X-pos Virtual RINEX Data

Virtual RINEX data is generated by the network management software for a user-defined location and time span. Virtual RINEX provides the same data that would have been observed at a user-defined location, where there is no physical reference station, but which lays within the area covered by a reference stations network.

X-pos provides a Virtual RINEX service: Virtual RINEX files can be generated using real X-pos reference data and network corrections pushed by Spider. Such files can be requested by SBC users via the User portal.

Virtual RINEX always requires a kind of GNSS network processing data: obtaining a RINEX file referring to a virtual location will be possible for those periods of time and positions for which an active cluster has provided sufficient network correction data, if successfully pushed to the X-pos data repository.

The Virtual RINEX Service can be accessed, on SBC User portal, through the Post Processing > RINEX Data page: by flagging the “Virtual RINEX” checkbox, the RINEX Data page layout changes to support the elements required for a Virtual RINEX request, so that users can enter their input requirements.

Only users with a suitable subscription can benefit from the Virtual RINEX service. According to the properties of the subscribed article, a limitation to the usage of the Virtual RINEX Data service might be in place; said limitation would be expressed in Epochs. Please note that the Virtual RINEX option is only available on SBC User portal if the Enable Virtual RINEX Service checkbox is flagged in the Settings > X-pos > General page of the Admin portal, SBC related settings section.

Virtual RINEX request

After flagging the “Virtual RINEX” checkbox on the RINEX Data page, this is adapted to the Virtual RINEX Service.

On the right side of the page, users can enter a marker name and number for the output virtual RINEX file, but this is not compulsory. If these pieces of information are not entered by the user, the default values displayed as placeholders in the corresponding fields will be used in the output RINEX files.

Latitude and longitude are the only mandatory fields before submitting a Virtual RINEX request. These define the input position for the request, which will also be the approximate position displayed in the header of the virtual observation file.

There are two ways to provide the input position for a virtual RINEX request.

• Users can manually enter input coordinates in the dedicated fields of the Virtual RINEX page, or copy and paste them in one of the formats listed below:

  • Decimal degrees and N/S/E/W, for example: 37.68455 N; 97.34110 W;
  • Decimal degrees and plus/minus (latitude preceded by a minus sign if it is south of the equator, and longitude if it is west of the prime meridian), for example: 37.68455°; –97.34110°;
  • Degrees/minutes/seconds and N/S/E/W, i.e. DMS (minutes and seconds are fractions of a degree: Each minute is one-sixtieth of a degree, and each second is one-sixtieth of a minute) for example: 37°41'26" N; 97°20'0" W;
  • Degrees/minutes/seconds and plus/minus, for example: 37°41'26"; –97°20'0".
  
  

  Pasted coordinates will be, if needed, automatically converted and displayed in sexagesimal degrees (Degrees/minutes/seconds and N/S/E/W), which are SBC default format for input coordinates.

  Validity ranges for Latitude are from [-90.0000000, 90.0000000] or [-90° 0’ 0.00’’, +90° 0’ 0.00’’], for Longitude from [-180.0000000, 180.0000000] or [-180° 0’ 0.00’’, +180° 0’ 0.00’’]. There is no limitation about the number of supported decimal digits after comma: values pasted by the user will be, if necessary, be displayed truncated in the GUI, but stored as they are for computation.

  Validation checks are in place to grant the usability of input coordinates and error messages will be displayed in case user tries to input out of range or invalid coordinates.

• A cursor on the map can be also used to select the input position for the Virtual RINEX files, by dragging and dropping the cursor on the required location. Moving the cursor on the map immediately updates the latitude and longitude fields (and the other way around).

  When first opening the VRINEX Request page on SBC, Latitude and Longitude fields are populated with the position of the cursor in the map, which is, as default, centered on the map. If manually deleting the content of the Lat and Long boxes without filling in new values, Lat and Long will not be left blank, but will be both populated with the latest used input values (i.e. the values used as input in the latest triggered Transformation request). N/S and E/W will be left as they were before manually deleting the cursor coordinates. In this way, the Lat and Long fields will never be blank.

  Necessary condition for submitting the Virtual RINEX request is that not only RINEX data, but also network correction data is available for the requested time span and position, for the real stations involved in the computation of the virtual file. Whatever way is used to enter input coordinates, the real reference stations involved in the virtual RINEX computation will be displayed on the map, highlighted in blue.

  These depend on the cluster configuration used for the network processing. The involved stations vary according to the user-defined input position. Color coding of the site markers inform on the data availability of RINEX data (green = 80 – 100 %, yellow = 30 – 80 %, red = 0 – 30 %), but only if the sites become blue it means that also network correction data is available.

  If this is the case, the Submit button in the Virtual RINEX page is made available (i.e. the request can be submitted) and, on its left, the available constellations are listed, according to the data of the real reference stations contributing to the Virtual RINEX computation.

  It is not mandatory to enter a value for the ellipsoidal height: if no value is entered by the user, the height of the master station will be used as default – if master and auxiliary sites are available for the user- position and time period. Maximum supported value for ellipsoidal height is 9999.99 m.

  The output observation rate for virtual RINEX files is customizable and, for the moment, limited to multiples of 1 second. Default observation rate is 1 second. Alternative rates can be chosen among the list provided in the drop-down menu in the Virtual RINEX page, before submitting the request.

  After clicking on “Submit”, users are asked to confirm their request. If they do so, they are immediately redirected to the Results page of the User portal.

  Once the Virtual RINEX Request is finalized, Virtual RINEX files can be downloaded from here.

  The real reference stations involved in the computation of the virtual RINEX are summarized in the header section of the file. For example:

  
  

  In this way, master and auxiliary stations are made known.

Virtual RINEX results

For each completed Virtual RINEX request, output is a zipped folder containing one observation file compliant (marker name and number, start time, duration, observation rate, approximate position) to the user-defined input parameters and one navigation file for each of the constellations available in the real (reference and network correction) data.

Virtual RINEX results are included in the Results page of the SBC User portal, where they are accessible via the Virtual RINEX Data tab. They are stored in the database and always available for download from the Results page.

Download will deliver the zipped virtual RINEX files in the local Download directory.

The name of the zipped folder is compliant to the RINEX naming convention and will contain the first four characters of the user-defined marker name, followed by the day of year and start time of the output data. If no marker name is entered by the user, “virt” will be used in the folder name.