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2003 Vol. 25, No. 8
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2003, 25(8): 1009-1013.
Abstract:
A pixel-level multisensor image fusion algorithm is proposed in this paper, and applied to fusion two SAR images of different frequency. A gray fusion image is firstly obtained using image fusion technique based on Kalman filter. Then, the gray fusion image, the enhanced details from two original images, are sent to RGB channels. A color fusion image is showed finally. The color fusion image includes more details, and the scene in it is easy to recognize.
A pixel-level multisensor image fusion algorithm is proposed in this paper, and applied to fusion two SAR images of different frequency. A gray fusion image is firstly obtained using image fusion technique based on Kalman filter. Then, the gray fusion image, the enhanced details from two original images, are sent to RGB channels. A color fusion image is showed finally. The color fusion image includes more details, and the scene in it is easy to recognize.
2003, 25(8): 1014-1020.
Abstract:
This paper presents a theoretical analysis in the sense of the Neyman-Pearson (N-P) test about the relationship between fusion rule and local decision rules in the parallel distributed detection fusion system with multiple sensors. It combines wavelet filter based on soft-threshold with the parallel distributed detection fusion system with multiple sensors ideally, and derives the determination of decision rules of two sub-optimal systems and globally optimal system completely. The detection performances of three systems above are computed numerically for the problem of detecting a known signal embeded in Rayleigh noise. The results obtained indicate that the presented method can enhance the radar detection performance remarkably.
This paper presents a theoretical analysis in the sense of the Neyman-Pearson (N-P) test about the relationship between fusion rule and local decision rules in the parallel distributed detection fusion system with multiple sensors. It combines wavelet filter based on soft-threshold with the parallel distributed detection fusion system with multiple sensors ideally, and derives the determination of decision rules of two sub-optimal systems and globally optimal system completely. The detection performances of three systems above are computed numerically for the problem of detecting a known signal embeded in Rayleigh noise. The results obtained indicate that the presented method can enhance the radar detection performance remarkably.
2003, 25(8): 1021-1028.
Abstract:
In this paper, based on analyzing the relationship between the symmetry of a filters transfer function and its impulse response sequence, a class of filter with sparse impulse response coefficients is presented. Using this class of filter as the prototype filter, the computational complexity of a FIR filter realized with FRM technique is further reduced. Then, the sampling rate alteration method based on FIR filter with FR.M structure, its architecture, computational complexity and the problem in designing are studied. Finally, this sampling rate alteration method is proved to be efficiency with examples.
In this paper, based on analyzing the relationship between the symmetry of a filters transfer function and its impulse response sequence, a class of filter with sparse impulse response coefficients is presented. Using this class of filter as the prototype filter, the computational complexity of a FIR filter realized with FRM technique is further reduced. Then, the sampling rate alteration method based on FIR filter with FR.M structure, its architecture, computational complexity and the problem in designing are studied. Finally, this sampling rate alteration method is proved to be efficiency with examples.
2003, 25(8): 1029-1034.
Abstract:
Multi-channel GPS satellite signal simulator provides realistic test signals for GPS receivers and navigation systems. In this paper, signals arriving the antenna of GPS receiver are analyzed from the point of view of simulator design. Focus is put on the estimation meth-ods of several signal parameters that are difficult to determine- directly according to existing experiential models due to various error factors. Based on the theory of Artificial Neural Net-work (ANN), an approach to simulate signal propagation delay, carrier phase, power, and other parameters using ANN is proposed. The architecture of the hardware-in-the-loop test system is given. The ANN training and validation process is described. Experimental results demon-strate that the ANN designed can simulate sample data statistically in high fidelity. Therefore the computation of signal state based on this ANN can meet the design requirement, and can be directly applied to the development of multi-channel GPS satellite signal simulator.
