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2002 Vol. 24, No. 11
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2002, 24(11): 1441-1446.
Abstract:
A novel method of texture-image classification with rotation-invariauce in DCT compressed-domain is proposed. By reordered the DCT coefficients for multi-resolution, the textnral features are extracted in DCT transformed-domain and these textural features can be used to classify texture-images in RLE bit-stream directly with rotation-invariancc. The experimental results demonstrate that texture-images can be classified at higher correct classification rate.
A novel method of texture-image classification with rotation-invariauce in DCT compressed-domain is proposed. By reordered the DCT coefficients for multi-resolution, the textnral features are extracted in DCT transformed-domain and these textural features can be used to classify texture-images in RLE bit-stream directly with rotation-invariancc. The experimental results demonstrate that texture-images can be classified at higher correct classification rate.
2002, 24(11): 1447-1453.
Abstract:
A multi-pose face recognition algorithm based on a hierarchical model and fusion decision is proposed in the paper. First, face images are divided into several classes based on their poses and every class into many sub-classes based on their subjects. Then, traditional face recognition technology based on eigenface is applied in the process of face recognition in every class. Finally, fusion decision is adopted to get the final result of face recognition based on the intermediate result of every class. It also, can get the result of its pose recognition and its computation time is far less than that of the traditional methods. The algorithm discussed above has been tested in the experiments of a multi-pose face database with total 100 subjects and 1200 face images, which consists of ORL, UMIST, Stirling and face database of authors lab. The results are encouraging.
A multi-pose face recognition algorithm based on a hierarchical model and fusion decision is proposed in the paper. First, face images are divided into several classes based on their poses and every class into many sub-classes based on their subjects. Then, traditional face recognition technology based on eigenface is applied in the process of face recognition in every class. Finally, fusion decision is adopted to get the final result of face recognition based on the intermediate result of every class. It also, can get the result of its pose recognition and its computation time is far less than that of the traditional methods. The algorithm discussed above has been tested in the experiments of a multi-pose face database with total 100 subjects and 1200 face images, which consists of ORL, UMIST, Stirling and face database of authors lab. The results are encouraging.
2002, 24(11): 1454-1461.
Abstract:
This paper proposes a new algorithm of optimal description of surface primitive. The 3-D surface parameters are estimated through fitting the range data to a quadric model. Based on an improved bias-corrected fitting algorithm, a probabilistic model with normal pdf to describe the statistical characteristics of the surface estimate is proposed. Consequently a metric defined as measure of reliability of the surface estimate is given. Towards reliable primitive extraction, a new method of estimation-based range image segmentation is thereby described. While the region homogeneity is defined on an optimal criterion, the region growing always converges to the state of the most reliable description of the extracted surface primitives. The experimental results with real range images are given.
This paper proposes a new algorithm of optimal description of surface primitive. The 3-D surface parameters are estimated through fitting the range data to a quadric model. Based on an improved bias-corrected fitting algorithm, a probabilistic model with normal pdf to describe the statistical characteristics of the surface estimate is proposed. Consequently a metric defined as measure of reliability of the surface estimate is given. Towards reliable primitive extraction, a new method of estimation-based range image segmentation is thereby described. While the region homogeneity is defined on an optimal criterion, the region growing always converges to the state of the most reliable description of the extracted surface primitives. The experimental results with real range images are given.
2002, 24(11): 1462-1469.
Abstract:
Edge detection is the process that attempts to characterize the intensity changes in the imagery. The critical goal of edge detection is the detection and characterization of significant intensity changes. Good detection, good localization and single response to a single edge are the three performance criteria for edge detection. Based on the mathematical formulations about detection, localization and single response criterion, the paper explains the theory to attain the optimal edge detection operator in details. The procedure of designing edge detection operators for any shape edges is introduced by illustrating to attain the one-dimensional step edge optimal detection operator. Based on the three performance criteria, the sine-operator is proposed. The sine-operator out-performs the first derivative of Gauss function according to the above three criteria. The results demonstrate that the sine-operator proposed in the paper can obtain good effects for both one-dimensional signal and two-dimensional image with noise.
Edge detection is the process that attempts to characterize the intensity changes in the imagery. The critical goal of edge detection is the detection and characterization of significant intensity changes. Good detection, good localization and single response to a single edge are the three performance criteria for edge detection. Based on the mathematical formulations about detection, localization and single response criterion, the paper explains the theory to attain the optimal edge detection operator in details. The procedure of designing edge detection operators for any shape edges is introduced by illustrating to attain the one-dimensional step edge optimal detection operator. Based on the three performance criteria, the sine-operator is proposed. The sine-operator out-performs the first derivative of Gauss function according to the above three criteria. The results demonstrate that the sine-operator proposed in the paper can obtain good effects for both one-dimensional signal and two-dimensional image with noise.
2002, 24(11): 1470-1474.
Abstract:
Based on UCA-RB-MUSIC algorithm(Mathews, et al., 1994) and 1-D null preprocessing algorithm (Wei Ping, et al, 1996), a 2-D UCA MUSIC algorithm for wide-band sources with arbitrary spatial null response is presented. The computer simulations indicate that the spatial wide-band interference can be suppressed exactly, the high precision and high resolution of UCA-RB-MUSIC algorithm is maintained, and the computational burden is reduced.
