共查询到19条相似文献，搜索用时 125 毫秒
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针对北斗卫星导航系统(BDS)在轨卫星原子钟的评估问题,从三个性能指标即准确度、漂移率和稳定性出发进行了评估,并利用同一时段的GPS/GLONASS星载原子钟性能评估结果做了比较。算例采用GPS 1751-1758共8周的数据,评估结果发现:BDS在轨卫星的准确度在10-11量级,漂移率在10-15量级,与GPS/GLONASS星载原子钟的水平相当,但钟的稳定性方面由于BDS存在着几颗天稳较大的钟,所以其天稳的平均值在10-13量级,比GPS和GLONASS卫星略差。 相似文献
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应用GPS技术对杭州湾跨海大桥进行首级控制网测量,结果表明:(1)合理布设GPS控制网,并采用设置深桩固埋测量标志、增加有效观测时间、加强数据可靠性与精确性的检验、选择科学及合理的坐标系统等方法,可提高观测数据的质量和精度。同时,对观测数据采用Bernese高精度基线处理软件和精密星历进行基线解算、网平差和坐标转换,保证了杭州湾跨海大桥首级控制网的精度在厘米级之内,使成果的质量达到优良。(2)Bernese基线数据的闭合环及复测基线的检核表明:同步环、异步环闭合差量值及复测基线互差量值全部符合限差要求,且在允许值的1/3以内的基线环数分别占93.3%、77.7%和100%,其成果精度达到优良。(3)GPS控制网的控制点点位的中误差全部满足±20mm的技术设计要求,并且有96.6%的控制点点位中误差在限差的1/3范围以内,精度较高。使用精密星历和广播星历两种不同的数据处理方法进行数据处理,其坐标互差吻合得较好,全部互差值均在限差允许值的1/2范围以内,且使用精密星历计算的成果精度明显高于使用广播星历计算的成果精度。 相似文献
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为了探究连续运行参考站网的实时动态相对定位(continuously operating reference stations-real time kinematic,CORS-RTK)无验潮技术在海岸带水下地形测量精度问题,以单波束测深数据为例,通过对比分析主测线与检查线交叉点误差以及有验潮和无验潮重合点误差两种方式,对基于CORS-RTK无验潮的海岸带水下地形测量数据精度进行分析。结果表明,CORS-RTK无验潮水下地形测量技术获取的测深点数据不符值比例为2.82%,说明CORS-RTK无验潮水下地形测量具有较高的可靠性;无验潮与验潮站相比,高程互差波动在-0.12~0.32m之间,平均值为0.11m,且偏差在0.2m以内的测深点占总样本的93.40%,说明有验潮与无验潮两种水下地形测量结果具有较好的一致性,可为CORS-RTK无验潮技术在海岸带水下地形测量中的广泛应用提供参考。 相似文献
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为实现远岸潮汐精确监测,基于GPS PPK技术开展了远距离高精度GPS验潮方法研究。研究给出了GPS潮位测量方法,其次联合GPS定位信息和IMU姿态信息,通过坐标转换原理得到瞬时水面的精确高程。在此基础上,研究利用基于FFT的低通滤波技术提取潮位信息。最后在烟台港进行了实际工程试验。试验结果表明,当GPS PPK验潮距离达98km时,潮位误差可控在!15cm以内,验潮精度仍可优于10cm。 相似文献
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GPS测量误差源及其控制分析 总被引：3，自引：2，他引：1
介绍了GPS测量中各种主要的非人为误差以及它们给测量带来的影响，对于精度控制问题，主要讨论的是小型控制网（基线长度10～20km）和局部地区应用中动态和准动态差分测量的精度控制方法。 相似文献
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We have computed estimates of the rate of vertical land motion in the Mediterranean Sea from differences of sea level heights measured by the TOPEX/Poseidon radar altimeter and by a set of tide gauge stations. The comparison of data at 16 tide gauges, using both hourly data from local datasets and monthly data from the PSMSL dataset, shows a general agreement, significant differences are found at only one location. Differences of near-simultaneous, monthly and deseasoned monthly sea level height time-series have been considered in order to reduce the error in the estimated linear-term. In a subset of 23 tide gauge stations the mean accuracy of the estimated vertical rates is 2.3 ± 0.8 mm/yr. Results for various stations are in agreement with estimates of vertical land motion from geodetic methods. A comparison with vertical motion estimated by GPS at four locations shows a mean difference of -0.04 ± 1.8 mm/yr, however the length of the GPS time-series and the number of locations are too small to draw general conclusions. 相似文献
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Vertical Land Motion in the Mediterranean Sea from Altimetry and Tide Gauge Stations 总被引：1，自引：0，他引：1
We have computed estimates of the rate of vertical land motion in the Mediterranean Sea from differences of sea level heights measured by the TOPEX/Poseidon radar altimeter and by a set of tide gauge stations. The comparison of data at 16 tide gauges, using both hourly data from local datasets and monthly data from the PSMSL dataset, shows a general agreement, significant differences are found at only one location. Differences of near-simultaneous, monthly and deseasoned monthly sea level height time-series have been considered in order to reduce the error in the estimated linear-term. In a subset of 23 tide gauge stations the mean accuracy of the estimated vertical rates is 2.3 ± 0.8 mm/yr. Results for various stations are in agreement with estimates of vertical land motion from geodetic methods. A comparison with vertical motion estimated by GPS at four locations shows a mean difference of ?0.04 ± 1.8 mm/yr, however the length of the GPS time-series and the number of locations are too small to draw general conclusions. 相似文献
