基于北斗RDSS的GPS区域差分技术

本文提出了一种基于北斗RDSS的GPS区域差分技术的实现方案,该方案克服了差分GPS技术受到参考站和用户站之间距离的限制。本系统中基准型GPS接收机伪距修正数的计算、用户接收机导航解算所需的卫星星历数据、时间数据、伪距信息和伪距修正数的提取以及差分算法实现和接收机定位算法全部在DSP＋FPGA中实现。通过试验数据分析比较可见,采用基于北斗RDSS的GPS区域差分技术,对GPS导航定位精度有明显提高,该技术为未来实现高精度GPS导航定位有一定的参考价值。     

厘米级“北斗”相对定位的试验验证

随着我国"北斗"卫星导航系统的发展,"北斗"精密相对定位的应用市场日益拓展.在动态对动态环境中,将基准站与移动站分别设在不同的车辆载体上,验证了"北斗"实时动态相对定位的精度.平台跑车和省道跑车结果显示水平相对定位误差和天向相对定位误差都在厘米级,表明"北斗"系统性能完全满足高精度应用的需求,能替代相应应用领域的全球定位系统(GPS).     

射频与基带参考时钟不同源对GPS载波相位平滑伪距定位的影响

无论GPS接收机的射频和基带参考时钟是否同源,都不会影响伪距定位。然而,对于载波相位平滑伪距定位,本文的理论分析表明:在新增卫星时,射频和基带参考时钟不同源将使新增星和原有星的平滑伪距钟差产生偏差,进而导致大幅度定位误差。在时钟同源和不同源两种条件下,利用自研的GPS基带芯片“航芯2E”,开展了大量硬件实验,验证了理论分析的正确性。论文得出的载波相位平滑伪距定位的接收机其射频和基带参考时钟必须同源的结论,对于GPS射频和基带芯片的模块化、系列化的规划和设计具有指导意义。      

一种基于载波相位时间差分的惯性/卫星组合方法

传统的惯性/卫星紧耦合组合导航系统使用卫星伪距/伪距率作为量测，卫星伪距率一般可以提供厘米/秒级精度的速度信息；而载波相位时间差分观测量可以达到毫米级精度且无需参考接收机。本文分析了载波相位时间差分的原理，并将其应用到惯性/卫星组合导航系统中；在滤波器的设计中使用状态延迟滤波法处理载波相位时间差分观测量，使惯性/卫星组合导航系统达到了较高的速度精度。     

Performance of the GLONASS P-code at L1 and L2 frequencies

The transmission of satellite signals at two widely spaced frequencies allows correction of the ionospheric delay. Both GPS and GLONASS transmit such signals, and to date there have been no published dual frequency GLONASS studies. This paper shows the fundamental accuracy of the Leeds University multichannel GPS/GLONASS receiver. Details are then given of the processing methods that have been used to obtain the ionospheric group delay using GLONASS L1 and L2 P-code measurements. Examples of the measured delay are provided and compared with the GPS model. Navigation results are shown using the P-code phase at L1 only and with a combination of the L1 and L2 measurements. An analysis of the accuracy of the P-code pseudorange and navigation capability is presented.     

双模导航接收机时间系统一致性研究

卫星导航接收机在某些特殊地域使用时,集成了GPS和GLONASS的双模接收机可以弥补单模接收机的劣势,从而明显提高定位的可靠性及可用性。而GPS和GLONASS时间系统的不一致性对GPS/GLONASS双模接收机有重要制约,对其定位精度产生了一定影响。对GPS和GLONASS的时间系统差异进行了研究,给出对其一致性分析的具体方法。可推广至多导航模块的接收机中,从而使定位精度更加精准可靠。     

Integrated GPS/GLONASS navigation: Algorithms and results

The presence of selective availability (SA) on GPS has led to a variety of proposals for mitigation of its effects, for example combining GPS with other sensors or by identifying and removing the SA using redundant information in the position solution. A further method for reducing the impact of SA is the combination of GPS and GLONASS measurements. GLONASS does not have any deliberate degradation. This paper describes several algorithms for combining GPS and GLONASS measurements in real time on a single receiver. There are two least squares solutions using the code phase measurements alone: one with the measurements from both systems weighted equally, and one with the measurements weighted by the covariance of the measurements. Kalman filters with no SA model, and first- and second-order models, using both the code and carrier phase to estimate user position and velocity, are also implemented. Two different adaptive schemes are compared which attempt to identify SA model parameters in real time. The algorithms are compared in terms of their positioning accuracy, computational overhead and robustness. A ten-channel GPS/GLONASS receiver developed at The University of Leeds is used to provide satellite data for the evaluation of the different methods.     

