De-noising of GPS Receivers Positioning Data Using Wavelet Transform and Bilateral Filtering

The need for precise position and navigation aids in many areas of industry is becoming increasingly apparent. There are many errors associated with the navigation solution of the global positioning system (GPS), including satellite ephemeris error, satellite clock error, ionospheric delay, tropospheric delay, multipath, receiver measurement error and selective availability (SA). Noise can create an error between centimeters to several meters. In this paper, the proposed technique applied to smooth noise for GPS receiver positioning data is based upon the analysis of wavelet transform (WT), bilateral filter (BF) and diffusivity function. The WT is a powerful tool of signal processing for its multiresolutional possibilities. BF is a local, non-linear and non-iterative technique. It is applied to approximation subband. We decompose a GPS positioning data into low-frequency and high-frequency components and apply BF on the approximation coefficients and diffusivity function on the detail coefficients at each decomposition level for data smoothing. A single-frequency and low-cost commercial GPS receiver manufactured by Rockwell Company is used to test our method. The experimental results on measurement data demonstrate the effectiveness of the proposed method; so that the total root mean square (RMS) error reduces to less than 0.29 m with SA on and 0.15 m with SA off using Daubechie wavelet.     

A Novel Artificial Intelligence Based Timing Synchronization Scheme for Smart Grid Applications

The smart grid control applications necessitate real-time communication systems with time efficiency for real-time monitoring, measurement, and control. Time-efficient communication systems should have the ability to function in severe propagation conditions in smart grid applications. The data/packet communications need to be maintained by synchronized timing and reliability through equally considering the signal deterioration occurrences, which are propagation delay, phase errors and channel conditions. Phase synchronization plays a vital part in the digital smart grid to get precise and real-time control measurement information. IEEE C37.118 and IEC 61850 had implemented for the synchronization communication to measure as well as control the smart grid applications. Both IEEE C37.118 and IEC 61850 experienced a huge propagation and packet delays due to synchronization precision issues. Because of these delays and errors, measurement and monitoring of the smart grid application in real-time is not accurate. Therefore, it has been investigated that the time synchronization in real-time is a critical challenge in smart grid applications, and for this issue, other errors raised consequently. The existing communication systems are designed with the phasor measurement unit (PMU) along with communication protocol IEEE C37.118 and uses the GPS timestamps as the reference clock stamps. The absence of GPS increases the clock offsets, which surely can hamper the synchronization process and the full control measurement system that can be imprecise. Therefore, to reduce this clock offsets, a new algorithm is needed which may consider any alternative reference timestamps rather than GPS. The revolutionary Artificial Intelligence (AI) enables the industrial revolution to provide a significant performance to engineering solutions. Therefore, this article proposed the AI-based Synchronization scheme to mitigate smart grid timing issues. The backpropagation neural network is applied as the AI method that employs the timing estimations and error corrections for the precise performances. The novel AIFS scheme is considered the radio communication functionalities in order to connect the external timing server. The performance of the proposed AIFS scheme is evaluated using a MATLAB-based simulation approach. Simulation results show that the proposed scheme performs better than the existing system.

     

Use of Satellite Technologies for Power System Measurements, Command, and Control

This paper analyzes the use of wide-area measurement technologies including satellite-based methods for the command and control of power systems. The methods studied include the global positioning system (GPS) and low earth orbit satellites (LEOS). Satellite technologies have been used in a variety of applications requiring precise timing between geographically diverse locations. The deregulation of the electric power industry is placing increased demands on power transmission system utilization. Because deregulated power systems utilize long-distance high-power exchanges, satellite-based communication systems are useful in control of geographically large interconnected power systems. In this paper, the satellite-based measurements and commands are introduced for wide-area control. With the support of wide-area signals, a multiagent supervisory-level power system stabilizer is proposed here as a potential wide-area control structure. Increased loading of transmission facilities is an impetus for accurate dynamic thermal overhead electrical conductor ratings. The application of satellite-based measurement for improving the dynamic thermal rating of overhead transmission circuits is suggested.     

基于FPGA的高精度守时方法研究

提出一种基于现场可编程门阵列(FPGA)的高精度守时方法,以统计学为基准,结合高精度恒温晶振和北斗/GPS双模接收器产生同步标准秒脉冲信号。当授时系统导航卫星失连,系统根据存储晶振脉冲数计算出均值和方差,动态设置系统晶振脉冲计数器阈值从而模拟产生高精度秒脉冲信号,消除晶振累积误差。实验结果表明,1h内授时系统守时误差小于250ns,可满足授时系统在电力、靶场等系统中的守时要求。     

Applications of New Fuzzy Inference-Based Tracking Loops for Kinematic GPS Receiver

