共查询到20条相似文献,搜索用时 31 毫秒
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Emilie Rebeyrol Olivier Julien Christophe Macabiau Lionel Ries Antoine Delatour Laurent Lestarquit 《GPS Solutions》2007,11(3):159-171
Spectrum limitations for navigation systems require that the various navigation signals broadcast by the Galileo system must
be combined and must utilize bandwidth-efficient modulations. At the L1 band, one of the most important questions is how to
combine all the Open Service signals and the Public Regulated Service signal at the payload level, while maintaining good
performance at reception. The Interplex modulation, a particular phase-shifted-keyed/phase modulation (PSK/PM), was chosen
to transmit these signals because it is a constant-envelope modulation, thereby allowing the use of saturated power amplifiers
with limited signal distortion. The Interplex modulation was also taken as baseline at the E6 band to transmit the three channels
and the services associated on the same carrier frequency. At the E5 band, the modulation must combine two different services
on a same constant envelope composite signal, while keeping the simplicity of a BOC implementation. The constant envelope
Alternate Binary Offset Carrier (ALTBOC) modulation was chosen as the solution to transmit the Galileo E5 band signal. The
main objective of this paper is to study these Galileo modulations. After the introduction, the E5 band signals are described,
followed by the Alternate BOC modulation which has been chosen to transmit them. The second part describes the general formulation
of the Interplex modulation and its key parameters for an optimal multiplexing of the Galileo L1 band signals. Since the Galileo
Open Service signals at the L1 band are still not yet completely specified, different test cases are considered and their
impact on the resulting choice for the Interplex modulation parameters is exposed. 相似文献
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With the advent of new global navigation satellite systems (GNSSs) and new signals, GNSS users will rely more on them to obtain higher-accuracy positioning. Evil waveform monitoring and assessment are of great importance for GNSS to achieve its positioning, velocity, and timing service with high accuracy. However, the advent of new navigation signals introduces the necessity to extend the traditional analyzing techniques already accepted for binary phase-shift keying modulation to new techniques. First, the well-known second-order step thread model adopted by the International Civil Aviation Organization is introduced. Then the extended new general thread models are developed for the new binary offset carrier modulated signals. However, no research has been done on navigation signal waveform symmetry yet. Simulation results showed that, waveform asymmetry may also cause tracking errors, range biases, and position errors in GNSS receivers. It is thus imperative that the asymmetry be quantified to enable the design of appropriate error budgets and mitigation strategies for various application fields. A novel evil waveform analysis method, called waveform rising and falling edge symmetry (WRaFES) method, is proposed. Based on this WRaFES method, the correlation metrics are provided to detect asymmetric correlation peaks distorted by received signal asymmetry. Then the statistical properties of the proposed methods are analyzed, and a proper deformation detection threshold is calculated. Finally, both simulation results and experimentally measured results of Beidou navigation satellite system (BDS) M1-S B1Cd signal are given, which show the effectiveness and robustness of the proposed thread models. 相似文献
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Weighted discriminators for GNSS BOC signal tracking 总被引:1,自引:1,他引:0
