Reading NMEA sentences
A GNSS receiver prints lines of text called NMEA sentences. Paste GGA lines from your Lab 1 log, or use the samples, and see each field decoded the way your gps_driver reads it: checksum, UTC time, latitude and longitude, fix quality, satellites in use, and HDOP.
Starting...
NMEA input
Paste lines from your Lab 1 log, one per line. The table updates as you type.
Try this
- Click the line marked Bad checksum. Only one digit of the altitude changed, but the checksum no longer matches, so your driver should drop the whole line.
- Look at the two red cards under a good fix. Reading ddmm.mmmm as plain degrees puts you about 30 km away; forgetting that W means negative puts you on the other side of the planet.
- Compare the fix quality of lines 1 to 3: standalone (1), RTK float (5), and RTK fixed (4). Those are the codes you will see from the RTK receiver in Lab 2.
- Paste a line from your own Lab 1 recording and check that your driver’s latitude and longitude match this page to 7 decimal places.
Notebook
Work with the same script in cells, like Jupyter, right here in the browser. Edit any cell and run it. Nothing is saved: Reset brings a cell back, and Download .ipynb keeps your edited version for VS Code or Jupyter.
Loading Python...
The Python script: nmea_gga.py
This is the script the page runs. Run it yourself with python3 nmea_gga.py.