共查询到20条相似文献,搜索用时 31 毫秒
1.
《Aerospace and Electronic Systems Magazine, IEEE》1998,13(11):41-46
Development of a new vehicle avionics suite is described, including integration of a low-cost, tightly-coupled integrated Inertial Navigation System/Global Positioning System (INS/GPS) to support vehicle guidance, navigation, and control (GN&C). A wide variety of next-generation low-cost launch vehicles could potentially benefit from integrated INS/GPS technology for GN&C and/or range safety applications. Coleman Aerospace Company (CAC) has developed a new low-cost avionics suite, the generic Integrated Mission Guidance & Tracking System (IMGTS), an open architecture, modular system that supports the requirements for various guidance applications and range safety tracking. As part of this development, Boeing North American, Inc. is supplying its Modular Miniature Integrated GPS/INS Tactical System (M-MIGITSTM) Military-Off-The-Shelf (MOTS) INS/GPS product to support CAC's IMGTS GN&C 相似文献
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The Television Relay Using Small Terminals (TRUST) Experiment was designed to advance and prornote the technology of broadcasting satellites. A constant envelope television FM signal was transmitted at C band to the ATS-6 Earth coverage hom and retransmitted at 860 MHz through the 9-m antenna to a low-cost direct-readout ground station. The experiment demonstrated that high-quality television and audio can be received by lowcost direct-receive ground stations. Predetection bandwidths significantly less than predicted by Carson's rule can be utilized with minimal degradation of either monochrome or color pictures. Two separate techniques of dual audio channel transmission have been demonstrated to be suitable for low-cost applications. 相似文献
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Ranging airport pseudolite for local area augmentation 总被引:2,自引:0,他引:2
This paper discusses the integration of an airport pseudolite (APL) into a local area augmented differential GPS based precision approach system. A prototype architecture is described that is being used to develop requirements for the local area augmentation system. Key features of this prototype system are presented along with its current performance. Key features discussed include the use of a multipath limiting antenna, APL signal structure factors, a unique APL automatic gain control, and GPS blanking technique to maximize APL tracking performance, while minimizing the electromagnetic interference to nominal DGPS performance 相似文献
4.
Van der Wal P. van Willigen D. 《IEEE transactions on aerospace and electronic systems》1978,(4):649-661
The combination of an antenna, a 100 kHz bandpass filter, a hard limiter, and a sequential detector can supply highly accurate Loran-C data to a digital processor, even under low signal-to-noise-ratio conditions. For such a simple, low-cost receiver, calculations are given for the accuracy of the envelope and phase tracking of the Loran-C signal as a function of the signal-to-noise (Gaussian and atmospheric) ratio, averaging time, and radian speed of the observer with respect to the transmitter. Mentioned are the quasi-noise censoring effects of the hard limiter. Besides the Loran-C application, the hard limiter-sequential detector system can in general be applied for low-cost, synchronous signal detection under poor signal-to-noise ratio. 相似文献
5.
Amin M.G. Liang Zhao Lindsey A.R. 《IEEE transactions on aerospace and electronic systems》2004,40(1):80-92
The mitigation of FM interference in GPS receivers is considered. In difference to commonly assumed wideband and narrowband interferers, the FM interferers are wideband, but instantaneously narrowband, and as such, have clear time-frequency (TF) signatures that are distinct from the GPS coarse acquisition (C/A) spread spectrum code. In the proposed technique, the estimate of the FM interference instantaneous frequency (IF) and the interference spatial signature are used to construct the spatiotemporal interference subspace. The IF estimates can be provided using existing effective linear or bilinear TF methods. The undesired signal arrival is suppressed by projecting the input data on the interference orthogonal subspace. With a multisensor receiver, the distinctions in both the spatial and TF signatures of signal arrivals allow effective interference suppressions. The deterministic nature of the signal model is considered and the known underlying structure of the GPS C/A code is utilized. We derive the receiver signal-to-interference-plus-noise ratio (SINR) under exact and perturbed IF values. The effect of IF estimation errors on both pseudorange measurements and navigation data recovery is analyzed. Simulation results comparing the receiver performances under IF errors in single and multiantenna GPS receivers are provided. 相似文献
6.
