共查询到18条相似文献,搜索用时 359 毫秒
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高灵敏度GPS捕获技术的分析与仿真 总被引:4,自引:0,他引:4
高灵敏度GPS定位技术是当今导航领域的一个研究热点,而高灵敏度GPS捕获技术是其中最重要的部分。常用的两种高灵敏度GPS信号捕获方法是相干积分和非相干积分。根据两种方法中的数学表达、概率密度函数得到了两种方法的处理增益及其变化趋势,从而为分析接收机信号检测和评估接收机工作效果提供了重要的依据;仿真实验得到了两种方法的实际效果,验证了理论分析。 相似文献
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在GPS接收机中,对GPS信号的捕获是最为关键的第一步。对GPS信号中伪码的初始相位和信号载频的估计是捕获的两个基本任务。在某些特定的环境下,比如室内、城市街道、树林,对信号的捕获变得困难。针对这个困难可以通过提高估计精度以减少估计误差带来的相关损失。但是信号累积和估计精度的提高都需要极大地增加运算量。本文提出了将CORDIC算法引入到GPS接收机,在保证大运算量的情况下,实现快速的计算时间。介绍了GPS信号捕获的基本原理,讨论了使用CORDIC算法的必要性以及实现方法。最后通过仿真验证了CORDIC算法能够有效提高GPS接收机的捕获速度。 相似文献
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一种改进的GPS微弱信号捕获方法 总被引:1,自引:0,他引:1
介绍了GPSL1载波中C/A码的捕获算法,以快速傅立叶变换为基础,采用相关积分和非相关积分对较长的信号进行处理,实现对GPS微弱信号的捕获.为验证这一算法,利用一组在室内采集的GPS L1C/A码IF数据,采用一般的信号捕获方法和改进的信号捕获方法分别进行了处理.结果显示,采用改进的方法捕获到了较微弱的GPS信号,提高了接收机的灵敏度. 相似文献
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弱GPS信号捕获算法的仿真实验研究 总被引:1,自引:0,他引:1
针对低信噪比环境下导航的需要,文章对低信噪比环境下弱GPS信号捕获算法进行了分析,重点对相关累加、非相关累加以及多重数据位循环相关累加捕获算法的信号处理流程和算法捕获性能进行讨论。通过特定的硬件装置获得真实的GPS信号,利用Matlab对上述3种常用的弱GPS信号捕获算法进行计算机仿真研究。根据理论分析和仿真结果可以看出,多重数据位循环相关捕获算法更适合检测低信噪比环境下的GPS信号。 相似文献
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GPS现代化和GPS信号重构技术的进展 总被引:2,自引:0,他引:2
介绍了GPS现代化计划和GPS信号重构技术的进展。GPS信号重构的目的是确保在某些特定区域的美军能够正常使用GPS而不受影响,而在同一区域与美军对立的一方既不能使用民用GPS信号,也不能使用GPS的军码,至于在该特定区域以外的民间GPS用户,则依然能够正常使用GPS;此外还重点介绍了由美国大地测量局(NGS)主持运行的GPS陆基增强系统(CORS)。 相似文献
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随着卫星导航定位技术及接收机的发展,软件接收机已成为当前研究的热点之一。根据北斗卫星导航定位系统(BDS)的接口控制文档(ICD),分析了BDS B1I信号,提出了一种基于并行码相位和并行频率捕获的算法,实现了对BDS-B1I/GPS信号的捕获跟踪、导航电文解码。利用HG-SOFTGPS02采集器采集的数据进行BDS/GPS定位,验证了该算法的可行性与合理性。 相似文献
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The tracking performance of High Sensitivity Global Positioning System (HSGPS) receivers under avalanche deposited snow was
investigated. Two field trials were held during April 2006 in the Canadian Rocky Mountains to study the factors affecting
GPS signals and positioning performance for avalanche rescue. The PLAN Group at the University of Calgary has developed the
miniature Global Navigation Asset Tracker (GNAT™) which integrates the SiRFstar III HSGPS receivers with a microcontroller,
onboard flash storage and a 2.4 GHz Zigbee radio modem. The test systems were placed down a 6 cm hole bored in avalanche deposited
snow for 2.5 h with data collected at 1 Hz. Post-mission analysis showed average GPS signal attenuation of approximately 11
to 13 dB within the first 1.5 m of avalanche debris. Sufficient GPS signals for positioning were received by GPS receivers
buried in 2.7 m of avalanche deposited snow. Methods of improving the GPS position beneath the avalanche debris were investigated,
resulting in horizontal position RMS values of 7.4 and 2.8 m at depths of 2.0 and 2.68 m respectively. 相似文献
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Reliability testing, namely receiver autonomous integrity monitoring (RAIM), consists of statistical testing of least-squares residuals of observations, e.g., on an epoch-by-epoch basis aiming towards reliable navigation fault detection and exclusion (FDE). In this paper, classic RAIM and FDE methods are extended with testing of range-rate residuals to find inconsistent velocity solutions in order to contribute to the reliability of the system with special focus on degraded signal