Modern Global Navigation Satellite System including Galileo and GPS III will employ multiplexed binary offset carrier (MBOC) modulation to achieve spectrum separation and enhanced tracking performance. A challenge of the MBOC or BOC signal tracking is the presence of ambiguities due to multiple sidepeaks of the autocorrelation functions. Several different techniques including multi-correlator and double estimator schemes have been proposed to address the ambiguity issue. We propose a class of ambiguity-free code tracking techniques by exploiting the unique features of the BOC modulation. In the proposed architecture, the incoming BOC-modulated signals are correlated with BOC-modulated replica and the spreading codes, respectively. Through a multiplicative combination strategy of the two correlator outputs, a noncoherent weighted discriminator is formed and shown to possess the ambiguity-free property. The multipath effect is assessed and compared with existing early-minus-late power and autocorrelation sidepeak cancellation technique discriminators. The noise effects of the theory and simulation are also discussed. In order to further verify the proposed scheme, a set of field data of a Galileo in-orbit validation satellite is collected and processed. It is demonstrated that the proposed method is simple to implement, free from ambiguities, and yields acceptable performance in the presence of multipath and noise. 相似文献
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MBOC(multiplexed binary offset carrier)是GPS—GALILEO互用和兼容性工作组推荐的信号调制体制,其实现方式分为TMBOC和CBOC两种,其中TMBOC(6,1,4/33)已被GPSL1C信号所采用。多径是众多卫星导航系统应用的主要误差源之一,由于不具备时间和空间的相关性,无法通过差分技术消除。本文基于窄相关技术和Double—Delta技术对TMBOC(6,1,4/33)的抗多径性能进行了分析,并与BPSK(1)及BOC(1,1)进行了对比。在同等条件下,TMBOC(6,1,4/33)的抗多径性能优于或等同于BPSK(1)及BOC(1,1)。 相似文献
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Compared with the traditional GPS L1 C/A BPSK-R(1) signal, wideband global navigation satellite system (GNSS) signals suffer more severe distortion due to ionospheric dispersion. Ionospheric dispersion inevitably introduces additional errors in pseudorange and carrier phase observations that cannot be readily eliminated by traditional methods. Researchers have reported power losses, waveform ripples, correlation peak asymmetries, and carrier phase shifts caused by ionospheric dispersion. We analyze the code tracking bias induced by ionospheric dispersion and propose an efficient all-pass filter to compensate the corresponding nonlinear group delay over the signal bandwidth. The filter is constructed in a cascaded biquad form based on the estimated total electron content (TEC). The effects of TEC accuracy, filter order, and fraction parameter on the filter fitting error are explored. Taking the AltBOC(15,10) signal as an example, we compare the time domain signal waveforms, correlation peaks, code tracking biases, and carrier phase biases with and without this all-pass filter and demonstrate that the proposed delay-equalization all-pass filter is a potential solution to ionospheric dispersion compensation and mitigation of observation biases for wideband GNSS signals. 相似文献
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Youssef Tawk Cyril Botteron Aleksandar Jovanovic Pierre-André Farine 《GPS Solutions》2012,16(2):243-258
The world of global navigation satellite systems has been enhanced with several new or improved signals in space aiming to
optimize accuracy, reliability, navigation solution, and interoperability between different constellations. However, such
developments bring various challenges to the receivers’ designers. For example, acquisition and tracking stages turn into
more complex processes while handling the increasing bandwidth requires additional processing power. In this context, we study
the code tracking of Galileo E5ab in a full band or of only one of its components, i.e., either E5a or E5b. More specifically,
an architecture for tracking the E5 pilot channel as an AltBOC(15,10) or BPSK(10) modulation is introduced, and the performance
of well-known discriminator types is analyzed using analytical derivations and simulations of linearity and stability regions,
thermal noise tracking errors, multipath error envelopes and tracking thresholds. Different parameters, such as the front-end
filter bandwidth, the early/late chip spacing, un-normalized and normalized discriminators, are taken into consideration.