Based on UCA-RB-MUSIC algorithm(Mathews, et al., 1994) and 1-D null preprocessing algorithm (Wei Ping, et al, 1996), a 2-D UCA MUSIC algorithm for wide-band sources with arbitrary spatial null response is presented. The computer simulations indicate that the spatial wide-band interference can be suppressed exactly, the high precision and high resolution of UCA-RB-MUSIC algorithm is maintained, and the computational burden is reduced.
2002, 24(11): 1475-1479.
Abstract:
The principle of multi-bit Phase Quantization Digital RF Memory (PQDRFM) and the implementation of Phase Quantizer (PQ) are discussed. The topology of PQ which is easy to monolithic integration is given. The factors affecting the spurious level of PQDRFM are investigated and the expression of the relationship of spurious level via the quantization bit number is given. The emphasis is put on the effect of the unbalance of PQ input amplitude and phase on the spurious level.
The principle of multi-bit Phase Quantization Digital RF Memory (PQDRFM) and the implementation of Phase Quantizer (PQ) are discussed. The topology of PQ which is easy to monolithic integration is given. The factors affecting the spurious level of PQDRFM are investigated and the expression of the relationship of spurious level via the quantization bit number is given. The emphasis is put on the effect of the unbalance of PQ input amplitude and phase on the spurious level.
2002, 24(11): 1480-1486.
Abstract:
Analysis and research on a novel method of constructing wavelets-lifting factorization is addressed. To arrive at a generalized interpretation of lifting based on the linear transform and transform matrix factorization, a new polyphase matrix representation is proposed. Moreover the equivalence of the conditions for perfect reconstruction between dual-subband FIR filtering implementation and the lifting is also proved. Additionally based on the duality theorem of complementary filter pairs, a new lifting factorization representation is suggested which brings lifting factorization to completion. Finally, to clarify the theory a concrete example of lifting factorization corresponding to (2,2) biorthogonal wavelet transform is presented, and the algorithm performance including reversibility, in-place implementation and computational complexity is also analyzed in brief.
Analysis and research on a novel method of constructing wavelets-lifting factorization is addressed. To arrive at a generalized interpretation of lifting based on the linear transform and transform matrix factorization, a new polyphase matrix representation is proposed. Moreover the equivalence of the conditions for perfect reconstruction between dual-subband FIR filtering implementation and the lifting is also proved. Additionally based on the duality theorem of complementary filter pairs, a new lifting factorization representation is suggested which brings lifting factorization to completion. Finally, to clarify the theory a concrete example of lifting factorization corresponding to (2,2) biorthogonal wavelet transform is presented, and the algorithm performance including reversibility, in-place implementation and computational complexity is also analyzed in brief.
2002, 24(11): 1487-1493.
Abstract:
In adaptive array, channel mismatch may severely degrade an arrays performance, one solution is adaptive compensation with taps added to channel, however, implementation in real time of this method is impossible if there are too many mismatched channel ripples because a good many taps are needed. An adaptive channel compensation method based on bandwidth partitioning is proposed in this paper which can resolve effectively the above problem. Theoretical analysis and computer simulation results demonstrate the effectiveness of the proposed method.
In adaptive array, channel mismatch may severely degrade an arrays performance, one solution is adaptive compensation with taps added to channel, however, implementation in real time of this method is impossible if there are too many mismatched channel ripples because a good many taps are needed. An adaptive channel compensation method based on bandwidth partitioning is proposed in this paper which can resolve effectively the above problem. Theoretical analysis and computer simulation results demonstrate the effectiveness of the proposed method.
2002, 24(11): 1494-1498.
Abstract:
The principle and application of numerical simulator of capacitance matrix for nano-electronic system called SJTU-NANO-FCACI is studied.-The algorithm of the program is analyzed. With the program, the capacitances of spherical capacitor, which are often used in nano-electronics, are calculated and compared with the approximate formula. The results demonstrate that the program has a high calculation precision, a fast calculation speed and can be used in many applications.
The principle and application of numerical simulator of capacitance matrix for nano-electronic system called SJTU-NANO-FCACI is studied.-The algorithm of the program is analyzed. With the program, the capacitances of spherical capacitor, which are often used in nano-electronics, are calculated and compared with the approximate formula. The results demonstrate that the program has a high calculation precision, a fast calculation speed and can be used in many applications.
2002, 24(11): 1499-1505.
Abstract:
In this paper beamforming and DOA estimation for multiuser are discussed in multipath circumstance. Decorrelating detector is adopted to detect multiuser. CSS (Cyclic Spatial Smoothing) algorithm is presented. The algorithm with spatial smoothing can keep array weight dimension unchanged. Its theoretical foundation is that cyclic propagation of the sampling signal covariance inverse matrix is equivalent to averaging of the covariance matrix. The estimated spatial signature is adopted to construct the covariance matrix for high resolution DOA estimation. The simulation results show that CSS has better performance for multiuser beamforming.
In this paper beamforming and DOA estimation for multiuser are discussed in multipath circumstance. Decorrelating detector is adopted to detect multiuser. CSS (Cyclic Spatial Smoothing) algorithm is presented. The algorithm with spatial smoothing can keep array weight dimension unchanged. Its theoretical foundation is that cyclic propagation of the sampling signal covariance inverse matrix is equivalent to averaging of the covariance matrix. The estimated spatial signature is adopted to construct the covariance matrix for high resolution DOA estimation. The simulation results show that CSS has better performance for multiuser beamforming.