Multi-channel GPS satellite signal simulator provides realistic test signals for GPS receivers and navigation systems. In this paper, signals arriving the antenna of GPS receiver are analyzed from the point of view of simulator design. Focus is put on the estimation meth-ods of several signal parameters that are difficult to determine- directly according to existing experiential models due to various error factors. Based on the theory of Artificial Neural Net-work (ANN), an approach to simulate signal propagation delay, carrier phase, power, and other parameters using ANN is proposed. The architecture of the hardware-in-the-loop test system is given. The ANN training and validation process is described. Experimental results demon-strate that the ANN designed can simulate sample data statistically in high fidelity. Therefore the computation of signal state based on this ANN can meet the design requirement, and can be directly applied to the development of multi-channel GPS satellite signal simulator.
2003, 25(8): 1035-1041.
Abstract:
Operating in the heavy congested SW band, HF radars use a quasi-random step frequency signal to avoid the interference bands. However, the sidelobe of this signal after matching processing is very high, thus would greatly debase the radars performance. In this paper, a range sidelobe processing technique is proposed on a basis of delicate signal analysis and a NN based algorithm is applied to realize the optimization computing. Simulation re-sults demonstrate this method could successfully suppress the maximum sidelobe with good numerical stability.
Operating in the heavy congested SW band, HF radars use a quasi-random step frequency signal to avoid the interference bands. However, the sidelobe of this signal after matching processing is very high, thus would greatly debase the radars performance. In this paper, a range sidelobe processing technique is proposed on a basis of delicate signal analysis and a NN based algorithm is applied to realize the optimization computing. Simulation re-sults demonstrate this method could successfully suppress the maximum sidelobe with good numerical stability.
2003, 25(8): 1042-1050.
Abstract:
Based on the side-looking SAR mode of distributed satellites SAR system, this paper gives the mathematical model of radar echo signal of distributed satellite SAR, and proposes a detecting and imaging algorithm of the moving targets with low velocity by suppressing the ground clutters. The results of theory analysis and simulation show that the algorithm can suppress the ground clutters efficiently, and enhance the detecting ranges of moving targets.
Based on the side-looking SAR mode of distributed satellites SAR system, this paper gives the mathematical model of radar echo signal of distributed satellite SAR, and proposes a detecting and imaging algorithm of the moving targets with low velocity by suppressing the ground clutters. The results of theory analysis and simulation show that the algorithm can suppress the ground clutters efficiently, and enhance the detecting ranges of moving targets.
2003, 25(8): 1051-1058.
Abstract:
The characteristics of ship wakes in SAR image is analysed, the model of speckle noise and its local statistic characteristics are also analyzed. A ship wake detection algorithm is proposed in this paper, which based on wavelet transform to suppress the speckle noise firstly and Radon transform to detect the ship wakes secondly. The results of data procession show that the proposed method is more efficient and more accurate to detect the ship wakes in SAR images than that of applying Radon transform to SAR images directly.
The characteristics of ship wakes in SAR image is analysed, the model of speckle noise and its local statistic characteristics are also analyzed. A ship wake detection algorithm is proposed in this paper, which based on wavelet transform to suppress the speckle noise firstly and Radon transform to detect the ship wakes secondly. The results of data procession show that the proposed method is more efficient and more accurate to detect the ship wakes in SAR images than that of applying Radon transform to SAR images directly.
2003, 25(8): 1059-1065.
Abstract:
In this paper, an adaptive segmentating, hybrid coding scheme of radar return is presented. Firstly, radar return is divided into two classes by adaptive Gaussian mixture model: foreground and background, the former is composed of moving targets, while the later is composed of still objects and repeat motion. Then Integer-to-integer wavelet transform is used for de-correlating the background and foreground, and an improved SPIHT codec is also used in coding wavelet coefficients of foreground in lossless way and wavelet coefficients of background in loss way. Experimental results show the scheme in this paper is better than codec based on SPIHT directly, and the PSNR of the reconstructed image is also increased about 0.3-0.5dB in average under the same bit rate compared with that of the latter one.
