共查询到20条相似文献，搜索用时 31 毫秒
1.
Peter F. de Bakker Christian C. J. M. Tiberius Hans van der Marel Roel J. P. van Bree 《GPS Solutions》2012,16(1):53-64
Stochastic properties of GNSS range measurements can accurately be estimated using a geometry-free short and zero baseline
analysis method. This method is now applied to dual-frequency measurements from a new field campaign. Results are presented
for the new GPS L5Q and GIOVE E5aQ wideband signals, in addition to the GPS L1 C/A and GIOVE E1B signals. As expected, the
results clearly show the high precision of the new signals, but they also show, rather unexpectedly, significant, slowly changing
variations in the pseudorange code measurements that are probably a result of strong multipath interference on the data. Carrier
phase measurement noise is assessed on both frequencies, and finally successful mixed GPS-GIOVE double difference ambiguity
resolution is demonstrated. 相似文献
2.
本项研究在双频消除电离层技术的基础上,根据北斗的三频特性,消除观测值中的几何观测量,得到消电离层消几何观测量的组合值,并且对同一地区两个测站同步观测数据的组合值站间单差处理,在伪距观测和载波观测两个方面,分析各类卫星观测值的噪声和多路径误差的相关特征,预估和评定北斗系统的观测质量.结果表明:地球静止轨道卫星观测值主要影... 相似文献
3.
Network-based geometry-free three carrier ambiguity resolution and phase bias calibration 总被引：5，自引：2，他引：3
Continuously operating reference stations (CORS) are increasingly used to deliver real-time and near-real-time precise positioning
services on a regional basis. A CORS network-based data processing system uses either or both of the two types of measurements:
(1) ambiguity-resolved double-differenced (DD) phase measurements, and (2) phase bias calibrated zero-differenced (ZD) phase
measurements. This paper describes generalized, network-based geometry-free models for three carrier ambiguity resolution
(TCAR) and phase bias estimation with DD and ZD code and phase measurements. First, the geometry-free TCAR models are constructed
with two Extra-Widelane (EWL)/Widelane (WL) virtual observables to allow for rapid ambiguity resolution (AR) for DD phase
measurements without distance constraints. With an ambiguity-resolved WL phase measurement and the ionospheric estimate derived
from the two EWL observables, an additional geometry-free equation is formed for the third virtual observable linearly independent
of the previous two. AR with the third geometry-free model requires a longer period of observations for averaging than the
first two, but is also distance-independent. A more general formulation of the geometry-free model for a baseline or network
is also introduced, where all the DD ambiguities can be more rigorously resolved using the LAMBDA method. Second, the geometry-free
models for calibration of three carrier phase biases of ZD phase measurements are similarly defined for selected virtual observables.
A network adjustment procedure is then used to improve the ZD phase biases with known DD integer constraints. Numerical results
from experiments with 24-h dual-frequency GPS data from three US CORS stations baseline lengths of 21, 56 and 74 km confirm
the theoretical predictions concerning AR reliability of the network-based geometry-free algorithms.
相似文献
| Chris RizosEmail: |
4.
Modernized GPS and Galileo will provide triple-frequency signals for civil use, generating a high interest to examine the improvement of positioning performance using the triple-frequency signals from both constellations over baselines up to hundreds or thousands of kilometers. This study adopts a generalized GPS/Galileo long-range approach to process the mutually compatible GPS and Galileo triple-frequency measurements for high-precision long baseline determination. The generalized approach has the flexibility to deal with GPS and Galileo constellations separately or jointly, and also the capability to handle dual or triple-frequency measurements. We compared the generalized long-range approach with the Bernese v5.0 software on two test baselines located in East Asia and obtained highly compatible computational results. Further, in order to assess possible improvement of GPS/Galileo long baseline determination compared with the current dual-frequency (L1/L2) GPS, we simulated GPS and Galileo measurements of the test baselines. It is shown that the current level of accuracy of daily baseline solutions can be improved by using the additional Galileo constellation. Both the additional constellation and the triple-frequency measurements can improve ambiguity resolution performance, but single-constellation triple-frequency ambiguity resolution is more resistant to the influences of code noise and multipath than dual-constellation dual-frequency ambiguity resolution. Therefore, in environments where large code noise or multipath is present, the use of triple-frequency measurements is the main factor for improving ambiguity resolution performance. 相似文献
5.
