共查询到18条相似文献，搜索用时 650 毫秒
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以双曲线定位原理实现了罗兰C／北斗组合导航，提出了HDOP的定义，以此分析了两系统组合前后的定位精度，并给出了定位精度的仿真。结果表明，组合后大大改善了罗兰C定位精度和定位可用范围，并弥补了北斗定位系统有源定位的不足。 相似文献
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本文对FURUNO气象传真接收各按钮的名称、功能作了简单介绍，详细地叙述了接收气象传真资料的方法，尤其是如何设置、修改定时接收时间表、自动地接收清晰的资料等，并对接收中常见的故障排除、调试方法亦做了介绍，以提供预报人员和操作人员使用。 相似文献
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本文对一个长基线水声跟踪系统给出定位计算公式,并进行了分析。该系统利用由三个接收点组成的接收阵测定目标到三接收点的距离,并且通过自校方法测定接收点坐标,从而计算目标位置。首先说明接收阵形状与定位精度有关,证明等边三角形接收阵形状为最佳。第二分析了由于三接收点相对深度不同但计算中仍采用同一深度计算时引入的误差,它与基阵形状、基阵线度、目标与接收阵平均相对深度及接收阵各点的相对深度有关,给出了接收点深度不同时计算目标位置的公武。第三部分计算了测量误差对定位误差的影响。 相似文献
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差分导航定位是海洋工程地震勘探中不可或缺的技术手段。差分导航定位分为局域差分和广域差分,文中分别介绍了隶属于局域差分的信标差分(RBN DGPS)系统和隶属于广域差分的星基差分(SBAS)系统。根据所在测区位置和定位精度要求的不同,海洋工程地震勘探选用不同的GPS定位设备可以接收不同系统提供的差分信号。导航软件也是海洋工程地震作业中必不可少的一部分,它不仅可以记录GPS定位设备的数据,还具有测线设计、坐标投影、航行轨迹显示等诸多功能。通过对导航软件的灵活应用和信号变换,导航软件还可以为地震系统提供触发信号。最后给出了一个海洋工程地震勘探实例。 相似文献
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东海近海渔场航空测温 总被引：1，自引：0，他引：1
为准确及时地向海洋渔业生产指挥部门提供大面积和准同步的渔场环境数据,为东海近海冬季带鱼汛捕捞作业提供海况信息速报,国家海洋局海洋环境预报中心、海洋技术研究所和上海海洋预报区台联合于1986年10—12月,在东海近海使用航空红外测温仪、投掷式测温浮标、罗兰C导航定位仪、彩色录像机等系统设备进行了五次渔场航空测温,测温精度小于±0.5℃。依据所测数据及时对监测海域的表层海水温度状况进行了分析,并与常年和前一年同期温度场作了对比分析,在监测现场还发布了五期测温速报。飞行监测范围为东海冬季带鱼洄游的主要渔场,即北纬28°-32°和东经124°以西海域。所获测温数据,由于具有快速、准确、同步和传输及时的优点,在冬季带鱼汛的生产指挥中发挥了积极作用,取得了良好的经济效益。 相似文献
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短排列多道反射地震接收缆较短，无水鸟、磁罗经、尾标等定位定深设备，给常规数据处理带来诸如观测系统定义等棘手问题；另外，无定深设备会造成接收缆不同接收段的沉放深度不同，破坏反射数据理论双曲线时距曲线关系。针对短排列多道反射地震数据，本文充分利用现场导航数据，计算实际激发点轨迹，再通过反距离比线性插值算法计算检波点的轨迹坐标，获得整个排列的实际观测系统参数。对因沉放深度不一致造成的扭曲时距曲线反射波，文中利用理论双曲线先计算共中心点道集的理论反射波位置，再推算排列中各接收道不同沉放深度处的静校正量，通过静校正拟合运算，消除接收排列非一致深度引起的反射波同相轴扭曲现象。将上述处理方法应用于南极海域短排列多道反射地震数据，最终获得了高分辨率叠加剖面，为后续地质解释提供了保障。 相似文献
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Walter J. Senus 《Marine Geodesy》2013,36(3):263-288
The current accuracy of sea‐going and airborne gravity measurements is not bounded by the precision of the gravimeter but by the precision with which external parameters such as vehicle velocity (speed), azimuthal heading, and geographic position can be determined. Uncertainties in these parameters are summed up in the Eötvös correction in the reduction of the measured data. This work investigates the suitability of baseline navigation systems, in particular Loran‐C and Omega, to further reduce the uncertainty of the Eötvös correction. Emphasis is placed on the velocity measurement error. A new algorithm is developed which derives velocity based upon the change in hyperbolic (or circular) grid readings, as opposed to the standard change in geographic position technique. A comparative analysis shows the new algorithm to be as precise as the currently used conventional calculation. Further, this simplified technique is accompanied with a 20‐fold reduction in computational complexity. Application of the results presented in this paper to the Loran‐C and Omega systems shows a velocity determination capability of 0.1 knot over a six minute integration time, and 0.05 knot for a 15 minute integration time for Loran‐C. The minimum error attainable in Omega is 0.1 knot when determined over a 17 minute measurement time. Further precision can be gleaned by applying the calculated error as a correction to subsequent velocity calculations. 相似文献
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Jonathan M. Bull Martin Gutowski Justin K. Dix Timothy J. Henstock Peter Hogarth Timothy G. Leighton Paul R. White 《Marine Geophysical Researches》2005,26(2-4):157-169
Chirp sub-bottom profilers are marine acoustic devices that use a known and repeatable source signature (1–24 kHz) to produce
decimetre vertical resolution cross-sections of the sub-seabed. Here the design and development of the first true 3D Chirp
system is described. When developing the design, critical factors that had to be considered included spatial aliasing, and
precise positioning of sources and receivers. Full 3D numerical modelling of the combined source and receiver directivity
was completed to determine optimal source and receiver geometries. The design incorporates four source transducers (1.5–13 kHz)
that can be arranged into different configurations, including Maltese Cross, a square and two separated pairs. The receive
array comprises 240 hydrophones in 60 groups whose group-centres are separated by 25 cm in both horizontal directions, with
each hydrophone group containing four individual elements and a pre-amplifier.
