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Record and Playback

Note: This is an optional feature for which the Record and Playback option (OPT-RP) is required.

The Record and Playback software converts recorded NMEA messages into scenario, trajectory, and event files. You can then upload these files to your GSG unit where they can be played back in order to recreate the original scenario.

Standard Workflow

  1. While traveling in a car along the planned test route, record NMEA data by using a GNSS receiver and antenna (included in the OPT-RP kit), connected to a laptop computer with StudioView installed on it. StudioView will record the data generated.
  2. Run the recorded trajectory through the Scenario Generator in StudioView. Note that your StudioView computer must be connected to the GSG unit, and that the OPT-RP option must be enabled.
  3. StudioView will automatically generate the scenario, event and trajectory files for you.

  4. Upload the generated scenario files to your GSG unit, and playback the scenario.

Installation of the OPT-RP Software

From the GSG Software CD, copy the file setup_vx.x.exe to your PC. Run the executable to install the Record and Playback software.

Usage Notes

  1. The Record and Playback software is intended for use with a properly licensed GSG. If your GSG needs a Record and Playback license, please contact Spectracom (see Technical Support.)
  2. The Record and Playback program uses the GSG VISA address to check for a valid license file. This address is also used to upload the results to the GSG if the Auto upload feature is enabled. GSG supports communication via TCP/IP, USB, and GPIB. For TCP/IP connections, this program will accept IPv4 addresses as well as VISA resource strings. The following lines describe the resource name syntax.
  3. VISA resource string format:
    • TCPIP[board]::host address[::LAN device name][::INSTR]
    • USB[board]::manufacturer ID::model code::serial number[::USB interface number][::INSTR]
    • GPIB[board]::primary address[::GPIB secondary address][::INSTR]
  4. For more information about the VISA address, please see:

    http://zone.ni.com/reference/en-XX/help/371361N-01/lvinstio/visa_map_address/

  5. The signal‐to‐noise ratio (SNR) is used to compare the level of a desired signal to the level of background noise. The SNR is expressed in decibels (dB) and is used to describe the GNSS signal strength in NMEA‐0183 GSV sentences.
  6. On the GSG unit, signal strength is specified in dBm, i.e. the power ratio in decibels of the measured power referenced to one milliwatt (mW). Since dB cannot be directly converted into dBm, the Record and Playback program relies on a decibel offset value. This offset value maps the NMEA signal strength (in dB) to the GSG signal strength (in dBm). An offset value of [‐160] is recommended to begin with. This value can be adjusted up or down until the offset is satisfactory.
  7. You must also specify any scenario options that cannot be extracted from NMEA sentences. These options include signal type, antenna model, troposphere model, temperature, pressure, humidity, and elevation mask. For more information, see under "Select" Menu.
  8. The input file name specifies the NMEA‐0183 file to parse. This file should only contain NMEA‐0183 GGA, RMC, and GSV sentences.
  9. The output file name specifies the name of the scenario as it will appear on the GSG unit. Do not include a file extension. The Record and Playback program outputs scenario, trajectory, and event files. It will automatically append the correct file extension for each output file. By default, the output files will be generated and saved in the same directory as the input file.