2002, 24(11): 1506-1511.
Abstract:
Based on higher-order cumulants, the blind estimation of complex mixed matrix for the difficult case of 2 sensors and 3 sources is addressed. When the number of source signals is greater than or equal to the number of sensors, the proposed algorithm can successfully estimate the channel matrix. The performance of the algorithm is evaluated by computer simulation.
Based on higher-order cumulants, the blind estimation of complex mixed matrix for the difficult case of 2 sensors and 3 sources is addressed. When the number of source signals is greater than or equal to the number of sensors, the proposed algorithm can successfully estimate the channel matrix. The performance of the algorithm is evaluated by computer simulation.
2002, 24(11): 1512-1516.
Abstract:
In this paper, a genetic algorithm is proposed for blind FIR system estimation based on a Single-Input-Multiple-Output (SIMO) model. The key proposition is that the parameters are estimated blindly by using a lower-order statistics based cost function thus the computation can be saved. Both the order and parameters of the channel are encoded in one chromosome, thus they can be estimated jointly without assuming the channel order is known. Simulation results show that the algorithm performs better than traditional algorithms.
In this paper, a genetic algorithm is proposed for blind FIR system estimation based on a Single-Input-Multiple-Output (SIMO) model. The key proposition is that the parameters are estimated blindly by using a lower-order statistics based cost function thus the computation can be saved. Both the order and parameters of the channel are encoded in one chromosome, thus they can be estimated jointly without assuming the channel order is known. Simulation results show that the algorithm performs better than traditional algorithms.
2002, 24(11): 1517-1524.
Abstract:
This paper investigates the fast fading channel with the mobile speed over 150km/h, which is used in 3G wireless communication system. Because the varying speed of channel coefficients exceeds the convergence speed of tracking algorithm, the normal time-domain based method fail. However, when transformed to frequency domain, the varying speed of channel coefficients becomes slow. Based on this observation, a novel approach to channel estimation is proposed in frequency domain. Compared with other algorithms, this method shows a good performance both in computation and tracing speed.
This paper investigates the fast fading channel with the mobile speed over 150km/h, which is used in 3G wireless communication system. Because the varying speed of channel coefficients exceeds the convergence speed of tracking algorithm, the normal time-domain based method fail. However, when transformed to frequency domain, the varying speed of channel coefficients becomes slow. Based on this observation, a novel approach to channel estimation is proposed in frequency domain. Compared with other algorithms, this method shows a good performance both in computation and tracing speed.
2002, 24(11): 1525-1529.
Abstract:
A new equalizer represented by a set of orthogonal multiwavelets is presented. Since multiwavelets can be orthogonal, compactly supported and linear phase, the multiwavelets transformed correlation matrices have less non-zero elements and smaller boundary effects than that of wavelet. So, a new multiwavelet transform domain newton-LMS adaptive equalization algorithm is described, and its complexity is O(N log N) by using the preconditioned conjugate gradient algorithm. Simulation shows its convergence speed is faster and its realization is easier.
A new equalizer represented by a set of orthogonal multiwavelets is presented. Since multiwavelets can be orthogonal, compactly supported and linear phase, the multiwavelets transformed correlation matrices have less non-zero elements and smaller boundary effects than that of wavelet. So, a new multiwavelet transform domain newton-LMS adaptive equalization algorithm is described, and its complexity is O(N log N) by using the preconditioned conjugate gradient algorithm. Simulation shows its convergence speed is faster and its realization is easier.
2002, 24(11): 1530-1536.
Abstract:
In this paper, a blind identification algorithm based on subspace decomposition for OFDM channels is proposed. Taking the received OFDM signal as an equivalent Single Input-Multiple Output (SIMO) oversampled signal, the channels parameters are estimated by subspace method.Without any training sequences and periodic pilot signals, blind channel identification for OFDM system is realized. The broadband OFDM mobile communication system usually has a number of subchannels and its channels response period is less than the OFDM symbols period, so it is better to divide the whole system into several subsystems, then each of them can be estimated separately with less complication.
In this paper, a blind identification algorithm based on subspace decomposition for OFDM channels is proposed. Taking the received OFDM signal as an equivalent Single Input-Multiple Output (SIMO) oversampled signal, the channels parameters are estimated by subspace method.Without any training sequences and periodic pilot signals, blind channel identification for OFDM system is realized. The broadband OFDM mobile communication system usually has a number of subchannels and its channels response period is less than the OFDM symbols period, so it is better to divide the whole system into several subsystems, then each of them can be estimated separately with less complication.
2002, 24(11): 1537-1543.
Abstract:
In a Code Division Multiple Access (CDMA) mobile communication system which supports integrated services, such as voice, data, and images, the variations of the forward transmit power of a base station after adding new connections are different for the services having different data rates and Quality of Service (QoS) requirements. Hence the forward transmit power must be constrained to preserve the system stability. This paper presents a method for forecasting the forward transmit power after adding a new connection of a predefined service type. The method is then exemplified by applying it to predict the forward transmit power in a typical system. The results are further validated by computer simulation.
