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1997 Vol. 19, No. 5
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1997, 19(5): 577-583.
Abstract:
Higher-order almost cycloststionary complex processes are complex random signals with almost periodically time-varying statistics, which is important to the research of non-Gaussian signals in information system. In this paper, smoothed polyperiodograms are proposed for related to cyclic polyspectral estimation and are shown to be consistent and asymptotically complex normal. Asymptotic covariance expressions are derived along with their computable forms.
Higher-order almost cycloststionary complex processes are complex random signals with almost periodically time-varying statistics, which is important to the research of non-Gaussian signals in information system. In this paper, smoothed polyperiodograms are proposed for related to cyclic polyspectral estimation and are shown to be consistent and asymptotically complex normal. Asymptotic covariance expressions are derived along with their computable forms.
1997, 19(5): 584-590.
Abstract:
This paper studies the problems which detect targets in the background clutters of millimeter-wave high resolution radar,and proposes a nonparametric detection method,which not only does less computation,but also is able to detect multiple extended targets along distance corridor,based on the position(range)orrelation information of one-dimensional range images of high resolution radar targets.The experiments,based on real data of millimeter-wave stepped frequency high resolution radar,have certified that the method presented is a very effective detection strategy for muliple extended targets.
This paper studies the problems which detect targets in the background clutters of millimeter-wave high resolution radar,and proposes a nonparametric detection method,which not only does less computation,but also is able to detect multiple extended targets along distance corridor,based on the position(range)orrelation information of one-dimensional range images of high resolution radar targets.The experiments,based on real data of millimeter-wave stepped frequency high resolution radar,have certified that the method presented is a very effective detection strategy for muliple extended targets.
1997, 19(5): 591-595.
Abstract:
Two modified censored mean (MCM) and modified unbiased censored mean (MUCM) CFAR algorithms are proposed. Both split the reference window into two sub-windows which apply CM or UCM method to create two local noise power estimations, the mean value of them are taken to set an adaptive threshold. Both use the automatic censoring technique proposed by He You (1994). Under Swerling II assumption, considering Rayleigh distributed noise and single-pulse square-law detection, the analytic expressions of Pfa, Pd and ADT of both are derived. By comparison with other schemes, the results show that their performance are evidently superior to that of GOSCA and OS in homogeneous background and in multiple target situations, in the case of IL=4, IR=2, the CFAR loss of MCM is improved by 2 dB relative to that of OS, that of MUCM is improved by 1.5 dB over OS. The performance of MCM is slightly better than that of CM, the performance of MUCM is the nearly same as that of UCM, but their sample sorting time is less than half of that of CM, UCM and OS.
Two modified censored mean (MCM) and modified unbiased censored mean (MUCM) CFAR algorithms are proposed. Both split the reference window into two sub-windows which apply CM or UCM method to create two local noise power estimations, the mean value of them are taken to set an adaptive threshold. Both use the automatic censoring technique proposed by He You (1994). Under Swerling II assumption, considering Rayleigh distributed noise and single-pulse square-law detection, the analytic expressions of Pfa, Pd and ADT of both are derived. By comparison with other schemes, the results show that their performance are evidently superior to that of GOSCA and OS in homogeneous background and in multiple target situations, in the case of IL=4, IR=2, the CFAR loss of MCM is improved by 2 dB relative to that of OS, that of MUCM is improved by 1.5 dB over OS. The performance of MCM is slightly better than that of CM, the performance of MUCM is the nearly same as that of UCM, but their sample sorting time is less than half of that of CM, UCM and OS.
1997, 19(5): 596-605.
Abstract:
This paper extends the Hopfield s autoassociative neural networks and the Kosko s bidirectional neural networks to the dynamic neural networks with infinite state, namely the distributed parameter neural networks. Their boundedness and stability theorems are given and proved. Especially, their spatio-temporal stability is studied and their stability criteria about the boundary conditions are given. Finally, a simulation is given.
This paper extends the Hopfield s autoassociative neural networks and the Kosko s bidirectional neural networks to the dynamic neural networks with infinite state, namely the distributed parameter neural networks. Their boundedness and stability theorems are given and proved. Especially, their spatio-temporal stability is studied and their stability criteria about the boundary conditions are given. Finally, a simulation is given.
1997, 19(5): 606-612.
Abstract:
One of the primary applications of higher order statistics has been for the time delay estimation of non-Gaussian signal in Gaussian spatially correlated noise. This paper studies the time delay estimation of Gaussian signal in the presence of unknown non-Gaussian spatially correlated noise. A hbrid approach for solving this problem is proposed. First, the third-order statistics of the measurements, thus those of the non-Gaussian noises are estimated; then the second-order statistics of the noises are computed by statistics projection; finally, cross-correlation based approaches are used to estimate time delay parameter. Simulation examples are also presented to demonstrate the effectiveness of the new approach.
