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1.
NLOS GPS signal detection using a dual-polarisation antenna 总被引：2，自引：2，他引：0
The reception of indirect signals, either in the form of non-line-of-sight (NLOS) reception or multipath interference, is a major cause of GNSS position errors in urban environments. We explore the potential of using dual-polarisation antenna technology for detecting and mitigating the reception of NLOS signals and severe multipath interference. The new technique computes the value of the carrier-power-to-noise-density (C/N 0) measurements from left-hand circular polarised outputs subtracted from the right-hand circular polarised C/N 0 counterpart. If this quality is negative, NLOS signal reception is assumed. If the C/N 0 difference is positive, but falls below a threshold based on its lower bound in an open-sky environment, severe multipath interference is assumed. Results from two experiments are presented. Open-field testing was first performed to characterise the antenna behaviour and determine a suitable multipath detection threshold. The techniques were then tested in a dense urban area. Using the new method, two signals in the urban data were identified as NLOS-only reception during the occupation period at one station, while the majority of the remaining signals present were subject to a mixture of NLOS reception and severe multipath interference. The point positioning results were dramatically improved by excluding the detected NLOS measurements. The new technique is suited to a wide range of static ground applications based on our results. 相似文献
2.
城市智能交通、自动驾驶等对高精度动态定位的需求为分米级甚至厘米级,但在城市复杂环境下信号遮挡、衰减和多径频繁发生,GNSS定位的可用性和精度严重降低。本文充分利用现有可用的多频多系统GNSS(GPS/BDS/Galileo/QZSS)数据,采用最新提出的单历元PPP宽巷模糊度固定方法(PPP-WAR),并与传统PPP方法和广域伪距增强精密定位方法进行对比试验,分析了这3种单点高精度定位方法在大都市高楼密布道路、小城镇狭窄道路和工业区开阔道路3种不同信号遮挡条件下的车载动态定位性能。结果表明,目前城市环境中的三频数据完整性高达94%以上,可满足基于多频GNSS单历元定位的需求。粗差阈值设定为3 m时,单历元PPP-WAR解在小城镇狭窄道路的水平定位误差RMS为0.41 m,达到了分米级定位精度,比广域伪距增强精密定位解和传统PPP解分别提高了53.9%和21.2%;3种方法在大都市高楼密布环境下的定位可用性均高于70%,在另外两种城市环境下的定位可用性均高于90%。粗差阈值0.5 m时,单历元PPP-WAR方法和传统PPP方法在小城镇狭窄道路环境中可用性依然可达~70%。单历元PPP-WAR方法受城市环境中4种典型地物(地下通道、高架桥、行道树和高楼)的影响最小。总之,在干扰因素多的城市复杂环境中单历元PPP-WAR方法更具优势,在干扰因素少的城市开阔环境中传统PPP方法更优。 相似文献
3.
The current low-cost global navigation satellite systems (GNSS) receiver cannot calculate satisfactory positioning results for pedestrian applications in urban areas with dense buildings due to multipath and non-line-of-sight effects. We develop a rectified positioning method using a basic three-dimensional city building model and ray-tracing simulation to mitigate the signal reflection effects. This proposed method is achieved by implementing a particle filter to distribute possible position candidates. The likelihood of each candidate is evaluated based on the similarity between the pseudorange measurement and simulated pseudorange of the candidate. Finally, the expectation of all the candidates is the rectified positioning of the proposed map method. The proposed method will serve as one sensor of an integrated system in the future. For this purpose, we successfully define a positioning accuracy based on the distribution of the candidates and their pseudorange similarity. The real data are recorded at an urban canyon environment in the Chiyoda district of Tokyo using a commercial grade u-blox GNSS receiver. Both static and dynamic tests were performed. With the aid of GLONASS and QZSS, it is shown that the proposed method can achieve a 4.4-m 1σ positioning error in the tested urban canyon area. 相似文献
4.
5.
