NI GNSS Simulation Toolkit Features

NI GNSS Simulation Toolkit Help

Edition Date: April 2013

Part Number: 372446D-01

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Simulating Real Locations using up to 12 GPS Satellites

The toolkit can simulate up to 12 GPS satellites. The number of GPS satellites chosen depends on the almanac and ephemeris files, GPS time, and receiver location that you specify. The toolkit validates several satellite parameters before simulating the satellites, including the following satellite parameters:

  • Valid Doppler value
  • Valid pseudorange
  • Good health of the satellite
  • Satellite elevation angle

If the satellite parameters are valid at the specified GPS time, the toolkit selects the satellite and uses it to simulate a GPS signal.

The toolkit collects GPS satellite information based on the almanac and ephemeris files that you specify. When this information is available, the toolkit continuously updates the Doppler shifts between the satellites and simulated receiver so that the simulated signal is as close to a real location as possible.

Selecting GPS Almanac Files

The toolkit requires you to provide almanac files in the SEM file format (.al3 or .AL3). The almanac files are available for download at the USCG Navigational Center GPS Almanac Information website at http://www.navcen.uscg.gov/?pageName=gpsAlmanacs. You can use a custom almanac file; however, the file must conform to the SEM file format.

Selecting GPS Ephemeris Files

The toolkit requires you to provide ephemeris files that conform to the Receiver Independent Exchange (RINEX) 2.0 format. The ephemeris files are available for download at the Crustal Dynamics Data Information System (CDDIS) GNSS Data website at http://cddis.gsfc.nasa.gov/gnss_datasum.html. You can use a custom ephemeris file; however, the file must conform to the RINEX 2.0 format.

Simulating Real Locations Using Up to 12 GLONASS Satellites

The toolkit can simulate up to 12 GLONASS satellites. The number of GLONASS satellites chosen depends on the almanac and ephemeris files, UTC time, and receiver location that you specify. The toolkit validates several satellite parameters before simulating the satellites, including the following satellite parameters:

  • Good health of the satellite
  • Satellite elevation angle

If the satellite parameters are valid at the specified UTC time, the satellite is selected and used to simulate a GLONASS signal.

The toolkit collects GLONASS satellite information based on the almanac and ephemeris files that you specify. When this information is available, the toolkit continuously updates the Doppler shifts between the satellites and simulated receiver so that the simulated signal is as close to a real location as possible.

Selecting GLONASS Almanac Files

The toolkit requires you to provide almanac files in .agl format. The almanac files are available for download at the Federal Space Agency Information-Analytical Centre at ftp://ftp.glonass-iac.ru/MCC/ALMANAC/. You can use a custom almanac file; however, the file must conform to the .agl file format.

Selecting GLONASS Ephemeris Files

The toolkit requires you to provide ephemeris files that conform to the Receiver Independent Exchange (RINEX) 2.01 format. The ephemeris files are available for download at the Crustal Dynamics Data Information System (CDDIS) GNSS Data website at at ftp://cddis.gsfc.nasa.gov/glonass/ or at the Federal Space Agency Information-Analytical Centre at ftp://ftp.glonass-iac.ru/MCC/BRDC/. You can use a custom ephemeris file; however, the file must conform to the RINEX 2.01 format.

Simulating Receiver Trajectories

The toolkit can simulate a variety of receiver trajectories using either the script or simple mode in the Trajectory Mode property or NIGPS_TRAJECTORY_MODE attribute.

On the Fly Input Mode

You can use the toolkit to simulate receiver trajectories by updating the receiver location on the fly.

Signal Generation Duration

You can use the toolkit to generate data for one ephemeris file, corresponding to 24 hours of signal generation capability.

Adjustable Satellite Power

You can use the toolkit to dynamically change the power of individual satellites by using software scaling on the individual GNSS-coded satellite data.

SBAS Capability

You can use the toolkit to simulate WAAS satellites to augment GPS L1 signal. WAAS is the only supported SBAS in the current version of the toolkit. The toolkit simulates only those user-specified WAAS satellites that are present in the WAAS GEO file.

Selecting WAAS GEO Files

You can provide the WAAS GEO files to the toolkit when WAAS is enabled. The WAAS GEO files are available for download at the WAAS Test Team website at http://www.nstb.tc.faa.gov/DisplayNSTBDataDownload.htm.

LabVIEW Real-Time Module Support

You can install the toolkit on a real-time target using the LabVIEW Real-Time Module.

Creating NMEA log files

You can use the toolkit to log simulated receiver position using NMEA format.

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