My professor (who is now unreachable on holiday) gave me files to work with for a mapping project. The files were retrieved from the Ordinance Survey Ireland webpage. They were used to differentially correct GIS data that had been collected in the field.

I don't recognize the file format, and I am unsure how I am meant to interact with these file types. The files have suffixes like .18N, .18G, etc. I have attached a picture. What is this format?

How do I use these files?

I'm working with Grass/QGIS.

the new files with the file format that I don't recognize

  • How big are those files and do you have any kind of metadata about it? – DirkB. Jul 22 '18 at 20:51
  • For the file highlighted in the picture above: Properties list "39.4 MB (41,385,568 bytes)" for size and that it contains 90 files. No metadata that I can find, unless it's in one of the 90 files - not sure how to open it so can't say for sure. – S Wolf Jul 22 '18 at 20:58
  • Did you already try to contact or check Ordinance Survey Ireland? I would try to change the file format to Software-formats you ususally used. – DirkB. Jul 22 '18 at 21:09
  • By "deferentially correct" I suspect you mean differentially correct [GPS data]. – PolyGeo Jul 22 '18 at 21:43
  • Hi Dirk, I did email OSI on Monday but haven't heard back. Hi PolyGeo, yes that is what I meant, thanks for the catch - have edited. – S Wolf Jul 22 '18 at 22:28

Those files are Receiver Independent Exchange Format (RINEX). Which is an open source standard for raw satellite navigation system data. For more information about the file format standards refer to this document. That document is quite thorough but a (very) brief description of the files:

  • 18 in the file extension refers to two digit year the data was collected in.
  • *o is an observation file. The meat of the data this contains the raw observable(s) collected in the field (C/A code, P or Y code, L1 and L2 or time, phase and range).
  • *n is a navigation file.
  • *g is a GLONASS navigation file.
  • *m is a meteorological data file.
  • RINEX files are ASCII based files so you can open them with any text editor, although there is not much you can do without processing the files further.

Without knowing what your task is it is difficult to say how you should work with this data but one common way would be to upload your observation file (18o) to the National Geodetic Survey (NGS) Online Positioning User Service (OPUS) to solve for the solution of the observables in the file. Even though your data is from Ireland according to this article from GPS World OPUS can still process data collected outside the US if it meets certain requirements.

  • Hi GeoSharp, Thank you for the description, that helps. I am mapping relevee site locations and vegetation communities. I have data for 50 sites I recorded with my Trimble, so in turn a great deal of these files. It isn't a very complex map, I just need to represent where my surveys took place. I haven't used such raw files before, I am used to the processed shapefile formats that one downloads from sites like Geologic Survey, etc. Since my data was collected in Ireland, I will see if we have a service similar to the NGS site. Thank you, and all other tips are valuable and welcome. – S Wolf Jul 24 '18 at 17:54
  • 1
    @SWolf according to this article from gps world OPUS can still process data collected outside the US if it meets certain requirements. – GeoSharp Jul 25 '18 at 6:13

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