Design and implementation of the simulation system for GPS new civil signals

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.

Research of Ionospheric Time-Delay Error Simulation in High Dynamic GPS Signal Simulator

The ionospheric time-delay is an important error source for GPS users. How tosimulate the ionospheric error is one of the key problems that need to be solved in high dynamicGPS signal simulator design. The ionospheric effects are related to the user's position. Based onthe analysis to the different ionospheric time-delay error correction methods for ground users andspace users, the approaches to calculate the ionospheric time-delay error in a high dynamic GPSsignal simulator are studied and the mathematic models are also given in this paper. The calculationproblem of eight ionospheric coefficients broadcasted in a GPS satellite message in differentapplication situations is solved. The validity of the ionospheric time-delay error calculationmethods given by this paper has been proved by simulations.

Synthetic Aperture Radar Raw Signals Simulation of Extended Scenes

A synthetic aperture radar (SAR) raw signal simulation algorithm for extended scenes is presented. This algorithm is based on the SAR two-dimensional system transform function (STF). To cope with range-variant nature of SAR STF and increase the speed of this algorithms, new formulas for range-variant phase corrections in range-Doppler (RD) domain are developed. In this way, many azimuth lines can be simulated with the same SAR STF. It only needs two-dimensional fast Fourier transform code and complex multiplications. Comparing with time-domain simulation algorithm, it is very simple and thus efficient. Simulation results have shown that this algorithm is accurate and efficient. Key words synthetic aperture radar - raw signal simulation - system transform function CLC number TP 751. 1 Foundation item: Supported by the National Natural Science Foundation of China (40376051)Biography: Sun Jin-yao (1967-), female, Ph. D. candidate, research direction: SAR image simulation and 3D recover for SAR image.

Quick System-Level DDR3 Signal Integrity Simulation Research

---Double data rate synchronous dynamic random access memory （DDR3） has become one of the most mainstream applications in current server and computer systems. In order to quickly set up a system-level signal integrity （SI） simulation flow for the DDR3 interface, two system-level SI simulation methodologies, which are board-level S-parameter extraction in the frequency-domain and system-level simulation assumptions in the time domain, are introduced in this paper. By comparing the flow of Speed2000 and PowerSI/Hspice, PowerSI is chosen for the printed circuit board （PCB） board-level S-parameter extraction, while Tektronix oscilloscope （TDS7404） is used for the DDR3 waveform measurement. The lab measurement shows good agreement between simulation and measurement. The study shows that the combination of PowerSI and Hspice is recommended for quick system-level DDR3 SI simulation.

Occurring Mechanism and Restraining Method Research of Numerical Noise Signal in Penetration Simulation

In hard target penetration simulation, the existing researches of the convergence of results are mainly concentrating in the corresponding relationship between penetration depth and mesh scales. However, the influence of the mesh difference on the penetration resistance and acceleration signals are seldom refer to. This paper presents the occurring mechanism and restraining method of numerical noise signal in penetration simulation. First, the concept of the noise signal izs proposed. By taking a 3D penetration simulation as example, the influence of the noise signal on the penetration resistance in different mesh scales and impact velocity is studied. To ensure the convergence of the computational results, the grid scale of the target is encrypted to 1：1：8. In addition, modem spectrum analysis method is introduced to further analyze the penetration resistance signal. The research results presented is useful to improve the computational accuracy of high speed projectile penetration simulation, and provide important reference for carrying out structural design and optimization of fuze system.

Method of fuzzy uniformity analysis for simulation underwater acoustic signals

Since the simulation underwater acoustic signal is used in the semi-object simulation experiment of underwater weapons, it has great impression upon simulation fidelity. It is asked that whether simulation signals can replace the real signal effectually. Considering the randomness of signals, the interval estimation of feature parameters of simulation signals is made. By comparing the obtained confidence interval with the corresponding accept interval, the concept of similarity coefficient of simulation signals is given. By making a statistical analysis for similarity coefficient, the uniformity information of simulation signals is extracted, and the fuzzy number which expresses the fuzzy uniformity level of simu- lation signals is obtained. The analysis method on fuzzy uniformity of simulation underwater acoustic signals is presented. It is indi- cated by the application in simulation of target radiated-noises that the method is suitable and effectual for the simulation research on underwater acoustic signals, and the analysis result may provide support for decision-making relative to perfecting simulation sys- tems and applying simulation signals.

