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2002 Vol. 24, No. 4
Display Method:
2002, 24(4): 433-438.
Abstract:
Based on video editing model, several important characteristics that can be used for detecting fade and dissolve, such as the variance, edge intensity, Effective Average gradient (EAG) and Double Chromatic Difference (DCD) of video sequence are derived. After comparison, the variances are used to achieve robust fade detection. It is approved that in terms of recall rate for dissolve detection, the variance, edge intensity and EAG have similar efficiency. So, the variances are used for selection of possible positions of dissolve transitions, which guarantees high recall rate, and the DCD are then used for further confirmation to improve precision rate. Since the detection is carried out on DC sequence, the computation complexity of this method is relatively low.
Based on video editing model, several important characteristics that can be used for detecting fade and dissolve, such as the variance, edge intensity, Effective Average gradient (EAG) and Double Chromatic Difference (DCD) of video sequence are derived. After comparison, the variances are used to achieve robust fade detection. It is approved that in terms of recall rate for dissolve detection, the variance, edge intensity and EAG have similar efficiency. So, the variances are used for selection of possible positions of dissolve transitions, which guarantees high recall rate, and the DCD are then used for further confirmation to improve precision rate. Since the detection is carried out on DC sequence, the computation complexity of this method is relatively low.
2002, 24(4): 439-444.
Abstract:
In this paper, a new medical image coding algorithm is reported. This type of algorithm is called interframe predictive coding of medical image using a wavelet transform for motion compensated estimation. Simulation results show that this new algorithm has better performance than the other algorithms of the same kind.
In this paper, a new medical image coding algorithm is reported. This type of algorithm is called interframe predictive coding of medical image using a wavelet transform for motion compensated estimation. Simulation results show that this new algorithm has better performance than the other algorithms of the same kind.
2002, 24(4): 445-449.
Abstract:
Among the wavelet image coding algorithms, SPIHT is the most well-known coding algorithm because of its outstanding preformance. But it needs too many memories for hardware implementation. LZC reduces the requirement of memory as well as its preformance. In this paper, SPIHT algorithm is modified by using the idea of LZC to reduce the momery and preserve its high performance. Also an approximated algorithm is proposed to accelerate the algorithm with insignificant loss.
Among the wavelet image coding algorithms, SPIHT is the most well-known coding algorithm because of its outstanding preformance. But it needs too many memories for hardware implementation. LZC reduces the requirement of memory as well as its preformance. In this paper, SPIHT algorithm is modified by using the idea of LZC to reduce the momery and preserve its high performance. Also an approximated algorithm is proposed to accelerate the algorithm with insignificant loss.
2002, 24(4): 450-454.
Abstract:
A new approach is presented for the task assignment in multi-station multi-satellite data reception mission management systems by applying the optimal assignment algorithm in c.ombinatorial mathematics based upon the definition of satellite data reception task collection and the construction of the assignment cost functions.
A new approach is presented for the task assignment in multi-station multi-satellite data reception mission management systems by applying the optimal assignment algorithm in c.ombinatorial mathematics based upon the definition of satellite data reception task collection and the construction of the assignment cost functions.
2002, 24(4): 455-460.
Abstract:
The eigenspace-based multiple constrained minimum variance beamformer (EMCMVB) is presented here, which combines the multiple constrained minimum variance beamformer (MCMBV) with the eigenspace-based beamformer. Coherent interference can be suppressed by the EMCMVB efficiently. The EMCMVB first gets the modified signal subspace by using the estimated arrival angles of coherent interferers and the eigenstructure of the correlation matrix, and then projects the MCMVB weight vector onto the modified signal subspace. The theoretical analysis indicates that the EMCMVB outperforms the MCMVB. Computer simulation results are also presented and demonstrate the merits of the EMCMVB.
The eigenspace-based multiple constrained minimum variance beamformer (EMCMVB) is presented here, which combines the multiple constrained minimum variance beamformer (MCMBV) with the eigenspace-based beamformer. Coherent interference can be suppressed by the EMCMVB efficiently. The EMCMVB first gets the modified signal subspace by using the estimated arrival angles of coherent interferers and the eigenstructure of the correlation matrix, and then projects the MCMVB weight vector onto the modified signal subspace. The theoretical analysis indicates that the EMCMVB outperforms the MCMVB. Computer simulation results are also presented and demonstrate the merits of the EMCMVB.
