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Dataset of reliable 10-figure GPS references of hi


#1

Details of this were posted in the rhb group and I am guessing that not everyone in our group is also in that, although I am aware quite a few are. A project to build a dataset of summits based on 10 digit GPS readings should be to our advantage especially in thick cloud. So since quite a number of us carry GPS units, I think we can probably help with this data collection. See http://www.biber.fsnet.co.uk/downloads.html for details of what they need. What do you think?
73
jim
gocqk


#2

In reply to G0CQK:

I think we can probably help with this data collection.

This looks an interesting project. However I think it is important that anybody who participates understands a bit about what they are trying to achieve. A 10 figure grid reference has a precision of 1 metre, but precision is not the same as accuracy. At this level, you need to take account of many sources of error that simply aren’t a problem at the 10 or 100 metre level.

I think the site itself explains it all rather well. In particular they know that the National Grid no longer has a mathematical relationship to real measurements, but is subject to a transformation expressed as a huge table. GPS receivers don’t have this table, so the transformations they do can be several metres out.

Personally I think they have made a rod for their own backs by holding their raw data in NGR format; I think they should have stuck to WGS84. (Ideally it should be ETRS89, since the WRG84 coordinates change over time due to continental drift). It only takes a few moments to switch most GPS receivers to display WGS84 coordinates, and this would eliminate many of the errors caused by dodgy transformations.