In this paper, an adaptive segmentating, hybrid coding scheme of radar return is presented. Firstly, radar return is divided into two classes by adaptive Gaussian mixture model: foreground and background, the former is composed of moving targets, while the later is composed of still objects and repeat motion. Then Integer-to-integer wavelet transform is used for de-correlating the background and foreground, and an improved SPIHT codec is also used in coding wavelet coefficients of foreground in lossless way and wavelet coefficients of background in loss way. Experimental results show the scheme in this paper is better than codec based on SPIHT directly, and the PSNR of the reconstructed image is also increased about 0.3-0.5dB in average under the same bit rate compared with that of the latter one.
2003, 25(8): 1066-1072.
Abstract:
In SAR azimuth signal processing, it is very common to subsample the raw data with a filter, which may reduce the Signal Noise Ratio(SNR) of the raw image. Since autofocus is to estimate the Doppler parameters from the raw data, with the reduced SNR, the result of autofocus may be incorrect. And images processed with the incorrect parameters will be worsened. This paper analyses the effect of SNR on autofocus and proposes an adaptive filter in SAR azimuth subsampling to keep SNR as high as possible, so that the performance of autofocus can be improved and higher image quality achieved. Finally, an image processed with the adaptive filter is contrasted with the result of a traditional filter, which proves the effectiveness of the adaptive filter on autofocus and the final image.
In SAR azimuth signal processing, it is very common to subsample the raw data with a filter, which may reduce the Signal Noise Ratio(SNR) of the raw image. Since autofocus is to estimate the Doppler parameters from the raw data, with the reduced SNR, the result of autofocus may be incorrect. And images processed with the incorrect parameters will be worsened. This paper analyses the effect of SNR on autofocus and proposes an adaptive filter in SAR azimuth subsampling to keep SNR as high as possible, so that the performance of autofocus can be improved and higher image quality achieved. Finally, an image processed with the adaptive filter is contrasted with the result of a traditional filter, which proves the effectiveness of the adaptive filter on autofocus and the final image.
2003, 25(8): 1073-1080.
Abstract:
The technology of clustering high resolution imagery is difficult, due to the fact that the minor components, such as roads, make the appearance of the same category region non-uniform. This paper proposes a new approach to cluster high resolution remote sensing imagery. The clustering approach includes three steps. First, eliminate the minor components in moving windows. The process uses 1-D morphological watershed technique to find the left threshold and the right threshold in the histogram. The gray levels beyond the two thresholds which result from minor components will replaced by the principle gray level. This process can improve the statistic measures when the moving windows contain some small hetero-objects. Second, compute the image characteristics in moving windows. Third, apply BPC neural network, which is combined by a back-propagation network and a competitive network, to cluster images according to the images characteristics. Three approaches are tested using SPOT images for clustering residential areas and agricultural areas in the suburb of Beijing. The experimental results show that the new clustering approach has the highest clustering accuracy.
The technology of clustering high resolution imagery is difficult, due to the fact that the minor components, such as roads, make the appearance of the same category region non-uniform. This paper proposes a new approach to cluster high resolution remote sensing imagery. The clustering approach includes three steps. First, eliminate the minor components in moving windows. The process uses 1-D morphological watershed technique to find the left threshold and the right threshold in the histogram. The gray levels beyond the two thresholds which result from minor components will replaced by the principle gray level. This process can improve the statistic measures when the moving windows contain some small hetero-objects. Second, compute the image characteristics in moving windows. Third, apply BPC neural network, which is combined by a back-propagation network and a competitive network, to cluster images according to the images characteristics. Three approaches are tested using SPOT images for clustering residential areas and agricultural areas in the suburb of Beijing. The experimental results show that the new clustering approach has the highest clustering accuracy.
2003, 25(8): 1081-1087.
Abstract:
One of the key issues in integrated dynamic IP and wavelength routing algorithm is how to determine whether it is better to route an arriving Label Switch Path (LSP) estab-lishment request over the existing topology or to open new wavelength paths, A new scheme, Bandwidth Defragment Method (BDM), is presented in this paper. It makes full use of the statistic information of the networking link-state and resource availability to determine how to route an arriving LSP request. The integrated dynamic Routing and Wavelength Assign-ment (RWA) algorithm based on BDM can reduce the numbers of bandwidth fragment and increase the utility of network resource. Simulation results show that the scheme can improve the performance of the network significantly.
