The problem of finding the optimum output quantizer for a given discrete memoryless channel is investigated, where the quantizer output has fewer values than the channel output. While mutual information has received a...
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ISBN:
(纸本)9781457720529
The problem of finding the optimum output quantizer for a given discrete memoryless channel is investigated, where the quantizer output has fewer values than the channel output. While mutual information has received attention as an objective function for optimization, the focus of this paper is use of the random coding exponent, which was originally derived by Gallager, as criteria. Two problems are addressed, where one problem is a partial problem of the other. The main result is a quantizer design algorithm, and a proof that it finds the optimum quantizer in the partial problem. The quantizer design algorithm is based on a dynamic programming approach, and is an extension of a mutual-information maximization method. For the binary-input case, it is shown that the optimum quantizer can be found with complexity that is polynomial in the number of channel outputs.
Polarization diversity has proved to be a useful tool for radar detection, especially when discrimination by Doppler effect is not possible. In this paper, we address the problem of improving the performance of polari...
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ISBN:
(纸本)9781424412754;1424412757;1424412765
Polarization diversity has proved to be a useful tool for radar detection, especially when discrimination by Doppler effect is not possible. In this paper, we address the problem of improving the performance of polarimetric detectors for targets in heavy inhomogeneous clutter. First, we develop a polarimetric detection test that is robust to inhomogeneous clutter. We run this polarimetric test against synthetic and real data to assess its performance in comparison with existing polarimetric detectors. Then, we propose a polarimetric waveform-design algorithm to further improve the target-detection performance. A numerical analysis is presented to demonstrate the potential performance improvement that can be achieved with this algorithm.
The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. Therefore, as a preparation for accidents of the wheels, it is important to consider the attitude control by 2 wheels. The purpose of ...
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ISBN:
(纸本)9781479978632
The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. Therefore, as a preparation for accidents of the wheels, it is important to consider the attitude control by 2 wheels. The purpose of this analysis is to find the feasible attitude by two reaction wheels under an initial angular momentum. When the initial angular momentum is not zero, a spacecraft has a drift term and the attitude cannot be controlled freely. Therefore, based on the equilibrium points analysis, this paper proposes the best antenna arrangement in terms of the attitude control by two reaction wheels. Moreover, a design algorithm of a controller that stabilizes a feasible attitude is provided by modifying our previous method.
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