scholarly journals Missile-Borne SAR Raw Signal Simulation for Maneuvering Target

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Weijie Xia ◽  
Yuanyuan Qi ◽  
Linlin Huang ◽  
Xue Jin
Keyword(s):  
Electromagnetic Scattering ◽  
High Speed ◽  
Signal Model ◽  
Maneuvering Target ◽  
Scattering Rate ◽  
Stop And Go ◽  
Radar Scattering ◽  
Signal Simulation ◽  
Simulation Input ◽  
Scattering Characteristic

SAR raw signal simulation under the case of maneuver and high-speed has been a challenging and urgent work recently. In this paper, a new method based on one-dimensional fast Fourier transform (1DFFT) algorithm is presented for raw signal simulation of maneuvering target for missile-borne SAR. Firstly, SAR time-domain raw signal model is given and an effective Range Frequency Azimuth Time (RFAT) algorithm based on 1DFFT is derived. In this algorithm, the “Stop and Go” (SaG) model is adopted and the wide radar scattering characteristic of target is taken into account. Furthermore, the “Inner Pulse Motion” (IPM) model is employed to deal with high-speed case. This new RFAT method can handle the maneuvering cases, high-speed cases, and bistatic radar cases, which are all possible in the missile-borne SAR. Besides, this raw signal simulation adopts the electromagnetic scattering calculation so that we do not need a scattering rate distribution map as the simulation input. Thus, the multiple electromagnetic reflections can be considered. Simulation examples prove the effectiveness of our method.

Performance analysis of differential geometric guidance law against high-speed target with arbitrarily maneuvering acceleration

2018 ◽  
Vol 233 (10) ◽  
pp. 3547-3563 ◽  
Author(s):  
Ke-Bo Li ◽  
Wen-Shan Su ◽  
Lei Chen
Keyword(s):  
High Speed ◽  
Control System Design ◽  
Proportional Navigation ◽  
Full Account ◽  
Guidance And Control ◽  
Maneuvering Target ◽  
Guidance Law ◽  
Classical Differential Geometry ◽  
Relative Dynamics ◽  
And Control

The interception of high-speed target with an arbitrary maneuvering acceleration causes serious troubles to the guidance and control system design of airborne missile. A novel guidance law based on the classical differential geometry curve theory was proposed not long ago. Although it is believed and numerically demonstrated that this differential geometric guidance law (DGGL) is superior to the classical pure proportional navigation (PPN) in intercepting high-speed targets, its performance has not been thoroughly analyzed. In this paper, using the Lyapunov-like approach, the performance of DGGL against the high-speed target with an arbitrary but upper-bounded maneuvering acceleration is well studied. The upper bounds of the LOS rate and commanded acceleration of DGGL are obtained, and conditions that guarantee the capture of this type of maneuvering target are also presented. The nonlinear relative dynamics between the missile and target is taken into full account. Finally, the proposed theoretical findings are demonstrated by numerical simulation examples.

Integrated guidance and control of interceptors with impact angle constraint against a high-speed maneuvering target

2019 ◽  
Vol 233 (14) ◽  
pp. 5192-5204
Author(s):  
Guanjie Hu ◽  
Jianguo Guo ◽  
Jun Zhou
Keyword(s):  
Control System ◽  
High Speed ◽  
Control Method ◽  
Impact Angle ◽  
Adaptive Sliding Mode Control ◽  
Guidance And Control ◽  
Maneuvering Target ◽  
Integrated Guidance And Control ◽  
And Control ◽  
Impact Angle Constraint

An integrated guidance and control method is investigated for interceptors with impact angle constraint against a high-speed maneuvering target. Firstly, a new control-oriented model with impact angle constraint of the integrated guidance and control system is built in the pitch plane by combining the engagement kinematics and missile dynamics model between the interceptor and target. Secondly, the flight path angle of the target is estimated by extended Kalman filter in order to transform the terminal impact angle constraint into the terminal line-of-sight angle constraint. Thirdly, a nonlinear adaptive sliding mode control law of the integrated guidance and control system is designed in order to directly obtain the rudder deflection command, which eliminates time delay caused by the traditional backstepping control method. Then the Lyapunov stability theory is used to prove the stability of the whole closed-loop integrated guidance and control system. Finally, the simulation results confirm that the integrated guidance and control method proposed in this paper can effectively improve the interception performance of the interceptor to a high-speed maneuvering target.