Carrier phase measurement is essential for high-accuracy measurement in kinematic global positioning system (GPS) applications. For GPS receiver design, a narrow noise bandwidth is desired to decrease phase jitter due to thermal noise. However, this bandwidth will deteriorate the capability of the tracking loop and result in cycle slipping. Based on bandwidth adjustment criteria, a novel intelligent GPS receiver is proposed for solving the carrier phase tracking problem in the presence of high dynamic environments. A phase error estimator is developed in the carrier loop to conduct the phase error signals; i.e., frequency and frequency ramp errors. Two kinds of fuzzy inference (FI)-based approaches, fuzzy logic control and adaptive neuro-fuzzy control methods, that are simple and have easy realization properties are designed to perform rapid and accurate control of the digital frequency phase-locked loop (FPLL). A new design procedure for kinematic GPS receiver development is also presented. The computer results show that the FI-based receivers achieve faster settling time and wider pull-in range than the conventional tracking loops while also preventing the occurrence of cycle slips.     

Development of a prototype,experimental single-channel sequencing navstar gps receiver: Part I—Hardware implementation

Late in 1988 the Navstar GPS satellite navigation operational phase is planned to commence, offering world-wide, continuous and precise position-fixing and timing information to observers on land, sea, air and in space. This paper describes the development of a particular type of Navstar receiver—a single-channel, single-frequency, sequencing C/A code unit—and results of various tests carried out on the present phase-II satellite constellation. Part I of the paper deals essentially with the NAVSTAR satellite system and receiver hardware implementation, whereas Part II concentrates on receiver software and system performance.     

A LIDAR sensor prototype with embedded 14-bit 52 ps resolution ILO-TDC array

High resolution light detection and ranging (LIDAR) systems enable rapid imaging and mapping for applications such as autonomous vehicles and robotics. This paper presents a high-resolution LIDAR sensor system-on-a-chip (SoC) prototype containing a 31 × 2 pixel channel array with the input time-of-flight resolved by a 32 × 1 time-to-digital converter (TDC) array. A low-power avalanche photodiode (APD) receiver front-end with output bit-line sharing allows an array implementation and achieves ? 22 dBm sensitivity. Injection-locked oscillators (ILOs) are utilized in a TDC design to both minimize clock distribution power and improve timing accuracy. An on-chip phase-looked loop calibrates for ILO global PVT variations and ensures reliability over a wide operating range. Fabricated in GP 65 nm CMOS, the 14-bit TDC consumes 788 μW/channel and achieves 52 ps resolution over an 830 ns full-scale range, 37.2 ps_rms single-shot precision, 11 ps_rms channel uniformity, and DNL/INL of 0.56/1.56 LSB, respectively. This electrical characterization projects that the SoC has the potential for 0.78 cm ranging precision over a 124 m maximum ranging distance. Sensor testing with a pulsed laser and an APD array hybrid-integrated with the CMOS SoC shows a measurement range of over 700 ns with a 3.2 ns maximum single-shot error.     

Development of a prototype,experimental single-channel sequencing navstar gps receiver: Part II—Software description

Late in 1988 the Navstar GPS satellite navigation operational phase is planned to commence, offering world-wide, continuous and precise position-fixing and timing information to observers on land, sea, air and in space. This paper describes the development of a particular type of Navstar receiver—a single-channel, single-frequency, sequencing C/A code unit—and results of various tests carried out on the present phase—II satellite constellation. Part I of this paper deals with the NAVSTAR satellite system and the development of receiver hardware, whereas Part II concentrates on software development and system performance.     

GPS多普勒差分测速算法

全球卫星定位系统(GPS)多普勒单点测速技术是单GPS天线测姿技术的核心,但其测速精度易受卫星速度误差、卫星钟漂、电离层延迟、对流层延迟以及飞行器位置误差等因素的影响。针对上述问题,提出结合GPS地面基准站卫导观测数据,对机载GPS多普勒观测量进行双差处理,从而得到GPS多普勒双差方程。求解该双差方程,能够有效缓解上述不利因素的影响,得到精度更好的飞行器实时速度。半实物仿真计算结果与跑车实验计算结果都表明多普勒差分测速精度大幅优于多普勒单点测速精度。     

单频GPS导航定位中的电离层延迟改正方法

电离层延迟是单频ＧＰＡ导航定位的主要误差源之一。本文提出了一种利用单频ＧＰＳ接收伪码载波相位实时观测数据实时估计和改正电离层延迟的方法，着重阐述了利用局部电离层垂直延迟模型和实时观测数据确定载波相位整周模糊度的步骤，并讨论了该电离层改正方法的优缺点和应用前景。     