2002, 24(4): 461-466.
Abstract:
A novel class of nonlinear adaptive active noise cancellation filter-sigmoid-based Volterra adaptive active noise cancellation filter is introduced. The normalized data and instantaneous error LMS algorithm is modified to update the coefficients of this sigmoid-based Volterra filter. Because the sigmoid-based Volterra adaptive filter, equivalent to second-order Volterra filter, is of the reduced coefficients and modularity, it is applied for adaptive active noise cancellation. Experimental results of adaptive active noise cancellation show that the proposed sigmoid-based Volterra adaptive active noise cancellation filter not only has good anti-noise performance, but also can be easily implemented.
A novel class of nonlinear adaptive active noise cancellation filter-sigmoid-based Volterra adaptive active noise cancellation filter is introduced. The normalized data and instantaneous error LMS algorithm is modified to update the coefficients of this sigmoid-based Volterra filter. Because the sigmoid-based Volterra adaptive filter, equivalent to second-order Volterra filter, is of the reduced coefficients and modularity, it is applied for adaptive active noise cancellation. Experimental results of adaptive active noise cancellation show that the proposed sigmoid-based Volterra adaptive active noise cancellation filter not only has good anti-noise performance, but also can be easily implemented.
2002, 24(4): 467-472.
Abstract:
In this paper, a new frequency-domain DAPSK+OFDM is proposed. Its modulation and demodulation are discussed, and its BER performance is analysed in AWGN channel. In the case f the typical AM channel, the simulation results indicate that the BER performance of frequency-domain DAPSK+OFDM is better than that of time-domain DAPSK+OFDM in Short Wave (SW) channel but poorer in Medium Wave (MW) channel. In short, it is reasonable to use frequency-domain DAPSK+OFDM in SW channel and time-domain DAPSK+OFDM in MW and Long Wave (LW) channel.
In this paper, a new frequency-domain DAPSK+OFDM is proposed. Its modulation and demodulation are discussed, and its BER performance is analysed in AWGN channel. In the case f the typical AM channel, the simulation results indicate that the BER performance of frequency-domain DAPSK+OFDM is better than that of time-domain DAPSK+OFDM in Short Wave (SW) channel but poorer in Medium Wave (MW) channel. In short, it is reasonable to use frequency-domain DAPSK+OFDM in SW channel and time-domain DAPSK+OFDM in MW and Long Wave (LW) channel.
2002, 24(4): 473-478.
Abstract:
A squaring method to find the maximal-ratio receive combining scheme of the orthogonal space-time block codes is presented. Furthermore, it is proved that this method can be used as a general method for the orthogonal space-time block codes. Considering the orthogonality, the minimum distance decisions for each output branch can be made respectively. The performance using this method is the same as that using the maximum likelihood decoding criterion while the complexity of decoding is much lower.
A squaring method to find the maximal-ratio receive combining scheme of the orthogonal space-time block codes is presented. Furthermore, it is proved that this method can be used as a general method for the orthogonal space-time block codes. Considering the orthogonality, the minimum distance decisions for each output branch can be made respectively. The performance using this method is the same as that using the maximum likelihood decoding criterion while the complexity of decoding is much lower.
2002, 24(4): 479-485.
Abstract:
In this paper, the problem of stability for the cellular neural networks(CNNs) with delay is studied. Two types of sufficient conditions for global asymptotic stability of cellular neural networks with delay are obtained by means of Lyapunov functional approach and the method of Razumikhin function. One type involves delay dependent results while the other type of results does not involve delays. The conditions obtained improve the existed results and may offer some referrence to the design of CNNs with delay.
In this paper, the problem of stability for the cellular neural networks(CNNs) with delay is studied. Two types of sufficient conditions for global asymptotic stability of cellular neural networks with delay are obtained by means of Lyapunov functional approach and the method of Razumikhin function. One type involves delay dependent results while the other type of results does not involve delays. The conditions obtained improve the existed results and may offer some referrence to the design of CNNs with delay.