In a Code Division Multiple Access (CDMA) mobile communication system which supports integrated services, such as voice, data, and images, the variations of the forward transmit power of a base station after adding new connections are different for the services having different data rates and Quality of Service (QoS) requirements. Hence the forward transmit power must be constrained to preserve the system stability. This paper presents a method for forecasting the forward transmit power after adding a new connection of a predefined service type. The method is then exemplified by applying it to predict the forward transmit power in a typical system. The results are further validated by computer simulation.
2002, 24(11): 1544-1550.
Abstract:
The errorcode performances of the Ultra-Wide Bandwidth (UWB) radio in single-tone jamming, in partial band jamming and in barrage noise jamming are investigated respectively. A parameter selection method which can improve the performance of UWB radio in jamming environment is resulted from theoretical analysis and computer simulation. These support that the UWB radio has good performance in jamming environment.
The errorcode performances of the Ultra-Wide Bandwidth (UWB) radio in single-tone jamming, in partial band jamming and in barrage noise jamming are investigated respectively. A parameter selection method which can improve the performance of UWB radio in jamming environment is resulted from theoretical analysis and computer simulation. These support that the UWB radio has good performance in jamming environment.
2002, 24(11): 1551-1558.
Abstract:
An object tracking method for semiautomatic video object segmentation is proposed in this paper. An objective function is constructed with mean square color error of blocks and edge strength of pixels. Then a multilevel ordering method with permissive error is used to accomplish the programming of this objective function so as to realize motion estimation and compensation of contour pixels. Thus the pixels in the current frame, which correspond to the contour pixels in the reference frame, are found out. As the contour pixels in the current frame, these pixels are connected to form a close curve by an objective of maximal edge strength. Thus the segmentation mask of the current frame is generated. The experimental results of this method on several test sequences are satisfactory.
An object tracking method for semiautomatic video object segmentation is proposed in this paper. An objective function is constructed with mean square color error of blocks and edge strength of pixels. Then a multilevel ordering method with permissive error is used to accomplish the programming of this objective function so as to realize motion estimation and compensation of contour pixels. Thus the pixels in the current frame, which correspond to the contour pixels in the reference frame, are found out. As the contour pixels in the current frame, these pixels are connected to form a close curve by an objective of maximal edge strength. Thus the segmentation mask of the current frame is generated. The experimental results of this method on several test sequences are satisfactory.
2002, 24(11): 1559-1565.
Abstract:
Differentiated Services(DS) architecture has been proposed by IETF to implement QoS in IP networks. However, research shows that there exists unfairness in DS network. This paper introduces the TCP friendly concept into DS network and defines TCP friendly fairness in DS architecture. Elaborate simulations are used to verify that current mechanisms in DS cannot guarantee the TCP friendly fairness; therefore, direct congestion control scheme is proposed to achieve the TCP friendly fairness.
Differentiated Services(DS) architecture has been proposed by IETF to implement QoS in IP networks. However, research shows that there exists unfairness in DS network. This paper introduces the TCP friendly concept into DS network and defines TCP friendly fairness in DS architecture. Elaborate simulations are used to verify that current mechanisms in DS cannot guarantee the TCP friendly fairness; therefore, direct congestion control scheme is proposed to achieve the TCP friendly fairness.
2002, 24(11): 1566-1572.
Abstract:
A fair electronic cash protocol based on trustee is presented by using RSA blind signature technique in this paper, the identity of multi-spender will be revealed by trustee with very high probability. Contrasting with the previous protocol, the users money cannot be withdrawn unless the trustee is in collusion with the bank, and the trustee can only trace the money that the bank asked him to trace. So the privacy of the user can be ensured to the maximum limit. Also this protocol can be used to trace the dubious cash and the owner, thereby it may be exploited to decrease the crimes like money laundering, blackmailing, etc. in the electronic cash system. This protocol requires off-line participation of trustee when users withdraw the cash, so it is efficient for implementation.
A fair electronic cash protocol based on trustee is presented by using RSA blind signature technique in this paper, the identity of multi-spender will be revealed by trustee with very high probability. Contrasting with the previous protocol, the users money cannot be withdrawn unless the trustee is in collusion with the bank, and the trustee can only trace the money that the bank asked him to trace. So the privacy of the user can be ensured to the maximum limit. Also this protocol can be used to trace the dubious cash and the owner, thereby it may be exploited to decrease the crimes like money laundering, blackmailing, etc. in the electronic cash system. This protocol requires off-line participation of trustee when users withdraw the cash, so it is efficient for implementation.
2002, 24(11): 1573-1580.
Abstract:
Bandwidth-delay product in MPLS is so high that TCP protocols hardly solve the congestion in MPLS. This paper proposes an Active Traffic and Congestion Control (ATCC) mechanism in MPLS and its model, which utilities the characters of MPLS. MPLS ATCC moves the endpoint congestion control algorithms into the network. The comparison with traditional TCP shows that ATCC can find and control the congestion in time, reduce the round-trip delay, and edit the ingress traffic. So MPLS ATCC improves the total throughput and the utility of buffer.
