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1994 Vol. 16, No. 6
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1994, 16(6): 561-568.
Abstract:
This paper addresses the harmonic retrieval problem in non-Gaussian ARMA noise. A hybrid ESPRIT approach using second- and third-order statistics is proposed. First, third-order statistics are used to identify the AR part of the non-Gaussian noise process, then the noisy measurements are filtered by AR polynomial, finally, the harmonic signal parameters are estimated. Simulation examples show the effectiveness and high resolution of the new approach.
This paper addresses the harmonic retrieval problem in non-Gaussian ARMA noise. A hybrid ESPRIT approach using second- and third-order statistics is proposed. First, third-order statistics are used to identify the AR part of the non-Gaussian noise process, then the noisy measurements are filtered by AR polynomial, finally, the harmonic signal parameters are estimated. Simulation examples show the effectiveness and high resolution of the new approach.
1994, 16(6): 569-575.
Abstract:
An LMS adaptive time delay estimation method with two windows is presented. This method can reduce the superfluous calculation greatly when the time of correlation is long. It is suitable for the time delay estimation of white band-limited random signals. The feasibility and the performances of this method are also studied.
An LMS adaptive time delay estimation method with two windows is presented. This method can reduce the superfluous calculation greatly when the time of correlation is long. It is suitable for the time delay estimation of white band-limited random signals. The feasibility and the performances of this method are also studied.
1994, 16(6): 576-581.
Abstract:
A new algorithm for the fast computation of a 2-D discrete cosine transform (DCT) is presented. It is shown that the N X N DCT, where N = 2m, can be computed using only N 1-D DCT's and additions, instead of using 2N 1-D DCT's, as in the conventional row-column approach. Hence the total number of multiplications for the proposed algorithm is only half of that required for the row-column approach, and is also less than that of most of other fast algorithms, while the number of additions is almost comparable to that of others.
A new algorithm for the fast computation of a 2-D discrete cosine transform (DCT) is presented. It is shown that the N X N DCT, where N = 2m, can be computed using only N 1-D DCT's and additions, instead of using 2N 1-D DCT's, as in the conventional row-column approach. Hence the total number of multiplications for the proposed algorithm is only half of that required for the row-column approach, and is also less than that of most of other fast algorithms, while the number of additions is almost comparable to that of others.
1994, 16(6): 582-590.
Abstract:
This paper presents two generalized modified OS-CFAR detectors and an automatic censoring technique. For these two new OS-CFAR detectors, analytic expressions of the false alarm rate, the detection probabilities and the measure of ADT under the Swerling 2 assumption are obtained. Their detection performances are analyzed in homogeneous background and in the presence of strong interfering targets, and they are compared with several previously proposed CFARs.
This paper presents two generalized modified OS-CFAR detectors and an automatic censoring technique. For these two new OS-CFAR detectors, analytic expressions of the false alarm rate, the detection probabilities and the measure of ADT under the Swerling 2 assumption are obtained. Their detection performances are analyzed in homogeneous background and in the presence of strong interfering targets, and they are compared with several previously proposed CFARs.
1994, 16(6): 591-597.
Abstract:
A method which uses the bidirectional search to decode Reed-Muller codes is presented. It is proved to be a generalized minimum distance (GMD) algorithm. The complexity is much simpler than that of Forney s method. The computer simulation shows that the performance of this approach is almost the same as that of maximum likelihood decoding (MLD).
A method which uses the bidirectional search to decode Reed-Muller codes is presented. It is proved to be a generalized minimum distance (GMD) algorithm. The complexity is much simpler than that of Forney s method. The computer simulation shows that the performance of this approach is almost the same as that of maximum likelihood decoding (MLD).
1994, 16(6): 598-604.
Abstract:
Using perturbation theories and a distance in manifolds, this paper initiates a testability condition for k-faults diagnosis in analog circuits with tolerance. In this condition, this paper mathematically elaborates how testability of a circuit with tolerance depends on both nominal data and measurable signals of the circuit. In addition, it is shown that this condition provides a theoretical basis for reasonably application of extreme methods to locate faults.