GNSS CODE AND CARRIER TRACKING IN THE PRESENCE OF MULTIPATH

It is well known that multipath represents a major error source in differential GNSS positioning. Errors produced are unique to each antenna position and so are uncorrelated between the reference station and the mobile receiver. Reduction techniques, such as narrow correlator spacing¹ and the multipath estimating delay lock loop (MEDLL)² have improved the situation. However, reflected signals emanating close to the antenna are not reduced by either technique. Carrier multipath is a particular problem because short delay multipath signals cause maximum carrier errors. This study describes the analysis that has been carried out into code and carrier tracking in the presence of multipath. Code tracking in this situation produces a non-zero mean error,³ and the source of this bias has been investigated. Code and carrier multipath errors of the global orbiting navigation satellite system (GLONASS) have been compared with those of the global positioning system (GPS). The effects of pre-correlation filtering on code and carrier multipath errors have been determined using data from a measured correlation function. The multipath fading bandwidth is also discussed, and fast and slow fading effects are presented. A comparison has been made of the performance of typical coherent and non-coherent code discriminators in the presence of multipath. The performance of the GPS and GLONASS P code signals have been determined with respect to code and carrier multipath errors. © 1997 by John Wiley & Sons, Ltd.     

Rapid and Precise GLONASS GDOP Approximation using Neural Networks

Russian global navigation satellite system (GLONASS) provides civilian and military users three-dimensional position determination and navigation services as same as US global positioning system. Geometric dilution of precision (GDOP) provides a simple interpretation of positioning precision. Usual method for GLONASS GDOP calculation is matrix inversion. However this process imposes a huge calculation load on receiver, especially when large number of visible satellites exists. To overcome this problem, artificial neural network is used. Different configurations and training methods are simulated on a data base obtained by a GLONASS receiver. Then navigation precision and execution times are explored and compared. Results show that recurrent neural network has 0.00024 RMS error, which is the best against other focused tools including feed forward back propagation and radial basis function neural network with usual training and with genetic algorithm adopted weights and biases.     

卫星导航时间传递性能的分析与比较

卫星导航系统本身具有时间传递性能,其时间传递技术包括接收机单点定位授时、两站点卫星共视和基于差分技术的相对时间同步,为分布式电子信息系统的固定站点和运动平台间的时间同步提供了高精度的时间同步手段。本文针对卫星导航多种时间传递模式的原理和性能展开分析,对GPS、GLONASS、GALILEO和Compass的时间传递性能进行对比分析。利用两套具有多系统多星座共视的载波相位时间传递技术的时间传递设备开展了长基线时间传递试验,试验结果表明利用卫星导航能够实现的1000km长基线时间传递的最佳精度可达5ns。     

GPS民用双频的载波相位测量定位

运用全球定位系统(GPS)进行定位导航,已在全球众多领域中得到了广泛的应用。在运用这种定位技术的方法中,伪距测量和载波相位测量得到了广泛的应用。载波相位测量的定位精度比伪距测量的定位精度高出两个数量级,在静态短基线载波相位测量中可达到mm量级的精度,在动态实时定位中可以达到cm量级的精度,所以定位的高精度使其具有了广泛的应用前景。但在载波相位测量中存在着整周模糊度求解的问题,故如何有效、快速、简便而精确地求解整周模糊度就成了一个关键问题。基于GPS两个民用频率,探讨和论述求解整周模糊度的方法。     

一种多基准接收机条件下的载波相位差分报文优化生成方法

实时动态相对定位(RTK)以其精度高的特点广泛适应于精密 RTK 测绘和高精度导航等领域。为了保证系统的完好性,基准站设置多台基准接收机,因此需要选取状态最优的基准接收机用于 RTK 定位的基准。在多基准接收机条件下,本文提出了完好性算法结合残差以及多基准优选的方法生成 RTK 报文,优选出状态最好的基准接收机,确保播发的报文数据质量高且卫星数多。该方法经过多次故障加注试验,验证了该方法能够优选出综合状态最佳的基准接收机作为基准,从而保证移动站的定位精度和定位成功率。     

GNSS伪距差分定位及其特色──GNSS卫星导航定位方法之二

GNSS伪距差分定位是一种能够获取较高导航定位测量精度的卫星导航定位方法,但是,它的设备较复杂,用户不仅需要使用一台GNSS信号接收机,而且需要设置提供DGNSS改正数据的基准站及其一台GNSS信号接收机,以及与之匹配的DGNSS数据链,才能够实现全天候、全天时和全球性地测量运动载体的7维状态参数。本文简要地论述了GNSS差分定位的基本原理及其实现。     

Slot stripline circular-polarization antennas for a few-element antenna array for a high-accuracy receiver of signals from global navigation satellite systems

New radiators for slot stripline leaky-wave circular-polarization antennas for high-accuracy GLONASS/GPS receivers have been developed. The main technical characteristics of antennas with new radiators have been theoretically and experimentally studied. It is shown that application of the new radiators improves the axial ratio, increases suppression of the cross polarization, increases the stability of the antenna phase center, and thus can increase the GLONASS/GPS positioning accuracy. The results of the analysis of the GLONASS/GPS positioning accuracy with the use of these antennas in an angle-measuring receiver and as elements of a few-element antenna array are presented.     