Xiaohong Zhang Mingkui Wu Wanke Liu Xingxing Li Shun Yu Cuixian Lu Jens Wickert 《Journal of Geodesy》2017,91(10):1225-1240
The successful launch of five new-generation experimental satellites of the China’s BeiDou Navigation Satellite System, namely BeiDou I1-S, I2-S, M1-S, M2-S, and M3-S, marks a significant step in expanding BeiDou into a navigation system with global coverage. In addition to B1I (1561.098 MHz) and B3I (1269.520 MHz) signals, the new-generation BeiDou-3 experimental satellites are also capable of transmitting several new navigation signals in space, namely B1C at 1575.42 MHz, B2a at 1176.45 MHz, and B2b at 1207.14 MHz. For the first time, we present an initial characterization and performance assessment for these new-generation BeiDou-3 satellites and their signals. The L1/L2/L5 signals from GPS Block IIF satellites, E1/E5a/E5b signals from Galileo satellites, and B1I/B2I/B3I signals from BeiDou-2 satellites are also evaluated for comparison. The characteristics of the B1C, B1I, B2a, B2b, and B3I signals are evaluated in terms of observed carrier-to-noise density ratio, pseudorange multipath and noise, triple-frequency carrier-phase ionosphere-free and geometry-free combination, and double-differenced carrier-phase and code residuals. The results demonstrate that the observational quality of the new-generation BeiDou-3 signals is comparable to that of GPS L1/L2/L5 and Galileo E1/E5a/E5b signals. However, the analysis of code multipath shows that the elevation-dependent code biases, which have been previously identified to exist in the code observations of the BeiDou-2 satellites, seem to be not obvious for all the available signals of the new-generation BeiDou-3 satellites. This will significantly benefit precise applications that resolve wide-lane ambiguity based on Hatch–Melbourne–Wübbena linear combinations and other applications such as single-frequency precise point positioning (PPP) based on the ionosphere-free code–carrier combinations. Furthermore, with regard to the triple-frequency carrier-phase ionosphere-free and geometry-free combination, it is found that different from the BeiDou-2 and GPS Block IIF satellites, no apparent bias variations could be observed in all the new-generation BeiDou-3 experimental satellites, which shows a good consistency of the new-generation BeiDou-3 signals. The absence of such triple-frequency biases simplifies the potential processing of multi-frequency PPP using observations from the new-generation BeiDou-3 satellites. Finally, the precise relative positioning results indicate that the additional observations from the new-generation BeiDou-3 satellites can improve ambiguity resolution performance with respect to BeiDou-2 only positioning, which indicates that observations from the new-generation BeiDou-3 satellites can contribute to precise relative positioning. 相似文献
6.
A. El-Mowafy 《GPS Solutions》2014,18(4):553-561
A method is presented for real-time validation of GNSS measurements of a single receiver, where data from each satellite are independently processed. A geometry-free observation model is used with a reparameterized form of the unknowns to overcome rank deficiency of the model. The ionosphere error and non-constant biases such as multipath are assumed changing relatively smoothly as a function of time. Data validation and detection of errors are based on statistical testing of the observation residuals using the detection–identification–adaptation approach. The method is applicable to any GNSS with any number of frequencies. The performance of validation method was evaluated using multi-frequency data from three GNSS (GPS, GLONASS, and Galileo) that span 3 days in a test site at Curtin University, Australia. Performance of the method in detection and identification of outliers in code observations, and detection of cycle slips in phase data were examined. Results show that the success rate vary according to precision of observations and their number as well as size of the errors. The method capability is demonstrated when processing four IOV Galileo satellites in a single-point-positioning mode and in another test by comparing its performance with Bernese software in detection of cycle slips in precise point-positioning processing using GPS data. 相似文献
7.