Using perturbation theories and a distance in manifolds, this paper initiates a testability condition for k-faults diagnosis in analog circuits with tolerance. In this condition, this paper mathematically elaborates how testability of a circuit with tolerance depends on both nominal data and measurable signals of the circuit. In addition, it is shown that this condition provides a theoretical basis for reasonably application of extreme methods to locate faults.
1994, 16(6): 605-613.
Abstract:
The concepts of associated graph G and associated hypergraph H are introduced for a switching function F(x1,,xn) with n variables. Then, the following methods and algorithms are derived: (1) The graph theory methods and branch-and-bound algorithm BBAPI for finding all prime implicants of F, (2) Algorithm AMSHT for finding a minimal sum for F by hypergraph theory. These methods are simple and intuitive. They are convenient not only for computation by hand but also for realization by a computer. Their computation efficency are higher than that of Karnaugh map method and Q-M tabular method which are customarily used.
The concepts of associated graph G and associated hypergraph H are introduced for a switching function F(x1,,xn) with n variables. Then, the following methods and algorithms are derived: (1) The graph theory methods and branch-and-bound algorithm BBAPI for finding all prime implicants of F, (2) Algorithm AMSHT for finding a minimal sum for F by hypergraph theory. These methods are simple and intuitive. They are convenient not only for computation by hand but also for realization by a computer. Their computation efficency are higher than that of Karnaugh map method and Q-M tabular method which are customarily used.
1994, 16(6): 614-622.
Abstract:
Computing complex argument Fresnel integral is a difficult problem meeting in electromagnetic scattering of lossy dielectric wedges. This paper makes use synthetically of series expansion and asymptotic expansion of complex argument Fresnel integral and the connections of the two expansions are found and analyzed. The computing of Fresnel integral in whole complex plane is so solved perfectly. With this method the computing speed is rapid and its precision is high. In addition, the symmetrical relations and complex zeros of Fresnel integral are studied also. Three-dimensional figure and two-dimension contour lines of Fresnel intergral in the complex plane are given.
Computing complex argument Fresnel integral is a difficult problem meeting in electromagnetic scattering of lossy dielectric wedges. This paper makes use synthetically of series expansion and asymptotic expansion of complex argument Fresnel integral and the connections of the two expansions are found and analyzed. The computing of Fresnel integral in whole complex plane is so solved perfectly. With this method the computing speed is rapid and its precision is high. In addition, the symmetrical relations and complex zeros of Fresnel integral are studied also. Three-dimensional figure and two-dimension contour lines of Fresnel intergral in the complex plane are given.
1994, 16(6): 623-630.
Abstract:
The problem of scattering of a plane electromagnetic wave incident on an impedance conducting cylinder cladded with a composite and anisotropic chiral medium sheath is solved. The formulas for calculating the electromagnetic fields in composite and anisotropic chiral media are derived. An analytic expression for the radar cross-section of an impedance cylinder coated with composite and anisotropic. chiral material is obtained by application of boundary conditions. Several typical results are also presented.
The problem of scattering of a plane electromagnetic wave incident on an impedance conducting cylinder cladded with a composite and anisotropic chiral medium sheath is solved. The formulas for calculating the electromagnetic fields in composite and anisotropic chiral media are derived. An analytic expression for the radar cross-section of an impedance cylinder coated with composite and anisotropic. chiral material is obtained by application of boundary conditions. Several typical results are also presented.
1994, 16(6): 631-640.
Abstract:
Based on the concept of time-frequency distribution, the relationship and differences among various time-frequency methods are described. Then the mathematical expression of continuous wavelet transform and its significant meaning in signal processing are discussed. Compared with short-time Fourier transform the special characteristics of continuous wavelet transform are shown. The concept of-the discrete case of continuous wavelet transform in time-scale plane is introduced. Finally, some applications and advances of wavelet transforms are reviewed based on concepts proposed in this paper.