Measuring the Qatar-Kazeron Fault Dip Using Random Finite Fault Simulation of September 27, 2010 Kazeron Earthquake and Analytical Signal Map of Satellite Magnetic Data

In this research the fault parameters causing the September 27, 2010 Kazeron Earthquake with a magnitude of MW = 5.8 (BHRC) were determined using the random finite fault method. The parameters were recorded by 27 accelerometer stations. Simulation of strong ground motion is very useful for areas about which little information and data are available. Considering the distribution of earthquake records and the existing relationships, for the fault plane causing the September 27, 2010 Kazeron Earthquake the length of the fault along the strike direction and the width of the fault along the dip direction were determined to be 10 km and 7 km, respectively. Moreover, 10 elements were assumed along the length and 7 were assumed along the width of the plane. Research results indicated that the epicenter of the earthquake had a geographic coordination of 29.88N - 51.77E, which complied with the results reported by the Institute of Geophysics Tehran University (IGTU). In addition, the strike and dip measured for the fault causing the Kazeron Earthquake were 27 and 50 degrees, respectively. Therefore, the causing fault was almost parallel to and coincident with the fault. There are magnetic discontinuities on the analytical signal map with a north-south strike followed by a northwest-southeast strike. The discontinuities are consistent with the trend of Kazeron fault but are several kilometers away from it. Therefore, they show the fault depth at a distance of 12 km from the fault surface.

Simulation of Multi-satellite GNSS Reflected Signals and Design of Simulator

Using GNSS-R technology for remote sensing of surface parameters has become a new trend in the field of remote sensing.With the rapid development of GNSS-R technology,GNSS-R simulation has become one of the new hot spots.Now the researches of the GNSS-R simulation are all the simulations that consider a single star or a single frequency point,and in actual applications,the signal captured by the receiver is often the reflected signals of multiple stars.In view of this situation,from the perspective of multi-satellite simulation,this paper gives the model of GNSS-R multi-satellite ocean simulation on the basis of analyzing the remote sensing principle,reflection signal model and simulation principle of GNSS-R technology.Based on the GNSS-R multi-satellite ocean simulation model and the fast parallel computing capability of GPU,the GNSS-R multi-satellite ocean simulator was designed.Finally,the direct and reflected signals generated by the GNSS-R multi-satellite simulator were tested and verified.The results show that the positioning result of the direct signal meets the positioning accuracy requirements;The delay-related power results obtained from the simulated two-satellite reflected signals processing are in good agreement with the theoretical model,and the correlation coefficients are all above 0.99;The generated signals are used for GNSS-R height measurement technology,the height measurement error is about 1.4~1.8 m,which is in line with the accuracy of the C/A code ranging receiver;And the parallel operation of the GPU for multi-satellite simulation calculation is 800—900 times higher than the traditional CPU calculation.It proves that the proposed model and the designed simulator are feasible and accurate.

IF signals simulation of three-dimensional radar

Based on the analysis of the principles of frequency-phase scanning 3-D （three-dimensional） radar and the scattering mechanism of 3-D radar, the target and clutter IF （intermediate frequency） signals model of frequencyphase scanning 3-D radar is presented. The IF signals model of different channels of 3-D radar is presented in one simple formula in which complex waveform effects are considered. The simulation results obtained during tests are also provided in the end.

Simulation of Raw Signal for Spaceborne Synthetic Aperture Radar(SAR)

The study on simulation of raw signal for spaceborne SAR aims at producing raw signal to test and evaluate the system and imaging algorithm. The model used for simulation includes a distributed target model, a platform and target geometry model, and a mathematical architecture used for generation of raw echo. Two aspects are stressed, one is the effects of earth ellip soid and attitude errors on radar impulse respense, the other is quick generation of range migration in azimuth frequency domain. Prescribed statistical characteristics of the model account for a realistic speckle of actual image. Finally, examples are given to validate the simulation of raw signal for spaceborne SAR.

Sensitivity Analysis and Selection of Check Index of Signal Intersection Simulation Model Based on VISSIM

Selecting check index quantitatively is the core of the calibration of micro traffic simulation parameters at signal intersection. Five indexes in the node (intersection) module of VISSIM were selected as the check index set. Twelve simulation parameters in the core module were selected as the simulation parameters set. Optimal process of parameter calibration was proposed and model of the intersection of Huangcun west street and Xinghua street in Beijing was built in VISSIM to verify it. The sensitivity analysis between each check index and simulation parameter in their own set was conducted respectively. Sensitive parameter sets of different check indices were obtained and compared. The results show that different indexes have different size of set, and average vehicle delay’s is maximum, so it’s necessary to select index quantitatively. The results can provide references for scientific selection of the check indexes and improve the study efficiency of parameter calibration.

Numerical Simulation Study of Vibration Characteristics of Cantilever Traffic Signal Support Structure under Wind Environment

Computational fluid dynamics(CFD)and the finite element method(FEM)are used to investigate the wind-driven dynamic response of cantilever traffic signal support structures as a whole.By building a finite element model with the same scale as the actual structure and performing modal analysis,a preliminary understanding of the dynamic properties of the structure is obtained.Based on the two-way fluid-structure coupling calculation method,the wind vibration response of the structure under different incoming flow conditions is calculated,and the vibration characteristics of the structure are analyzed through the displacement time course data of the structure in the crosswind direction and along-wind direction.The results show that the maximum response of the structure increases gradually with the increase of wind speed under 90°wind direction angle,showing a vibration dispersion state,and the vibration response characteristics are following the vibration phenomenon of galloping;under 270°wind direction angle,the maximum displacement response of the structure occurs at the lower wind speed of 5 and 6m/s,and the vibration generated by the structure is vortex vibration at this time;the displacement response of the structure in along-wind direction increaseswith the increase of wind speed.The along-wind displacement response of the structure will increase with increasing wind speed,and the effective wind area and shape characteristics of the structurewill also affect the vibration response of the structure.

