Reference Station user strategies in a tectonic environment

Author:Penny Boviatsou

地震是对构造板之间运动的反应。随着两个板以稳定的速度一起推动，沿板边界的岩石变得越来越压力，直到最终必须给出东西为止 - 地震沿着板边界区域的某个地方发生。

New Zealand lies at the edge of both the Australian and Pacific tectonic plates. The Australian and Pacific plates push against each other along a curving boundary and generally don't move smoothly past each other. They move in a series of small rapid motions, each of which is accompanied by earthquakes.

SmartFix,基于世界上最大的参考tation network, HxGN SmartNet, is New Zealand’s most extensive GNSS reference station network with more than 70 stations nationwide. SmartFix delivers centimetre level, real-time kinematic corrections, post processing solutions and sub-metre GIS corrections. HxGN SmartNet is an integrated 24/7 GNSS network RTK and correction service, built on the world’s largest reference network, enabling GNSS-capable devices to quickly determine precise positions.

“Providing a real-time kinematic (RTK) correction service over the internet and RINEX files for post processing, our customers can enjoy the benefits of SmartFix,” said Bruce Robinson, director at Global Survey Limited. “If their GPS or GNSS receiver can connect to the internet, SmartFix can deliver the data they need.”

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Earthquakes shaking up New Zealand

新西兰有两种类型的地震。北岛下方的深层地震形成了一个定义明确的乐队（地震区），从马尔伯勒（Marlborough）穿过怀特岛（White Island）。浅层地震往往发生在这个地震带的东南部，而较深的地震发生在西北。

新西兰Geonet是地震委员会（EQC），GNS科学和新西兰土地信息之间的合作伙伴关系，监视该国所有地质危害，每天将50至80次地震定位，每年约20,000。地震可以在新西兰任何时候发生。

These earthquakes are continually altering the shape of New Zealand and while a lot of the movement is small and unfelt, it is continual and the result is perceivable, measurable and locally variable. The measurable and variable part is what the reference station network SmartFix needs to deal with.

There are many examples of rapid movements that combine lateral and vertical movements. Such movements are clearly not uniformed; this variability creates challenges for those who need to establish reliable survey control or those who run reference station networks.

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Investigating earthquake activity

尽管新西兰不断移动和deforming under the influence of the Australian and Pacific tectonics plates, the country’s datum is designed to provide constant unchanging coordinates for features.

Datums define how coordinates, longitudes and latitudes or heights, relate to physical locations. Projections are different ways of representing a position in a datum, for example as northings and eastings used on topographic maps. Together, they define New Zealand's coordinate systems.

为了管理这种变形，基准本身正在移动和变形，并与新西兰的土地质量一起移动和变形 - 它是一个“板固定”的基准。

The New Zealand datum is known as NZGD2000, and this datum is based on International Terrestrial Reference Frame (ITRF) 1996 as at the position on the feature on January 1, 2000. Because the datum is deforming, NZGD2000 coordinates no longer reflect the true positions of points relative to one another.

The local area distortion, however, is small, and for most applications, the deformation can be and is ignored. This allow for distances, bearings and areas to be calculated directly from NZGD2000 coordinates. This deformation, however, needs to be continually addressed and managed by the reference station administrators.

The error in ignoring the variation is no more than one millimetre in a kilometre for each year since 2000. A deformation model is periodically applied to account for deformation due to earthquakes, regarding calculating NZGD2000 coordinates, and as the measurement of the deformation model becomes more accurate.

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在新西兰运行参考站时面临挑战

The NZGD2000 datum was set on January 1, 2000 – the last time everything fit together nicely. Since 2000, New Zealand has had 17.5 years of differential movement, and while the coordinates of the mark have not changed, the relative position has. A point surveyed today, from three different reference stations, will likely have three different NZGD2000 coordinates dependant on the reference station used.

“Education of clients is a major part of SmartFix administrator job here in New Zealand, as we are upskilling users to understand the geodetic implications of station selection,” said Robinson.

第二个挑战是获得并选择Leica GNSS Spider参考站软件所需的参考站的两个坐标。这两个坐标是当前的时期坐标，以确保网络的可靠性和NZGD2000坐标的可靠性。GNSS蜘蛛解决方案是一个集成软件套件，用于集中控制和操作GNSS参考站和网络，并帮助管理新西兰等复杂环境。

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A reliable and efficient solution

使用HXGN SmartNet（新西兰的SmartFix）之类的网络节省了现场工作人员的时间，因为它阻止了单独的基站设置，并且避免了由于损坏或被盗的基础而导致控制失败的风险，并消除了无线电干扰问题。测量师长期以来使用GNSS网络来节省时间和金钱，并消除潜在的错误来源。

而不是随身携带：

• GPS接收器
• batteries and cables
• two radios
• 三脚架和杆子
• 并为每个项目建立自己的本地基础，

网络用户只需携带带有内部调制解调器或外部手机的GPS或GNSS智能天线（Rover），然后使用该设备快速访问永久参考站网络。这些永久电台的组合数据用于生成RTK校正，并在比传统无线电解决方案更大的距离下提供准确的定位。

“At Survey Global we are committed to the growth of the SmartFix (SmartNet) network,” said Robinson. “It enables our customers to get reliable and repeatable NZGD2000 coordinates, despite the tectonic challenges, and for the user it makes them more efficient, allowing them to complete projects on time and on budget.”