针对城市复杂环境中单一BDS导航受多路径（multipath,MP）和非视距（non-line-of-sight,NLOS）信号干扰导致精度下降的问题,提出一种附加运动学约束的抗差无迹卡尔曼滤波（unscented Kalman filter,UKF）算法。该算法基于新息向量构造等价权函数,克服了位置及接收机钟差初值不准确引起的抗差性能下降问题。同时,利用载体的近似运动方向和高程约束,进一步增强滤波解。实测车载试验结果表明,本文方法可有效抑制MP和NLOS信号的干扰,提高城市环境中的BDS导航精度。 相似文献
6.
针对GNSS接收机在室内环境中面临的强烈的信号衰减、非视距传播和互相关效应的问题,提出了一种基于粗时段导航和RAIM算法解决A-GNSS室内定位问题的方法,并利用BDS数据验证了该方法的可靠性。结果表明,粗时段导航算法能够提供连续可靠的定位结果,应用于微弱信号环境;基于组合FDE的RAIM算法能够增加定位结果可用率,解决室内卫星信号存在的非视距传播和互相关效应的问题。基于粗时段导航与RAIM算法的A-GNSS定位技术能够应用于室内定位,仿真定位结果水平方向RMS在10 m以内。 相似文献
7.
In integrated systems for accurate positioning, which consist of GNSS, INS, and other sensors, the GNSS positioning accuracy has a decisive influence on the performance of the entire system and thus is very important. However, GNSS usually exhibits poor positioning results in urban canyon environments due to pseudorange measurement errors caused by multipath creation, which leads to performance degradation of the entire positioning system. For this reason, in order to maintain the accuracy of an integrated positioning system, it is necessary to determine when the GNSS positioning is accurate and which satellites can have their pseudorange measured accurately without multipath errors. Thus, the objective of our work is to detect the multipath errors in the satellite signals and exclude these signals to improve the positioning accuracy of GNSS, especially in an urban canyon environment. One of the previous technologies for tackling this problem is RAIM, which checks the residual of the least square and identifies the suspicious satellites. However, it presumes a Gaussian measurement error that is more common in an open-sky environment than in the urban canyon environment. On the other hand, our proposed method can estimate the size of the pseudorange error directly from the information of altitude positioning error, which is available with an altitude map. This method can estimate even the size of non-Gaussian error due to multipath in the urban canyon environment. Then, the estimated pseudorange error is utilized to weight satellite signals and improve the positioning accuracy. The proposed method was tested with a low-cost GNSS receiver mounted on a test vehicle in a test drive in Nagoya, Japan, which is a typical urban canyon environment. The experimental result shows that the estimated pseudorange error is accurate enough to exclude erroneous satellites and improve the GNSS positioning accuracy. 相似文献
8.
在精密定位中,GNSS接收机天线相位中心变化是必须进行改正的影响因素。目前成熟的微波暗室法和自动机器人法,对于一般用户而言,不具备相关实验条件,而野外相对法相对简单、易操作。为此,本文利用相对检测法,对GNSS接收机天线相位中心变化进行检测。实例表明,此方法可获得精度优于±3 mm的检测结果,因此可利用此方法对其他类型天线PCV值进行检测,也可借鉴此方法对北斗接收机天线相位中心变化进行检测。同时论文分析了影响检测精度,提出了有益改进建议。 相似文献
9.
随着大众市场对高精度定位需求增加,基于低成本小型化设备的全球卫星导航系统(GNSS)高精度定位成为研究热点之一. 本文以低成本多系统GNSS接收机μ-blox M8P型号为例,分析其观测数据质量,研究其伪距单点定位和单频载波相对定位的定位性能和特点,为低成本GNSS接收机高精度定位应用提供参考. 实验结果表明,与测量型接收机相比,μ-blox输出GNSS观测值的载噪比略小,伪距和载波相位的测量噪声较大. 静态模式下,μ-blox的单频载波相对定位(基线长度约为430 m)可以提供厘米级的定位精度;城市环境动态模式下,其单频载波相对定位可提供亚米级至米级的定位精度. 信号受限环境下,GPS／GLONASS双系统能够提供更稳定的定位结果. 相似文献
10.