One of the primary applications of higher order statistics has been for the time delay estimation of non-Gaussian signal in Gaussian spatially correlated noise. This paper studies the time delay estimation of Gaussian signal in the presence of unknown non-Gaussian spatially correlated noise. A hbrid approach for solving this problem is proposed. First, the third-order statistics of the measurements, thus those of the non-Gaussian noises are estimated; then the second-order statistics of the noises are computed by statistics projection; finally, cross-correlation based approaches are used to estimate time delay parameter. Simulation examples are also presented to demonstrate the effectiveness of the new approach.
1997, 19(5): 613-618.
Abstract:
This paper presents the performance analysis of the MUSIC algorithm in the presence of channel mismatching. Theoretical expression for the error of DOA estimating with MUSIC algorithm and Cramer-Rao bound are derived. It is compared with simulations performed for some representative cases. The results of theoretical expression and simulation show that existence of channel mismatching will increase the error of DOA estimating and degrade its performance.
This paper presents the performance analysis of the MUSIC algorithm in the presence of channel mismatching. Theoretical expression for the error of DOA estimating with MUSIC algorithm and Cramer-Rao bound are derived. It is compared with simulations performed for some representative cases. The results of theoretical expression and simulation show that existence of channel mismatching will increase the error of DOA estimating and degrade its performance.
1997, 19(5): 619-624.
Abstract:
Based on time delay technology and MUSIC algorithm, a novel estimating multiple frequencies approach of signal with sampling rate which is least Nyquist sampling rate is presented in this paper. With choosing delay time properly, the estimated frequencies are unambiguous. Computer simulation confirms its availability.
Based on time delay technology and MUSIC algorithm, a novel estimating multiple frequencies approach of signal with sampling rate which is least Nyquist sampling rate is presented in this paper. With choosing delay time properly, the estimated frequencies are unambiguous. Computer simulation confirms its availability.
1997, 19(5): 625-630.
Abstract:
Based on human visible performance an APICM method is proposed.The core of the method is that the method can suppresses the reconstruction noise in frequency bands where it is most visible in order to achieve spatial reconstructing noise shaping by using noise feedback filter.Meanwhile, some noises are added into frequency bands where it is less visible in order to achieve noise smooth of overall reconstructing image. Therefore,the coarser nonuniform quantizer(the smaller number of quantization levels)can be used in order to achieve the better reconstruction image.The method not only has low designing complexity but only has a performance of noise shaping better than that of a standard DPCM system.
Based on human visible performance an APICM method is proposed.The core of the method is that the method can suppresses the reconstruction noise in frequency bands where it is most visible in order to achieve spatial reconstructing noise shaping by using noise feedback filter.Meanwhile, some noises are added into frequency bands where it is less visible in order to achieve noise smooth of overall reconstructing image. Therefore,the coarser nonuniform quantizer(the smaller number of quantization levels)can be used in order to achieve the better reconstruction image.The method not only has low designing complexity but only has a performance of noise shaping better than that of a standard DPCM system.
1997, 19(5): 631-636.
Abstract:
A large class of linear structure functions satisfying correlation immunity of order one is found by the studying of linear structural Boolean functions. The known enumeration bounds of correlation-immune Boolean functions are greatly improved. The best updated lower bounds are found.
A large class of linear structure functions satisfying correlation immunity of order one is found by the studying of linear structural Boolean functions. The known enumeration bounds of correlation-immune Boolean functions are greatly improved. The best updated lower bounds are found.
1997, 19(5): 637-642.
Abstract:
An orthonormal wavelets based equalizer (OWBE) is presented. The equalizer is represented by a set of orthonormal wavelets and the corresponding coefficients. The paper gives the structure and also the adaption algorithm of the OWBE. Theoretical analysis show that the OWBE convergences faster than the conventional FIR LMS based equalizer (LTE), while the increase in the computational complexity is very little. Several simulations are performed to evaluate the behavior of the OWBE.
An orthonormal wavelets based equalizer (OWBE) is presented. The equalizer is represented by a set of orthonormal wavelets and the corresponding coefficients. The paper gives the structure and also the adaption algorithm of the OWBE. Theoretical analysis show that the OWBE convergences faster than the conventional FIR LMS based equalizer (LTE), while the increase in the computational complexity is very little. Several simulations are performed to evaluate the behavior of the OWBE.
1997, 19(5): 643-648.
