高动态GNSS导航接收机中扩展卡尔曼跟踪算法的研究

针对高动态GNSS导航接收机跟踪环节中动态性和噪声性能的问题,该文提出一种基于信号参数估计结构的扩展卡尔曼跟踪环。该文首先对高动态GNSS信号进行建模,使用扩展卡尔曼参数估计来实现载波跟踪,并用载波多普勒辅助码环,有效地提高了高动态导航接收机的跟踪性能。仿真结果表明,相比传统上的锁频环辅助锁相环,该文提出的环路具有更小的跟踪误差以及更好的噪声特性。     

一种低复杂度GPS载波跟踪环路设计

 GPS接收机载波跟踪环路的鉴别器和滤波器设计决定了跟踪环路的性能,也在很大程度上决定了GPS接收机的性能.本文在分析了传统锁相环和锁频环鉴别器算法的基础上,提出了一种锁相锁频环共用四象限反正切函数单元的鉴别器算法;同时,在研究了基于双线性Z变换积分器与矩形波数字积分器的滤波算法基础上,提出了一种基于矩形波数字积分器的锁频环辅助锁相环的滤波器算法.综合这两种新算法给出一种低复杂度的GPS接收机锁相锁频环设计方法.通过理论分析与仿真实验,证实该GPS载波跟踪环路设计不但具有良好的跟踪性能,且与传统设计方案相比具有运算量小,复杂度低,占用资源少等优点,更易于工程实现.     

直扩导航系统中数字科思塔斯环的FPGA设计与实现

引言 扩频接收机载波的同步包括捕获和跟踪两个过程,载波捕获即多普勒频移的粗略估计通常包含在伪码同步过程中,而精确的载波相位及多普勒频移则通过FLL（锁频环）和PLL（锁相环）跟踪来实现。锁频环直接跟踪载波频率,而锁相环则直接对载波相位进行跟踪。锁相环具有较高的跟踪精度,但对通信链路干扰的容忍能力差,特别是受载体动态引入的多普勒频移影响较大;而锁频环具有较好的动态性能,但跟踪精度较低。     

北斗导航载波锁相环和锁频环的混合应用

为满足北斗导航接收机的复杂动态条件下的使用,本文提出了一种锁频环和锁相环混合跟踪的载波跟踪方法,提高北斗导航接收机在高动态下的载波跟踪性能,通过对载波跟踪环的参数进行了研究。设计并实现了一种在DSP端进行环路控制,在FPGA端完成载波的剥离的载波环路跟踪方案,测试结果表明,该方案能实现高动态下载波信号的快速精确跟踪,具有良好的实时性和推广价值。     

高动态GNSS接收机载波环性能评估与仿真

高动态GNSS接收机在航天和制导武器应用中越来越普遍,很多文献上都说明了接收机能够跟踪30 g,甚至更高动态的加速度,以及50 g/s以上的加加速度。从跟踪门限以及跟踪精度的角度出发,分析了各种跟踪环路的性能,找出了锁频环辅助锁相环的跟踪上界,并给出了二阶锁频环,三阶锁相环的各种噪声带宽下的理论下界,以及高动态GNSS接收机经常使用的辅助的三阶锁相环的仿真结果。所设计的跟踪环路已经在实际应用中得到使用,性能非常稳定,加速度能够达到50 g,加加速度达到60 g/s。     

一种GPS信号载波跟踪技术

本文提出一种锁相环(PLL)与锁频环(FLL)相级联的 GPS 信号载波跟踪方法， 该方法兼顾了 PLL 的载波跟踪精度与 FLL 的动态适应性，经过验证，该方法可以实现对高动态信号的精确跟踪。     

高动态多进制扩频信号的载波跟踪技术研究

针对高动态环境下多进制扩频信号的载波同步问题,在分析锁相环(PLL)和锁频环(FLL)环路各自优点的基础上,研究了采用锁频环和锁相环相结合的方式进行载波信号跟踪。利用FLL动态适应能力较强和PLL具有较好跟踪精度的特点,实现动态信号的快速、精确跟踪。理论分析和仿真结果表明,该方法具有良好的跟踪效果。     

一种基于FLL和PLL的复合载波环的跟踪精度分析

基于卫星通信高动态、高精度的需求,提出了一种锁频环与锁相环相结合的双环载波跟踪系统.通过分析热噪声和动态应力对载波环跟踪精度的影响,指出了锁相环和锁频环的优缺点,给出了复合载波环的结构框图和工作流程.最后通过系统仿真,证明了复合载波环比单一载波环具有更全面的性能.     

一种新型结构数字载波跟踪环及其Z域稳态性能分析

 提出一种具有串联环路结构的新型数字载波跟踪环,以解决极低载噪比下高动态载波信号的跟踪问题.在输入纯载波信号时,通过建立Z域全相位模型,对新型载波环稳态性能和稳定条件进行了理论推导,得到稳态相差和稳定条件与环路参数间的解析式.理论分析表明,该新型载波环的动态跟踪能力等价于高阶锁相环,且稳定条件比后者更容易满足.仿真结果验证了上述结论.所得结论可用于评估接收机载波跟踪性能及指导环路设计,并为设计高阶锁相环提供了一种新思路.     