随着多个GNSS系统不断建成,天空中的导航卫星越来越多,使得RTK作业时的观测量也越来越多,这对提高单频单历元RTK的可靠性起到了至关重要的作用。本文分析了GLONASS信号频分多址的特点,对GPS/GLONASS/BDS单历元单频RTK定位的算法和模型进行了研究,提出了一种适用于三系统组合条件下短基线单频单历元RTK定位的算法,并采用实测数据对算法进行了验证,结果表明,GPS/GLONASS/BDS单历元单频RTK定位是可行的。 相似文献
11.
辅助全球定位系统通过蜂窝网基站提供给A-GPS接收机捕获辅助信息、辅助星历、时间与概略坐标,解决了微弱信号下的定位问题。从信号捕获到完成跟踪,解码导航电文需要经历相关锁定、相位锁定、比特同步、帧同步等过程,在信号很弱以至于无法实现帧同步、不能解调卫星TOW的情况下,常规定位算法无法实现定位。文中提出多普勒与伪码相位结合的A-GPS快速定位算法,利用伪码相位值进行伪距重构法消去整数毫秒伪距中隐含的公共误差,利用多普勒定位提供的初值保证初始位置和时间误差在0.5光毫秒以内,实现了粗时间、粗位置辅助下利用多普勒与伪码相位值的A-GPS快速定位。 相似文献
12.
精密定位的质量控制和完好性评估是实时全球卫星导航系统(GNSS)导航应用不可或缺的环节,尤其是在GNSS易受损害的城市峡谷等场景下,这种需求更加迫切.广域精密单点定位(PPP)瞬时分米级定位,利用GNSS三频信号形成的两个宽巷观测值可以实现单点单历元分米级定位.然而,在城市复杂环境中,反射信号、严重多路径以及其他信号干扰对定位造成的影响无法准确评估与识别,限制了PPP瞬时分米级单点定位的应用.完好性概念中的高级接收机自主完好性监测(ARAIM)可以计算用户定位误差最小置信区间的上限保护水平(PL)以评估定位有效性,可经过一定改进用于PPP瞬时定位的质量控制.针对当前ARAIM中计算PL的误差模型难以适应高精度定位需求的问题,提出了一种改进的ARAIM PL算法,称其为BARAIM(Back Advanced Receiver Autonomous Integrity Monitoring).使用PPP三频组合观测值残差对ARAIM权与误差模型进行修正以计算PL.基于不同复杂程度的环境下采集的车载数据对算法进行了验证,对PL的改进情况以及导航的可用性提升情况进行评估.结果表明:在不同环境下,基于改进的B-ARAIM算法得到的PL,相比传统方法得到的PL更符合城市定位的需要,将PL降低了30%~70%.此方法有助于将ARAIM算法应用在高精度GNSS定位领域. 相似文献
13.
全球卫星导航系统（GNSS）目前得到了十分广泛的应用,但是GNSS信号到达地面的功率很低,同时民用信号的格式是公开的,因此极易受到各种无意和人为故意的干扰,会对GNSS定位和授时的精度造成影响．查找和消除干扰源十分重要,目前通用的干扰源查找手段是采用测向设备实现干扰源的交叉定位,但在不知道GNSS干扰源的大致位置时,采用测向设备查找干扰源将耗费很长的时间．如果能够通过提取一些通用接收机的输出量实现干扰源的粗定位,就可以为测向定位提供初始参考位置和大概的查找范围．本文利用几乎所有的通用接收机都能输出的位置信息实现干扰源的粗定位,随着GNSS接收机逼近干扰源,会造成接收机位置信息的丢失,随着GNSS接收机远离干扰源,接收机又会重新获取位置信息,本文利用一定区域内众多受干扰的接收机的位置信息丢失点和位置信息重捕获点来实现干扰源的粗定位．通过仿真验证,分析了该技术的定位误差,仿真结果表明,该方法能够实现GNSS干扰源的粗定位,为进一步准确查找干扰源提供位置参考． 相似文献
14.
