Parameters of Exterior Ballistic Feature Points Extraction in Radar Measurement Data by EMD

The problem of measuring exterior ballistic feature points is always difficult to solve and it is essentiale on exterior ballistic measurement. By analysis of radar reflection characteristics and non-stationary echo signals of exterior ballistic feature points, the echo data of exterior ballistic feature points is measured by using the continuous wave radar. The parameters of feature points are extracted by the empirical mode decomposition method (EMD) of Hilbert-Huang transform (HHT) spectrum analysis technique. The radar echo signal model and EMD extraction model are established to analyze the exterior ballistic mutation point detection and EMD extraction method of aliasing echo signal. Typical feature point parameters of exterior ballistic in rocket flight tests are carried out and the effectiveness of the method is verified. A new method of measuring the parameters of exterior ballistic feature point is therefore presented.     

A new image processing method for discriminating internal layers from radio echo sounding data of ice sheets via a combined robust principal component analysis and total variation approach

Discriminating internal layers by radio echo sounding is important in analyzing the thickness and ice deposits in the Antarctic ice sheet.The signal processing method of synthesis aperture radar(SAR)has been widely used for improving the signal to noise ratio(SNR)and discriminating internal layers by radio echo sounding data of ice sheets.This method is not efficient when we use edge detection operators to obtain accurate information of the layers,especially the ice-bed interface.This paper presents a new image processing method via a combined robust principal component analysis-total variation(RPCA-TV)approach for discriminating internal layers of ice sheets by radio echo sounding data.The RPCA-based method is adopted to project the high-dimensional observations to low-dimensional subspace structure to accelerate the operation of the TV-based method,which is used to discriminate the internal layers.The efficiency of the presented method has been tested on simulation data and the dataset of the Institute of Electronics,Chinese Academy of Sciences,collected during CHINARE 28.The results show that the new method is more efficient than the previous method in discriminating internal layers of ice sheets by radio echo sounding data.     

Range Ambiguity Elimination in a Short-Range FMCW Radar System

Modified implementation architecture for sinusoidal frequency modulation is introduced to extract the range information from the received radar echo. Range ambiguity problem arises because the range is calculated from the estimated phase of the received signal which is wrapped into （0, 2π]. By integrating Doppler frequency shifts, the variation of range can be estimated and used as an auxiliary information to help eliminating the corresponding range ambiguity. The performance of the new technique is evaluated by simulations. The results show that this technique is robust to sever phase noise and can be used effectively for ambiguity elimination of the modified sinusoidal frequency modulated continuous wave radar.     

Modeling and Analysis of the Impacts of Temporal-Spatial Variant Troposphere on Ground-Based SAR Imaging of Asteroids

The near-Earth asteroid collisions could cause catastrophic disasters to humanity and the Earth, so it is crucial to monitor asteroids. Ground-based synthetic aperture radar(SAR) is an observation technique for high resolution imaging of asteroids. The ground-based SAR requires a long integration time to achieve a large synthetic aperture, and the echo signal will be seriously affected by temporal-spatial variant troposphere. Traditional spatiotemporal freezing tropospheric models are ineffectiv...     

Practical calibration method for instantaneous polarization radar systems utilizing a metal sphere

A practical calibration method is proposed for instantaneous polarization radar systems.The method only needs one measurement by using a metal sphere.The distortions of system and the actual polarization scattering matrix（PSM）of target can be obtained.First,an instantaneous polarization radar system is presented.The system can obtain PSM by a single pulse echo.The dual-polarization antenna can transmit and receive two orthogonal polarization waves.The multilayer micro-strip patch antenna is adopted for this kind of radar system.Second,based on the multi-port network theory,the operation and system errors of instantaneous polarization radar system are analyzed.By making assumption on the cross-talk factors of antenna,distortion matrices of R and Tare derived.Finally,the calibration method based on instantaneous polarization measurement is introduced.Simulation results show the performance of this calibration method.The values of calibrated PSM are in agreement with the actual ones after calibration.     

Design and Realization of Numerical Control Ladder Diagram Edition Software

1 Introduction Along with the computer and the numerical control technology rapid development ,the programmable con-troller (PLC) not only can carry on the logical control to the digital quantity,but also has mathematics opera-tion,the data processing,the movement control ,the si mulation measures PIDcontrol functionandso on,anditis i mportant constituent of the numerical control system. The PLC procedure is a part of numerical control sys-temprogram,although it generally provides the stand…     

Research of Hybrid Modulation Radar Signal

Based on the advantage of phase coded signal and stepped frequency signal, a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency (PCSF) signal. By analyzing its waveform and ambiguity function, the comparison between Stepped-Frequency(SF) signal and PCSF signal is given, which shows that the PCSF signal is better than SF signal. Finally, the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal, realize the same equivalent bandwidth with less pulse number, and solve the conflict among the stepped frequency, the number of pulse, and transmit average power. Under the premises of a certain range resolution, this new hybrid modulation radar signal not only raises the data rate of radar system, but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore, this new hybrid modulation radar signal can be widely used in application.     

