What is this tool?

NMEA Generator is a tool for drawing paths on a map. A path represents a person walking or driving around while carrying a GPS device which gives them their current position at regular time intervals, for example once per second. After drawing a path, you can store it as sequence of NMEA sentences on a text file.

Adding single points

The "add point" tool is selected by default when you start the NMEA Generator. When you click on the map using this tool, you add a point to your path. A point represents a position obtained using the GPS device being carried around.

The time elapsed between two consecutive points is always the same and equal to one second by default, but this can be changed on "global settings".

Deleting a point

To delete a point, select the "delete point" tool and click on the point you wish to delete.

Deleting all points (clearing the map)

To delete all points, simply reload the page. The map view will be preserved, so you will not lose the location you are currently working on.

Moving a point manually

The "move point" tool can be used to manually move points around. To move a point, click on it first to select it: the point will then start following the mouse cursor. Clicking once again will release the point at its current position.

Setting latitude and longitude values for a point

The "edit point" tool allows you to directly set the latitude and longitude values for a point. First, select a point, then you will be able to change its latitude and longitude values on the menu. Pressing the "Enter" key will move the point to a new specified location. To release the point, click anywhere on the map.

Adding multiple points on a straight line

With the "multi-point line" tool, you can draw multiple points along a line with the same distance from each other. When you click on the map, all preview points will be added to your path.

Since the time elapsed between two consecutive points is always the same, the "multi-point line" tool represents motion along a straight line with constant velocity. The distance between consecutive points can be changed on the menu, and the associated speed is shown right below it.

Changing the GPS frequency

By default, the time elapsed between two consecutive points on the map is one second. To change this, click on "global settings" and modify the GPS frequency value. This value defines how many positions are obtained per second, so setting it to 10Hz means the time elapsed between two consecutive points will be 100 milliseconds (0.1 seconds).

The GPS frequency is a global setting, so changing its value will affect the associated speeds at all points. As an example, increasing the GPS frequency by a factor of 10 means all speeds will be increased by a factor of 10 as well.

Generating and loading NMEA files

After drawing the desired path, you can generate a file containing a sequence of NMEA (GGA, GSA and RMC) sentences representing the path drawn. To do that, click on the "Generate NMEA file" button.

You can also load NMEA files generated with this or other applications. The path represented by this file will then be drawn automatically on the map. The positions of the points are extracted from the GGA sentences.

Reporting bugs

For reporting a bug, please send an e-mail to diego@assencio.com.

Who created this marvelous tool?

The NMEA Generator has been created by Diego Assencio.