Measuring England's highest peak

Author:Staff

英国许多敏锐的登山者都熟悉著名的“三峰” - 苏格兰，威尔士和英格兰的最高山峰：

1. Ben Nevis
2.斯诺登
3. Scafell Pike

最近，军械调查大不列颠（OS）重新测量了斯诺登（Snowdon）和本·尼维斯（Ben Nevis）的峰会，以使用最新技术来验证其高度。

With the 80th anniversary of the triangulation of Great Britain in 2016, the time was right to re-measure the height of the remaining one; Scafell Pike, Cumbria – England’s highest peak.

In early 2016, the re-measurement of Great Britain’s highest peak, Ben Nevis in Scotland revealed with great enthusiasm that Ben Nevis was indeed higher than was previously thought.The published height increased from 1,344m to 1,345m after rounding-up.

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Reaching for the stars

As part of the ITV series Countrywise, Ordnance Survey was approached by the show to help presenter Ben Fogle re-measure the height of Scafell Pike. Ordnance Survey turned to Leica Geosystems’ professional equipment and solutions to help deliver this exciting project. The new self-learningLeica GS16 GNSS smart receiverwas deemed the best tool for the job.

Scafell Pike’s height published on the Ordnance Survey maps was derived from measurements last taken in the 1937 during the triangulation of Great Britain. The current height is rounded to 978 metres. A re-measuring of the mountain was certainly needed.

该项目的目的是使用最新的GNSS技术重新衡量山区。除了对英格兰最高峰的真实高度进行准确的测量外，这项工作还验证了大约79年前进行的先前测量。

Fogle and outside broadcast team set off on the trail from Wasdale Head to Scafell Pike with a team of surveyors from Ordnance Survey. They carried with them the latest Leica Geosystems GNSS technology, a newly released Leica GS16 smart receiver, Leica CS35 rugged tablet computer and a level and staff. This compact lightweight solution was a far cry from the theodolites carried in the original survey all those years ago.

Due to the challenging remote location of the mountain top and the absence of a mobile phone signal, it was not possible to use Network RTK corrections. Nor was it possible to attain a base and rover RTK solution via radio due to the distance from known points in the valley and obscuring terrain. For the highest level of accuracy, post-processing of a static session would definitively calculate the new height. By using the Leica GS16 receiver, however, it was also possible to calculate the new height to within a few centimetres whilst at the summit of the mountain by using the SmartLink service provided by Leica Geosystems for a quick value.

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What is SmartLink?

SmartLink is a Precise Point Positioning (PPP) service that enables the GNSS user toachieve real-time centimetre accurate positioning worldwide, ideal when working in remote areas around the globe. SmartLink does not require a local RTK base station or network RTK infrastructure to operate meaning lower capital investments in equipment and the ease of simply visiting the site with a SmartLink compatible receiver is the only requisite.

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SmartLink如何工作？

SmartLink is based on the tried and tested PPP technique, originally developed in the early 1990s for off-shore positioning such as in the oil and gas industries where operations are usually remote – consequently away from reference stations and communications links. SmartLink includes a global network of GNSS reference stations, communications links and diverse network control centres, all with redundancy for guaranteed availability of service for critical operations.

SmartLink corrects or models GNSS error sources such as ionospheric and tropospheric delays and satellite orbits and clocks. Correction signals are then computed and uplinked to a series of seven geostationary satellites and broadcast to the compatible GNSS receiver, such as the Leica GS16 used on Scafell Pike. By delivering GNSS corrections via satellite, the common weakness of network RTK – the mobile phone network - is overcome.

Leica Geosystems’ continual innovation has recently brought the benefits of using SmartLink to the land survey community. A positive side-effect of usingSmartLink is particularly of interest to regular RTK users should the RTK Data Link be interrupted, such as due to mobile network busy or terrain obscuring radio links, then SmartLink seamlessly bridges the gap to maintain uninterrupted centimetre positioningeliminating the frustration of downtime awaiting data links to be restored.

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Reaching the peak of performance

在山顶上，将左侧GS16安装在山顶触发支柱上，以观察卫星信号并计算触发支柱的高度。Leica GS16的多功能性还允许记录原始观察结果，以便在办公室进行确定的静态后处理。

Bernese Scientific软件用于使用精确的Ephemeris数据，OS NET V2009坐标参考框架和OSTN15/ OSGM15转换和Geoid模型来批准SmartLink。有趣的是，为了证明实时智能链接获得的高度的质量，后处理计算的高度仅差异2-4厘米。

OS Head of Multi-Media, Andy Steggall, who took part in the expedition says, “it was remarkable that the OS surveyors of yesteryear were so accurate. What was such a major physical effort then has been replaced with the precision accuracy provided by state of the art equipment now. But it shows that the tradition of dedication and commitment to getting it right burns brightly. We’re sure the story will make compelling TV. We can reveal that the new height calculated for the highest point in England is 978.072 metres Above Ordnance Datum (AOD) in accordance with the current geoid model, OSGM15.”