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为了了解潮流从西北太平洋经吕宋海峡进入南海内的变化及其垂向结构,本文利用在吕宋海峡附近沿东西方向布放的多套潜标同步获得的高分辨率ADCP长时间连续观测上层海流资料,使用调和分析方法将实测海流分解成3部分:不随时间变化的定常流、周期性潮流和剩余流,并将潮流分解为正压潮流和斜压潮流。通过对实测海流中各组分的分析,得到以下结论:该区域潮流类型在不同深度上有明显变化;M2潮自吕宋海峡传入南海后强度显著减弱75%左右,K1、O1分潮在上层强度减弱约三分之一。从垂向变化来看,在潮流强度上,各站点垂直方向上潮流强度均发生变化。从方向上看,各分潮潮流椭圆东西向特征明显,长轴变化较大,短轴(南北向特征)垂向变化不显著;潮流运动主要沿逆时针方向,垂直方向上潮流明显减弱或增强时会发生转向。斜压潮流主要集中在上表层,100m左右以下随深度逐渐减弱。东西方向斜压潮流能量比正压潮流强,而南北向的流比较稳定,且斜压潮流能量远小于正压潮流。定常流强度在各站点呈现相似的变化趋势,随深度变化减弱。 相似文献
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Comparing to single BeiDou Navigation Satellite System (BDS) Precise Point Positioning (PPP), a method which can more quicklydetermine the ambiguity parameters of BDS through applying the contribution of GPS observations is proposed and analyzed in this article. The numerical examples and analysis show that the ionosphere-free ambiguities of BDS satellites can be determined and converged more quickly because of the contribution of GPS observations. The average improvement of the convergent speed of positioning is 18.5% and its positioning accuracy in N, E, and U components are improved by 29.4, 30.3, and 34.4%, respectively, with the contribution of the a priori coordinates obtained from GPS observations. This method is useful for single BDS system positioning when there is a priori information provided by GPS or other sensors which be replaced by and can be applied at the beginning of the computation. 相似文献
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Christopher Watson Richard Coleman Neil White John Church Ramesh Govind 《Marine Geodesy》2003,26(3):285-304
An absolute calibration of the TOPEX/Poseidon (T/P) and Jason-1 altimeters has been undertaken during the dedicated calibration phase of the Jason-1 mission, in Bass Strait, Australia. The present study incorporates several improvements to the earlier calibration methodology used for Bass Strait, namely the use of GPS buoys and the determination of absolute bias in a purely geometrical sense, without the necessity of estimating a marine geoid. This article focuses on technical issues surrounding the GPS buoy methodology for use in altimeter calibration studies. We present absolute bias estimates computed solely from the GPS buoy deployments and derive formal uncertainty estimates for bias calculation from a single overflight at the 40-45 mm level. Estimates of the absolute bias derived from the GPS buoys is -10 ± 19 mm for T/P and +147 ± 21 mm for Jason-1 (MOE orbit) and +131 ± 21 mm for Jason-1 (GPS orbit). Considering the estimated error budget, our bias values are equivalent to other determinations from the dedicated NASA and CNES calibration sites. 相似文献
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Correction factors based on the catch ratios of egg and larval densities in the southern waters of Korea were estimated for
anchovyEngraulis japonica. This was undertaken in order to adjust ichthyoplankton data from different sampling methods, gear types and time. Samples
were collected during ichthyoplankton surveys in Korean waters from 1983 to 1994. The ratios for egg densities obtained in
vertical tows with a NORPAC net (ring Φ, 45 cm) compared to those obtained in oblique tows with a KOB net (ring Φ, 80 cm)
were 0.86 (CV = 0.65), 1.22 (CV = 0.36), and 0.93 (CV = 0.42) for early, middle, and later developmental stages, respectively.