动态环境下载波锁相跟踪环的信号级仿真

在接收信号载噪比一定的前提下,针对GPS软件接收机在不同运动状态下载波环跟踪的问题,仿真研究了不同环路的跟踪性能:在低加速度动态下采用2阶锁相环跟踪更佳,在高加速度动态下则应该采用3阶锁相环跟踪。通过仿真验证了环路的有效性。此外通过仿真发现当载噪比和滤波器噪声带宽一定的情况下,选择合适的预检测积分时间可以有利于载波跟踪。     

INS辅助GPS载波跟踪环分析

高动态环境会造成较大的多普勒频移,这使得一般的GPS接收机在没有外界辅助的情况下难以可靠工作.为了同时满足高动态GPS接收机动态性能和噪声抑制两方面的需要,GPS/INS紧耦合系统利用INS的信息辅助GPS接收机的载波跟踪回路.对紧耦合系统的关键技术--INS辅助GPS载波跟踪回路进行了系统分析,阐述了INS信息辅助G...     

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.     

引入微分控制思想的辅助GPS载波跟踪环路设计

 载波信号跟踪环路制约着GPS接收机的工作性能,针对其易受高动态和弱信号等环境干扰的缺陷,提出一种引入微分控制思想、应用SINS辅助接收机载波跟踪环路的设计方法.剖析应用于载波跟踪的相位锁定环(Phase Locked Loop,PLL),并将其近似为PI控制模型;在验证辅助信息引入时环路系统稳定的基础上,增加类微分控制项,利用SINS的输出和时钟误差信息估算的多普勒频率作为跟踪环路的中心频率,辅助PLL实现载波信号跟踪;仿真结果表明提出方法能够有效地缩短跟踪环路带宽,缓解热噪声和动态应力之间的矛盾,进而改善载波环路的频率响应和跟踪误差.     

矢量跟踪算法快速重跟性能分析

当卫星导航信号受到一段时间干扰或遮蔽时,信号载噪比下降,传统跟踪环路失锁。信号恢复时,针对传统跟踪环路不能及时重新跟踪问题,应用矢量跟踪算法,进行跟踪。分析了在真实GPS数据加上仿真噪声之后矢量/频率锁定环路（VDFLL）的性能以及与传统环路进行对比,试验证明矢量跟踪具有快速重跟性能。     

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.     

基于软件的GPS信号捕获跟踪算法研究

对GPS软件接收机的捕获和跟踪部分进行了研究。对于捕获模块,通过对常用串行搜索捕获算法和并行频域搜索捕获算法的比较和分析,提出了一种新型并行码相位搜索捕获算法;对于跟踪模块,提出采用非相干延迟锁相环对码进行跟踪,同时采用Costas环对载波进行跟踪;最后,从捕获和跟踪的GPS信号中提取出导航电文,并根据电文中的参数计算出了用户的位置坐标,并在Matlab中对用户的位置坐标进行了定位解算验证。     

Frequency stability requirements for space communications and tracking systems

Space communications and tracking systems impose stringent requirements on stable frequency sources. "Flicker" (1/f) noise and environmental modulation are two types of oscillator instability affecting typical space systems performance. Examples of several systems are presented with the source requirements for each. Earth satellite systems impose stability requirements of the order of 10^-10over periods of seconds to hours depending on the individual experiment. A typical system requires phase noise of less than 5° rms in a receiver of 12 Hz bandwidth at S-band. An example is presented of a spacecraft transponder which must maintain phase noise below 45° peak-to-peak under vibration of 3g peak from 10 Hz to 10 KHz.     

A low jitter, low spur multiphase phase-locked loop for an IR-UWB receiver

A low jitter,low spur multiphase phase-locked loop(PLL) for an impulse radio ultra-wideband(IR-UWB) receiver is presented.The PLL is based on a ring oscillator in order to simultaneously meet the jitter requirement, low power consumption and multiphase clock output.In this design,a noise and matching improved voltage-controlled oscillator(VCO) is devised to enhance the timing accuracy and phase noise performance of multiphase clocks.By good matching achieved in the charge pump and careful choice of the l...     

高动态GPS接收机环路跟踪技术研究

为了解决加速度45g、加加速度10g/s的高动态环境下GPS信号的载波跟踪、码跟踪及其精度问题,提出了一种综合考虑动态和精度性能的载波环和码环优化设计方案,探讨了高动态情况下载波环和码环的结构设计及捕获转跟踪技术,分析了FLL/PLL/DLL环路的动态应力、暂态响应和鉴别器特性,总结了实用的控制策略和环路带宽。该方案经自主开发的软件接收机测试验证,可以在达到很高动态特性的同时满足一定的测距精度和定位精度要求。     

A fast lock frequency synthesizer using an improved adaptive frequency calibration

An improved adaptive frequency calibration (AFC) has been employed to implement a fast lock phase-locked loop based frequency synthesizer in a 0.18 μm CMOS process. The AFC can work in two modes: the frequency calibration mode and the store/load mode. In the frequency calibration mode, a novel frequency-detector is used to reduce the frequency calibration time to 16 μs typically. In the store/load mode, the AFC makes the voltage-controlled oscillator (VCO) return to the calibrated frequency in about 1 μs by loading the calibration result stored after the frequency calibration. The experimental results show that the VCO tuning frequency range is about 620-920 MHz and the in-band phase noise within the loop bandwidth of 10 kHz is -82 dBc/Hz. The lock time is about 20 μs in frequency calibration mode and about 5 μs in store/load mode. The synthesizer consumes 12 mA from a single 1.8 V supply voltage when steady.