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2003 Vol. 25, No. 5
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2003, 25(5): 577-584.
Abstract:
In this paper, the single observer-passive location method using phase difference change rate is introduced based on existing methods. The direction of the target can be obtained with phase difference between two orthogonal interferometers on the observer and the radial distance with corresponding phase difference change rate. Then the target can be located with high speed and precision. Locating expressions are given when the observer is flying with a fixed posture angle. Simulations show that this method is effective.
In this paper, the single observer-passive location method using phase difference change rate is introduced based on existing methods. The direction of the target can be obtained with phase difference between two orthogonal interferometers on the observer and the radial distance with corresponding phase difference change rate. Then the target can be located with high speed and precision. Locating expressions are given when the observer is flying with a fixed posture angle. Simulations show that this method is effective.
2003, 25(5): 585-591.
Abstract:
In this paper, ground slow-moving target imaging via airborne interferometric SAR/ISAR technique is investigated. Land clutter suppression and SCR improvement are achieved by range and cross-range two-dimensional high resolution of SAR. imaging and spatial domain cancellation of interferometer. True azimuth of moving target is determined using phase-comparison interferometer. Furthermore, high resolution image of the slow-moving target is obtained by IS AR processing. The block diagram and the operational principle of the airborne interferometric SAR./ISAR system are discussed in detail. Quantitative relations for SAR,, interferometer spatial domain cancellation, direction finding and ISAR processing are derived. Theoretical analysis and preliminary computer simulation reveal the validity of this technique.
In this paper, ground slow-moving target imaging via airborne interferometric SAR/ISAR technique is investigated. Land clutter suppression and SCR improvement are achieved by range and cross-range two-dimensional high resolution of SAR. imaging and spatial domain cancellation of interferometer. True azimuth of moving target is determined using phase-comparison interferometer. Furthermore, high resolution image of the slow-moving target is obtained by IS AR processing. The block diagram and the operational principle of the airborne interferometric SAR./ISAR system are discussed in detail. Quantitative relations for SAR,, interferometer spatial domain cancellation, direction finding and ISAR processing are derived. Theoretical analysis and preliminary computer simulation reveal the validity of this technique.
2003, 25(5): 592-597.
Abstract:
Stepped-frequency is a kind of high range resolution waveform, which is used to obtain broad effective bandwidth by sequentially changing of carrier frequency over sub-pulses in one burst, so it reduces requirements on instantaneous bandwidth and receiver. However, this waveform is so sensitive to radial velocity between radar and targets that the loss of range resolution and loss of SNR are brought to SAR system. In the paper, the effect of radial velocity on synthetic range profile is discussed thoroughly first, then two important parameters, target range shift and range spread, are defined in terms of the phase of synthetic range function. Furthermore, the enhancement of the range sample resolution only makes the synthetic range profile present more details, but it will not change the range resolution.
Stepped-frequency is a kind of high range resolution waveform, which is used to obtain broad effective bandwidth by sequentially changing of carrier frequency over sub-pulses in one burst, so it reduces requirements on instantaneous bandwidth and receiver. However, this waveform is so sensitive to radial velocity between radar and targets that the loss of range resolution and loss of SNR are brought to SAR system. In the paper, the effect of radial velocity on synthetic range profile is discussed thoroughly first, then two important parameters, target range shift and range spread, are defined in terms of the phase of synthetic range function. Furthermore, the enhancement of the range sample resolution only makes the synthetic range profile present more details, but it will not change the range resolution.
2003, 25(5): 598-605.
Abstract:
The effects on performance of the space-borne Synthetic Aperture Radar(SAR,) clue to antenna pattern and the beam steering are studied, especially emphasis on the ambiguities, the spatial resolutions and the signal to noise ratio. The directivity control and beam forming of active phased array are studied. Based on these studies, the phased array for the two swaths space-borne scan-SAR system is designed and simulated. Furthermore, the reliability of the phased array is studied and a high reliable design utilizing redundancy is proposed.