The results obtained are used to illustrate the main advantages and drawbacks of tracking the E5 signal as well as to help
defining the main tracking loop parameters for an enhanced performance. 相似文献
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低轨卫星导航信号增强能够弥补现有中高轨导航卫星信号收敛慢、信号弱的不足,在下一代导航定位技术中占有重要地位。武汉大学研制的珞珈一号科学实验卫星搭载了导航增强载荷,能够在轨自动计算轨道和钟差,并自主生成和播发双频测距信号,首次实现了低轨卫星平台的导航信号增强。就珞珈一号卫星导航增强信号的质量,包括信号载噪比、伪距和载波相位测量精度以及单星授时精度进行了评估,结果显示,珞珈一号卫星高仰角的伪距和载波相位测量精度分别优于1.5 m和1.7 mm,能够满足导航信号增强的需求。珞珈一号卫星单星授时的精度在10~30 ns量级,证明了珞珈一号卫星星地测距链路的正确性和有效性。 相似文献
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GPS Solutions - In order to satisfy the need for combining signals in a constant-envelope modulation, we propose a new dual-frequency constant-envelope modulation (DCEM), called asymmetric... 相似文献
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对全球导航卫星的信号体制进行了专利检索分析,综合考虑信号调制、多路复用等技术,分别以导航卫星的信号调制方式、信号生成方式、信号编码方式为检索领域,对全球导航卫星系统申请专利进行全面而系统的检索。在初检基础上,以空间段、星上技术为依据进行复检并深入分析,指出该领域未来发展方向。为我国未来全球导航卫星系统信号体制的设计提出知识产权规避措施和发展建议。 相似文献
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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
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Oliver Montenbruck Christoph Günther Sebastian Graf Miquel Garcia-Fernandez Johann Furthner Hanspeter Kuhlen 《GPS Solutions》2006,10(2):146-153
In late December 2005 the GIOVE-A test satellite was launched by the European Space Agency (ESA) to secure the frequencies for the Galileo system and to provide a platform for testing the new navigation signals. We performed an initial assessment of these signals using the 30 m deep space antenna of the DLR ground station in Weilheim (Germany). The antenna gain raised the signals above the noise level, thus allowing a detailed analysis even without knowledge of the ranging codes. The present paper covers the analysis of the L1/E1 signals, which includes a discussion of the spectrum, the time domain signal and a decoding of the spreading codes for the Open Service. 相似文献
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Characterization of Compass M-1 signals 总被引:7,自引:4,他引:3
André Hauschild Oliver Montenbruck Jean-Marie Sleewaegen Lennard Huisman Peter J. G. Teunissen 《GPS Solutions》2012,16(1):117-126
An analysis of observations from China’s first medium earth orbit satellite Compass M-1 is presented, with main focus on the
first orbit and clock solution for this satellite. The orbit is computed from laser ranging measurements. Based on this orbit
solution, the apparent clock offset is estimated using measurements from two GNSS receivers, which allow Compass tracking.
The analysis of the clock solutions reveals unexpectedly high dynamics in the pseudorange and carrier-phase observations.
Furthermore, carrier-to-noise density ratio, pseudorange noise, and multipath are analyzed and compared to GPS and GIOVE.
The results of the clock analysis motivate further research on the signals of the geostationary satellites of the Compass
constellation. 相似文献
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北斗三频无几何相位组合周跳探测与修复 总被引:1,自引:0,他引:1
推导了Compass三频无几何组合周跳探测的理论模型,并分析了探测精度。通过多频组合理论构造了较优的无几何周跳探测检验量,并对存在的不敏感周跳组合进行了分析。为了保证探测的完备性,联合运用两个合适的无几何组合作为探测检验组合进行周跳探测,并筛选了较优的探测检验组合。针对无几何组合最多只能两个线性无关,无法修复三个频点上的周跳的问题,探索了无几何探测检验组合联合一个伪距/载波组合进行周跳修复的方法。最后利用Compass三频实测数据,选用了无几何探测检验组合(-1,-1,2)与(-1,2,-1)和伪距/载波组合(1,3,-4)进行了验证分析。试验表明,该方法能够探测出所有大小的周跳,并且可以单历元修复周跳值,可适用于动态导航定位,有一定的实用性。 相似文献
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北斗卫星导航系统的进展、贡献与挑战 总被引:29,自引:7,他引:22
卫星导航发展已进入百花齐放、群星争艳的时代。主要评述我国北斗卫星导航系统的发展、应用、贡献及面临的挑战。介绍北斗卫星导航系统的建设原则和建设步骤;介绍我国北斗卫星导航系统在兼容与互操作框架下在频率、坐标系统、时间系统方面的兼容与互操作实现概况;描述北斗导航系统在冗余度概念下的主要贡献;简要说明北斗导航验证系统的重要应用和面临的主要挑战。 相似文献