基于人工神经网络的GPS卫星信号模拟器信号估计方法

多通道全球定位系统(GPS)卫星信号模拟器用来为GPS接收机和导航系统提供逼真的测试信号。该文从模拟器设计的角度对到达GPS接收机天线的卫星信号进行了分析,着重讨论了因众多误差因素影响而不易直接利用经验模型确定的几个波形参量的估计问题。基于人工神经网络(ANN)理论,提出一种利用ANN来模拟信号传播延迟、载波相位、信号功率等参量的方法。给出了基于ANN的模拟器闭环测试系统的结构。并对所设计的ANN进行了训练和验证,仿真实验结果表明,所设计的ANN能够在统计意义上逼真地模拟样本数据,从而使基于ANN的模拟器信号状态参量计算能够满足设计要求,可以直接应用于多通道GPS信号模拟器的研制。     

平流层飞艇对GPS接收机的干扰优势

为解决地面干扰衰减严重、干扰效果不理想的问题,提出了将干扰机置于平流层飞艇的思想。在对GPS伪距测量精度分析的基础上,推导了干扰位置与GPS接收机接收到的干扰功率之间的关系,得到了不同干扰位置下伪距测量方差的数学模型。在给定GPS伪距测量误差的前提下,仿真分析了干扰平台高度与干扰效果之间的关系,结果验证了平流层飞艇载干扰器的高度优势。     

GPS SATELLITE SIMULATOR SIGNAL ESTIMATION BASED ON ANN

Multi-channel Global Positioning System （GPS） satellite signal simulator is used to provide realistic test signals for GPS receivers and navigation systems. In this paper, signals arriving the antenna of GPS receiver are analyzed from the viewpoint of simulator design. The estimation methods are focused of which several signal parameters are difficult to determine directly according to existing experiential models due to various error factors. Based on the theory of Artificial Neural Network （ANN）, an approach is proposed to simulate signal propagation delay, carrier phase, power, and other parameters using ANN. The architecture of the hardware-in-theloop test system is given. The ANN training and validation process is described. Experimental results demonstrate that the ANN designed can statistically simulate sample data in high fidelity. Therefore the computation of signal state based on this ANN can meet the design requirement, and can be directly applied to the development of multi-channel GPS satellite signal simulator.     

A self-duty-cycled 7.2–8.5 GHz IR-UWB receiver for low power and low data rate applications

A self-duty-cycled non-coherent impulse radio-ultra wideband receiver targeted at low-power and low-data-rate applications is presented. The receiver is implemented in a 130 nm CMOS technology and works in the 7.2–8.5 GHz UWB band, which covers the IEEE 802.15.4a and 802.15.6 mandatories high-band channels. The receiver architecture is based on a non-coherent RF front-end (high gain LNA and pulse detector) followed by a synchronizer block (clock and data recovery or CDR function and window generation block), which enables to shut down the power-hungry LNA between pulses to strongly reduce the receiver power consumption. The main functions of the receiver, i.e. the RF front-end and the CDR block, were measured stand-alone. A maximum gain of 40 dB at 7.2 GHz is measured for the LNA. The RF front-end achieves a very low turn-on time (<1 ns) and an average sensitivity of ?92 dBm for a 10^?3 BER at a 1 Mbps data rate. A root-mean-square (RMS) jitter of 7.9 ns is measured for the CDR for a power consumption of 54 µW. Simulation results of the fully integrated self-duty-cycled 7.2–8.5 GHz IR-UWB receiver (that includes the measured main functions) confirm the expected performances. The synchronizer block consumes only 125 µW and the power consumption of the whole receiver is 1.8 mW for a 3% power duty-cycle (on-window of 30 ns).     

A BiCMOS time interval digitizer based on fully-differential,current-steering circuits

A time interval digitizer cell with a 0-16 ns input range and a nominal LSB width of 1.0 ns has been integrated in a 2-μm BiCMOS technology, The circuit exhibits both integral and differential nonlinearity below 0.15 LSB and a timing error of 0.32 ns RMS. Logic gate propagation delays are used as time measurement units, and the nominal value of the delays is set by an on-chip phase-locked loop (PLL). Fully-differential, current-steering circuits with low voltage swings are used to implement the time interval digitizer so as to generate minimal switching noise. The cell is to be used in the monolithic, multi-channel realization of a high-sensitivity, mixed-signal data acquisition front-end. By virtue of the time digitization architecture used, the average power dissipation of the cell is only 19.8 mW, despite the use of circuits that dissipate static power, and the layout area is a compact 448 μm×634 μm     

Design and Optimization of Dual Band Microstrip Antenna Using Particle Swarm Optimization Technique

Dual-frequency operation of antenna has become a necessity for many applications in recent wireless communication systems, such as GPS, GSM services each operating at two different frequency bands. A new technique to achieve dual band operation from different types of microstrip antennas is presented here. An evolutionary design process using a particle swarm optimization (PSO) algorithm in conjunction with the method of moments (MoM) is employed effectively to obtain the geometric parameters of the antenna performance. In this article a PSO based on IE3D®? method is used to design dual band inset feed microstrip antenna. Maximum return loss is obtained at 2.4 GHz is ?43.95 dB and at 3.08 GHz is ?27.4 dB. Its bandwidth, of 33.54 MHz, ranges from 2.38355 GHz to 2.41709 GHz. Simulated and experimental results of the antenna are discussed.     