One of the key issues in integrated dynamic IP and wavelength routing algorithm is how to determine whether it is better to route an arriving Label Switch Path (LSP) estab-lishment request over the existing topology or to open new wavelength paths, A new scheme, Bandwidth Defragment Method (BDM), is presented in this paper. It makes full use of the statistic information of the networking link-state and resource availability to determine how to route an arriving LSP request. The integrated dynamic Routing and Wavelength Assign-ment (RWA) algorithm based on BDM can reduce the numbers of bandwidth fragment and increase the utility of network resource. Simulation results show that the scheme can improve the performance of the network significantly.
2003, 25(8): 1088-1094.
Abstract:
Handoffs in a mobile cellular communications environment will become an increas-ingly important issue as cell sizes shrink to accommodate an increasingly large demand for service. CDMA cellular systems use soft handoff. To cope with the channel shortages, many schemes were proposed. In this paper, a new handoff scheme is proposed that is called the handoff algorithm based on channel borrowing and signal prediction priority queuing. If there is no idle channel when the handoff requests arrive the cell, it will borrow channels from station-ary calls participating in soft handoff and allocate the borrowed channels to handoff requests by moving calls. If there is no channel can be borrowed, it will put handoff requests into queue, using signal prediction priority queuing method. A comparison is made between the performances of the proposed scheme.and other schemes.
Handoffs in a mobile cellular communications environment will become an increas-ingly important issue as cell sizes shrink to accommodate an increasingly large demand for service. CDMA cellular systems use soft handoff. To cope with the channel shortages, many schemes were proposed. In this paper, a new handoff scheme is proposed that is called the handoff algorithm based on channel borrowing and signal prediction priority queuing. If there is no idle channel when the handoff requests arrive the cell, it will borrow channels from station-ary calls participating in soft handoff and allocate the borrowed channels to handoff requests by moving calls. If there is no channel can be borrowed, it will put handoff requests into queue, using signal prediction priority queuing method. A comparison is made between the performances of the proposed scheme.and other schemes.
2003, 25(8): 1095-1100.
Abstract:
This paper presents a structure based on noncoherent-SPRT algorithm for the sequence acquisition under large frequency offset and low signal to noise ratio in DS/SS systems. The emphasis is put on the effect of frequency offset and partial correlation of GOLD sequence on parameters. It is shown by the theoretical analysis and computer simulation that the good acquisition performance can been achieved. And this structure can been implemented with moderate complexity.
This paper presents a structure based on noncoherent-SPRT algorithm for the sequence acquisition under large frequency offset and low signal to noise ratio in DS/SS systems. The emphasis is put on the effect of frequency offset and partial correlation of GOLD sequence on parameters. It is shown by the theoretical analysis and computer simulation that the good acquisition performance can been achieved. And this structure can been implemented with moderate complexity.
2003, 25(8): 1101-1107.
Abstract:
In this paper, a novel adaptive power and rate control scheme is studied, the BER. (Bit Error Rate) formula for the wideband CDMA system with this scheme is derived, and the numerical results of performance analysis in flat fading and frequency-selective channels are given respectively. In this scheme, the transmit power and rate are adapted by the mobile based on the variations of the fading channel. Firstly the predicted Probability Distribution Function (PDF) is divided into several regions equally, and the threshold values among these regions are got. Then the thresholds are used in adaptive power and rate control in a way similar to the traditional power control technique. The numerical results show that the theoretical BER performance of wideband CDMA system can be improved effectively by this scheme.
In this paper, a novel adaptive power and rate control scheme is studied, the BER. (Bit Error Rate) formula for the wideband CDMA system with this scheme is derived, and the numerical results of performance analysis in flat fading and frequency-selective channels are given respectively. In this scheme, the transmit power and rate are adapted by the mobile based on the variations of the fading channel. Firstly the predicted Probability Distribution Function (PDF) is divided into several regions equally, and the threshold values among these regions are got. Then the thresholds are used in adaptive power and rate control in a way similar to the traditional power control technique. The numerical results show that the theoretical BER performance of wideband CDMA system can be improved effectively by this scheme.