Microwave-assisted high-speed modulation of semiconductor lasers

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1057-1063 ◽  
Author(s):  
Chung Y. Wu ◽  
Chang Z. Guo ◽  
J. M. Xu
Keyword(s):  
Semiconductor Lasers ◽  
High Speed ◽  
Optical Gain ◽  
Large Signal ◽  
Microwave Assisted ◽  
Active Layers ◽  
Gain Variation ◽  
Speed Modulation ◽  
Signal Simulation ◽  
High Speed Modulation

The electron temperature in the active layers of a semiconductor laser can be raised higher than that of the lattice by an externally applied microwave field. This results in a reduction in the optical gain and forms the basis of laser modulation by microwave heating. The gain variation under electron gas heating is calculated. A complete small signal analysis of current modulation, electron heating modulation, and combined or microwave-assisted modulation of semiconductor lasers is presented. In addition, the sensitivities of the electron and photon responses among the three modulation schemes are compared. Some large signal simulation results of high-speed digital modulation are also included.

scholarly journals Investigating the Threshold Conditions of Air Breakdown with Mode-Locked Q-Switched Laser Pulses, and the Temporal Dynamics of Induced Plasma with Self-Scattering Phenomenon

2021 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Kai-Ting Yen ◽  
Chih-Hung Wu ◽  
Pin-Hsun Wang ◽  
Pi-Hui Tuan ◽  
Kuan-Wei Su
Keyword(s):  
High Speed ◽  
Temporal Dynamics ◽  
Laser Pulses ◽  
Mode Locking ◽  
Excitation Pulse ◽  
Plasma Radiation ◽  
Breakdown Threshold ◽  
Scattering Rate ◽  
Threshold Conditions ◽  
Air Breakdown

A Q-switched Nd:YAG laser with mode-locked modulations is utilized to explore the laser-induced air breakdown. The various modulation depths of the mode-locking within the Q-switched pulse can be utilized to investigate the threshold conditions. With the GHz high-speed detectors to accurately measure the temporal pulse shape pulse by pulse, it is verified that the air breakdown threshold is crucially determined by the peak-power density instead of the energy density from the statistic results, especially for mode-locked Q-switched lasers. The stability of the system for laser-induced breakdown can be evaluated by threshold width through fitting the statistical result. Otherwise, by measuring the temporal characteristics of the excitation pulse and the induced plasma, it is further found that the plasma radiation displays a few-nanoseconds time delay to the excitation pulse and shows a decaying tail to be 10 times longer than the plasma build-up time. Moreover, the incident laser pulse is observed to be self-scattered by the air breakdown, and a rapidly modulated scattering rate is found with a slight delay time to the excitation mode-locked subpulse modulations.

scholarly journals A 21st Century Warship With a 21st Century Propulsion System

1998 ◽  
Author(s):  
Mark Carter ◽  
Magnus Olsson ◽  
Jan-Erik Gustavson ◽  
Joe Ranero
Keyword(s):  
21St Century ◽  
Diesel Engines ◽  
High Speed ◽  
Propulsion System ◽  
Design Features ◽  
Signal Model ◽  
Turbine Engine ◽  
Low Speed

The Visby Class Corvette will enjoy the advantages of a Combined Diesel or Gas (CODOG) turbine arrangement in which the diesel engines are used for low-speed mine hunting and ASW missions, while the four turbines can be operated either individually or in pairs to provide cruise or high-speed dash capability. The integration of these features into a single gearbox, the design of the Allied Signal model TF50A turbine engine, and the integration of the CODOG system into the ship is discussed herein. Attention is focused on the unique design features which provide the “stealth” capabilities of this ship.

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