Effective Sea Clutter Spectrum Extraction Method for HFSWR in Adverse Conditions

An effective approach in solving the sea clutter spectrum extraction problem is studied in the paper. Different from the conventional signal to noise ratio (SNR) method based on Doppler frequency or range domain information, a method is developed to characterize the differences between the sea echo and those interferences are by signal to interference plus noise ratio (SINR) which jointly utilizing the range, Doppler frequency and azimuth domain information. Furthermore, these differences can be adaptable to adverse conditions by forming the necessary boundaries and constraints in searching of the maximum SINR, which greatly promotes the extraction of sea clutter spectrum. The real high frequency surface wave radar (HFSWR) data demonstrate that the proposed method is less influenced by those interferences and can effectively extract the sea clutter spectrum even under the adverse conditions. Furthermore, it has been shown as an effective method for ship detection and sea state remote sensing of HFSWR.     

Chaff Jamming Recognition of Radar

A modified chaff jamming recognition method of radar is investigated using grey relational analysis (GRA) based on the difference in echo correlation characteristics between a complex rigid target and chaff cloud in time domain.Slice method (SM),a novel modeling approach,is proposed to construct an electromagnetic scattering model of chaff cloud in a scenario with slowly moving platform that is targeted.The diffusion characteristics and echo characteristics of the chaff cloud are analyzed.The GRA of a real target and chaff cloud shows that the adjacent return waves have a good correlation for the target but a weak correlation for chaff cloud.Since the correlation degree of chaff cloud's echo is far lower than that of a complex rigid target's,the chaff jamming can be identified by setting a reasonable threshold.Simulation results are presented to verify the effectiveness of this method.     

Measuring system of high polymers' pyromagnetic effect

The measurement system is the main equipment of the project.Based on the characteristic of experiment system,a sensor array is designed,and used to continually acquire the global magnetic field.A scientific scheme is developed to get the signal processing and temperature compensation for nondirective weak magnetic field.The software of sampling control system is given,which is complied using C language in Labwindows/CVI.Taking computer as main engine,the system can acquire the nondirective weak magnetic field automatically and continuously use the sensor array,the change of magnetic field can be shown in real-time and intuitively.     

Chaff Jamming Recognition of Radar

A modified chaff jamming recognition method of radar is investigated using grey relational analysis (GRA) based on the difference in echo correlation characteristics between a complex rigid target and chaff cloud in time domain.Slice method (SM),a novel modeling approach,is proposed to construct an electromagnetic scattering model of chaff cloud in a scenario with slowly moving platform that is targeted.The diffusion characteristics and echo characteristics of the chaff cloud are analyzed.The GRA of a real target and chaff cloud shows that the adjacent return waves have a good correlation for the target but a weak correlation for chaff cloud.Since the correlation degree of chaff cloud's echo is far lower than that of a complex rigid target's,the chaff jamming can be identified by setting a reasonable threshold.Simulation results are presented to verify the effectiveness of this method.     

Doppler Signal Simulation and Analytic System for Radio Fuze

A system for simulating and analyzing the Doppler signal of air-target fuse is established by constructing two parts:Doppler signal testing with simulation and Doppler signal analysis.The first part establishes the near-field target characteristic model where the Doppler spectrum in different encounter condition is obtained.The second part mainly deals with a general purpose hardware platform to obtain and process the Doppler signal as well as a software to estimate the Doppler spectrum.The model and the result of Doppler spectrum analysis were verified by experiments.     

A stealthy method to determine the relative position and velocity for satellite formation flying

To achieve the satellite formation control and the succeed formation missions, we present a new stealthy method to determine the relative states between formation satellites. In this method, the combination of a CCD camera and laser radar is used as the relative measure sensors. To reduce electromagnetic radiation, the laser radar works intermittently to minimize the probability of being discovered. And an unscented Kalman filter (UKF) is applied to estimate the relative states. The observability of this method is analyzed. The validity and effectiveness of the method is demonstrated in a typical application of formation relative navigation.     

A Multi-Interface Remote Monitoring and Control System Architecture Based on Embedded Server

This paper presents a multi-interface embedded server architecture for remote real-time monitoring system and distributed monitoring applications.In the scheme,an embedded microprocessor （LPC3250 from NXP） is chosen as the CPU of the embedded server with a linux operation system （OS） environment.The embedded server provides multiple interfaces for supporting various application scenarios.The whole network is based on local area network and adopts the Browser/Server （B/S） model.The monitoring and control node is as a browser endpoint and the remote node with an embedded server is as a server endpoint.Users can easily acquire various sensors information through writing Internet protocol address of remote node on the computer browser.Compared with client/server （C/S） mode,B/S model needs less maintain and can be applicable to large user group.In addition,a simple network management protocol （SNMP） is used for management of devices in Internet protocol （IP） networks.The results of the demonstration experiment show that the proposed system gives good support to manage the network from different user terminals and allows the users to better interact with the ambient environment.     