2003, 25(8): 1108-1113.
Abstract:
This paper points out the contradiction between the way of computing the differential characteristic probability and the principle of differential cryptanalysis, gives a deep reaserch on it and proposes a equivalent sufficient condition. The goal of the work is trying to solve the problem of the basic theoretic foundation for differential cryptanalysis.
This paper points out the contradiction between the way of computing the differential characteristic probability and the principle of differential cryptanalysis, gives a deep reaserch on it and proposes a equivalent sufficient condition. The goal of the work is trying to solve the problem of the basic theoretic foundation for differential cryptanalysis.
2003, 25(8): 1114-1119.
Abstract:
The Domain Decomposition FDTD (DD-FDTD) method is presented for solving complex 3-D problems and improving the accuracy of solutions. According to the features of the problem, the original domain is decomposed into several sub-domains. In each sub-domain, the conforrnal meshes are created in local coordinates and the FDTD computation is carried out independently in local meshes. In the iteration procedure of FDTD, the data are exchanged between adjacent sub-domains with overlapped meshes. An interpolating and error-modifying scheme proposed here integrates the sub-domains and leads to a more exact solution. A complex 3-D aperture antenna problem is calculated by using this method and the accuracy of the solution validates the usefulness and exactness of this method.
The Domain Decomposition FDTD (DD-FDTD) method is presented for solving complex 3-D problems and improving the accuracy of solutions. According to the features of the problem, the original domain is decomposed into several sub-domains. In each sub-domain, the conforrnal meshes are created in local coordinates and the FDTD computation is carried out independently in local meshes. In the iteration procedure of FDTD, the data are exchanged between adjacent sub-domains with overlapped meshes. An interpolating and error-modifying scheme proposed here integrates the sub-domains and leads to a more exact solution. A complex 3-D aperture antenna problem is calculated by using this method and the accuracy of the solution validates the usefulness and exactness of this method.
2003, 25(8): 1120-1125.
Abstract:
The dipole antenna array with trough reflector is widely applied to base stations for mobile communications. In order to simulate the antenna units and the trough reflector accurately and take the limitation of computation resources into account, this paper employs a kind of non-uniform FDTD algorithm in analyzing the radiation pattern. The numerical results show the effectiveness of this algorithm for antenna problems.
The dipole antenna array with trough reflector is widely applied to base stations for mobile communications. In order to simulate the antenna units and the trough reflector accurately and take the limitation of computation resources into account, this paper employs a kind of non-uniform FDTD algorithm in analyzing the radiation pattern. The numerical results show the effectiveness of this algorithm for antenna problems.
2003, 25(8): 1126-1129.
Abstract:
In this paper, a kind of rectanglar double gap output cavity model is studied. Si-ulation of the model with Mafia and ISFEL3D, three dimension electromagnetic field calculation software, is given. The frequency, characteristic impedance and field distribution of operating mode TM1202 obtained. The model is made and the test result of the model accords with the calculation. The analysis of the test and calculation is given. The study of this model has provided the foundation for further development of TM1202 high order high frequency output system of multi-beam Klystron.
In this paper, a kind of rectanglar double gap output cavity model is studied. Si-ulation of the model with Mafia and ISFEL3D, three dimension electromagnetic field calculation software, is given. The frequency, characteristic impedance and field distribution of operating mode TM1202 obtained. The model is made and the test result of the model accords with the calculation. The analysis of the test and calculation is given. The study of this model has provided the foundation for further development of TM1202 high order high frequency output system of multi-beam Klystron.
2003, 25(8): 1130-1134.