Abstract:
The analysis of cell loss rates in an ATM Mux with loss priorities is an important problem in the study of traffic control in ATM networks. In this paper, the loss rates of the cells with different priorities in an ATM Mux are analyzed by approximating the actual input process with two-state MMDP and fluid flow technique, and the analytical expressions of the relation between the loss rates and the buffer size are obtained. Simulation shows that our approach is sufficiently accurate for applications.
The analysis of cell loss rates in an ATM Mux with loss priorities is an important problem in the study of traffic control in ATM networks. In this paper, the loss rates of the cells with different priorities in an ATM Mux are analyzed by approximating the actual input process with two-state MMDP and fluid flow technique, and the analytical expressions of the relation between the loss rates and the buffer size are obtained. Simulation shows that our approach is sufficiently accurate for applications.
1997, 19(5): 649-657.
Abstract:
An improved perturbation technique (equivalent small parameter method) proposed in a recent paper (Int. J. Electronics, 1989, 67(3): 403-414) has been successfully applied to steady-state analysis of DC-DC PWM switching converters. This paper extends the algorithm to transient analysis of a broader class of non-linear systems. As an example, the transient respoase of a PWM switching converter is analyzed to demonstrate its simplicity and accuracy.
An improved perturbation technique (equivalent small parameter method) proposed in a recent paper (Int. J. Electronics, 1989, 67(3): 403-414) has been successfully applied to steady-state analysis of DC-DC PWM switching converters. This paper extends the algorithm to transient analysis of a broader class of non-linear systems. As an example, the transient respoase of a PWM switching converter is analyzed to demonstrate its simplicity and accuracy.
1997, 19(5): 658-664.
Abstract:
This paper presents a sample circuit model for no internal phase shift and single longitudinal mode DFB-LD, basing on the coupling wave equations for period waveguide structure and the rate equation for carrier density. The simulated results from this model are agree with the reports in the literature.
This paper presents a sample circuit model for no internal phase shift and single longitudinal mode DFB-LD, basing on the coupling wave equations for period waveguide structure and the rate equation for carrier density. The simulated results from this model are agree with the reports in the literature.
1997, 19(5): 665-668.
Abstract:
The characteristics of Ti: LiNbO3 traveling wave modulator have been analyzed in this paper, taking into account the reflection coefficient of the terminator. The main emphasis of the present work is placed on the description of the effect of the reflection coefficient on the bandwidth, the half-wave voltage and the time domain response.
The characteristics of Ti: LiNbO3 traveling wave modulator have been analyzed in this paper, taking into account the reflection coefficient of the terminator. The main emphasis of the present work is placed on the description of the effect of the reflection coefficient on the bandwidth, the half-wave voltage and the time domain response.
1997, 19(5): 669-676.
Abstract:
By using the theory of clipping voltage-switches, two kinds of master/slave nMOS quaternary flip-flops are designed.These flip-flops have the capability of two-input presetting and double-rail complementary outputs. A modulo-16 up counter and a modulo-10 up counter are designed by using JKLM type flip-flop. It is shown that these flip-flops can be flexibly used to design quaternary sequential circuits.
By using the theory of clipping voltage-switches, two kinds of master/slave nMOS quaternary flip-flops are designed.These flip-flops have the capability of two-input presetting and double-rail complementary outputs. A modulo-16 up counter and a modulo-10 up counter are designed by using JKLM type flip-flop. It is shown that these flip-flops can be flexibly used to design quaternary sequential circuits.
1997, 19(5): 677-681.
Abstract:
By using some definitions and restrictions, an ordinary logical expression-the characteristic equation for one external urge and an orbitrary state of n-state variables potential asynchronous sequential logical circuit is obtained. The characteristic equation combines express with the state table, the conditions satisfied by the state variable numbers and stable state numbers when happen sequential hazards are deduced. The basic laws which are particularly used to study sequential hazards are given.
By using some definitions and restrictions, an ordinary logical expression-the characteristic equation for one external urge and an orbitrary state of n-state variables potential asynchronous sequential logical circuit is obtained. The characteristic equation combines express with the state table, the conditions satisfied by the state variable numbers and stable state numbers when happen sequential hazards are deduced. The basic laws which are particularly used to study sequential hazards are given.
1997, 19(5): 682-687.