2002, 24(4): 486-491.
Abstract:
Lifting scheme, which is a new approach of constructing the second-generation wavelets, can also be used to construct first-generation ones. Compared with Daubechiess construction approach, lifting scheme can easily be grasped by readers who are not well equipped with Fourier analysis. The following fact will be proved using Lawton matrix in this paper: almost all wavelets constructed using lifting scheme satisfy the biorthogonal condition. Another topic in this paper is to ensure linear-phase property of new ones. Some examples are given to demonstrate how to construct linear-phase biorthogonal wavelets.
Lifting scheme, which is a new approach of constructing the second-generation wavelets, can also be used to construct first-generation ones. Compared with Daubechiess construction approach, lifting scheme can easily be grasped by readers who are not well equipped with Fourier analysis. The following fact will be proved using Lawton matrix in this paper: almost all wavelets constructed using lifting scheme satisfy the biorthogonal condition. Another topic in this paper is to ensure linear-phase property of new ones. Some examples are given to demonstrate how to construct linear-phase biorthogonal wavelets.
2002, 24(4): 492-498.
Abstract:
This paper deals with the influence induced by multipath propagation and optimal selection of M/N when frequency diversity technique is used. To ensure the detection statistic and choose the correct M and N, it must be known that the probability density function (PDF) of the noise plus target times the multipath factor. Differ from other papers, the more general model of reflection is adopt, the PDF is derived for a nonfluctuating target and for a Rayleigh target, then the relation between M/N and P_D/P_F is got by multi-pulse detection in multipath. (compared with free-space).
This paper deals with the influence induced by multipath propagation and optimal selection of M/N when frequency diversity technique is used. To ensure the detection statistic and choose the correct M and N, it must be known that the probability density function (PDF) of the noise plus target times the multipath factor. Differ from other papers, the more general model of reflection is adopt, the PDF is derived for a nonfluctuating target and for a Rayleigh target, then the relation between M/N and P_D/P_F is got by multi-pulse detection in multipath. (compared with free-space).
2002, 24(4): 499-506.
Abstract:
This paper derives the ideal AGC(Automatic Gain Control) algorithm for SAR system from the statistical model of SAR echoes. Compared with the conventional algorithm, the two methods have both advantages and disadvantages. The conventional method is much more stable than the ideal one under the condition of low signal-to-noise ratio. But its gain and dynamical range are always much smaller than the practical needed one. This paper puts forward a new AGC algorithm using maximum likelihood estimation, which inherits all the virtues of the tow methods above and overcomes their drawbacks as well. The results are satisfactory via computer simulations.
This paper derives the ideal AGC(Automatic Gain Control) algorithm for SAR system from the statistical model of SAR echoes. Compared with the conventional algorithm, the two methods have both advantages and disadvantages. The conventional method is much more stable than the ideal one under the condition of low signal-to-noise ratio. But its gain and dynamical range are always much smaller than the practical needed one. This paper puts forward a new AGC algorithm using maximum likelihood estimation, which inherits all the virtues of the tow methods above and overcomes their drawbacks as well. The results are satisfactory via computer simulations.
2002, 24(4): 507-513.
Abstract:
Based on the multiplication speckle model, the statistical characteristics of the polarimetric signatures are analyzed,which include co-polar and cross-polar ratios and co-polar phase difference for multi-look polarimetric SAR data. With the simulated data, the effect of the estimated accuracy of the polarimetric signatures on the performance of the algorithm for suppressing the speckle is analyzed. in addition, based on the features of the polarimetric signatures, applying them on the Bayes classifier, the accuracy of classification can be compared with the optimum polarimetric classifier.
Based on the multiplication speckle model, the statistical characteristics of the polarimetric signatures are analyzed,which include co-polar and cross-polar ratios and co-polar phase difference for multi-look polarimetric SAR data. With the simulated data, the effect of the estimated accuracy of the polarimetric signatures on the performance of the algorithm for suppressing the speckle is analyzed. in addition, based on the features of the polarimetric signatures, applying them on the Bayes classifier, the accuracy of classification can be compared with the optimum polarimetric classifier.