Bandwidth-delay product in MPLS is so high that TCP protocols hardly solve the congestion in MPLS. This paper proposes an Active Traffic and Congestion Control (ATCC) mechanism in MPLS and its model, which utilities the characters of MPLS. MPLS ATCC moves the endpoint congestion control algorithms into the network. The comparison with traditional TCP shows that ATCC can find and control the congestion in time, reduce the round-trip delay, and edit the ingress traffic. So MPLS ATCC improves the total throughput and the utility of buffer.
2002, 24(11): 1581-1588.
Abstract:
Reservation is frequently used in the local area network (LAN). One of the most famous application is IEEE802.5 reservation protocol. In order to make use of the reservation protocol in the annular MAN, it is necessary to pay more attention to the characteristics of the integrated services. Their purpose is not only assuring the high rank information can reserve token in ahead but also preventing the low rank information (especially the lowest rank information) waiting for a long time. This paper proposes high protocol which can solve the problem rationally. The motif is properly enhancing QoS (Quality of Service) for the low rank information at the cost of the decrease of QoS for the high one. Simulation results show that the improved IEEE802.5 reservation protocol is adapt to MAN which has integrated service.
Reservation is frequently used in the local area network (LAN). One of the most famous application is IEEE802.5 reservation protocol. In order to make use of the reservation protocol in the annular MAN, it is necessary to pay more attention to the characteristics of the integrated services. Their purpose is not only assuring the high rank information can reserve token in ahead but also preventing the low rank information (especially the lowest rank information) waiting for a long time. This paper proposes high protocol which can solve the problem rationally. The motif is properly enhancing QoS (Quality of Service) for the low rank information at the cost of the decrease of QoS for the high one. Simulation results show that the improved IEEE802.5 reservation protocol is adapt to MAN which has integrated service.
2002, 24(11): 1589-1596.
Abstract:
Basing on the DOS models aggregating ability, the client layers services with different QoS requirements can be mapped directly into the optical channel. Then the different QoS requirements of the client layers services can be reflected by the different priorities of the connection request at the border optical node in a DOS domain. A wavelength graph method is presented in the multi-fiber WDM optical transport network to reduce the blocking probability of the connection request. Two optical QoS routing strategies, concentrating method and equalizing method, are proposed. The two methods are compared by simulation results of the network performance in different dynamic traffic load situations.
Basing on the DOS models aggregating ability, the client layers services with different QoS requirements can be mapped directly into the optical channel. Then the different QoS requirements of the client layers services can be reflected by the different priorities of the connection request at the border optical node in a DOS domain. A wavelength graph method is presented in the multi-fiber WDM optical transport network to reduce the blocking probability of the connection request. Two optical QoS routing strategies, concentrating method and equalizing method, are proposed. The two methods are compared by simulation results of the network performance in different dynamic traffic load situations.
2002, 24(11): 1597-1601.
Abstract:
The Generalized Hamming Weights (GHW) of linear codes characterize the cryptography performance of the code on the wire-tap channel of type two. In this paper, the GHW of a kind of cyclic code, the one-step majority-logic decodable code, which is invariant under the group of afhne permutation , is studied. The GHW of the code is estimated, and some examples are given.
The Generalized Hamming Weights (GHW) of linear codes characterize the cryptography performance of the code on the wire-tap channel of type two. In this paper, the GHW of a kind of cyclic code, the one-step majority-logic decodable code, which is invariant under the group of afhne permutation , is studied. The GHW of the code is estimated, and some examples are given.
2002, 24(11): 1602-1607.
Abstract:
In this paper, a way of secure digital communication based on occasional coupling and generalized chaotic synchronization is proposed. The period of every signal bit is divided into two parts: T1 and T2. During T1, generalized chaotic synchronization is fulfilled, and in T2, the transmitted signal is extracted by a special way. The relation between T1, T2 and the security as well as the performance of signal extraction are also analyzed. Numerical simulations are performed to show the effectiveness of this communication scheme.
In this paper, a way of secure digital communication based on occasional coupling and generalized chaotic synchronization is proposed. The period of every signal bit is divided into two parts: T1 and T2. During T1, generalized chaotic synchronization is fulfilled, and in T2, the transmitted signal is extracted by a special way. The relation between T1, T2 and the security as well as the performance of signal extraction are also analyzed. Numerical simulations are performed to show the effectiveness of this communication scheme.
2002, 24(11): 1608-1613.
Abstract:
By using coefficient matrix representation of LFSR s output sequences and analyzing the eigenvector representation of the coefficient matrix, the output sequences of LFSR is expressed, where the coefficients completely rely on the initial input values of the LFSR and the roots of the reciprocal polynomial of LFSR s minimum polynomial. The result is more explicit than the former result.
By using coefficient matrix representation of LFSR s output sequences and analyzing the eigenvector representation of the coefficient matrix, the output sequences of LFSR is expressed, where the coefficients completely rely on the initial input values of the LFSR and the roots of the reciprocal polynomial of LFSR s minimum polynomial. The result is more explicit than the former result.
2002, 24(11): 1614-1619.