In the complex urban environments, land vehicle navigation purely relying on GNSS cannot satisfy user needs due to the loss of satellite signals caused by obstructions such as buildings, tunnels, and trees. To solve this problem, we introduce a GPS-/MSINS-/magnetometer-integrated urban navigation system based on context awareness. In this system, the data from the Micro Strapdown Inertial Navigation System (MSINS) are used to analyze and detect the context knowledge of vehicles, whose sensor errors can be compensated by the heuristic drift reduction algorithm for different motion situations. When GPS is available, the vehicle position can be estimated by unscented Kalman Filter, whereas in the case of GPS outages, the vehicle attitude is provided by an attitude and heading reference system and the motion constraints-aided algorithm is used to complete the positioning. In the experiment validation, the integrated navigation system is set up by low-cost inertial sensors. The result shows that the proposed system can achieve high accuracy when GPS is available. For most of the time without GPS, the system can guarantee the positioning precision of 10 m and compensate the errors of MSINS effectively, which fully satisfies positioning needs in complex urban environments. 相似文献
15.
Improved network-based single-epoch ambiguity resolution using centralized GNSS network processing 总被引：1，自引：1，他引：0
Network real-time kinematic (NRTK) positioning is today’s industry standard for high-precision applications. Once network ambiguities are fixed, the network engine processes simultaneous observations from a number of continuously operating reference stations to compute corrections for users operating within the network area. Users are treated as passive nodes of the network. However, if two-way communication is available, then users could transmit their observations to the central processing facility where the network can treat them as active nodes, densifying the existing network infrastructure. This multiple rover network (MRN) concept exploits the additional information provided by users in a GNSS network. One application is to use the shorter inter-receiver distances to improve the success rate of single-epoch ambiguity resolution. This is also the goal of the subset ambiguity resolution algorithm, which improves the single-epoch success rate by allowing a subset of ambiguities to be resolved. We present an enhanced processing strategy to complement centimeter-level single-epoch NRTK positioning. This approach combines a single-baseline and an MRN solution with the partial ambiguity resolution algorithm and is only possible for a centralized GNSS network architecture. The algorithm is tested against the standard network ambiguity resolution strategy of full-set ambiguity fixing with respect to the nearest reference station. A 24-h dataset from the Southern California Integrated GNSS network is used with a configuration of three reference stations and four users. The enhanced solution achieves a mean ambiguity resolution success rate of 83% over all four users and all epochs, compared to 32% for the conventional technique. 相似文献
16.
随着全球卫星导航系统（global navigation satellite system,GNSS）进入多系统时代,空中导航卫星的可见卫星数不断增加,中国北斗卫星导航系统（BeiDou navigation satellite system,BDS）已开始面向用户提供三频导航信号,这都有利于改善单历元实时动态定位（real-time kinematic,RTK）的精度和可靠性。中长基线单历元RTK通常采用电离层无关组合算法,但是该方法将观测噪声进行了放大,模糊度固定成功率随着基线长度的增加而明显降低。提出一种BDS/GPS（global positioning system）中长基线单历元多频RTK定位算法,先以较高成功率快速固定BDS的两个超宽巷模糊度,继而通过简单变换得到BDS宽巷模糊度,然后将其辅助提高GPS宽巷模糊度固定成功率,最后采用将电离层延迟误差参数化的策略以提高BDS/GPS窄巷模糊度固定成功率。结合实测数据进行验证分析,结果表明本文算法是可行的。 相似文献
17.
The location requirements for emergency callers outside urban areas can hardly be fulfilled without global navigation satellite
systems (GNSS). Consequently, interest in positioning techniques based on use of a GNSS such as GPS or on the cellular network
infrastructure itself is growing rapidly in the mobile-telephone community. Moreover, the increasing demand for commercial
location-based services (LBS) has driven cellular-phone and network manufacturers to focus on positioning solutions which
are even more accurate than the regulatory mandates for positioning of emergency callers. One example of these upcoming LBS
is our PARAMOUNT project, which aims at improving user-friendly info-mobility services for hikers and mountaineers by combining
wireless communications (GMTS), satellite navigation (GNSS) and geographic information systems (GIS), based on a mobile client/server
architecture. The availability of mobile phones or PDAs with combined GNSS and cellular network-based wireless communication
on a high integration level is one primary demand of such LBS applications. Based on this, we will give some initial answers
to the question of whether mobile handset architecture synergies exist for the combination of GNSS with wireless location
in CDMA cellular wireless networks. In order to identify synergies, we will outline similarities and differences between wireless
communication and satellite navigation. In this respect, we pay particular attention to the so-called RAKE receiver architecture
employed in mobile CDMA cellular handsets. Our initial investigations will show that the RAKE receiver architecture, on which
mobile CDMA cellular handsets are based, will most likely be the one most suitable for achieving synergies between the two
positioning techniques within the same mobile handset architecture. Consequently, several receiver components could be used
to handle both types of signals (navigation and communications), resulting in a reduction of manufacturing costs and in a
decrease in energy consumption.