Precise relative positioning using real tracking data from COMPASS GEO and IGSO satellites 总被引：14，自引：5，他引：9
China completed a basic COMPASS navigation network with three Geostationary and three Inclined Geosynchronous satellites in orbit in April 2011. The network has been able to provide preliminary positioning and navigation functions. We first present a quality analysis using 1-week COMPASS measurements collected in Wuhan. Satellite visibility and validity of measurements, carrier-to-noise density ratio and code noise are analyzed. The analysis of multipath combinations shows that the noise level of COMPASS code measurements is higher than that of GPS collected using the same receiver. Second, the results of positioning are presented and analyzed. For the standalone COMPASS solutions, an accuracy of 20 m can be achieved. An accuracy of 3.0 m for the vertical, 1.5 m for the North and about 0.6–0.8 m for the East component is obtained using dual-frequency code only measurements for a short baseline. More importantly, code and phase measurements of the short baseline are processed together to obtain precise relative positioning. Kinematic solutions are then compared with the ground truth. The precision of COMPASS only solutions is better than 2 cm for the North component and 4 cm for the vertical. The standard deviation of the East component is smaller than 1 cm, which is even better than that of the East component of GPS solutions. The accuracy of GPS/COMPASS combination solutions is at least 20 % better than that of GPS alone. Furthermore, the geometry-based residuals of double differenced phase and code measurements are analyzed. The analysis shows that the noise level of un-differenced phase measurements is about 2–4 mm on both B1 and B2 frequencies. For the code measurements, the noise level is less than 0.45 m for B1 CA and about 0.35 m for B2 P code. Many of the COMPASS results presented are very promising and have been obtained for the first time. 相似文献
8.
Adaptive wavelet transform based on cross-validation method and its application to GPS multipath mitigation 总被引：3，自引：2，他引：1
Global positioning system (GPS) multipath disturbance is a bottleneck problem that limits the accuracy of precise GPS positioning
applications. A method based on the technique of cross-validation for automatically identifying wavelet signal layers is developed
and used for separating noise from signals in data series, and applied to mitigate GPS multipath effects. Experiments with
both simulated data series and real GPS observations show that the method is a powerful signal decomposer, which can successfully
separate noise from signals as long as the noise level is lower than about half of the magnitude of the signals. A multipath
correction model is derived based on the proposed method and the sidereal day-to-day repeating property of GPS multipath signals
to remove multipath effects on GPS observations and to improve the quality of the GPS measurements. 相似文献
9.
Kees De Jong 《GPS Solutions》1999,3(2):11-18
In this article, the influence of biases in GPS code observations on the estimated parameters of the geometry-free model is
investigated. This is done for undifferenced as well as double-differenced data from short baselines, that is, baselines for
which ionospheric effects may be assumed absent. It is shown how introducing a linear model for code multipath affects the
original model parameters. The performance of the original and extended model is illustrated by analyzing data from a single
receiver and a short baseline. ? 1999 John Wiley & Sons, Inc. 相似文献
10.
对搭载美国BlackJack接收机的CHAMP/GRACE-A/Jason-2卫星和搭载国产接收机的HY2A/ZY3/TH1卫星的星载GPS数据的伪距多路径误差与观测噪声进行了研究,重点分析了国产接收机伪距多路径误差的变化特性,并研究了多路径误差与观测噪声对星载GPS自主定轨的影响。结果表明:国产接收机的C/A码与P1码伪距观测精度要整体差于美国的BlackJack接收机,而P2码伪距观测精度要整体优于BlackJack接收机;国产接收机P1码伪距受多路径效应影响较大,其多路径误差随高度角减小存在单调递增的变化趋势,其中HY2A、ZY3与TH1卫星的多路径误差最大分别可达3.6 m、1.8 m与0.7 m;这种单调递增变化的多路径误差会导致星载GPS自主定轨位置结果在径向与切向产生系统性偏差。 相似文献
11.
Real-time cycle slip detection in triple-frequency GNSS 总被引：7，自引：2，他引：5
The modernization of the global positioning system and the advent of the European project Galileo will lead to a multifrequency global navigation satellite system (GNSS). The presence of new frequencies introduces more degrees of freedom in the GNSS data combination. We define linear combinations of GNSS observations with the aim to detect and correct cycle slips in real time. In particular, the detection is based on five geometry-free linear combinations used in three cascading steps. Most of the jumps are detected in the first step using three minimum-noise combinations of phase and code observations. The remaining jumps with very small amplitude are detected in the other two steps by means of two-tailored linear combinations of phase observations. Once the epoch of the slip has been detected, its amplitude is estimated using other linear combinations of phase observations. These combinations are defined with the aim of discriminating between the possible combinations of jump amplitudes in the three carriers. The method has been tested on simulated data and 1-second triple-frequency undifferenced GPS data coming from a friendly multipath environment. Results show that the proposed method is able to detect and repair all combinations of cycle slips in the three carriers. 相似文献
12.
Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning 总被引：1，自引：1，他引：0
Lawrence Lau 《GPS Solutions》2017,21(2):461-474
Repeatable satellite orbits can be used for multipath mitigation in GPS-based deformation monitoring and other high-precision GPS applications that involve continuous observation with static antennas. Multipath signals at a static station repeat when the GPS constellation repeats given the same site environment. Repeat-time multipath filtering techniques need noise reduction methods to remove the white noise in carrier phase measurement residuals in order to retrieve the carrier phase multipath corrections for the next day. We propose a generic and robust three-level wavelet packets based denoising method for repeat-time-based carrier phase multipath filtering in relative positioning; the method does not need tuning to work with different data sets. The proposed denoising method is tested rigorously and compared with two other denoising methods. Three rooftop data sets collected at the University of Nottingham Ningbo China and two data sets collected at three Southern California Integrated GPS Network high-rate stations are used in the performance assessment. Test results of the wavelet packets denoising method are compared with the results of the resistor–capacitor (RC) low-pass filter and the single-level discrete wavelet transform (DWT) denoising method. Multipath mitigation efficiency in carrier phase measurement domain is shown by spectrum analysis of two selected satellites in two data sets. The positioning performance of the repeat-time-based multipath filtering techniques is assessed. The results show that the performance of the three noise reduction techniques is about 1–46 % improvement on positioning accuracy when compared with no multipath filtering. The statistical results show that the wavelet packets based denoising method is always better than the RC filter by 2–4 %, and better than the DWT method by 6–15 %. These results suggest that the proposed wavelet packets based denoising method is better than both the DWT method and the relatively simple RC low-pass filter for noise reduction in multipath filtering. However, the wavelet packets based denoising method is not significantly better than the RC filter. 相似文献
13.
一种基于交叉证认技术的自适应小波变换及其在削减GPS多路径误差中的应用 总被引：2，自引：1，他引：1
多路径效应影响是目前限制GPS定位精度进一步提高的瓶颈。提出用交叉证认技术自动识别小波分解的信号层,再通过小波重构实现降噪和信号提取,并将该方法应用于GPS多路径误差的削减中。对模拟数据和实际GPS观测资料的分析表明,该方法能合理分离不同噪声水平下资料序列中的信号和噪声;当噪声水平小于信号振幅的一半时,能成功分离资料序列中的高频信号。同时,运用该方法得到的多路径改正模型和GPS多路径效应的重复性,可有效地削弱多路径效应的影响,提高GPS定位精度。 相似文献
14.
15.
Multipath disturbance is one of the most important error sources in high-accuracy global positioning system (GPS) positioning and navigation. A new data filtering method, based on the Vondrak filter and the technique of cross-validation, is developed for separating signals from noise in data series, and applied to mitigate GPS multipath effects in applications such as deformation monitoring. Both simulated data series and real GPS observations are used to test the proposed method. It is shown that the method can be used to successfully separate signals from noise at different noise levels, and for varying signal frequencies as long as the noise level is lower than the magnitude of the signals. A multipath model can be derived, based on the current-day GPS observations, with the proposed method and used to remove multipath errors in subsequent days of GPS observations when taking advantage of the sidereal day-to-day repeating characteristics of GPS multipath signals. Tests have shown that the reduction in the root mean square (RMS) values of the GPS errors ranges from 20% to 40% when the method is applied. 相似文献
16.
从探测与修复周跳的观测值线性组合人手,分析非差方式下M-W组合和电离层残差组合对周跳的探测能力,探讨两种组合相结合的优越性.研究分析相结合算法对地面低动态数据和星载GPS高动态数据的适应能力,实验结果表明此算法对GPS双频动态观测数据的周跳探测、修复具有较好的适用性和实用性. 相似文献
17.
As a first step towards studying the ionosphere with the global navigation satellite system (GNSS), leveling the phase to the code geometry-free observations on an arc-by-arc basis yields the ionospheric observables, interpreted as a combination of slant total electron content along with satellite and receiver differential code biases (DCB). The leveling errors in the ionospheric observables may arise during this procedure, which, according to previous studies by other researchers, are due to the combined effects of the code multipath and the intra-day variability in the receiver DCB. In this paper we further identify the short-term temporal variations of receiver differential phase biases (DPB) as another possible cause of leveling errors. Our investigation starts by the development of a method to epoch-wise estimate between-receiver DPB (BR-DPB) employing (inter-receiver) single-differenced, phase-only GNSS observations collected from a pair of receivers creating a zero or short baseline. The key issue for this method is to get rid of the possible discontinuities in the epoch-wise BR-DPB estimates, occurring when satellite assigned as pivot changes. Our numerical tests, carried out using Global Positioning System (GPS, US GNSS) and BeiDou Navigation Satellite System (BDS, Chinese GNSS) observations sampled every 30 s by a dedicatedly selected set of zero and short baselines, suggest two major findings. First, epoch-wise BR-DPB estimates can exhibit remarkable variability over a rather short period of time (e.g. 6 cm over 3 h), thus significant from a statistical point of view. Second, a dominant factor driving this variability is the changes of ambient temperature, instead of the un-modelled phase multipath. 相似文献
18.