Abstract:
Trilemma effect is an important criteria for the self-convergence deflection system. The influence of the higher order Trilemma effects should be taken into account for the correction of the higher-order deflection aberrations. In this paper, up to the seventh-order Trilemma effects are analyzed with region-cutting by means of the correction theory of the multipole field deflection aberration. The expressions of the various order of Trilemma constant are given, in which the seventh-order Trilemma constant can be used as a criteria of the deflection aberration correction at large deflection angle
Trilemma effect is an important criteria for the self-convergence deflection system. The influence of the higher order Trilemma effects should be taken into account for the correction of the higher-order deflection aberrations. In this paper, up to the seventh-order Trilemma effects are analyzed with region-cutting by means of the correction theory of the multipole field deflection aberration. The expressions of the various order of Trilemma constant are given, in which the seventh-order Trilemma constant can be used as a criteria of the deflection aberration correction at large deflection angle
1997, 19(5): 688-694.
Abstract:
A brief introduction of some major vacuum microelectronic devices is presented including field emitter arrays(FEA), feild emission displays(FED) and the vacuum microelectronic devices in microwave and millimeter-wave bands. The paper mainly discusses the requirements for FEA by the mentioned devices, possible solutions to the requirements, and further research topics. As an example, the paper also discusses research topics and problems about vacuum microelectronic microwave tubes.
A brief introduction of some major vacuum microelectronic devices is presented including field emitter arrays(FEA), feild emission displays(FED) and the vacuum microelectronic devices in microwave and millimeter-wave bands. The paper mainly discusses the requirements for FEA by the mentioned devices, possible solutions to the requirements, and further research topics. As an example, the paper also discusses research topics and problems about vacuum microelectronic microwave tubes.
1997, 19(5): 695-700.
Abstract:
In this paper, periodic calibration conception of spaceborne microwave radiometer is systematically described with the emphasis on calibration pattern, equation and error budget. Developments in other countries are also reviewed, understanding which is very beneficial to design our own radiometer periodic calibration system.
In this paper, periodic calibration conception of spaceborne microwave radiometer is systematically described with the emphasis on calibration pattern, equation and error budget. Developments in other countries are also reviewed, understanding which is very beneficial to design our own radiometer periodic calibration system.
1997, 19(5): 701-704.
Abstract:
This paper introduces an intelligent information inquiring system. Users can inquire the knowledgebase by using the media of text, image and speech. The question may be in different forms of representation to the same semantic content. The system produces answers which have substantial content and form, also it can enlarge its knowledgebase conveniently through learning.
This paper introduces an intelligent information inquiring system. Users can inquire the knowledgebase by using the media of text, image and speech. The question may be in different forms of representation to the same semantic content. The system produces answers which have substantial content and form, also it can enlarge its knowledgebase conveniently through learning.
1997, 19(5): 705-708.
Abstract:
This paper is devoted to the system for fire detection and extinction which uses power line as bus. And the spread spectrum technology is introduced to the system for fire detection and extinction. According to the low power density and high interference suppression characteristic of the spread spectrum communication system, it can decrease the high error code rate of the system which only uses FSK or ASK modulation method. The characteristic of error code probability in this system is analyzed.
This paper is devoted to the system for fire detection and extinction which uses power line as bus. And the spread spectrum technology is introduced to the system for fire detection and extinction. According to the low power density and high interference suppression characteristic of the spread spectrum communication system, it can decrease the high error code rate of the system which only uses FSK or ASK modulation method. The characteristic of error code probability in this system is analyzed.
1997, 19(5): 709-712.
Abstract:
Based on the characters and engineering modeling of Laser Radar Cross Section(LRCS) for the object with rough surface, some methods of geometric modeling and hidden processing for complex object are analyzed and discussed in this paper. The angular distributions of backscatter-ing of laser radar cross section for airplane model are computed at 1.06m. The numerical results are in good agreement with experimental data.
Based on the characters and engineering modeling of Laser Radar Cross Section(LRCS) for the object with rough surface, some methods of geometric modeling and hidden processing for complex object are analyzed and discussed in this paper. The angular distributions of backscatter-ing of laser radar cross section for airplane model are computed at 1.06m. The numerical results are in good agreement with experimental data.
1997, 19(5): 713-716.
Abstract:
A formula for computing the spectrum of function af b is presented by using the spectrum of function f, and affine approach problem of multi-valued logical functions is discussed.
A formula for computing the spectrum of function af b is presented by using the spectrum of function f, and affine approach problem of multi-valued logical functions is discussed.
1997, 19(5): 717-720.
Abstract:
This paper presents a practical secret voting scheme for large scale electronic elections. The scheme enables a voter to engage in not only the estate election, but also some different electronic elections simultaneously by using a single signature obtained from administrator.
This paper presents a practical secret voting scheme for large scale electronic elections. The scheme enables a voter to engage in not only the estate election, but also some different electronic elections simultaneously by using a single signature obtained from administrator.