Abstract:
This paper studies the range sidelobe suppression techniques for long-biphase coded signals by applying digital processing in Frequency domain. By analyzing the spectrum characteristics, a design method in frequency domain for Sidelobe Suppression Filters (SSF), which is suitable for various code lengths and different code sequences, is presented. As an example, computer simulations and experimental results of 127-bit biphase coded signals processed by the SSF are also given. When fd = 0, RMS are achieved to 50dB and 43dB for simulations and experiments respectively. These show that biphase coded signal SSF designed by this method can be applied in modern radar systems, and the satisfactory performance are achieved.
This paper studies the range sidelobe suppression techniques for long-biphase coded signals by applying digital processing in Frequency domain. By analyzing the spectrum characteristics, a design method in frequency domain for Sidelobe Suppression Filters (SSF), which is suitable for various code lengths and different code sequences, is presented. As an example, computer simulations and experimental results of 127-bit biphase coded signals processed by the SSF are also given. When fd = 0, RMS are achieved to 50dB and 43dB for simulations and experiments respectively. These show that biphase coded signal SSF designed by this method can be applied in modern radar systems, and the satisfactory performance are achieved.
2002, 24(11): 1620-1626.
Abstract:
Based on the side-looking mode SAR of distributed satellites SAR system. This paper gives the mathematical model of SAR echo signal, and proposes a imaging algorithm of the single satellite SAR of distributed satellite SAR and imaging algorithm of distributed satellite SAR system by beamforming and multilook. The results of theory analysis and simulation show that the algorithm can enhance SNR and suppress the speckle noise of resulted image without changing the resolution of SAR image, improve images quality.
Based on the side-looking mode SAR of distributed satellites SAR system. This paper gives the mathematical model of SAR echo signal, and proposes a imaging algorithm of the single satellite SAR of distributed satellite SAR and imaging algorithm of distributed satellite SAR system by beamforming and multilook. The results of theory analysis and simulation show that the algorithm can enhance SNR and suppress the speckle noise of resulted image without changing the resolution of SAR image, improve images quality.
2002, 24(11): 1627-1633.
Abstract:
The phase information becomes more and more important in the field of SAR applications. Considering the statistical independent property between phase and amplitude of SAR raw data, a new method is provided that the amplitude and phase of raw data are compressed respectively. In this paper, a flow chart shows that procession of the algorithm. The algorithm performance is analyzed based on real SAR raw data. Finally, the AP (Amplitude Phase) algorithm is compared with the BAQ algorithm. The performance of the AP algorithm is proved to be fine, especially in terms of the reservation of phase information.
The phase information becomes more and more important in the field of SAR applications. Considering the statistical independent property between phase and amplitude of SAR raw data, a new method is provided that the amplitude and phase of raw data are compressed respectively. In this paper, a flow chart shows that procession of the algorithm. The algorithm performance is analyzed based on real SAR raw data. Finally, the AP (Amplitude Phase) algorithm is compared with the BAQ algorithm. The performance of the AP algorithm is proved to be fine, especially in terms of the reservation of phase information.
2002, 24(11): 1634-1640.
Abstract:
Based on an analysis of the principle SISAR shadow imaging, the effect on target shadow image due to nonconstant velocity rotation relative to the target is first examined, and a compensation method is also presented. In addition, the effect on target shadow image due to target motion parameters is described. Eventually, a target recognition approach on the basis of the invariable parameters obtained is proposed. The computer simulations show the efficiency of the method.
Based on an analysis of the principle SISAR shadow imaging, the effect on target shadow image due to nonconstant velocity rotation relative to the target is first examined, and a compensation method is also presented. In addition, the effect on target shadow image due to target motion parameters is described. Eventually, a target recognition approach on the basis of the invariable parameters obtained is proposed. The computer simulations show the efficiency of the method.
2002, 24(11): 1641-1647.
Abstract:
This paper introduces an algorithm used in estimation of the phase error of chirp signal. Firstly, the algorithm applies Range Cell Migration Correction (MCRC) to SAR signals with chirp scaling method, and processes on azimuth compression only. Then the phase error of the radar chirp signal is estimated by applying the auto-focus method, for example, Map Drift (MD) or Phase Gradient Algorithm (PGA) to the azimuth processing of signals. Further correction on estimated phase error is applied to discussion of the factors that influent the phase error estimation. The algorithm is proved by computer simulation.
This paper introduces an algorithm used in estimation of the phase error of chirp signal. Firstly, the algorithm applies Range Cell Migration Correction (MCRC) to SAR signals with chirp scaling method, and processes on azimuth compression only. Then the phase error of the radar chirp signal is estimated by applying the auto-focus method, for example, Map Drift (MD) or Phase Gradient Algorithm (PGA) to the azimuth processing of signals. Further correction on estimated phase error is applied to discussion of the factors that influent the phase error estimation. The algorithm is proved by computer simulation.
2002, 24(11): 1648-1658.
Abstract:
Using the Wishart joint distribution of the scattering amplitude functions, the probability density functions (PDFs) of four Stokes parameters for multilook polarimetric SAR data are derived. The PDFs are formulated analytically with dependence upon the look number and mean values of the Stokes parameters, and are compared with the results by R. Touzi and A. Lopes (1996). The statistic histograms of four Stokes parameters are validated by the AirSAR imagery at multi-P, L, C bands observed over some typical sites such as water, sparse trees and forest. An effective look-number might be especially assigned to have excellent matching with the AirSAR data. Potential application of the statistics of four Stokes parameters to classification of the terrain types is studied.