The effects on performance of the space-borne Synthetic Aperture Radar(SAR,) clue to antenna pattern and the beam steering are studied, especially emphasis on the ambiguities, the spatial resolutions and the signal to noise ratio. The directivity control and beam forming of active phased array are studied. Based on these studies, the phased array for the two swaths space-borne scan-SAR system is designed and simulated. Furthermore, the reliability of the phased array is studied and a high reliable design utilizing redundancy is proposed.
2003, 25(5): 606-611.
Abstract:
Through the comparison between quantum systems and information processing in human brain it can be found that there are many similar mathematical expressions both in quantum theory and neural networks, with some formula a generalized Hebb learning algorithm is proposed based on quantum system, and its convergence performance is also certified. Finally, a quantum neural computational model in a quantum dot system is designed, after analysing it results in that this model can realize the learning of simple logic.
Through the comparison between quantum systems and information processing in human brain it can be found that there are many similar mathematical expressions both in quantum theory and neural networks, with some formula a generalized Hebb learning algorithm is proposed based on quantum system, and its convergence performance is also certified. Finally, a quantum neural computational model in a quantum dot system is designed, after analysing it results in that this model can realize the learning of simple logic.
2003, 25(5): 612-618.
Abstract:
In this paper, by introducing an extended neural network model which can be easily identified on-line, a neural network model reference adaptive control method based on a feedforward-feedback structure is proposed for a class of nonlinear systems whose outputs are not measurable. A training algorithm with global convergence is offered, and the stability of the control system is analyzed. The simulation results show that this method is effective, anrl it has good robustness for both the selection of original network weights and the disturbance of plant parameters.
In this paper, by introducing an extended neural network model which can be easily identified on-line, a neural network model reference adaptive control method based on a feedforward-feedback structure is proposed for a class of nonlinear systems whose outputs are not measurable. A training algorithm with global convergence is offered, and the stability of the control system is analyzed. The simulation results show that this method is effective, anrl it has good robustness for both the selection of original network weights and the disturbance of plant parameters.
2003, 25(5): 619-625.
Abstract:
Cosine Modulated Filter(CMF) bank is a kind of broadly used filter bank. By proving the equivalence of the Perfect Reconstruction(PR) conditions of time-analysis and frequency-analysis, the inherent relationship between Time Domain Aliasing Cancellation(TDAC) and CMF is found. By the means, the useful results of the two methods can be conveniently. Finally, a new kind of nonuniform filter bank is built based on TDAC which can be easily modified to audio coding in accord with psychoacoustics.
Cosine Modulated Filter(CMF) bank is a kind of broadly used filter bank. By proving the equivalence of the Perfect Reconstruction(PR) conditions of time-analysis and frequency-analysis, the inherent relationship between Time Domain Aliasing Cancellation(TDAC) and CMF is found. By the means, the useful results of the two methods can be conveniently. Finally, a new kind of nonuniform filter bank is built based on TDAC which can be easily modified to audio coding in accord with psychoacoustics.
2003, 25(5): 626-632.
Abstract:
An improved voice activity detection algorithm based on high order statistics is proposed. The algorithm can be applied in the 3rd generation mobile communication system. The simulation shows that Gaussian or non-Gaussian symmetric distributed noises in mobile background environment can be detected accurately and suppressed by the new algorithm.
An improved voice activity detection algorithm based on high order statistics is proposed. The algorithm can be applied in the 3rd generation mobile communication system. The simulation shows that Gaussian or non-Gaussian symmetric distributed noises in mobile background environment can be detected accurately and suppressed by the new algorithm.
2003, 25(5): 633-638.
Abstract:
In this paper, a new CLSCMA-based blind adaptive multiuser detection which can be used in multipath channel is proposed. Analysis and simulations show that the approach converges fast and has a good performance, so it is a good adaptive multiuser detection.
In this paper, a new CLSCMA-based blind adaptive multiuser detection which can be used in multipath channel is proposed. Analysis and simulations show that the approach converges fast and has a good performance, so it is a good adaptive multiuser detection.
