G-Nut/Anubis - summary of meta data

Anubis reports meta data collected from the RINEX header and, optionally, from the user settings.

Currently, this part is aimed to support easy grepping of specific meta data over the time (a sequence of Anubis extraction files).

In future, it is aimed to support a full cross-checking of RINEX header meta data with any other central meta data sources such as site log files, database etc. as well as with values estimated from data itself.

NOTE: The format of this part is considered as preliminary and may still significantly change.

G-Nut/Anubis - observation types

Anubis collects information about all observation types, satellites and constellations contained in RINEX observation file and enables to compare it with meta data reported in the RINEX header. Anubis reports supports the filtering (e.g. using linux grep command) of any sequence of extraction files for specific keywords. In this way, any variation in individual receiver tracking capability can be easily accessed in long-term.

The first verbosity (sec_obs="1") provides a summary about available satellites and observation types for each individual GNSS constellation.

The second verbosity (sec_obs="2") lists avaible satellites for each specific observation types and each GNSS constellation.

G-Nut/Anubis - satellite elevations and azimuths

If navigation messages are available, Anubis is able to calculate position of satellites and report individual satellite azimuth and elevations. The information is reported in a fixed format applying the user request sampling interval (int_smp="20") and list of all satellites. Azimuths and elevations for individual satellites can be thus easily combined with other parts of Anubis report in order to visualize the results such as code multipath, cycle slips, signal strength, bands etc.

Anubis is able to read more individual GNSS RINEX 2.XX and individual or combined RINEX 3.xx navigation files. Since version 1.3.0, Anubis supports output of merged navigation messages into a single file in the RINEX 3.02 format.

The plot below provides sky plots of all available GNSS constellations and complete them with marking epochs and satellites with a single-frequency observation (in black points), which indicates a loss of dual-/multi-tracking capability.

NOTE: The completeness of the report strongly depends on the quantity and quality of provided navigation messages by user.

Anubis GNSS QC skyplot

G-Nut/Anubis - frequency bands

Anubis checks number of bands for a) individual epochs, b) satellites and c) type of observations (code/phase). All epochs with at least 4 satellites, observed from a single system, are considered as usable (see UseEp in Summary). Epochs with only single-frequency code or phase observations are counted as incomplete because dual-frequency measurements are considered as a minimum standard for precise applications (xCoEp/xPhEp in Summary). Similarly, satellite-specific code and phase observations are counted for as incomplete, and reported as xCoSv/xPhSv in Summary.

The section "Bands" than provides more details about frequency bands tracked for code and phase observations and all satellites in a user request sampling rate (int_stp="20"). Via setting sec_bnd="1" user requests a summary report of per cents of complete dual-/multi-band observations (see listing, the first part). For code and phase observations at pre-defined epochs and for all satellites the keyword is GNSCEP and GNSLEP, respectively. Count of single-band observations at the given epoch is given in the first data column labeled as SngFreq. If set sec_bnd="2", Anubis reports also epoch-wise band counting for all satellites and phase/code observations (see listing, the second part) using the user request sampling rate.

First figure shows a summary of all available bands for individual satellites (constellations in colors) for code (ligth) and phase (dark) observations.

Anubis GNSS - available frequency bands
Anubis GNSS - available frequency bands

Second figure shows time variation of the number of all available satellites for all constellations (in color) including number of satellites providing a single-frequency only (gray = all epochs, black = user request epochs only).

G-Nut/Anubis - data pre-processing

When requested, Anubis performs carrier phase pre-processing which includes receiver clock jump detection and phase cycle-slip detection and estimation. Since version 1.3.0, Anubis checks carrier phase observations from all signals at all frequencies and all GNSS satellite constellations. Summary report is provided when set sec_pre="1" and the following informations are reported (see also listing below):

  • Clk_Jmp - number of receiver clock jumps
  • CS_Total - number of all phase cycle-slips and carrier-phase interruptions
  • CS_Slips - number of identified real phase cycle-slips during a continous phase tracking
  • CS_Epoch - number of carrier-phase interruptions due to missing epoch (counts all previously observed satellites and signals)
  • CS_Satell - number of carrier-phase interruptions due to temporary unavailable satellites
  • CS_Signal - number of carrier-phase interruptions due to temporary unavailable signals

Detail reports on clock jumps epochs and calculated phase cycle-slips are provided if set sec_pre="2".
Both lists are sorted by epochs and cycle slips provided with specific line for individual satellites while reporting all common signals.