K. Deergha Rao M. N. S. Swamy 《IEEE transactions on aerospace and electronic systems》2006,42(4):1464-1474
A new approach is proposed for the suppression of FM jammers in C/A code GPS receivers. This approach is based on the cascading of the augmented-state approximate conditional mean (ASACM) filter and the discrete wavelet transform (DWT) filter. An ASACM filter for single interference suppression in spread-spectrum systems has been reported in the recent literature. However, the formulation of the ASACM filter and its performance analysis is lacking in the case of suppression of multiple FM interferences. The ASACM filter is formulated here for the suppression of multiple FM jammers. Further, a DWT filter using biorthogonal wavelet is suggested for the suppression of FM jammers. Finally, these two filters are cascaded to get an optimum performance for higher jammer to signal ratio, which is of importance in the GPS, for the case of suppression of multiple FM jammers. The performance of the proposed filters is analyzed through simulation examples for the suppression of single and multiple FM jammers in GPS receivers 相似文献
7.
Preliminary results of a simulation effort to evaluate the requirements and feasibility of the global positioning system (GPS) as a civil air navigation system are presented. Evaluation is made of GPS requirements, from operational considerations, such as application to nonprecision approaches. The conceptual low-cost GPS receiver simulated here does not correct for the ionospheric or trophospheric delay, is sequential in nature, tracks only four satellites, and is not mechanized to make independent range rate measurements based on the Doppler shift of the GPS carrier frequency. The proposed GPS system has significantly different performance characteristics from the presently used VHF omnidirectional range (VOR) solidus distance-measuring equipment (DME) system. The GPS is a low signal level system and many have a relatively slow data rate due to the low-cost sequential receiver design. The results indicate that although the conceptual low-cost GPS receiver/ navigator is potentially more accurate than a VOR, the accuracy may degrade during aircraft turns and satellite shielding periods. 相似文献
8.
为解决环路未锁定、无法找出正确的导航数据位跳变点时极弱全球定位系统(GPS)信号跟踪问题,通过分析信号跟踪模型和相关器1 ms采样数据特性,将最优路径动态规划算法应用于GPS位同步,并提出基于平方根无迹卡尔曼滤波(SRUKF)和位同步结合的载波联合跟踪算法。建立了适合位同步的SRUKF载波环参数估计模型,针对位同步的实现条件和无相位频率先验信息的情况,将位同步模块提前,研究设计了环路未锁定时串行和并行两种弱信号跟踪方案。位同步跟踪完成后环路采用单独的SRUKF工作方式。实验结果证实该文提出的算法具有较高的数据位边缘检测概率(EDR)和参数估计性能,而无须关心环路是否处于锁定状态,能够对载噪比低至22 dB/Hz的弱信号实现跟踪。 相似文献
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Hurd W.J. Statman J.I. Vilnrotter V.A. 《IEEE transactions on aerospace and electronic systems》1987,(4):425-437
A new high dynamic global positioning system (GPS) receiver ispresented and its performance characterized by analysis,simulation, and demonstration. The demonstration receiver is abreadboard model capable of tracking a single simulated satellitesignal in pseudorange and range rate. Pseudorange and range rateestimates are made once every 20 ms, using a maximum likelihoodestimator, and are tracked by means of a third-order fadingmemory filter in a feedback configuration. The receiver trackspseudorange with rms errors of under 1 m when subjected tosimulated 50 g, 40 g/s circular trajectories. The tracking thresholdis approximately 28 dB·Hz, which provides 12 dB margin relativethe the minimum specified signal strength, assuming 3.5 dB systemnoise figure and 0 dB antenna gain. 相似文献
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GPS/SINS超紧组合导航的性能分析 总被引:1,自引:0,他引:1
GPS接收机在高动态环境下很容易失锁,特别是载体的高动态造成的应力对接收机载波跟踪环影响很大。为了解决高动态环境下的组合导航,分析了GPS接收机载波跟踪环的测量误差和跟踪门限,采用惯导速度辅助GPS接收机跟踪环路的超紧组合结构。超紧组合需要涉及到GPS接收机跟踪环内部编排及高动态环境下的实验数据,难度较大。针对超紧组合仿真专门开发了GPS实时软件接收机、高动态GPS中频信号仿真器和惯导模拟器并构建了一个完整的GPS/SINS超紧组合仿真系统。仿真结果表明,该超紧组合导航系统可以跟踪50g的加速度和10倍音速。 相似文献
13.