2003, 25(5): 639-643.
Abstract:
Starting from the sufficient and necessary condition of existence of solution for power assignment in a single cell WCDMA (Wideband Code Division Multiple Access) system, this paper obtains the system capacity under non-ideal power control through modeling the target SIR(Signal to Interference Ratio) with a log-normal random variable. This provides a criterion for determining the trade-off between the information rate of VBR(Variable Bit Rate) traffic and the capacities of CBR(Constant Bit Rate) and VBR. traffics in mobile communica-tions, Analysis and numerical results show that the system performance is notably declined by non-idea power control, and that the information rate and system capacity are exchangeable. As a result, the system can be adapted to diverse performance requirements for various services by varying the control parameters, then the resource utilization and quality of services of the system can be improved.
Starting from the sufficient and necessary condition of existence of solution for power assignment in a single cell WCDMA (Wideband Code Division Multiple Access) system, this paper obtains the system capacity under non-ideal power control through modeling the target SIR(Signal to Interference Ratio) with a log-normal random variable. This provides a criterion for determining the trade-off between the information rate of VBR(Variable Bit Rate) traffic and the capacities of CBR(Constant Bit Rate) and VBR. traffics in mobile communica-tions, Analysis and numerical results show that the system performance is notably declined by non-idea power control, and that the information rate and system capacity are exchangeable. As a result, the system can be adapted to diverse performance requirements for various services by varying the control parameters, then the resource utilization and quality of services of the system can be improved.
2003, 25(5): 644-649.
Abstract:
The transmit power is a major radio resource and requires careful planning and control if optimal system performance and maximal user capacity are to be achieved. In this paper, a new power control algorithm based on pricing is proposed in the context of third gener-ation multimedia rnultirate Wideband CDMA (WCDMA) mobile communications. Firstly, the paper defines the multiplication of users data rate and minimum required SIR as users demand of network resource, and then derives the relationship between system capacity, transmit power and normalized demand called network resource share. By introducing uniform-price auction, the paper uses pricing to maximize the social benefit by making efficient allocations of transmit power, when demand exceeds supply which leads to congestion. In the end, numerical results are presented to validate the analytical results and the proposed power control algorithm.
The transmit power is a major radio resource and requires careful planning and control if optimal system performance and maximal user capacity are to be achieved. In this paper, a new power control algorithm based on pricing is proposed in the context of third gener-ation multimedia rnultirate Wideband CDMA (WCDMA) mobile communications. Firstly, the paper defines the multiplication of users data rate and minimum required SIR as users demand of network resource, and then derives the relationship between system capacity, transmit power and normalized demand called network resource share. By introducing uniform-price auction, the paper uses pricing to maximize the social benefit by making efficient allocations of transmit power, when demand exceeds supply which leads to congestion. In the end, numerical results are presented to validate the analytical results and the proposed power control algorithm.
2003, 25(5): 650-653.
Abstract:
In this paper, a new algorithm to construct GMW sequences and cascaded GMW sequences by shift sequences is proposed. This algorithm simplifies the conventional algorithm to construct GMW sequences and cascaded GMW sequences, significantly improves the efficiency, and the feasibility of this algorithm is verified.
In this paper, a new algorithm to construct GMW sequences and cascaded GMW sequences by shift sequences is proposed. This algorithm simplifies the conventional algorithm to construct GMW sequences and cascaded GMW sequences, significantly improves the efficiency, and the feasibility of this algorithm is verified.
2003, 25(5): 654-656.
Abstract:
In this paper, the new concepts of the permutation distance and the permutation with the maximum distance are given. The formula counting the number of the permutation with the maximum distance is also given.
In this paper, the new concepts of the permutation distance and the permutation with the maximum distance are given. The formula counting the number of the permutation with the maximum distance is also given.
2003, 25(5): 657-663.