The ratios for larval densities for vertical and oblique tows varied depending on size. For yolk-sac and small larvae (< 4
mm), the ratios were 3.08 (CV = 0.45) and 1.98 (CV = 1.34), while those of 4-6 mm, 6-8 mm, and 8-10 mm larvae were 0.44 (CV
= 1.31), 0.45 (CV = 1.70), and 0.56 (CV = 2.50), respectively. Ratios of day/night densities for larvae of 4-10 mm lengths
were lower (0.01-0.06) in offshore catches than values obtained in coastal areas (0.44-0.46) and similar values (0.16-0.04)
for vertical and oblique tows. Our results indicated that vertical towing is more efficient for sampling early life stages
(from eggs to larvae less than 4 mm long), while oblique towing is more efficient for larvae longer than 4 mm due to depth
preferences for each developmental stage (e.g., changes in egg buoyancy and vertical migration of larvae). 相似文献
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Pierre Exertier Joë lle Nicolas Philippe Berio David Coulot Pascal Bonnefond Olivier Laurain 《Marine Geodesy》2004,27(1):333-340
The French Transportable Laser Ranging System (FTLRS), a highly transportable Satellite Laser Ranging (SLR) instrument, was set up in Corsica (from January to September 2002) for participating to the JASON-1 altimeter verification phase. In addition to the tracking of oceanographic satellite missions and in order to perform an accurate positioning, the FTLRS also acquired laser ranging data on geodetic satellites, STARLETTE and STELLA essentially.
The paper describes the analysis strategy mainly based on the use of a short-arc orbit technique to compute accurate 1 cm local orbits, and then the geocentric positioning (2-3 mm relative to GPS). Finally, we established the JASON-1 absolute calibration value, based on 9 SLR short-arcs (between cycles 1 and 26), at 108.2 ± 8.7 mm; the 10-day repeatability is of 26.1 mm showing that a great accuracy has been reached. 相似文献
The paper describes the analysis strategy mainly based on the use of a short-arc orbit technique to compute accurate 1 cm local orbits, and then the geocentric positioning (2-3 mm relative to GPS). Finally, we established the JASON-1 absolute calibration value, based on 9 SLR short-arcs (between cycles 1 and 26), at 108.2 ± 8.7 mm; the 10-day repeatability is of 26.1 mm showing that a great accuracy has been reached. 相似文献
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Gopal S. Gopalapillai 《Marine Geodesy》2013,36(3):247-267
An orthogonal system of interferometry baselines aboard a geostationary satellite is considered primarily as a global positioning and navigation system. The mathematical model based on the relationship between the measured phase differences, the known transmitter positions, and other systematic error model parameters is derived. A generalized Least‐Squares estimation procedure is used for the solution of the unknown transmitter positions. Study of the effects of the various system and error model parameters on the position accuracy reveals that this accuracy is critically dependent on the baseline length and the magnitude of the random component of the measuring errors. With a 50‐m baseline, the obtainable accuracy at a frequency of 1.5 GHz is comparable to that of the NAVSTAR/ GPS system. Considering the interest and needs of the potential users for a multicapability system, this interferometry system is considered a major improvement over existing and planned navigation systems. 相似文献