In order to research on the design and implementation of a modernized GPS civil signals simulation system,a brief review of the modernized GPS signals is introduced,including the signal structure and characteristics o...In order to research on the design and implementation of a modernized GPS civil signals simulation system,a brief review of the modernized GPS signals is introduced,including the signal structure and characteristics of L2C,L5 and L1C signals.The design and implementation of the main modules of the simulation system is described in detail.The simulation system is mainly composed of parameter setting,system initialization,signal generator,noise generator,disturbance generator,signal synthesis,low-pass filter,A/D conversion and storage.The simulation results based on Matlab are then presented,and the power spectral density（PSD） of all navigation signals is analyzed.The simulation system completes the physical layer simulation of a modernized GPS new civil signal and can provide a controllable signal source for designing and testing of modernized GPS civil receivers,especially for the signal processing algorithm design of the GPS software receiver.展开更多
The performance analysis and simulation of coding schemes based on the modeling Ka band fixed satellite channel have been presented. The results indicate that concatenated codes with large inner interleaving depth ha...The performance analysis and simulation of coding schemes based on the modeling Ka band fixed satellite channel have been presented. The results indicate that concatenated codes with large inner interleaving depth have good performance and high spectrum efficiency. The studies also show that simple block interleaving is very effective in combating the slow frequency nonselective fading of Ka band.展开更多
The device is used for the test on the fuze detonating time according to the initial velocity of the projectile and the altitude and speed of enemy aircraft flight. For the special requirements of the high-speed signa...The device is used for the test on the fuze detonating time according to the initial velocity of the projectile and the altitude and speed of enemy aircraft flight. For the special requirements of the high-speed signal acquisition in the process, the characteristics of the measured signal are analyzed. The system is investigated in chip selection, signal transmission, signal processing, signal storage, post-production PCB design, etc. The appropriate measures and solutions which affect the integrity and accuracy of the signal in each process are proposed. The rules for the layout of the device and wiring are made. The result show that the measurement values are accurate without loss of data.展开更多
Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, ener...Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, energy conservation and so on. MAZE and DYNA2D program is used to dispose these models and results of the simulating of elements of explosive trains in a typical fuse are obtained. It is helpful for designing fuses.展开更多
In order to minimize the delays and stops caused by the early started coordinated green phase of the vehicle- actuated signal systems, a stochastic offsets calculation method based on the new types of advanced traffic...In order to minimize the delays and stops caused by the early started coordinated green phase of the vehicle- actuated signal systems, a stochastic offsets calculation method based on the new types of advanced traffic management system （ATMS） data is proposed. As the mainline green starts randomly in vehicle-actuated signal systems, the random theory is applied to obtain the distribution of the unused green time at side streets based on the green gap-out mechanism. Then, the green start time of the mainline can be selected at the point with maximum probability to minimize the delays or stops caused by the randomly started mainline green. A case study in Maine, USA, whose traffic conditions are similar to those of the middle-size Chinese cities, proves that the proposed method can significantly reduce the travel time and delays.展开更多
基金The National Natural Science Foundation of China (No.41104015)Foundation of Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology of Ministry of Education (No.201011)
文摘In order to research on the design and implementation of a modernized GPS civil signals simulation system,a brief review of the modernized GPS signals is introduced,including the signal structure and characteristics of L2C,L5 and L1C signals.The design and implementation of the main modules of the simulation system is described in detail.The simulation system is mainly composed of parameter setting,system initialization,signal generator,noise generator,disturbance generator,signal synthesis,low-pass filter,A/D conversion and storage.The simulation results based on Matlab are then presented,and the power spectral density（PSD） of all navigation signals is analyzed.The simulation system completes the physical layer simulation of a modernized GPS new civil signal and can provide a controllable signal source for designing and testing of modernized GPS civil receivers,especially for the signal processing algorithm design of the GPS software receiver.
文摘The performance analysis and simulation of coding schemes based on the modeling Ka band fixed satellite channel have been presented. The results indicate that concatenated codes with large inner interleaving depth have good performance and high spectrum efficiency. The studies also show that simple block interleaving is very effective in combating the slow frequency nonselective fading of Ka band.
文摘The device is used for the test on the fuze detonating time according to the initial velocity of the projectile and the altitude and speed of enemy aircraft flight. For the special requirements of the high-speed signal acquisition in the process, the characteristics of the measured signal are analyzed. The system is investigated in chip selection, signal transmission, signal processing, signal storage, post-production PCB design, etc. The appropriate measures and solutions which affect the integrity and accuracy of the signal in each process are proposed. The rules for the layout of the device and wiring are made. The result show that the measurement values are accurate without loss of data.
文摘Through system analysis of typical explosive trains in various fuses, physical and correspondent mathematical models of typical explosive trains are established, based on mass conservation, momentum conservation, energy conservation and so on. MAZE and DYNA2D program is used to dispose these models and results of the simulating of elements of explosive trains in a typical fuse are obtained. It is helpful for designing fuses.
基金The National Natural Science Foundation of China(No. 50422283 )China Postdoctoral Science Foundation (No.20110491333)
文摘In order to minimize the delays and stops caused by the early started coordinated green phase of the vehicle- actuated signal systems, a stochastic offsets calculation method based on the new types of advanced traffic management system （ATMS） data is proposed. As the mainline green starts randomly in vehicle-actuated signal systems, the random theory is applied to obtain the distribution of the unused green time at side streets based on the green gap-out mechanism. Then, the green start time of the mainline can be selected at the point with maximum probability to minimize the delays or stops caused by the randomly started mainline green. A case study in Maine, USA, whose traffic conditions are similar to those of the middle-size Chinese cities, proves that the proposed method can significantly reduce the travel time and delays.