Abstract:
A new forgery attack is proposed to Tseng-Jan s group signature scheme(1999), anyone can produce a valid group signature with this forgery attack. In this paper, a new modified and secure group signature scheme is presented in point of the forgery attacks proposed by this paper and Z.C. Li, et al.(2000). The new scheme can not only resist all kinds of forgery attacks, but also preserve the main merits in Tseng-Jan s scheme. Furthermore, the new scheme can revoke group member according to need.
A new forgery attack is proposed to Tseng-Jan s group signature scheme(1999), anyone can produce a valid group signature with this forgery attack. In this paper, a new modified and secure group signature scheme is presented in point of the forgery attacks proposed by this paper and Z.C. Li, et al.(2000). The new scheme can not only resist all kinds of forgery attacks, but also preserve the main merits in Tseng-Jan s scheme. Furthermore, the new scheme can revoke group member according to need.
2003, 25(5): 664-670.
Abstract:
In this paper a method of generating 2k pseudo-random sequences to obtain stable long period of m-sequences and high complexity of chaotic sequences is discussed. A quasi-chaotic function acts as Mealy limited state machine and m-sequence acts as its input. The periodic nature of sequences is analyzed and the randomness of sequences is tested. The simulation results in chip of FPGA for frequency hopping code generator are reported.
In this paper a method of generating 2k pseudo-random sequences to obtain stable long period of m-sequences and high complexity of chaotic sequences is discussed. A quasi-chaotic function acts as Mealy limited state machine and m-sequence acts as its input. The periodic nature of sequences is analyzed and the randomness of sequences is tested. The simulation results in chip of FPGA for frequency hopping code generator are reported.
2003, 25(5): 671-676.
Abstract:
This paper discusses the principle of relative adiabatic computing of single channel transmission gate from the idea of finite dynamic power dissipation. On the basis of above principle, the cross-coupled dynamic adiabatic memorial units and adiabatic flip-flops are designed by single channel and double channel transmission gate. Finally, this paper gives appraisal of two classes memorial units and adiabatic flip-flops in lower power dissipation circuits. Above theory is verified by computer simulator.
This paper discusses the principle of relative adiabatic computing of single channel transmission gate from the idea of finite dynamic power dissipation. On the basis of above principle, the cross-coupled dynamic adiabatic memorial units and adiabatic flip-flops are designed by single channel and double channel transmission gate. Finally, this paper gives appraisal of two classes memorial units and adiabatic flip-flops in lower power dissipation circuits. Above theory is verified by computer simulator.
2003, 25(5): 677-682.
Abstract:
In the condition of high-voltage, heavy-current and high-frequency electric circuit, there is a certain difficult to inspect and supervise the electric circuit. On introducing a new method of complexity measure analysis, the authors manage to inspect the circuit fault status by analyzing synthetic signal. Compared with the traditional method, the present method has the advantages of high speed, easy operation, less expenses, safety, no destruction, etc. and can be used as a reliability predicting measure for electric circuit system.
In the condition of high-voltage, heavy-current and high-frequency electric circuit, there is a certain difficult to inspect and supervise the electric circuit. On introducing a new method of complexity measure analysis, the authors manage to inspect the circuit fault status by analyzing synthetic signal. Compared with the traditional method, the present method has the advantages of high speed, easy operation, less expenses, safety, no destruction, etc. and can be used as a reliability predicting measure for electric circuit system.
2003, 25(5): 695-699.
Abstract:
After introducing the concept of fuzzy measures and Choquet fuzzy integral, infor-mation fusion for target recognition can turn into generalized Lebesgue integral of recognition result with respect to the degree of importance of source. This paper presents a generalized recognition flow in decision-level information fusion based on Choquet fuzzy integral, and pro-vides a method for measuring the degree of importance of source. The algorithm is proved in the real IR/MMW fusion recognition system, the fusion result of recognition which compares with that of D-S evidence theory shows the efficiency of the method based on Choquet fuzzy integral.