Based on the concept of time-frequency distribution, the relationship and differences among various time-frequency methods are described. Then the mathematical expression of continuous wavelet transform and its significant meaning in signal processing are discussed. Compared with short-time Fourier transform the special characteristics of continuous wavelet transform are shown. The concept of-the discrete case of continuous wavelet transform in time-scale plane is introduced. Finally, some applications and advances of wavelet transforms are reviewed based on concepts proposed in this paper.
1994, 16(6): 641-645.
Abstract:
A fast high resolution method based on rank-revealing QR decomposition is analysed, and an analytical expression of the variance of the direction of arrival estimation error is presented. Simulation results verify the analysis.
A fast high resolution method based on rank-revealing QR decomposition is analysed, and an analytical expression of the variance of the direction of arrival estimation error is presented. Simulation results verify the analysis.
1994, 16(6): 646-650.
Abstract:
Based on the brief introduction of the principle of wavelet analysis, this paper gives a summary of several typical wavelet bases from the point of veiw of perfect reconstruction of signal and emphasizes that designing wavelet bases which are used to decompose the signal into two-band form is equivalent to designing a two-band filters with perfect or nearly perfect property. The generating algorithm corresponding to Daubechies bases and some simulated results are also shown in this paper.
Based on the brief introduction of the principle of wavelet analysis, this paper gives a summary of several typical wavelet bases from the point of veiw of perfect reconstruction of signal and emphasizes that designing wavelet bases which are used to decompose the signal into two-band form is equivalent to designing a two-band filters with perfect or nearly perfect property. The generating algorithm corresponding to Daubechies bases and some simulated results are also shown in this paper.
1994, 16(6): 651-654.
Abstract:
Ultra-thin (20-100nm) polymethylmethacrylate (PMMA) films prepared by Langmuir-Blodgett techniques have been explored as high resolution electron beam resists. A Hitachi S-450 scanning electron microscope (SEM) has been refitted for a high resolution electron beam exposure system. The lithographic properties and exposure conditions of LB PMMA films were investigated. 0.15um lines-and-spaces patterns were achieved by using the SEM as the exposure tool. The results demonstrate that the etch resistance of such films is sufficiently good to allow patterning of a 20-nm aluminum film suitable for mask fabrication.
Ultra-thin (20-100nm) polymethylmethacrylate (PMMA) films prepared by Langmuir-Blodgett techniques have been explored as high resolution electron beam resists. A Hitachi S-450 scanning electron microscope (SEM) has been refitted for a high resolution electron beam exposure system. The lithographic properties and exposure conditions of LB PMMA films were investigated. 0.15um lines-and-spaces patterns were achieved by using the SEM as the exposure tool. The results demonstrate that the etch resistance of such films is sufficiently good to allow patterning of a 20-nm aluminum film suitable for mask fabrication.
1994, 16(6): 655-659.
Abstract:
This paper proposes a new arterial pulse detector using optic fiber sensor, and describes the theory, experimental set-up and experimental results of the apparatus. The optic fiber sensor is the detecting part that can detect the arterial pulses. The optical signal of the arterial pulses will be transformed into electrical signal. After signal processing, the image of arterial pulses is displayed on an oscilloscope.
This paper proposes a new arterial pulse detector using optic fiber sensor, and describes the theory, experimental set-up and experimental results of the apparatus. The optic fiber sensor is the detecting part that can detect the arterial pulses. The optical signal of the arterial pulses will be transformed into electrical signal. After signal processing, the image of arterial pulses is displayed on an oscilloscope.
1994, 16(6): 660-666.
Abstract:
In this paper, switches are considered as fixed branches, thereby the topology of a SCN becomes time-invariant. The technique for analysis of time-invariant networks is applied to SCN s. A systematic time-invariant topology analysis method of multiphase SCN s in Z-domain-a state variable approach is derived.
In this paper, switches are considered as fixed branches, thereby the topology of a SCN becomes time-invariant. The technique for analysis of time-invariant networks is applied to SCN s. A systematic time-invariant topology analysis method of multiphase SCN s in Z-domain-a state variable approach is derived.
