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§ 008. Why UBX not converted to RINEX OBS?


Table of contents:

# Intro

Sometimes RINEX Tools service is provided by UBLOX UBX files for RINEX converting which unfortunately can't be converted. Here we'd like to point on few obvious reasons why UBX log can't be converted to RINEX and how to pre-check UBX log to be sure in advance it has all the data required for RINEX converting.

# Minimal requirements to UBX logs

First, let's start w/ minimal requirements to UBLOX UBX logs provided into RTools for successful converting to RINEX OBS. These requirements are:

  • The receiver should track satellites (obviously, nothing tracked - nothing to be converted)
  • The receiver should already determine GPS time
  • The log should contain UBX-RXM-RAWX message (receiver raw measurements like code, phase etc)
  • UBX-RXM-RAWX should be logged w/ standard rate (say, once per 5 min - is not 'standard' rate)

As one may see, requirements are not difficult to be met. And yet...

# Case 1. No UBX, NMEA only

Ok, first example. Sounds like standard UBX log. Upload it into RTools for RINEX converting.

Converting to RINEX is failed... RTools inform us that file format doesn't meet requirements or not supported.

Indeed - are we sure that there are UBX messages inside? Are we sure the log was logged at right baud rate of serial port? Let's check it!

WAY service will help us w/ it. Go to WAY uploading page, choose our 'unconvertable' UBX log and set up SCAN mode. WAY will check the file for ALL known / supported formats and protocols and will give us short statistic w/ detected messages types.

Well, the log contains NMEA messages only! There is no binary UBX data at all. Now it is clear why RTools refused to convert it to RINEX.

# Case 2. No UBX-RXM-RAWX

Well, one extra file. At first glance there is binary messages inside, file extension is *.UBX. And yet... Converting to RINEX is failed again. RTools informs us that 'UBX-RXM-RAWX' message w/ raw measurements is not found.

Let's check w/ WAY. Wow! Just NAV-HPPOSLLH message. Looks like someone forgot to enable UBX-RXM-RAWX output in u-center.

# Summary

Requirements to UBX logs are listed which must be met for effective converting to RINEX. Few practical examples of 'bad' UBX logs are considered. It is shown how to scan UBLOX UBX log file and get idea of what is inside w/ help of WAY online service.


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