Electronic Publication 相似文献
18.
Dae Hee Won Eunsung Lee Moonbeom Heo Sangkyung Sung Jiyun Lee Young Jae Lee 《GPS Solutions》2014,18(2):177-187
In urban canyons, buildings and other structures often block the line of sight of visible Global Navigation Satellite System (GNSS) satellites, which makes it difficult to obtain four or more satellites to provide a three-dimensional navigation solution. Previous studies on this operational environment have been conducted based on the assumption that GNSS is not available. However, a limited number of satellites can be used with other sensor measurements, although the number is insufficient to derive a navigation solution. The limited number of GNSS measurements can be integrated with vision-based navigation to correct navigation errors. We propose an integrated navigation system that improves the performance of vision-based navigation by integrating the limited GNSS measurements. An integrated model was designed to apply the GNSS range and range rate to vision-based navigation. The possibility of improved navigation performance was evaluated during an observability analysis based on available satellites. According to the observability analysis, each additional satellite decreased the number of unobservable states by one, while vision-based navigation always has three unobservable states. A computer simulation was conducted to verify the improvement in the navigation performance by analyzing the estimated position, which depended on the number of available satellites; additionally, an experimental test was conducted. The results showed that limited GNSS measurements can improve the positioning performance. Thus, our proposed method is expected to improve the positioning performance in urban canyons. 相似文献
19.
全球导航卫星系统反射测量(GNSS+R)最新进展与应用前景 总被引：4，自引：0，他引：4
全球导航卫星系统(GNSS)具有全天候、近实时、高精度的特点,可持续发射L波段信号,广泛应用于定位、导航和授时(PNT)。随着GNSS技术的发展,最近GNSS反射信号可探测地球表面特征,即GNSS反射测量(GNSS+R)。结合GNSS接收机天线位置和介质信息,利用延迟测量值可以确定表面粗糙度和表面特性。GNSS+R作为当前GNSS和遥感领域的研究热点,取得了一些研究进展和成果。本文详细介绍了GNSS+R原理和方法及其最新应用进展,包括各种GNSS+R技术手段和方法,以及海洋、陆地、水文、植被和冰雪等遥感应用,特别是最新BeiDou-R和TDS-1研究进展。最后给出了GNSS+R应用前景和展望,包括多GNSS系统、GNSS+R接收机、GNSS+R卫星计划和新兴应用等。 相似文献
20.
智能手机凭借其普遍性、便携性和低成本等优势,已成为大众用户导航与位置服务的主流终端载体,其多频多系统GNSS（global navigation satellite system）观测值的开放进一步激发了手机高精度定位的研究。然而,受限于消费级GNSS器件性能,手机卫星观测值呈现出信号衰减严重、伪距噪声大、粗差周跳多等问题;并且受城市复杂环境影响,手机GNSS定位的连续性、可靠性也难以保证。提出一种城市场景手机GNSS/ MEMS（micro-electro mechanical system）融合的车载高精度定位方案。首先,构建了速度约束的GNSS差分定位模型;然后,通过手机内置MEMS与车辆运动约束,在挑战环境下进行GNSS/MEMS融合精密定位。实验结果表明,在开阔和树荫场景下,速度约束方法可达到分米至米级定位精度,相比于常规方法分别提升了35.2%和78.9%;在高架场景下,GNSS/MEMS融合定位的精度和连续性均提升显著;在隧道场景下,MEMS推算位置累积误差约为2.5%。实验结果初步表明,手机GNSS具备开阔环境下的车道级定位能力,手机GNSS/MEMS融合可提升城市复杂环境下车载定位的精度和连续可用性。 相似文献