How to Convert GNSS Logs for Post-Processing: UBX, LLH, RINEX Explained
If you work with GNSS receivers for post-processing, whether it’s PPK or static surveying, you’ll need to understand and convert GNSS log formats like UBX, LLH, or RINEX. These files hold the satellite data needed to compute precise positions later — but only if you use the correct format!
In this post, we’ll explain the common GNSS log types, why you need to convert them, and how to do it step by step using tools like RTKLIB, Emlid Studio, and GNSS Converter.
📁 Common GNSS Log Formats
- UBX – Raw binary format from u-blox GNSS chips. Needs conversion before use.
- LLH – Latitude, Longitude, Height. Usually post-processed output.
- RINEX – Standard format for raw satellite observations. Required for PPK/static processing.
- NMEA – Standardized GPS data output. Good for live location, but not useful for PPK.
🔄 Why Convert GNSS Logs?
Most post-processing software — such as RTKLIB, Emlid Studio, or Pix4D — requires RINEX format. This format allows precise positioning by combining satellite observation data from a base and a rover.
🛠️ Tools for GNSS Log Conversion
- 🔧 RTKCONV (part of RTKLIB)
- 🧰 Emlid Studio (Windows/Mac)
- 📱 SW Maps (some export formats)
📚 Step-by-Step: Convert UBX to RINEX with RTKLIB
- Install RTKLIB and open
RTKCONV - Load your
.ubxfile from your GNSS receiver - Set the output format to RINEX 3.03 or 2.11
- Click “Convert” — it will output .OBS and .NAV files
These RINEX files can now be used in RTKPOST or Emlid Studio for further processing.
📚 Convert LLH to CSV
If your GNSS software exports LLH (Latitude, Longitude, Height), you can usually convert this to a CSV for import into CAD/GIS software. Many mapping apps like SW Maps and Field Genius support CSV export directly.
🎯 Tip: Always Save Raw Logs!
Even if you’re working with real-time RTK, saving raw logs allows you to reprocess the data later with better base coordinates or longer baselines.
✅ Best Practice for PPK Projects
- ✔️ Log raw data in UBX or RINEX format
- ✔️ Record both rover and base logs
- ✔️ Use accurate antenna heights and settings
- ✔️ Convert to RINEX and process with matching time windows
📥 Download Useful Tools
Need Help with GNSS File Conversion?
If you’re stuck converting logs or choosing the right post-processing method, we can help. Contact us for free advice and support — especially if you’re using second-hand receivers.
🛒 Check available GNSS equipment
Coming up next: Setting Up Your First Static GNSS Survey with Free Tools