Within the framework of the NIKA project1 for the development of a "Generalized System for processing and Management of Medical Images", we have integrated a Digital Subtraction Angiography (DSA) station and...
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The performance of two adaptive algorithms, the LMS and the adaptive delay algorithm, for measuring the actual delay between two blood volume pulse (BVP) signals is studied. Results are obtained from an experimental s...
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The performance of two adaptive algorithms, the LMS and the adaptive delay algorithm, for measuring the actual delay between two blood volume pulse (BVP) signals is studied. Results are obtained from an experimental setup examined with several test signals as well as pairs of BVP signals for a subject's three different cardiovascular conditions.
We formulate the spotlight-mode synthetic aperture radar (SAR) imaging problem as a maximum a posteriori (MAP) estimation problem. Our statistical perspective offers an alternative to standard SAR processing technique...
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We formulate the spotlight-mode synthetic aperture radar (SAR) imaging problem as a maximum a posteriori (MAP) estimation problem. Our statistical perspective offers an alternative to standard SAR processing techniques by incorporating prior knowledge about either the data quality or the underlying reflectivity function. In our formulation we consider exploiting the similarity between computer assisted tomography (CAT) and spotlight-mode SAR, which was first exposed by Munson et al. (1983). We present the effectiveness of the proposed approach by imagery formed from simulated spotlight-mode SAR data.
By expressing the frequency response of a Nyquist filter as a convolution of two functions, the mathematical complexity required to find the impulse response of the filter is reduced. Moreover, more efficient Nyquist ...
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By expressing the frequency response of a Nyquist filter as a convolution of two functions, the mathematical complexity required to find the impulse response of the filter is reduced. Moreover, more efficient Nyquist filters than the popular Raised Cosine filter (i.e. wider 3 dB bandwidth, same absolute bandwidth, and shorter or same length impulse response) are generated by using well known Window functions such as Ramming and Blackman.
The map-drift SAR autofocus is implemented with the maximum entropy method to exploit its high sensitivity in spectral estimation. The set of processing steps is presented in this paper. The ERS-1 data set is processe...
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ISBN:
(纸本)962442117X
The map-drift SAR autofocus is implemented with the maximum entropy method to exploit its high sensitivity in spectral estimation. The set of processing steps is presented in this paper. The ERS-1 data set is processed with both the new and conventional techniques. Their sensitivities and efficiencies are compared and discussed.
Synthetic aperture radar (SAR) systems are increasingly demanding for real real-time performance. As part of an effort to develop a real-time range-Doppler digital SAR processor to produce image maps of the scanned ar...
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ISBN:
(纸本)0780338367
Synthetic aperture radar (SAR) systems are increasingly demanding for real real-time performance. As part of an effort to develop a real-time range-Doppler digital SAR processor to produce image maps of the scanned area immediately as raw data are collected, this paper describes the conceptual architecture design for a high-speed front-end video pre-filtering. The evolved architecture consists of richly interconnected planes of novelly-adapted Modified Transverse FIR parallel tapped delay elements. Both the range and azimuth prefilterings are performed simultaneously in a continuous input-output flow without the need to worry about corner turning caused by azimuth preprocessing on data samples that are collected in the range direction.
The phase-gradient autofocus (PGA) technique is robust over a wide range of imagery and phase error functions but the convergence usually requires 4-6 iterations. The authors propose to speed up the estimation converg...
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ISBN:
(纸本)0780338367
The phase-gradient autofocus (PGA) technique is robust over a wide range of imagery and phase error functions but the convergence usually requires 4-6 iterations. The authors propose to speed up the estimation convergence by selectively increasing the pool of quality synchronisation sources and not to be limited by the range pixels of the SAR map. This is highly probable since each range bin contains more than 1 prominent scatterers across the integration aperture. It is also highly probable that the least brightest selected scatterer in a range gate may turn out to be of higher energy as compared to the maximum brightest scatterer of another gate. With appropriate target filtering to finally select the quality scatterers out of the large pool and higher-order phase error measurement tool, the new algorithm achieves near convergence quality without iteration. The authors named this solution the Quality PGA algorithm (QPGA).
In this paper, the least-square design problem of 2-D FIR digital filters with arbitrary frequency responses is investigated. By exposing and exploiting some of the characteristics of the complex matrices associated w...
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In this paper, the least-square design problem of 2-D FIR digital filters with arbitrary frequency responses is investigated. By exposing and exploiting some of the characteristics of the complex matrices associated with the approximation problem, a closed-form solution is developed. The solution is presented as an explicit expression for the impulse response corresponding to the desired frequency response specifications. Thus, the method avoids the usual time-consuming procedures of optimization or matrix inversion and makes an extremely fast calculation of the filter's coefficients possible. It is also shown that when this solution is used to design some specific classes of filters, further computational savings can be achieved. Design examples for both linear-phase and nonlinear-phase filters are considered.
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