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GPS信号快速捕获方案研究 总被引:5,自引:1,他引:5
设计在高动态环境下工作的GPS接收机,其难点之一在于对卫星伪码的快速捕获。针对缩短GPS接收机捕获伪随机码时间的问题,本文在对GPS信号结构作出分析的前提下,介绍了时域滑动相关的常规捕获方法;提出了基于FFT的快速捕获技术,并在matlab环境下做了系统仿真,仿真结果显示捕获速度可以得到显著提高。 相似文献
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针对 GPS M码授权码流获取问题,提出 1种新的基于调制域增强副载波剥离的方法。该方法利用 GPS C/A码和 M码码片起始位的相关性,在调制域上利用 BOC调制短码信息对 GPS M码信号进行累加增强,获取授权码流。首先,利用公开的 GPS C/A码辅助获取 GPS信号载波相位和 C/A码码相位;然后,分别利用获得的 GPS信号载波相位和 C/A码码相位,完成 GPS C/A码与交调量的剥离以及 M码授权码的初始相位对准;进一步,利用 BOC调制短码信息在调制域上实现累加增强,完成副载波剥离,获得 GPS M码授权码流;最后,利用实际采集信号对所提方法有效性进行了验证,并与现有方法进行了对比。结果表明,所提方法能够克服带宽内 P(Y)信号旁瓣能量对 M码授权码提 取的影响,可带来 3.5 dB左右的性能改善。 相似文献
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提出了伪码相位一载波频率二维搜索伪码捕获结构在低信噪比大多普勒频移情况下捕获性能恶化的问题,给出了一种中频端简单数字处理算法的解决方案,并分析了该算法的性能。仿真表明,改进的伪码相位一载波频率二维搜索伪码捕获结构在低信噪比大多普勒频移情况下解决了捕获性能恶化的问题。 相似文献
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建立了伪码捕获和跟踪过程的数学模型;推导出了伪码捕获的检测概率和虚警概率,提出了改进的双Dwell搜索方法;对一阶、二阶、三阶DDLL的动态跟踪性能及输入随机噪声影响进行了定量分析。研究结果表明,双Dwell搜索方法能显著缩短平均捕获时间,应根据不同的系统动态特点,选择不同的环路参数,以优化码跟踪环的特性。 相似文献
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针对扩频系统中出现的伪码错锁问题,分析了产生伪码错锁的原因,根据伪码自相关性和互相关性特点,从伪码捕获策略、错锁自动判决策略等角度研究了伪码防错锁措施:选择自相关性和互相关性尽可能好的码;合理设置捕获门限;减小多普勒捕获范围;采用并行伪码捕获方法,并在捕获过程中防止载波错捕现象发生;单独建立验证通道,进行相关值比较判决等。实践表明,采用文中方法可提高正确捕获概率,缩短捕获时间,从硬件设计上有效解决了伪码错锁问题。 相似文献
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GPS卫星无线电导航系统预计在1995年投入正式运行。GPS信号中的P码仅供美军和特别用户使用,C/A码则向全世界民用开放。C/A码受选择可用性(SA)影响,导航静度下降到一个适当水平。为提高GPS定位精度,各国都争相研究差分GPS(DGPS)。本文从GPS误差入手,主要就DGPS原理和实现方法进行讨论。 相似文献
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《Aerospace and Electronic Systems Magazine, IEEE》1988,3(6):7-10
The accuracy of clear acquisition (C/A) code for civilian users of the Global Positioning System, in comparison with precise (P) code, is discussed. Different design techniques for GPS receivers are presented. The 1-ms range ambiguity of C/A code is discussed, and a solution is given. Intentional degradation of GPS signals and denial of accuracy is discussed, and some predictions are presented. The issue of government support and protection of domestic GPS industry against possible unfair international competition is briefly discussed 相似文献
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Modeling and analysis for the GPS pseudo-range observable 总被引:3,自引:0,他引:3
Weihua Zhuang Tranquilla J. 《IEEE transactions on aerospace and electronic systems》1995,31(2):739-751
In this paper, a digital system for the Global Positioning System (GPS) pseudo-range observable is modeled and analyzed theoretically. The observable is measured in a GPS receiver by accurately tracking the pseudorandom noise (PRN) code phase of the input GPS signal using a digital energy detector and a digital delay lock loop (DDLL). The following issues are presented: (1) mathematical modeling of the digital PRN code acquisition and tracking system, (2) the closed-form expression derivation for the detection and false-alarm probabilities of the acquisition process and for the variance of code phase tracking error, and (3) the linear and nonlinear performance analysis of the DDLL for optimizing the receiver structures and parameters with tradeoff between the tracking errors due to receiver dynamics and due to input noise 相似文献
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Impact of GPS Acquisition Strategy on Decision Probabilities 总被引:3,自引:0,他引:3
《IEEE transactions on aerospace and electronic systems》2008,44(3):996-1011
The first stage of processing within a GPS receiver consists of the signal acquisition process, the output of which provides a rough estimation of code delay and Doppler frequency. The strong dependence of the acquisition performance on the decision strategy is shown, establishing the role of decision probabilities. Three acquisition strategies are analyzed and a new model describing the performance of a hybrid acquisition system is developed. The theoretical models are validated by simulations, and secondary phenomena, generally neglected in the literature, are also discussed. 相似文献
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干扰环境下直扩系统中DMF捕获性能研究 总被引:2,自引:0,他引:2
基于数字匹配滤波器(DMF)的捕获电路具有较快的捕获速度,因此它在直扩系统(DSSS)中得到了广泛的应用。为了在干扰环境下进一步提高其捕获性能,本文对影响捕获性能的检测概率和虚警概率进行了分析;并对直扩系统中基于DMF的平均捕获时间进行了计算机仿真,从而找到了在平均捕获时间较小时应该满足的信干比、干噪比和判决门限,为改善直扩系统的捕获性能提供了理论依据。 相似文献
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Performance analysis of GPS carrier phase observable 总被引:3,自引:0,他引:3
The accuracy analysis of Global Positioning System (GPS) carrier phase observable measured by a digital GPS receiver is presented. A digital phase-locked loop (DPLL) is modeled to extract the carrier phase of the received signal after a pseudorandom noise (PRN) code synchronization system despreads the received PRN coded signal. Based on phase noise characteristics of the input signal, the following performance of the first, second, and third-order DPLLs is analyzed mathematically: (1) loop stability and transient process; (2) steady-state probability density function (pdf), mean and variance of phase tracking error; (3) carrier phase acquisition performance; and (4) mean time to the first cycle-slipping. The theoretical analysis is verified by Monte Carlo computer simulations. The analysis of the dependency of the phase input noise and receiver design parameters provides with an important reference in designing the carrier phase synchronization system for high accuracy GPS positioning 相似文献