Technique for order performance by similarity to ideal solution for solving complex situations in multi-criteria optimization of the tracking channels of GPS baseband telecommunication receivers

Global positioning system (GPS) has undergone intensive development, starting as an advanced specialized tool to a general-purpose gadget used in our daily lives. GPS exists in new technologies, applications, and consumer products, especially in smartphones and tablets. In a GPS receiver design, power consumption and localization accuracy are critical factors that affect the outcome of a GPS receiver system. Theoretically, increasing the number of required tracking channels in a GPS baseband receiver increases the design complexity and size of this system. Thus, power consumption can significantly increase. The receiver should acquire and track numerous satellites to improve the location accuracy of a position, thereby indicating that the receiver requires a high number of tracking channels. Thus, optimizing these tracking channels to balance the conflict among performance parameters is a difficult and challenging task. This paper presents a technique for order performance by similarity to ideal solution (TOPSIS) for solving complex situations for multi-criteria optimization of the tracking channels of GPS baseband telecommunication receiver. Nine operation modes of GPS receiver were evaluated by each design parameter, such as power consumption, localization accuracy, and time with no position available for static and dynamic positioning. Then, the TOPSIS was utilized and implemented to measure and rank the overall performance of tracking channel selection. Results of this study indicate that (1) multi-objective optimization is a reliable strategy for visualizing the trade-off among the GPS design parameters and providing a dynamic power consumption planning. (2) The best aggregated performance of the GPS receiver occurs when the number of tracking channels equals five and six for static and dynamic positioning, respectively. (3) The most frequent number of available satellites is eight, whereas the other number of satellites is a rare case to acquire. However, GPS standards require that available GPS satellites are constantly 12 at any time and place.     

基于分段信噪比加权的GPS定位方法

在基于GPS的飞行器定位中,GPS卫星的情况与地面不同,传统的GPS选星算法有局限性.为了实现飞行器快速、可靠的定位,提出了一种新的基于分段信噪比加权的GPS定位方法.实验表明,相对传统选星算法,本方法的定位稳定性更好、精度更高、计算时间较短,能够满足飞行器快速、可靠定位的要求.     

Experimental observations of carrier phase acceleration in conditions of polar ionosphere

The paper presents a comparative analysis of the quality of measuring the phase carrier of signals from GLONASS and GPS navigation satellites and spectrum of small-scale irregularities of electron density in conditions of a nonstationary and inhomogeneous polar ionosphere. It is shown that small-scale irregularities of the electron density in the ionosphere can lead to a substantial nonstationary increase in the acceleration of the phase carrier of both GPS and GLONASS by a factor of 1.3–2.5 from the background level.     

Understanding signals from glonass navigation satellites

In late 1986 details of the radio-frequency signal structure currently employed by the pre-operational GLONASS satellite navigation system were revealed by the Satellite Communications Group at Leeds University. Since then further investigation has resulted in a successful interpretation of most of the data message transmitted on the civil code, sufficient to allow the design and construction of a GLONASS receiver capable of the same level of performance as can now be achieved with NAVSTAR GPS. Details of the message content relating to location of GLONASS satellites for the purposes of position-fixing and time-referencing are presented for the first time.     

一种GPS定位解算算法的研究

GPS 利用卫星发射的无线电信号，通过计算卫星与 GPS 接收机之间的相对位置， 进而确定出用户接收机在地球上的位置，可以为用户接收机提供实时的定位、测速和授时等服务。 通过使用最小二乘法，对 GPS 的定位解算算法进行研究，设计了一种基于最小二乘法的 GPS 定位解算算法。通过使用模拟源对所设计的 GPS 定位算法进行了定位解算试验验证，将定位解算结果与设定的模拟接收机位置进行比较，试验结果表明，该定位解算算法具有良好的定位效果。     

GPS软件接收机中微弱信号捕获算法研究

信号捕获的目的是确定接收机当前所在位置的可见卫星号,进而计算可见卫星的载波频率和伪随机码相位信息.目前随着GPS接收机应用的日益广泛,如何在弱信号环境下实现定位的问题日益突出.普通的GPS接收机不能捕获和跟踪到导航卫星信号,只能设法提高GPS接收机的灵敏度来实现导航和定位.为了解决微弱信号情况下的GPS信号捕获问题,在...