On the link between GPS pseudorange noise and day-boundary discontinuities in geodetic time transfer solutions 总被引：1，自引：3，他引：1
When neglecting calibration issues, the accuracy of GPS-based time and frequency transfer using a combined analysis of code
and carrier phase measurements highly depends on the noise of the GPS codes. In particular, the pseudorange noise is responsible
for day-boundary discontinuities which can reach more than 1 ns in the time transfer results obtained from geodetic analysis.
These discontinuities are caused by the fact that the data are analyzed in daily data batches where the absolute clock offset
is determined by the mean code value during the daily data batch. This pseudorange noise is not a white noise, in particular
due to multipath and variations of instrumental delays. In this paper, the pseudorange noise behavior is characterized in
order to improve the understanding of the origin of the large day-boundary discontinuities in the geodetic time transfer results.
In a first step, the effect of short-term noise and multipath is estimated, and shown to be responsible for only a maximum
of 150 ps (picoseconds) of the day-boundary jumps, with only one exception at NRC1 where the correction provides a jump reduction
of 300 ps. In a second step, a combination of time transfer results obtained with pseudoranges only and geodetic time transfer
results is used to characterize the long-term evolution of pseudorange errors. It demonstrates that the day-boundary jumps,
especially those of large amplitude, can be explained by an instrumental effect imposing a common behavior on all the satellite
pseudoranges. Using known influences as temperature variations at ALGO or cable damages at HOB2, it is shown that the approach
developed in this study can be used to look for the origin of the day-boundary discontinuities in other stations. 相似文献
19.
北斗伪距观测值存在特有的多路径系统性偏差,偏差的数量级达到几个分米到米。该系统偏差可分为两类:一类是IGSO/MEO卫星随高度角变化的伪距系统性偏差;另一类是GEO卫星(高度角仅微小变化)明显的伪距系统性偏差。系统性的伪距偏差导致GEO卫星MP序列的标准偏差较大,本文针对GEO卫星伪距偏差问题提出了一种基于卡尔曼滤波的修正方法,修正后的GEO卫星MP序列的标准偏差下降了10%~16%。基于伪距相位组合的单频PPP技术的伪距权重较大,会受到北斗伪距偏差的影响,分析表明该系统性偏差将导致单频PPP定位结果高程方向产生约1m的偏差。对GEO伪距偏差采用提出的卡尔曼滤波修正方法进行修正,并应用Wanninger和Beer的高度角模型消除IGSO/MEO观测值伪距偏差,本文对修正后的单频精密单点定位精度进行了分析。4个multi-GNSS experiment(MGEX)站10d观测数据的分析结果表明:仅改正和卫星多路径误差,高程方向定位结果精度可改善65%左右;采用本文方法对GEO卫星的多路径修正后,该方向定位结果精度改善比例将进一步提高至75%左右。 相似文献
20.
A first assessment of GLONASS CDMA L3 ambiguity resolution and positioning performance is provided. Our analyses are based on GLONASS L3 data from the satellite pair SVNs 755-801, received by two JAVAD receivers at Curtin University, Perth, Australia. In our analyses, four different versions of the two-satellite model are applied: the geometry-free model, the geometry-based model , the height-constrained geometry-based model, and the geometry-fixed model. We study the noise characteristics (carrier-to-noise density, measurement precision), the integer ambiguity resolution performance (success rates and distribution of the ambiguity residuals), and the positioning performance (ambiguity float and ambiguity fixed). The results show that our empirical outcomes are consistent with their formal counterparts and that the GLONASS data have a lower noise level than that of GPS, particularly in case of the code data. This difference is not only seen in the noise levels but also in their onward propagation to the ambiguity time series and ambiguity residuals distribution. 相似文献