Signal modulating noise effect in bistable stochastic resonance systems and its analog simulation

The effect of signal modulating noise in bistable stochastic resonance systems was studied theoretically and experimentally. A mathematical analysis was made on the bistable stochastic resonance model with small system parameters. An analogue circuit was designed to perform the effect. The effect of signal modulating noise was shown in the analog simulation experiment. The analog experiment was conducted for two sinusoidal signals with different frequencies. The results show that there are a sinusoidal component corresponding to the input sinusoidal signal and a noise component presented as a Wiener process corresponding to the input white noise in the system output. By properly selecting system parameters, the effect of signal modulating noise can be manifested in the system output.

Control strategies and hardware-in-the-loop simulation for bus signal priority

It is considered as an important and effective means to give priority to the development of public transit which can improve the efficiency of transportation resources utilization and alleviate traffic jams. Public transit signal priority belongs to the "time priority" among the right-of-way priorities. After reviewing the existing bus priority signal control strategies and the advances in related technologies at home and abroad, this article analyzed the breakthrough direction of the bus signal priority design technologies suitable for China's conditions, and then proposed the hardware and software systems and the modules for the bus priority signal control system. Finally, the hardware-in-the-loop simulation (HILS) was introduced to evaluate bus priority signal control programs in order to optimize the control strategies.

The Improved Design of Multi-channel Thin Gap Chamber Simulation Signal Source for the ATLAS Detector Upgrade

We develop an improved design of thin gap chamber （TGC） simulation signal source. To further simulate the feature of TGC detector, a novel thought is proposed. The TGC source has 256 channels. Every channel can randomly output the signal in 25 ns. The design is based on true random number generator （TRNG）. Considering the electrical connection between the TGC source and the developing trigger electronics, the GFZ connector is used. The experimental results show that the improved TGC simulation signal source can uniformly output the random signal in every channel. The output noise is less than 3 mVrms.

Simulation of Diode-Pumped Q-Switched Nd:YAG Laser Generating Eye-Safe Signal in IOPO Environment

Numerical simulation of diode-pumped Q-switched Nd:YAG laser leading to the generation of eye-safe signal in singly resonant Intracavity Optical Parametric Oscillator (IOPO) is presented. Starting from rate equations, the time dependent laser equations have been solved numerically, whereas the space-dependent OPO equations analytically. Our results show that 1.4 J diode laser (810 nm) pulse with 200 msec width, delivers 30 mJ Nd:YAG laser (1064 nm) pulse with 5 n-second width. This Nd:YAG laser further generates 9 mJ eye safe signal (1570 nm) pulse with 2.5 n-second width.

Simulation of Automotive Engine Phase Signal Based on Closed-Loop Strategy

In this paper, an automotive engine phase signal simulation algorithm is proposed based on a closed-loop feedback strategy, and its corresponding model is built. The signal incentives are carried out in the front-end, and the synchronization capture and comparison are conducted in the back-end. The phase simulation of signal output is achieved using closed-loop strategy, which can effectively eliminate the inconsistency between crankshaft and camshaft phases, and thus the accuracy and flexibility of phase signal generation are guaranteed. Experimental results show that the proposed algorithm is real time, and the deviation of simulated signals from actual phase signals is small. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

Radio Frequency Environment Effect Algorithms and Implementation in Signal-level Radar System Simulation

In radar system simulation,the reliability of simulation results depends not only on radar and target models,but also on radio frequency (RF) environment models,including clutter,multipath,diffraction,atmosphere refraction and attenuation.In traditional radar function simulation,all of these factors are grouped into a single pattern-propagation factor and can only give limited information for radar models.In signal-level simulation,radar models require simulated echoes should include information such as delay,doppler frequency,polarization,etc.By discussing and analyzing the principles and algorithms of RF environment effects (clutter,multipath,diffraction,atmosphere refraction and attenuation),this paper is supposed to provide a general RF environment model in signal-level.Algorithms for the Weibull clutter with Gaussian power spectral density (PSD) is discussed;A standard multipath and diffraction algorithm is analyzed,and the spherical earth and knife edge(SEKE)diffraction algorithm is introduced;The ray-tracing algorithm and the effective earth model are discussed;Algorithms for the absorption of oxygen and vapor are introduced;For certain algorithms,some practical advice is given.Finally,an object-oriented RF environment effects model is implemented,which has been dedicatedly designed for signal-level simulations and can provide relatively authentic simulated RF environment for the signal-level simulation of radar systems.Two simulation examples including clutter model and multipath and diffraction model are carried out and analyzed.

Simulation of large-scale numerical substructure in real-time dynamic hybrid testing

A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom （DOFs）. Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained.