Repository navigation
comm_b: drop dead UM check in decodeCommB - #155
Merged
Merged
Conversation
decodeCommB rejects the message if mm->DR != 0 || mm->UM != 0, but decodeModesMessage calls decodeCommB (MB field) before it decodes UM, and the message struct is zeroed beforehand, so mm->UM is always 0 at that point and the UM condition has never had any effect. Remove it and say so in the comment; DR is decoded earlier and keeps working. No behaviour change. Measured on a live feed at SKCL (30 min, 5513 DF20/21): UM != 0 in 4 replies (0.1 %), none of them a plausible BDS 5,0/6,0; DR != 0 in 1.0 %. Making the UM check effective instead would start rejecting Comm-B replies carrying a multisite interrogator identifier (IIS), which some SSR networks use, so I did not do that. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_011BqHQDHRKNRuJHR4oQB55L
wiedehopf
approved these changes
Sep 23, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
decodeCommB rejects the message if mm->DR != 0 || mm->UM != 0, but decodeModesMessage calls decodeCommB (MB field) before it decodes UM, and the message struct is zeroed beforehand, so mm->UM is always 0 at that point and the UM condition has never had any effect. Remove it and say so in the comment; DR is decoded earlier and keeps working.
No behaviour change. Measured on a live feed at SKCL (30 min, 5513 DF20/21): UM != 0 in 4 replies (0.1 %), none of them a plausible BDS 5,0/6,0; DR != 0 in 1.0 %. Making the UM check effective instead would start rejecting Comm-B replies carrying a multisite interrogator identifier (IIS), which some SSR networks use, so I did not do that.