Suk-Seung Hwang Shynk J.J. 《IEEE transactions on aerospace and electronic systems》2006,42(2):489-502
The global positioning system (GPS) is a one-way satellite-based navigation system employing spread-spectrum techniques that is widely used for commercial and military applications. Although the very low signal-to-noise ratio (SNR) is handled by the large spreading gain, GPS is susceptible to high-power interference signals and various types of jammers. We propose multicomponent receiver architectures for GPS interference suppression. A conventional antenna system is first considered which utilizes a minimum-variance distortionless-response (MVDR) beam former and assumes that the GPS signal angle of arrival (AOA) and the antenna model are known at the receiver. However, this receiver is sensitive to AOA estimation errors and can have a high computational complexity. This sensitivity problem is eliminated by a multicomponent system based on a multistage matched filter (MF). Since this MF receiver also has a high computational complexity because the jammer AOAs must be estimated, we introduce a blind interference canceler based on the constant modulus (CM) array that is insensitive to AOA estimation errors and has a low computational complexity. Computer simulations are provided to illustrate the performance of the various systems for interference suppression in example signal scenarios. 相似文献
14.
Bertiger W.I. Lichten S.M. Katsigris E.C. 《Aerospace and Electronic Systems Magazine, IEEE》1989,4(2):16-25
High-accuracy orbits have been determined for satellites of the Global Positioning System (GPS), with submeter orbit accuracy demonstrated for two well-tracked satellites. Baselines of up to 2000 km in North America determined with the GPS orbits shows daily repeatability of 0.3-2 parts in 108 and agree with very long baseline interferometry (VLBI) solutions at the level of 1.5 parts in 10 8. Tests used to assess orbit accuracy include orbit repeatability from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked for eight hours each day shows RMS errors below 1 m even when predicted more than three days outside of a 1-week data arc. These results demonstrate the powerful relative positioning capability available from differential GPS tracking. Baselines have also been estimated between Florida and sites in the Caribbean region over 1000 km away, with daily repeatability of 1-4 parts in 108. The best orbit estimation strategies included data arcs of 1-2 weeks, process noise models for tropospheric fluctuations, combined processing of GPS carrier phase and pseudorange data, and estimation of GPS solar pressure coefficients 相似文献
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研究了GPS软件接收机的捕获与跟踪算法。分析了时域串行滑动相关捕获算法和频域基于FFT的并行相关捕获算法,设计了适合GPS软件接收机的并行算法,实现了对空中可见卫星的捕获。针对GPS信号的特点,设计了基于DLL与PLL相结合方法的GPS跟踪算法。利用实测中频信号对上述捕获与跟踪算法进行了验证分析,测试结果表明,基于FFT的并行相关捕获算法能够有效增强软件接收机的捕获能力,采用DLL与PLL相结合的方法能够实现对GPS信号的有效跟踪。 相似文献
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针对无人机测控与信息传输系统中地面设备笨重、跟踪速度慢等问题,提出地面天线采用智能天线的方法,利用MUSIC(MUltiple SIgnal Classification,多重信号分类)算法实现对机载终端的DOA(Direction Of Ar-rival,波达方向)估计,并添加去相关操作对抗多径,利用基于LCMV(Linearly Constrained Minimum Variance,线性约束最小方差)准则的波束成形算法完成波束赋形,相较于传统的机械跟踪方式,具有设备质量小、成本低、机动性灵活性强和跟踪速度快等优势.仿真和实际测试结果表明,采用DOA估计和波束成形算法的智能天线能够在保证高增益的同时,实时准确地估计出有用信号和多径信号的来波信号方向,并正确完成波束指向,具有很高的工程应用价值. 相似文献
19.
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