Robust Audio Blind Watermarking Algorithm Based on Haar Transform

To solve the problem of low capacity of audio watermarking information and poor robustness of impact resistance, a digital audio watermark algorithm based on wavelet transform is presented in this paper. In this algorithm, the fine and approximate components are obtained when the Haar wavelet base is used to convert each frame of the audio signal to its discrete transform. Then the HAS algorithm is applied to the fine component embedded with watermark to realize encryption process. The original audio carrier signal is not needed in extraction, as long as the signal is embedded after the frame is divided. The first two sections of each frame are implemented in Haar transform respectively to get the fine and approximate component. The watermark images are obtained from the former two fine components of the energy watermark sequence after calculating, comparing and extracting. The simulation results show that there is a certain transparency for the algorithm, a good robustness against the resampling and low pass filtering attack.     

A novel absolute displacement detecting magnetic sensor

A novel magnetic grating based on calibration was proposed.Two tracks,look-up track and index track,were used to realize absolute output.Magnets of look-up track were magnetized according to N-S-N-S,and magnetic field was sensed by 6 linear Hall sensors.Three signals whose phase shift is 120° were obtained through difference,and the offset of magnetic head in a signal period could be obtained by look-up table;Magnets of index track were magnetized according to pseudorandom binary sequence.Hall sensors were used to get the absolute offset of the signal period to which the magnetic head is belonged.The magnetic grating was calibrated using a higher resolution optical grating:output of optical grating and signals from magnetic grating were sampled at the same time and transmitted to computer,the relation between them could be got and stored in MCU for looking-up.The displacement was got according to Hall signals while in working state.A magnetic grating prototype was made,and it could realize absolute detecting in 2048 mm and the resolution could achieve to 0.001 mm.Its structure is simple,cost is very low and it is suitable for mass production.     

Functional Virtual Prototyping in Vehicle Chassis Reform Analysis and Improvement Design

The CAD/CAM/CAEintegration technique hasbeen obtained more and more attentions by automo-bile manufacturers,it is the trend in vehicle model-ing,and it plays a more and more i mportant role inautomobile design and development[1].However,theload of the traditional integration is too heavy to ef-fectively make use of Refs.[2,3].Hence,more prac-tical considerations must beincludedin effective mod-elling and si mulation.The present study is based on a practical projectfor a light bus front sus…     

High-Speed Noise-Based Random Bit Generator by Removing 1/f Noise with Differential Comparison

A design scheme of high-speed physical random bit generator is proposed by utilizing a wideband white noise as an entropy source. The difference operation between the wideband noise signal and its delayed signal is done to produce a series of binary code by a differential comparator.The D flip-flop,which is triggered by a clock, samples the output of the comparator. A random bit sequence at rates of up to 720.Mbit/s is obtained after the exclusive-OR operation. The differential comparison on noise signals can effectively eliminate 1/f characteristics of the amplified noise, and correct the probability density distribution deviation of noise signal amplitude. The quality of the resulting random sequence is verified using common tests of statistical randomness.     

Co-simulation platform for single-shaft parallel HEVs based on Cruise+Matlab/Simulink

We reversely analyzed the energy management strategy （EMS） for a single-shaft parallel hybrid electric vehicle （HEV）, and build a forward co-simulation platform based on Cruise and Matlab. The vehicle dynamics model is built with Cruise, and control model is set up with Matlab/Simulink environment. The data between the two models are transferred by the Matlab API interface in Cruise. After mechanical and signal connections are completed, we establish the computing tasks and take the simulations of vehicle＇ s power performance, economy, and emission performance. The simulation results match the actual measurement results, which show that the co-simulation platform is correct and feasible. The platform can be used not only for a basic simulation platform to optimize further EMS, but also for the development of actual control system.     

Multistatic radar analysis based on ambiguity function and Cramér-Rao lower bounds

The primary goal of this work is to characterize the impact of weighting selection strategy and multistatic geometry on the multistatic radar performance. With the relationship between the multistatic ambiguity function （AF） and the multistatie Cram6r-Rao lower bound （CRLB）, the problem of calculating the multistatic AF and the multistatic CRLB as a performance metric for multistatic radar system is studied. Exactly, based on the proper selection of the system parameters, the multistatic radar performance can be significantly improved. The simulation results illustrate that the multistatic AF and the multistatic CRLB can serve as guidelines for future multistatic fusion rule development and multistatic radars deployment.