Using the Wishart joint distribution of the scattering amplitude functions, the probability density functions (PDFs) of four Stokes parameters for multilook polarimetric SAR data are derived. The PDFs are formulated analytically with dependence upon the look number and mean values of the Stokes parameters, and are compared with the results by R. Touzi and A. Lopes (1996). The statistic histograms of four Stokes parameters are validated by the AirSAR imagery at multi-P, L, C bands observed over some typical sites such as water, sparse trees and forest. An effective look-number might be especially assigned to have excellent matching with the AirSAR data. Potential application of the statistics of four Stokes parameters to classification of the terrain types is studied.
2002, 24(11): 1659-1663.
Abstract:
This paper describes the design and realization of the azimuth preprocess in the real-time imaging processor of SAR with programmable logic device by the method of sub-aperture using band-pass filter. The azimuth preprocess circuit implementation and its result are presented. It can be gotten that the circuit performance is satisfactory in operation efficiency, integration degree, implementation convenience and expandability.
This paper describes the design and realization of the azimuth preprocess in the real-time imaging processor of SAR with programmable logic device by the method of sub-aperture using band-pass filter. The azimuth preprocess circuit implementation and its result are presented. It can be gotten that the circuit performance is satisfactory in operation efficiency, integration degree, implementation convenience and expandability.
2002, 24(11): 1664-1667.
Abstract:
In this paper, a new blanket jamming approach to Synthetic Aperture Radar (SAR) is proposed, and its effect to SAR image is analyzed. This method is compared with classical noise jamming technique by means of SJR (Signal to Jamming Ratio) gain and jamming power gain of SAR system. In addition, the simulation results are given.
In this paper, a new blanket jamming approach to Synthetic Aperture Radar (SAR) is proposed, and its effect to SAR image is analyzed. This method is compared with classical noise jamming technique by means of SJR (Signal to Jamming Ratio) gain and jamming power gain of SAR system. In addition, the simulation results are given.
2002, 24(11): 1668-1674.
Abstract:
This paper discusses an applied high resolution airborne SAR signal processing system, its processing flow and its architecture. It also discusses the possible applications to other intense signal processing areas. Since the universal bus, mircoprocessors, DSP chips and Linux have been applied, both hardware and software modules in this system have been standardized. This will accelerate the further development.
This paper discusses an applied high resolution airborne SAR signal processing system, its processing flow and its architecture. It also discusses the possible applications to other intense signal processing areas. Since the universal bus, mircoprocessors, DSP chips and Linux have been applied, both hardware and software modules in this system have been standardized. This will accelerate the further development.
2002, 24(11): 1675-1681.
Abstract:
In this paper, the divergence characterization of false location in moving passive location system is analysised. Conclusion that false location is kind of nonstationary random of mean value with trend is presented. A novel method for false location identification based on nonstationary verification is brought forward. Simulations prove the algorithm valid even in the high noisy environment.
In this paper, the divergence characterization of false location in moving passive location system is analysised. Conclusion that false location is kind of nonstationary random of mean value with trend is presented. A novel method for false location identification based on nonstationary verification is brought forward. Simulations prove the algorithm valid even in the high noisy environment.
2002, 24(11): 1682-1686.
Abstract:
The structure of fee data automatically collecting system in public utility is introduced. With the study of the security of the system, a synthetic security scheme is put forth, which is using random number to decide the sequences of the data to be transmitted, inserting random numbers with no use to improve information redundance, using monodirectional hash function to get the exclusive value of the transmitted data and adopting the one time encrypt to encipher the hash value and the random number. This method is simple and highly efficient.
The structure of fee data automatically collecting system in public utility is introduced. With the study of the security of the system, a synthetic security scheme is put forth, which is using random number to decide the sequences of the data to be transmitted, inserting random numbers with no use to improve information redundance, using monodirectional hash function to get the exclusive value of the transmitted data and adopting the one time encrypt to encipher the hash value and the random number. This method is simple and highly efficient.
2002, 24(11): 1687-1691.
Abstract:
Domain decomposition method (DDM) based on the Schwarz alternating method is divergent when it is used to analyze waveguide problems. In the paper, an absorbing fictitious boundary condition (FBC) is presented to generate an iterative DDM for waveguide problems. The FBC which connects the subdomains on fictitious boundaries is developed according to the actual field distribution in the waveguide to ensure the propagation of waves between adjacent subdomains. And the relaxation algorithm is introduced to improve the speed of iterative subdomains. And the relaxation algorithm is introduced to improve the speed of iterative convergence. Finally, a number of numerical examples are given to demonstrate its efficiency.
Domain decomposition method (DDM) based on the Schwarz alternating method is divergent when it is used to analyze waveguide problems. In the paper, an absorbing fictitious boundary condition (FBC) is presented to generate an iterative DDM for waveguide problems. The FBC which connects the subdomains on fictitious boundaries is developed according to the actual field distribution in the waveguide to ensure the propagation of waves between adjacent subdomains. And the relaxation algorithm is introduced to improve the speed of iterative subdomains. And the relaxation algorithm is introduced to improve the speed of iterative convergence. Finally, a number of numerical examples are given to demonstrate its efficiency.
2002, 24(11): 1692-1697.