Mobile GPS carrier phase tracking using a novel intelligent dual‐loop receiver

Carrier phase information is necessary for accurate measurements in global positioning system (GPS) applications. This paper presents a novel intelligent GPS carrier tracking loop with variable‐bandwidth characteristics for fast acquisition and better tracking capability in the presence of dynamic environments. Our dual‐loop receiver is composed of a frequency‐locked loop‐assisted phase‐locked loop structure, the fuzzy controllers (FCs), and the ATAN discriminator functions. The soft‐computing FCs provide the time‐varying loop gains to perform accurate and reliable control of the dual‐loop paradigm. Once the phase dynamic errors become large under kinematic conditions, the fuzzy loop gains increase adaptively and achieve rapid acquisition. On the other hand, when the tracking errors approach zero in the steady state, the loop gains decrease and the corresponding dual‐loop receiver returns to a narrowband system. Four types of carrier phase signals, i.e. phase offset, decaying sinusoidal phase jitter, frequency offset, and frequency ramp offset, are considered to emulate realistic mobile circumstances. Simulation results show that our proposed receiver does achieve a superior performance over conventional tracking loops in terms of faster settling time and wider acquisition range while preventing the occurrence of cycle slips. Copyright © 2008 John Wiley & Sons, Ltd.     

Novel SREKF-based recurrent neural predictor for narrowband/FM interference rejection in GPS

The GPS provides accurate positioning and timing information that is useful in various applications. A new adaptive neural predictor for GPS jamming suppression applications is proposed. The effective and computationally efficient square-root extended Kalman filter (SREKF) algorithm is adopted to adjust the synaptic weights in the nonlinear recurrent architecture and thereby estimate the stationary and non-stationary narrowband/FM waveforms. Cholesky factorization is employed in Riccati recursion to improve numerical stability because of the propagation of round-off errors in conventional KF equations. The main characteristics of the proposed SREKF-based canceller are their rapid convergence and favorable tracking performance. Simulation results reveal that its SNR improvement factor exceeds the factors of conventional LMS, RLS, ENA and TLFN filters in single-tone CWI, multi-tone CWI, pulse CWI and FM jamming environments, respectively.     

GPS/INS超紧致耦合压制干扰能力分析

采用带限高斯噪声和同速率伪码相关信号对全球定位系统(GPS)/惯导系统(INS)超紧致耦合导航系统GPS军码接收机实施压制干扰。通过分析GPS P(Y)码和M码信号功率谱变化特点,对以上两种压制干扰进行信号参数的优化确定,进而计算出参数优化后的干扰信号造成GPS/INS超紧致耦合GPS军码接收机载波环路失锁时射频前端处所需的最小干扰功率。考虑干扰信号入射角与接收天线增益的关系,仿真得到不同高度干扰源发射功率与有效干扰距离的关系曲线。根据要地目标的防护需求,对不同制导武器所需的连续压制干扰作用距离进行定量分析,并在此基础上对沿来袭制导武器航路附近部署的多干扰源位置坐标和数量设置问题完成建模求解。     

Performance of a MANET directional MAC protocol with angle‐of‐arrival estimation

The use of directional antennas in mobile ad hoc networks (MANETs) has shown to offer large throughput gains relative to omnidirectional antennas. When used in ad hoc networks, directional medium‐access‐control (DMAC) protocols usually require all nodes, or part of nodes, to be aware of their exact locations. This location information is typically provided using a global positioning system (GPS). Although GPS systems are designed to be as nearly accurate as possible, there are still estimation errors that can cause a relatively large deviation from the actual GPS receiver position. In this paper, we investigate the effect of inaccurate node position estimation on the throughput of these protocols. Our results clearly indicate that the advantages of DMAC protocols diminish if the available position information is not accurate enough. As an alternative, we propose an efficient DMAC protocol that utilizes signal parameter estimation via the rotational invariance technique (ESPRIT) for direction‐of‐arrival (DOA) estimation; alleviating the need for GPS and, hence, avoiding the degrading associated with typical GPS position estimation errors. Moreover, unlike GPS‐based protocols, our protocol is suitable for both outdoor and indoor applications. Under different operating conditions and channel models, our simulation results show the throughput improvement achieved using the proposed protocol relative to the IEEE 802.11. Copyright © 2007 John Wiley & Sons, Ltd.