The Geo++® GNTOOLS software package contains a group of program modules for data management at stations in a GNSMART reference station network.


With GNCRON, tasks to be carried out at regular intervals at a station can be automated. This may cover the modules contained in the GNTOOLS package, or any desired external programs or batch files.

The desired start times of individual programs can be flexibly configured. The date (day and month) as well as the time (hours and minutes) or the day of the week can be freely selected (as in the UNIX cron command). Combinations of these settings are also possible.

For example, using GNCRON a programme may be started every Sunday morning at 5 a.m., to thin out all data over fourteen days old down to a 15 second sampling rate. A second program could also be started on the first day of each month, to delete all RINEX data over six months old.


The GNPURGE program allows the selective deletion of files in a directory tree which meet specific pre-set criteria. Such criteria can include the age of the file, combined with one or more file types. For example with a single call-up from GNPURGE all log files over eight weeks old from a particular station may be deleted. Empty sub-directories are automatically deleted.


DThe RXSUMARY program generates a compressed summary of RINEX file contents, for example the number of data records, the recording interval, etc., from a RINEX directory tree in accordance with the GNREF file naming convention. If RXSUMARY is linked with mailbox software, external users can be rapidly informed of the current data situation.


The GNPACKRX program generates the appropriate files in Compressed and/or Compact RINEX format from RINEX files. It can for example be used with the GNPACKD compression module (included in every GNREF package) as the standard compression software at a GNREF reference station.


GN_RX is a program to read and write RINEX files, with many different possibilities for their processing. GN_RX has access to the following options:

  • Thinning out of RINEX files. Observations with higher sampling rates (e.g. 1 second) can be reduced to lower rates (e.g. 15 seconds).
  • Extraction of intervals with given start and end times. From a data set with continuous RINEXobservations, desired intervals can be extracted. The data set can also be assembled from several files, for example RINEX hourly files. The files are found automatically if they conform to the GNREF file naming convention. If the files are in compressed form (GNPACKD) they are automatically recognised and decompressed.
  • Production of the Compact RINEX format, according to Hatanaka. This international standard format decreases the redundancy in RINEX observations by numerical reduction. The resulting Compact RINEX observation files have only about 30% of the volumes of normal RINEX observation files.
  • In addition, GN_RX can generate Compressed RINEX files, likewise conforming to the RINEX standard, using the UNIX compress algorithm. The files so produced in Compact Compressed RINEX have only about 10% of the volume of the original RINEX files.

GN_RX supports the RINEX file naming conventions with the following recommended file extensions:

RINEX Dateityp normal compressed
GPS or GLONASS Observation rxo rxy
GPS or GLONASS Compact Observation (Hatanaka) rxd rxe
GPS Navigation rxn rxx
GLONASS Navigation rxg rxv

GN_RX can also handle the alternate RINEX file extensions with “rx” replaced by the last two ciphers of the year (e.g. “99o” instead of “rxo”).


GN_RX and GNPACKRX make use of the following programs, which are contained in the GNTOOLS package or may be used individually:

Program Task
rxo2rxd production of Compact RINEX (Hatanaka) from RINEX
rxd2rxo production of RINEX from Compact RINEX (Hatanaka)
rxo2rxo extraction of RINEX observation data
rxn2rxn extraction of RINEX navigation data
gnx2z compression with the compress algorithm
gnz2x decompression with the uncompress algorithm


SSR2RX generates RINEX observation files from GNSMART status information (State Space Representation, SSR), which completely describe the error budget of a GNSS network through staus models and the corresponding status parameters. SSR files are written regulary in a reference network, e.g. by the program GNNET. Especially in large networks the storage space requirements of SSR files are only a small percentage of the original observation files of all stations.

With SSR2RX for example

  • “Virtual RINEX” files for an arbitrarily choosen position (VRS-RINEX), or
  • RINEX data of a real reference station without station dependent errors (e.g. multi-path)

can be generated. Beside the position also start and End time for the RINEX files can be selected. As the observation interval an arbitrary time span can be choosen, even extrem short intervals of less than one second can be generated.

GNTOOLS Applications

The modules of the GNTOOLS package are set up for inclusion in a GNSMART reference station network or in a GNREF reference station. The data organisation is supported in accordance with the GNREF file naming convention. GN_RX knows the GN_DATA directory structure including weekly and daily directories. GNTOOLS can of course also be installed outside the GNREF station environment, for example for post-processing of GPS observations using the GEONAP software package.

Operating Systems

The GNTOOLS programs are currently available for the following operating systems:

  • OS/2 Warp 4
  • Linux (except GNCRON and SSR2RX)
  • Windows NT 4.0 and higher
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