2002, 24(4): 514-519.
Abstract:
A new airborne slow-moving target detection method for mechanically scanned antennas is analyzed in detail. Compared with conventional DPCA technology under engineering conditions, the method is easily realized and its performance is higher than that of DPCA. Finally the simulation result is presented.
A new airborne slow-moving target detection method for mechanically scanned antennas is analyzed in detail. Compared with conventional DPCA technology under engineering conditions, the method is easily realized and its performance is higher than that of DPCA. Finally the simulation result is presented.
2002, 24(4): 520-526.
Abstract:
Passive-star Time-Wavelength Division Multiplexing (TWDM) is an attractive technology suitable for very high speed large capacity communication. One of its key issues is to find a minimum frame length with arbitrary traffic pattern and arbitrary tuning latencies. This paper presents a new algorithm named MTC for this issue. The simulation results show that MTC achieves better performance than previous scheme. It is an efficient media access protocol for TWDM networks.
Passive-star Time-Wavelength Division Multiplexing (TWDM) is an attractive technology suitable for very high speed large capacity communication. One of its key issues is to find a minimum frame length with arbitrary traffic pattern and arbitrary tuning latencies. This paper presents a new algorithm named MTC for this issue. The simulation results show that MTC achieves better performance than previous scheme. It is an efficient media access protocol for TWDM networks.
2002, 24(4): 527-533.
Abstract:
In accordance with the uplink frame structure of WCDMA system, this paper develops the LS-DRMAT algorithm proposed by Z. Rong, et al.(1997) into a new algorithm named LMS-DRMAT with training sequence. The use of training sequence does not complicate the application of the new algorithm in WCDMA system because the existed pilot bits in each WCDMA frame slot act as the the training sequence for the new algorithm. The proposed algorithm cuts down lots of computational complexity of LS-DRMAT algorithm which simplifies its application in WCDMA system. Furthermore, the simulation experiments indicate that the new algorithm can perform much lower BER than LS-DRMAT.
In accordance with the uplink frame structure of WCDMA system, this paper develops the LS-DRMAT algorithm proposed by Z. Rong, et al.(1997) into a new algorithm named LMS-DRMAT with training sequence. The use of training sequence does not complicate the application of the new algorithm in WCDMA system because the existed pilot bits in each WCDMA frame slot act as the the training sequence for the new algorithm. The proposed algorithm cuts down lots of computational complexity of LS-DRMAT algorithm which simplifies its application in WCDMA system. Furthermore, the simulation experiments indicate that the new algorithm can perform much lower BER than LS-DRMAT.
2002, 24(4): 534-538.
Abstract:
This paper proposes a new method to exploit the symmetric structure of prototype filters and provides a practical implementation structure which can be used in FPGAs, DSPs or commercial available digital filters. In the development of WCDMA mobile communication systems, this method is proposed to implement 64-order baseband shaping filter.
This paper proposes a new method to exploit the symmetric structure of prototype filters and provides a practical implementation structure which can be used in FPGAs, DSPs or commercial available digital filters. In the development of WCDMA mobile communication systems, this method is proposed to implement 64-order baseband shaping filter.
2002, 24(4): 539-544.
Abstract:
In this paper, the blind multiuser detector operating over multipath fading channel with high-power Narrow Bandwidth Interference (NBI) is presented. It has the basic structure of RAKE receiver in which every path signal could be traced by MMSE optimization strategy, therefore it can suppress the NBI and Multi-Access Interference (MAI) over multipath fading channel. It has been proved by the simulation results that the performance of the detector is superior to those without considering NBI suppression.
In this paper, the blind multiuser detector operating over multipath fading channel with high-power Narrow Bandwidth Interference (NBI) is presented. It has the basic structure of RAKE receiver in which every path signal could be traced by MMSE optimization strategy, therefore it can suppress the NBI and Multi-Access Interference (MAI) over multipath fading channel. It has been proved by the simulation results that the performance of the detector is superior to those without considering NBI suppression.
2002, 24(4): 545-551.
