The PositioNZ Global Positioning System (GPS) data service provides RINEX data from continuously recording GPS receivers located around New Zealand and the Chatham Islands. The data are recorded at 30 second intervals and supplied as RINEX files of either 1 hour or 24 hour duration.
LINZ archives data for all PositioNZ stations in the Receiver Independent Exchange (RINEX) format. RINEX is an internationally recognised format that is developed by the GNSS community for observation data, navigation data, clock data and many other data types. LINZ currently collects GPS and GLONASS observational data from PositioNZ stations and provides navigational data for the GPS constellation.
Three ways to download PositioNZ RINEX data:
- Download web form
- FTP web access
- By URL with known RINEX file name (refer to the RINEX file naming convention)
Rinex observation files (.yyo)
Availability from end of observation period (95% of the time)
Rinex navigational file (.yyn)
LINZ does not collect RINEX navigational data from the PositioNZ network. The navigation files (autoddds.yyn) that accompany the PositioNZ RINEX files are broadcast ephemeris data for the GPS constellation. These are acquired from SOPAC (Scripps Orbit and Permanent Array Center) housed within the University of California, San Diego.
GLONASS Navigation files (.yyg) are available for download from CDDIS and other International GNSS Service analysis centres.
Rinex file naming convention
The RINEX files are named according to a convention as follows: codeddds.yyt
The components of this name are as follows:
The lower case geodetic code of the mark, eg "auck" for Auckland. Navigation files use the name "auto".
The day number of the file starting at 1 on 1 January of each year
The session code for the file. This is "0" for the 24 hour data file. The hourly sessions are named "a"to "x" where a is from 00:00 hours to 01:00 hours (UTC time), and x is from 23:00 hours to 24:00 hours.
The last two digits of the year of the file, eg "02" for 2002
The type of data in the file, either "o" for observations files, "d" for observation files with the Hatanaka compression scheme applied, or "n" for navigation files.
These files may have Unix compression applied, in which case a ".Z" is added to the filename.
Rinex file compression
Two file compression schemes are used to reduce the storage size of RINEX files.
- Hatanaka compression: Hatanaka RINEX compression was developed by Yuki Hatanaka to reduce the size of RINEX files by taking advantage of the special characteristics of GNSS data, and by removing extraneous information. To convert a RINEX file to or from Hatanaka format requires special software. This can be obtained from ftp://terras.gsi.go.jp/software/RNXCMP
- Unix file compression: Unix file compression is a generic compression method supported on all unix systems. This method is often supported by compression software on other platforms (for example WinZip on Microsoft Windows).
For the PositioNZ RINEX files the effect of compression is shown below by listing the typical size of the compressed file as a percentage of the size of the equivalent uncompressed file.