Abstract:
To solve the problems of the complexity of SVM-MUD model and the number of support vectors, a new algorithm for nonlinear multiuser detection is proposed in the paper. The algorithm introduced the forgetting factor to get the support vectors at the first training. The number of support, vectors is decreased by 28%. Then, the structure of the Riemannian geometry is introduced in the input space, and using the Riemannian geometric modifies the kernel function of the classifier and gets less improved support vectors at the second training. The algorithm simplifies the SVM-MUD model of the algorithm at the cost of only a little more bit error rate and decreases the computational complexity. Simulation results illustrate, that the algorithm has an excellent effect on multipath interference suppression and shows that its performance can closely match that of the optimal detector.
To solve the problems of the complexity of SVM-MUD model and the number of support vectors, a new algorithm for nonlinear multiuser detection is proposed in the paper. The algorithm introduced the forgetting factor to get the support vectors at the first training. The number of support, vectors is decreased by 28%. Then, the structure of the Riemannian geometry is introduced in the input space, and using the Riemannian geometric modifies the kernel function of the classifier and gets less improved support vectors at the second training. The algorithm simplifies the SVM-MUD model of the algorithm at the cost of only a little more bit error rate and decreases the computational complexity. Simulation results illustrate, that the algorithm has an excellent effect on multipath interference suppression and shows that its performance can closely match that of the optimal detector.
2003, 25(8): 1135-1138.
Abstract:
This paper presents how to implement the corner turn memory which is the important phase in synthetic aperture radar real-time processor by using SDRAM as the memory. SDRAM controller is described in detail including auto pre-charge function, refresh control circuit and address generation module.
This paper presents how to implement the corner turn memory which is the important phase in synthetic aperture radar real-time processor by using SDRAM as the memory. SDRAM controller is described in detail including auto pre-charge function, refresh control circuit and address generation module.
2003, 25(8): 1139-1142.
Abstract:
In communication systems, the application of microstrip active antenna is useful for the simplification and downsizing of the system. But because the antenna is integrated with active devices, the harmonics produced by the active devices can result in the spurious radiation of the antenna. In this paper, the application of PBG(Photonic Band-Gap) structure to the active antenna is studied, and the calculated result and experimental result all indicate that the application of PBG structure can drastically diminish the radiation of harmonics, so the performance of system is improved.
In communication systems, the application of microstrip active antenna is useful for the simplification and downsizing of the system. But because the antenna is integrated with active devices, the harmonics produced by the active devices can result in the spurious radiation of the antenna. In this paper, the application of PBG(Photonic Band-Gap) structure to the active antenna is studied, and the calculated result and experimental result all indicate that the application of PBG structure can drastically diminish the radiation of harmonics, so the performance of system is improved.
2003, 25(8): 1143-1147.
Abstract:
Round robin scheduling algorithm is a classic scheduling algorithm with many ap-plications. An FPGA implementation by using barrel shifter and pipelined priority encoder is presented in this paper with considering the FPGA structure characteristic and systems requirement. And the performance and resource consumption of the implementation are dis-cussed. The test result shows that the implementation of the algorithm is effective and fit for the FPGA structure. The system with the implementation of algorithm runs very well.
Round robin scheduling algorithm is a classic scheduling algorithm with many ap-plications. An FPGA implementation by using barrel shifter and pipelined priority encoder is presented in this paper with considering the FPGA structure characteristic and systems requirement. And the performance and resource consumption of the implementation are dis-cussed. The test result shows that the implementation of the algorithm is effective and fit for the FPGA structure. The system with the implementation of algorithm runs very well.
2003, 25(8): 1148-1152.
Abstract:
Electromagnetic leakage of video display unit becomes the focus of wide interest recently. An image-reconstruction system is presented here using electromagnetic leakage from video display unit. In this system a loop antenna is employed to receive the radiation. After being magnified, A/D transferred, the received data are processed by computer to reconstruct the image. The experiment shows the feasibility and good performance of this system.
Electromagnetic leakage of video display unit becomes the focus of wide interest recently. An image-reconstruction system is presented here using electromagnetic leakage from video display unit. In this system a loop antenna is employed to receive the radiation. After being magnified, A/D transferred, the received data are processed by computer to reconstruct the image. The experiment shows the feasibility and good performance of this system.