Abstract:
This paper investigates the performance of the AAL2 packet voice multiplexer as a function of the transmission capacity of the ATM VC when the ATM VC bandwidth utilization is constant. A conclusion is drawn that packet delay and probability of packet loss will decrease when the transmission capacity of the ATM VC increases. Finally, an implementation of AAL2 packet voice multiplexer is presented which can easily multiplex the voice calls from multiple El voice circuit.
This paper investigates the performance of the AAL2 packet voice multiplexer as a function of the transmission capacity of the ATM VC when the ATM VC bandwidth utilization is constant. A conclusion is drawn that packet delay and probability of packet loss will decrease when the transmission capacity of the ATM VC increases. Finally, an implementation of AAL2 packet voice multiplexer is presented which can easily multiplex the voice calls from multiple El voice circuit.
2002, 24(4): 552-556.
Abstract:
Based on fourth-order cumulants, a new optimizing criterion is discussed and proven to have the global minima, while the minima satisfy the decorrelating conditions. Thereby, a new scheme for the blind multiuser detection can be obtained by solving the optimization problem. Then, an adaptive algorithm for the blind multiuser detection is given using method of the steepest descent. The computer simulation further demonstrates the results.
Based on fourth-order cumulants, a new optimizing criterion is discussed and proven to have the global minima, while the minima satisfy the decorrelating conditions. Thereby, a new scheme for the blind multiuser detection can be obtained by solving the optimization problem. Then, an adaptive algorithm for the blind multiuser detection is given using method of the steepest descent. The computer simulation further demonstrates the results.
2002, 24(4): 557-562.
Abstract:
This paper studies chaotic attractors in nonautonomous nonlinear systems. Based on the mathematical analysis and digital simulation of the Genesio system in detail, a cell model of chaotic attractor in a kind of nonautonomous systems is obtained.
This paper studies chaotic attractors in nonautonomous nonlinear systems. Based on the mathematical analysis and digital simulation of the Genesio system in detail, a cell model of chaotic attractor in a kind of nonautonomous systems is obtained.
2002, 24(4): 563-567.
Abstract:
On the basis of theory of three essential circuits elements, this paper presents a universal synthesis of bipolar circuits. The generalized binary signal to be applicable to voltagemode and current-mode circuits is introduced first. Then the simplified theorem on origin signal and load is proved, which is used for anlayzing the structure of any unit circuits, for deducing the relevant expression in component stage and for finding out a new manner to realize TTL and ECL circuits. In accordance with the above theory a new low voltage TTL circuit and multimeitter ECL circuit in component stage are found out. The above theory is proved to be correct through experiments on circuits.
On the basis of theory of three essential circuits elements, this paper presents a universal synthesis of bipolar circuits. The generalized binary signal to be applicable to voltagemode and current-mode circuits is introduced first. Then the simplified theorem on origin signal and load is proved, which is used for anlayzing the structure of any unit circuits, for deducing the relevant expression in component stage and for finding out a new manner to realize TTL and ECL circuits. In accordance with the above theory a new low voltage TTL circuit and multimeitter ECL circuit in component stage are found out. The above theory is proved to be correct through experiments on circuits.
2002, 24(4): 568-572.
Abstract:
The data transmission control schemes have the significant influences on the packet delay and system capacity. In this paper, three types of data transmission control schemes are presented and their influences on the system performance are simulated. Through the simulation, some conclusions on the feature of these schemes are made.
The data transmission control schemes have the significant influences on the packet delay and system capacity. In this paper, three types of data transmission control schemes are presented and their influences on the system performance are simulated. Through the simulation, some conclusions on the feature of these schemes are made.
2002, 24(4): 573-576.
Abstract:
This paper presents the design and implementation of system control for HDTV video decoder. The principle of the system control is described in detail too. FPGA is adopted for its programmable and reconfigurable features. The system control works perfectly and steadily which ensures the perfect work of decoder and display buffer.
This paper presents the design and implementation of system control for HDTV video decoder. The principle of the system control is described in detail too. FPGA is adopted for its programmable and reconfigurable features. The system control works perfectly and steadily which ensures the perfect work of decoder and display buffer.