environments. Reliability enhancement efforts discussed include a Backward-FDE scheme based on statistical outlier detection and an iteratively reweighted robust estimation technique, a modified Danish method. In addition, measurement weighting assigned to code and Doppler observations is assessed in the paper in order to allow fitting a priori variance models to the estimation processes. The schemes discussed are also suitable in terms of computational convenience for a combined GPS/Galileo system. The objective of this paper is to assess position and velocity reliability testing and enhancement in urban and indoor conditions and to analyze the navigation accuracy conditions with high sensitivity GPS (HSGPS) tests. The results show the necessity of weighted estimation and FDE for reliability enhancement in degraded signal-environment navigation. 相似文献
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Indoor GNSS signals are typically received with poor signal-to-noise ratio, which impairs the acquisition stage of common
global positioning system (GPS) receivers. Extending the coherent integration time increases the acquisition sensitivity,
but the data-bit-rate limits the maximum achievable performance. Non-coherent processing also improves the detection performance,
but indoor signals require a large amount of accumulations resulting in significant squaring loss. Moreover, both strategies
have high computational complexity which fixes demanding requirements for stand alone mass-market terminals operating in real
time. A sensitivity–complexity trade-off is therefore mandatory. Assisted-GPS, which is included in 3GPP specifications, reduces the overall acquisition complexity and enhances sensitivity. In this paper
we describe a low-complexity-assisted data-wipe-off technique that enables the high-sensitivity acquisition of GPS signals.
The method is based on the acquisition of the strongest signal in order to obtain information that eases the acquisition of
the weaker ones. The analysis also addresses sources of sensitivity loss, such as Doppler effects and local oscillator inaccuracies.
A test campaign with real signals and integration times up to 2 s validates the method, demonstrating the effectiveness of
the proposed technique in indoor environments. 相似文献
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随着GPS定位技术的不断发展,GPS定位技术已被广泛用于各种工程控制网的建立.本文针对具体项目探讨了小区域内GPS控制网的建立、外业数据的采集和内业数据的处理,并对控制网质量进行了精度分析. 相似文献
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Andrew G. Dempster 《GPS Solutions》2008,12(3):179-185
Comb filters can be designed by replacing single delays in digital filters by multiple delays. These filters are “periodic”
in the sense that their frequency response repeats itself at fixed intervals. They are thus well suited to a signal such as
GPS L1 which has a spectrum made up of lines separated by the code repetition frequency of 1 kHz. In this paper we examine
how periodic filters can be used in a conventional GPS L1 receiver. We find that comb filters assist with acquisition of weak
signals, and can improve code-tracking performance. 相似文献
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本文给出了GPS/GLONASS双模接收机的总体设计方案,重点对弱信号环境下的接收机信号捕获进行了讨论,采用并行码相位搜索方法和改进的循环相关算法分别对GLONASS信号和GPS信号进行捕获;并利用真实数据对双模接收机性能进行了仿真研究,重点对接收机捕获弱信号的能力,以及在不同信噪比和不同累加数据长度下的捕获概率进行了讨论,结果表明该双模接收机在不需要较长数据长度的情况下能够捕获低信噪比环境下的卫星导航信号,提高了接收机的灵敏度。 相似文献