Abstract:
Scattering from three-dimensional cavities is solved using the wavelet-MoM method, while the moment matrix is sparsified with help of the wavelet transform. The advantages of this method over conventional MoM with respect to execution time is demonstrated through numerical tests.
Scattering from three-dimensional cavities is solved using the wavelet-MoM method, while the moment matrix is sparsified with help of the wavelet transform. The advantages of this method over conventional MoM with respect to execution time is demonstrated through numerical tests.
2002, 24(11): 1698-1702.
Abstract:
Starting from the problem of complicated structure and difficult design using digital circuits in hardware implementation of fuzzy control table, a method for converting the fuzzy control table to K-map of multivalued logic and designing fuzzy control table look-up circuit at switch-level using the K-map is proposed. Using the method, the ECL circuit for implementing the table of the universe composed of five elements is designed. The example shows that the method has the characteristics of simple and feasible, and the designed ECL circuit has simple structure and high-speed inference ability.
Starting from the problem of complicated structure and difficult design using digital circuits in hardware implementation of fuzzy control table, a method for converting the fuzzy control table to K-map of multivalued logic and designing fuzzy control table look-up circuit at switch-level using the K-map is proposed. Using the method, the ECL circuit for implementing the table of the universe composed of five elements is designed. The example shows that the method has the characteristics of simple and feasible, and the designed ECL circuit has simple structure and high-speed inference ability.
2002, 24(11): 1703-1707.
Abstract:
According to the features of hard real-time systems, GA is improved in making initial group, crossover and mutation operator, etc.. A pre-run-time scheduler of hard real-time systems is implemented, and the process sequence is optimized for the given task set in order to meet the deadlines. Finally, the validity of the GA is verified through simulation with testing case.
According to the features of hard real-time systems, GA is improved in making initial group, crossover and mutation operator, etc.. A pre-run-time scheduler of hard real-time systems is implemented, and the process sequence is optimized for the given task set in order to meet the deadlines. Finally, the validity of the GA is verified through simulation with testing case.
2002, 24(11): 1708-1713.
Abstract:
The work function Single-Walled Carbon NanoTubes (SWCNTs) is investigated using Field Emission Microscopy (FEM). Since electron states of absorbed atoms and molecules dominate field emission from SWCNTs at room temperature, any measure prior to desorption could not obtain the work function of clean SWCNTs. So field emission patterns of clean SWCNTs are firstly achieved after SWCNTs are treated at high temperatures, then I-V behaviors of clean SWCNTs are measured. The radius of the bundle SWCNTs is known from its image of Transmission Electron Microscopy (TEM) so that the ratio factor could be calculated using 3 different formulas, hence the work function of clean SWCNTs is determined from the slope of Fowler-Nordheim plot.
The work function Single-Walled Carbon NanoTubes (SWCNTs) is investigated using Field Emission Microscopy (FEM). Since electron states of absorbed atoms and molecules dominate field emission from SWCNTs at room temperature, any measure prior to desorption could not obtain the work function of clean SWCNTs. So field emission patterns of clean SWCNTs are firstly achieved after SWCNTs are treated at high temperatures, then I-V behaviors of clean SWCNTs are measured. The radius of the bundle SWCNTs is known from its image of Transmission Electron Microscopy (TEM) so that the ratio factor could be calculated using 3 different formulas, hence the work function of clean SWCNTs is determined from the slope of Fowler-Nordheim plot.
2002, 24(11): 1714-1717.
Abstract:
In this paper, the system framework of IP Sec and TCP/IP software is researched, and a security model embedded with VPN is given. The model can realize the IP Sec without detail of OS TCP/IP, and decrease the cost of VPN.
In this paper, the system framework of IP Sec and TCP/IP software is researched, and a security model embedded with VPN is given. The model can realize the IP Sec without detail of OS TCP/IP, and decrease the cost of VPN.
2002, 24(11): 1718-1721.
Abstract:
A new quadratic chaos class is presented, whose Lyapunov exponents are calculated. The two ways to chaos-breakdown of torus to chaos and period-doubling-bifurcation to chaos are observed in the type III chaos structure of this class, so for the first time these two ways to chaos are observed in a same system.
A new quadratic chaos class is presented, whose Lyapunov exponents are calculated. The two ways to chaos-breakdown of torus to chaos and period-doubling-bifurcation to chaos are observed in the type III chaos structure of this class, so for the first time these two ways to chaos are observed in a same system.
2002, 24(11): 1722-1727.
Abstract:
In this paper an application of Immune Algorithm (IA) to frequency sampling technique in FIR digital filter design is presented. Two examples of lowpass and highpass FIR filter are provided. Experimental data have shown that the value of transition band sample obtained by IA can be ensured to be optimal and the frequency characteristic of the filter is improved. The comparison is made between IA and Genetic Algorithm (GA) in the application, and the convergence speed of IA is faster than that of GA.
In this paper an application of Immune Algorithm (IA) to frequency sampling technique in FIR digital filter design is presented. Two examples of lowpass and highpass FIR filter are provided. Experimental data have shown that the value of transition band sample obtained by IA can be ensured to be optimal and the frequency characteristic of the filter is improved. The comparison is made between IA and Genetic Algorithm (GA) in the application, and the convergence speed of IA is faster than that of GA.
