The Trimble Company was formed in 1978 by
three employees from Hewlett-Packard and coincided with the first Global
Positioning System (GPS) satellite, the NavStar, being launched. The company concentrates on developing
positioning and navigation products.
One of these products is the Trimble
GeoExplorer 6000 Series. The 6000 is an
innovative piece of equipment and comes as either the Geo XH or Geo XT. The advantage of the XH is its Floodlight
technology. This is standard in this
model and delivers improved positioning accuracy in challenging mountain
environments when part of the view is obstructed, such as under trees or beside
trig pillars.
One of the major advantages of the Trimble is
that it can function without an external antenna as one is built into it. This enables the surveyor to gather accurate
data and use the Trimble without the need to carry additional heavy
equipment. The instrument itself is compact,
only weighs 2lb and appears to need only 2 – 5 minutes data collection to
produce acceptable levels of accuracy (+/- 0.1m).
However, operating the Trimble as a stand-alone instrument does have its
drawbacks. The major drawback is how to
accurately determine bwlch or summit positions if not visually obvious, as is
often the case. This then has to be carried out by instrumental methods, for
example via level and staff, Abney level or RTK (Real Time Kinematic) GNSS
measurements.
The Trimble GeoXH 6000 on the summit of Cyrniau (SJ 063 251) a Pedwar and marginal HuMP above Llangynog in mid Wales |
Although I have a pole, tripod, bipod and
external antenna I envisage the majority of the surveys conducted under the
moniker of Mapping Mountains will be carried out with just the Trimble. Because of this I need to differentiate the
surveys I conduct from those carried out by G&J Surveys. As a member of G&J Surveys, I know that
we follow a rigorous protocol to determine both summit and col positions and
follow guidelines set out by the Ordnance Survey. When operating the Trimble for Mapping
Mountains I will usually do so as a single surveyor, and as described above,
this does have limitations. However,
that is not to say that the data I will produce with the Trimble will not be
accurate, but it does mean that sometimes the quoted margin of uncertainty will
be greater than we usually quote within G&J Surveys.
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