancelling for teleconference system is a problem in double talk condition. The correlation processing algorithm was defined by the authors to solve this problem. In this paper, a new fast implementation in the frequency domain with correlation initialization and step size normalization is introduced. The new frequency-domain ECLMS (FECLMS) algorithm requires only 2.7% of the ECLMS computational loads. The new algorithm is superior as compared with conventional one in double-talk with speech signal. (C) 2004 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： echo cancelling double talk correlation algorithm frequency domain

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