How to Convert UBX to RINEX and Check the Output

If you recorded your u-blox receiver's output as a .ubx file using u-center, u-center 2, or a custom logging app, and your processing software asks for RINEX, you can convert it with the RoboGNSS RINEX converter. It is free with an account and accepts files up to 50 MB. You do not need to install a desktop converter.

The recording must contain raw GNSS observations. Your next step might be a base-coordinate calculation in OPUS or a post-processed kinematic (PPK) workflow, depending on what you recorded and what your software accepts.

When to convert a UBX file

Use the converter when you have a raw receiver recording and need to:

• Prepare an observation file for a positioning service that accepts RINEX.
• Supply base or rover observations to your PPK software.
• Share observations with someone who uses different GNSS software.

Check whether your destination already accepts UBX. If it does, you may be able to use the original recording directly.

Before recording: enable the raw-data messages

For a receiver that supports full raw measurements, such as the ZED-F9P or ZED-X20P, enable these messages on the port connected to your logging app:

• UBX-RXM-RAWX for the raw observations used to create the RINEX observation file.
• UBX-RXM-SFRBX for the broadcast navigation data used to create a navigation file.

Use the logging app appropriate for your receiver to save the incoming binary UBX messages. A position-only track is not enough. Check your receiver's documentation before collecting data: raw-data support and message names vary by model and generation. The ZED-F9P data sheet and ZED-X20P data sheet describe these two messages.

Convert your log in five steps

1. Open the RINEX converter and sign in. Do this before choosing your file.
2. Choose your receiver log. Select the original .ubx file, up to 50 MB.
3. Choose the input format. Start with Auto-detect, or select u-blox UBX if you know the file's format.
4. Choose the RINEX version your processing software accepts. The default is 3.04; 3.02 and 2.11 are also available. For a UBX log, the recording date can be left blank; when entering a date, use the recording date rather than today's date.
5. Select Convert to RINEX, then download the ZIP. Extract it to find the observation file and, when the recording provides it, a navigation file.

Keep the original UBX recording alongside the converted files. If you later need a different RINEX version, you can convert the original again.

Check the result before processing

Start with the observation file, which ends in .obs. The navigation file, when included, ends in .nav; follow your processing software's instructions for which files to load.

Open the observation file in a text editor or GNSS software and check:

• Recording date and time span. Confirm that it covers the session you need. The date the file was converted is separate from the dates of its observations.
• Recorded signals. Check that the file contains the satellite signals and frequencies your next step requires. Changing the file format cannot add measurements that were never recorded.
• Antenna details. Confirm the antenna model and measured height wherever your processing software asks for them. Do not assume a blank field or a zero height describes your setup.

For a field-by-field explanation, see Robota's guide to RINEX files.

Before sending the file to OPUS

OPUS accepts RINEX 2 and RINEX 3, but the recording must also meet its observation requirements. These include dual-frequency GPS L1/L2 data, a stationary antenna, and a suitable recording duration. A short or single-frequency recording does not become suitable simply because it converts successfully.

OPUS uses only the GPS observations, even when a file includes other satellite constellations. Check that the required GPS measurements are present; recording other constellations does not replace them.

Check the current NGS requirements before collecting data or submitting a file. Enter the correct antenna type and antenna height when you submit.

If the conversion does not give you what you need

No observations found: Check that raw-observation logging was enabled on the receiver and that you selected the correct input format. A position-only track or NMEA log cannot replace the measurements needed for this workflow. u-blox's raw-data guide explains which receivers support them.

No navigation file: Check whether your logging app captured the receiver's navigation messages. If your processing software needs navigation data, follow that software's instructions for supplying a suitable navigation file.

The next service rejects the file: Check its accepted RINEX versions, required signals, recording duration, and antenna information. A successful conversion is the file-preparation step; the positioning service still has its own requirements.

Ready to prepare your log? Convert your UBX file to RINEX, then check the result before starting your processing job.