Nmea Wizard

Overview

This dialog can be found in ‘Menu-Project-Nmea Wizard’.

The wizard is designed to create NMEA files from routes or tracks. It writes NMEA GGA sentences that can be used as input for other applications.

If not already contained the wizard adds the necessary timing and elevation data to the output.

NMEA GGA Sentences

The NMEA GGA sentence is one of the most common sentences used with GPS receivers. It contains information about position, elevation, time, number of satellites used, fix type, and correction age. A NMEA output file contains a series of timestamped sentences covering a certain amount of time.

$GPGGA,231938.00,4810.4404,N,01147.5834,E,1,08,0.0,513.0,M,,M,,*7f
$GPGGA,231938.10,4810.4403,N,01147.5834,E,1,08,0.0,513.0,M,,M,,*79
$GPGGA,231938.20,4810.4401,N,01147.5834,E,1,08,0.0,513.0,M,,M,,*78
$GPGGA,231938.30,4810.4400,N,01147.5834,E,1,08,0.0,513.0,M,,M,,*78
$GPGGA,231938.40,4810.4398,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*78
$GPGGA,231938.50,4810.4397,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*76
$GPGGA,231938.60,4810.4395,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*77
$GPGGA,231938.70,4810.4394,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*77
$GPGGA,231938.80,4810.4392,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*7e
$GPGGA,231938.90,4810.4391,N,01147.5835,E,1,08,0.0,513.0,M,,M,,*7c

Usage

  1. Select a single track or route.

  2. Call this NMEA Wizard.

  3. Update the field ‘Course Name’. This name will be used as file Name for the output.

  4. Set the ‘Interval’ field in milliseconds.

    Example:
    Let’s say it is required to have 10 entries per second in the Nmea output. 1/10s == 100ms, so the interval needed to be set to 100.

    The wizard interpolates the given route/track timing values according to this interval in a way that the NMEA output is isochronal. It uses the WGS84 ellipsoid as earth reference.

  5. Update field “Start Time” if necessary and specify the time the NMEA output starts with.

    The time specified here is in local time whereas the NEMA sentences contain UTC time. The wizards does the conversion from local to UTC time automatically.

  6. Tick ‘Average Speed’ and specify the average speed for the course. The NMEA sentences must contain timestamps. So if the route/track does not contain timing data the NMEA conversion would fail.

    For all pace units (seconds per …) the value can be specified in format: HH:MM:SS (hour:minute:second).

    • 00:04:45 s/km means 4 minutes and 45 seconds per kilometer.
    • 00:06:10 s/mi means 6 minutes and 10 seconds per mile.

    The checkbox ‘Average Speed’ has three options:

    • Unchecked: The wizard uses the timing values already contained in the route/track. If the route/track does not contain or contains incomplete timing data the wizard will show an error message.
    • Checked: The wizards overwrites the existing route/track timing data with recalculated values based on the given speed.
    • Indeterminate (default option): If the route/track timing is incomplete or missing the wizard recalculates the timing. In case the timing is already complete no changes will be applied.

  7. Tick ‘Update Elevation’ in order to force the wizard to update the elevation values of all calculated course points. The elevation is one filed of the NMEA output sentences.

    This checkbox has three options:

    • Unchecked: The wizard takes the elevation contained in the route/track. If the route/track does not contain or contains incomplete elevation data the related NMEA sentence will not contain altitude values.
    • Checked: The wizards overwrites the existing route/track elevation data with data from an offline elevation data source. This operation fails if no offline elevation data source is available.
    • Indeterminate (default option): If the route/track elevation data is incomplete or missing the wizard tries to retrieve the data from an offline elevation data source (if installed). It doesn’t show an error if this operation fails.

  8. Save the course to a NMEA-file by pressing the related ‘Save’-button. A file dialog appears for choosing destination folder and file name.

If desired use the ‘Default’ button to reset all settings of this wizard to an optimum.

Tip: Tick the checkbox ‘Close wizard after saving’ in order to save a button press and close the wizard automatically after having successfully saved the course.

Manage settings

At the top of the wizard a combobox labeled ‘Profile’ can be found. Press the ‘+’ button to the right of this combobox in order to save the current settings and assign a name to them.

Settings saved in a profile are persistent and can be used to quickly arrange a certain setup, e.g. for a particular workout or sports activity. Use the combobox in order to restore saved settings.

Use the ‘-’ button to delete a profile. Deleting a profile does not change the current settings, the settings remain unchanged until a different profile is selected.