After careful consideration, it was concluded that the only way to determine with sufficient accuracy the source–receiver
geometry, was to fix the sources and receivers within a rigid array. Positional information for the array is given by a Real
Time Kinematic GPS and attitude system incorporating four antennas to give position, heading, pitch and roll. It is shown
that this system offers vertical positioning accuracy with a root-mean-square (rms) error less than 2.6 cm, while the horizontal
positioning rms error was less than 2.0 cm. The system is configured so that the Chirp source signature can be chosen by software
aboard the acquisition vessel.
The complete system is described and initial navigational and seismic data results are presented. These data demonstrate that
the approach of using fixed source-receiver geometry combined with RTK navigation can provide complete 3D imaging of the sub-surface. 相似文献
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Shipborne GPS attitude determination during MMST-93 总被引：1，自引：0，他引：1
Lachapelle G. Cannon M.E. Lu G. Loncarevic B. 《Oceanic Engineering, IEEE Journal of》1996,21(1):100-104
The attitude parameters of a ship underway were measured using a configuration of four 10-channel NovAtel Model 951 narrow-correlator-spacing receivers. These C/A code receivers have output rates of up to 10 Hz and maintain effective carrier phase lock under relatively harsh ship dynamics. The attitude parameters are calculated independently at each epoch using differential carrier phase measurements, carrier phase ambiguities are resolved on-the-fly by constraining the approximately known distances between the antennas that are rigidly mounted on the ship. Carrier phase thermal noise and multipath are minimized by mounting the antennas as far apart as possible. The four-antenna configuration provides redundancy and further improves accuracy. During the Matthew Motion Sensor Trials (MMST-93) conducted off the coast of Halifax, Nova Scotia, in June-July 1993, the GPS-derived attitude parameters were compared with those obtained with a Honeywell HG1050 ring laser gyro inertial navigation system (INS) which provides roll and pitch with an accuracy of 15 arcsecs and heading with an accuracy of 2 arcmins. To simulate rough weather conditions, sharp maneuvers were performed to induce roll angles in excess of 10°. No accuracy degradation nor any loss of GPS measurements occurred. The RMS agreement between GPS and INS derived attitude parameters is better than 2 arcmins in heading, 1 arcmin in pitch and 3 arcmins in roll. This level of accuracy demonstrates the capability of GPS for cost-effective shipborne attitude determination at an accuracy level of 0.05 相似文献
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Silivra A.A. Spiesberger J.L. Fabrikant A.L. Hurlburt H.E. 《Oceanic Engineering, IEEE Journal of》1997,22(1):143-150
A basin-scale acoustic tomography simulation is carried out for the northeast Pacific Ocean to determine the accuracy with which time must be kept at the sources when clocks at the receivers are accurate. A sequential Kalman filter is used to estimate sound-speed fluctuations and clock errors. Sound-speed fluctuations in the simulated ocean are estimated from an eddy-resolving hydrodynamic model of the Pacific forced by realistic wind fields at daily resolution from 1981-1993. The model output resembles features associated with El Nino and the Southern Oscillation, as well as many other features of the ocean's circulation. Using a Rossby-wave resolving acoustic array of four fixed sources and twenty drifting receivers, the authors find that the percentage of the modeled ocean's sound-speed variance accounted for with tomography is 92% at 400-km resolution, regardless of the accuracy of the clocks. Clocks which drift up to hundreds of seconds of error or more for a year do not degrade tomographic images of the model ocean. Tomographic reconstructions of the sound-speed field are insensitive to clock error primarily because of the wide variety of distances between the receivers from each source. Every receiver “sees” the same clock error from each source, regardless of section length, but the sound-speed fluctuations in the modeled ocean cannot yield travel times which lead to systematic changes in travel time that are independent of section length. The Kalman filter is thus able to map the sound-speed field accurately in the presence of large errors at the source's clocks 相似文献
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本文对动态测量中偏心改正的原理、方法及其精度进行了探讨.在大比例尺工程水深测量定位中,若测深仪换能器与定位系统接收天线不处于同一铅垂线上,并且偏心过大,超过定位精度要求时,必须进行偏心改正.经过偏心改正后的定位精度才能保证大比例尺测图定位要求. 相似文献