fix(GPS): correct GPS_RTCM_DATA fragmentation for MAVLink reassembly - #14772
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DonLakeFlyer merged 3 commits intoAug 8, 2026
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Match MAVLink/ArduPilot/PX4 rules: unfragmented packets up to 180 bytes, zero-length terminator for exact 180 multiples under 4 fragments, and stream oversized (>720) payloads as unfragmented chunks instead of overflowing the 2-bit fragment ID. Emit one UDP-validated RTCM frame per sequence.
RTCMUdpInput now emits one CRC-valid frame per signal instead of concatenating frames, which left extractValidFrames without callers. Concatenated multi-frame output is exactly the shape that broke GPS_RTCM_DATA sequencing, so drop it rather than leave it around.
Add RTCMUdpInputTest: raw passthrough with validation off, one signal per CRC-valid frame, bad-CRC frames dropped mid-stream, and parser state carried across split datagrams. RTCMUdpInput now resolves port 0 to the actual bound port so tests can bind ephemerally without racing for a fixed port. Also cover the 541..719 pack() range (four fragments with a non-full tail, no terminator).
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #14772 +/- ##
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+ Coverage 25.47% 32.72% +7.25%
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Files 769 784 +15
Lines 65912 67602 +1690
Branches 30495 31311 +816
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+ Hits 16788 22120 +5332
+ Misses 37285 30596 -6689
- Partials 11839 14886 +3047
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Build ResultsPlatform Status
All builds passed. Pre-commit
Pre-commit hooks: 0 passed, 0 failed, 0 skipped. Test Resultslinux-coverage-integration: 37 passed, 0 skipped Code Coverage
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Updated: 2026-08-07 03:26:44 UTC • Commit: 20a96c1 • Triggered by: Android |
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Pull request overview
Corrects RTCM-to-MAVLink packetization to satisfy ArduPilot and PX4 reassembly requirements.
Changes:
- Handles fragmentation boundaries, terminators, and oversized frames correctly.
- Emits validated UDP RTCM frames individually.
- Adds comprehensive packetization and UDP tests.
Reviewed changes
Copilot reviewed 13 out of 13 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
src/GPS/RTCM/RTCMMavlink.h |
Defines packetization API and limits. |
src/GPS/RTCM/RTCMMavlink.cc |
Implements compliant fragmentation and streaming. |
src/GPS/RTCM/RTCMUdpInput.h |
Documents per-frame validated emission. |
src/GPS/RTCM/RTCMUdpInput.cc |
Emits each valid RTCM frame separately. |
src/GPS/RTCM/RTCMParser.h |
Removes obsolete extraction API. |
src/GPS/RTCM/RTCMParser.cc |
Removes concatenating extraction implementation. |
test/GPS/RTCMMavlinkTest.h |
Declares packetization tests. |
test/GPS/RTCMMavlinkTest.cc |
Tests fragmentation boundaries and flags. |
test/GPS/RTCMUdpInputTest.h |
Declares UDP input tests. |
test/GPS/RTCMUdpInputTest.cc |
Tests validation and per-frame emission. |
test/GPS/RTCMParserTest.h |
Removes obsolete test declarations. |
test/GPS/RTCMParserTest.cc |
Removes extraction tests. |
test/GPS/CMakeLists.txt |
Registers the new unit tests. |
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Summary
Make QGC's
GPS_RTCM_DATApacking match the MAVLink reassembly contract used by ArduPilot and PX4.Problem
RTCMMavlinktreated payloads of size 180 as fragmented without a completion marker, omitted the required zero-length terminator for exact multiples of 180 under four fragments, and could emit fragment IDs beyond 0–3 for RTCM frames larger than 720 bytes. ArduPilot discards incomplete sequences; PX4 carries an explicit compatibility workaround for older QGC senders.Solution
RTCMParser::extractValidFrames— concatenating frames back into one blob is the pattern that broke sequencing