After introducing the concept of fuzzy measures and Choquet fuzzy integral, infor-mation fusion for target recognition can turn into generalized Lebesgue integral of recognition result with respect to the degree of importance of source. This paper presents a generalized recognition flow in decision-level information fusion based on Choquet fuzzy integral, and pro-vides a method for measuring the degree of importance of source. The algorithm is proved in the real IR/MMW fusion recognition system, the fusion result of recognition which compares with that of D-S evidence theory shows the efficiency of the method based on Choquet fuzzy integral.
2003, 25(5): 700-703.
Abstract:
This paper presents a method which links direct solution and Newton iterative method to calculate ship s position. First, a result of the combination hyperbolic equations is got using the direct solution on the sphere and is taken as the ship s approximate position. Then, Newton iterative method is applied to caculate △ and AA. When △ and △ are less than which is given as a convergent standard beforehand, the ship s position calculated is the correct one. In general, only iterating two or three times, the calculating accuracy is about one second.
This paper presents a method which links direct solution and Newton iterative method to calculate ship s position. First, a result of the combination hyperbolic equations is got using the direct solution on the sphere and is taken as the ship s approximate position. Then, Newton iterative method is applied to caculate △ and AA. When △ and △ are less than which is given as a convergent standard beforehand, the ship s position calculated is the correct one. In general, only iterating two or three times, the calculating accuracy is about one second.
2003, 25(5): 704-710.
Abstract:
In order to allocate the bandwidth more efficiently and simply, this paper analyzes the limitation of the DRR(Deficit Round Robin) algorithm in the packet switch, and proposes an algorithm based on deducting credit and interleaving the output packets. The improved algorithm lowers the scheduling overhead, smoothes the output burst and is very simple for hardware implementation. Analysis indicates the improved algorithm has better fairness over DRR, in many cases. Results from analysis show that the scheme is able to maintain bandwidth and is affected by the number of credits less.
In order to allocate the bandwidth more efficiently and simply, this paper analyzes the limitation of the DRR(Deficit Round Robin) algorithm in the packet switch, and proposes an algorithm based on deducting credit and interleaving the output packets. The improved algorithm lowers the scheduling overhead, smoothes the output burst and is very simple for hardware implementation. Analysis indicates the improved algorithm has better fairness over DRR, in many cases. Results from analysis show that the scheme is able to maintain bandwidth and is affected by the number of credits less.
2003, 25(5): 711-715.
Abstract:
In this paper, the concept of correlation-immune permutations and a constru method for these permutations are proposed, and the enumeration problem of correlc immune permutations constructed by this method is solved.
In this paper, the concept of correlation-immune permutations and a constru method for these permutations are proposed, and the enumeration problem of correlc immune permutations constructed by this method is solved.
2003, 25(5): 716-720.
Abstract:
This paper derives in detail the horizontal radiated electric fields from an elec-trically small radiator which may be well represented by the electric dipole and the magnetic moments, then the Lees corresponding formula are modified. Theoretical results compared with experimental data measured directly over OATS agree well. This shows that GTEM cell measurements are correlative with OATS emission measurements. For the electrically small radiator, GTEM cell may be used not only for EMS test but also for EMI test.
This paper derives in detail the horizontal radiated electric fields from an elec-trically small radiator which may be well represented by the electric dipole and the magnetic moments, then the Lees corresponding formula are modified. Theoretical results compared with experimental data measured directly over OATS agree well. This shows that GTEM cell measurements are correlative with OATS emission measurements. For the electrically small radiator, GTEM cell may be used not only for EMS test but also for EMI test.
2003, 25(5): 683-694.
Abstract:
Gyroklystron is one of the most promising high-power coherent millimeter wave sources. The configuration and operating mechanism of the gyroklystrons are briefly introduced. The state-of-art and developing trend are reviewed in detail. Some remaining critical problems are also discussed and some suggestions are also presented.
Gyroklystron is one of the most promising high-power coherent millimeter wave sources. The configuration and operating mechanism of the gyroklystrons are briefly introduced. The state-of-art and developing trend are reviewed in detail. Some remaining critical problems are also discussed and some suggestions are also presented.
