Skip to content

Off-grid: the two official clients use different frequencies, and off-grid does not switch modem settings #3372

Description

@laserir

Summary

Two problems with off-grid (client repeat), found while a user was testing a third-party MeshCore firmware
against a stock T114. Both make the off-grid frequency less of a "well-known meeting point" than intended.

1. The two official clients use different off-grid frequencies.

  • The official MeshCore Android app puts off-grid on 869.945 MHz
  • MeshCore Open uses 869.000 MHz

Both were observed by the same reporter, with screenshots, in
laserir/MCLite#49. Two users who both enable off-grid, both on
official clients, can end up on different frequencies and never find each other. Since the whole value of a
reserved off-grid frequency is that everyone lands on the same one without coordinating, this defeats the
feature quietly, in the situation where it is least convenient to debug.

For what it is worth, 869.000 is what the documentation I could find describes: issue #1700 reports the app
restricting the choice to 433.0 / 869.0 / 918.0, and community guides list the presets as Off-Grid 433 MHz
(433.000), Off-Grid 869 MHz (869.000) and Off-Grid 918 MHz (918.000). I could not find 869.945 documented
anywhere, so it looks like the app moved and the rest did not follow. Either value is fine as an answer; what
would help is one value.

2. Off-grid changes only the frequency, so users from different regions still cannot talk.

Enabling off-grid switches the frequency and leaves spreading factor, bandwidth and coding rate at whatever the
node's normal region preset uses. So an EU/UK Narrow node (SF8 / BW62.5 / CR8) and a Netherlands node
(SF7 / BW62.5 / CR5) both switch to the same off-grid frequency and still cannot demodulate each other.

That is the case off-grid seems aimed at: people who did not plan ahead together, meeting in the field. Two
users from neighbouring countries at the same event is not an edge case. A preset that fixed SF, BW and CR
along with the frequency would make the meeting point actually work.

Why I am reporting rather than patching

I maintain MCLite, a MeshCore-based firmware for the T-Deck Plus and
T-Watch Ultra. Neither of these is fixable downstream: I cannot make the two official clients agree, and if I
pick one frequency I break compatibility with the users of the other. For now MCLite lets the user choose which
client to match, and offers one complete preset that also fixes the modem settings for MCLite-to-MCLite use.
That is a workaround, not a fix.

Notes

  • The February 2026 blog post on off-grid mode says the reserved frequencies were "still being settled/finalised",
    so this may simply be unfinished rather than a regression.
  • https://api.meshcore.nz/api/v1/config serves the normal region presets but has no off-grid entries, so there
    is currently no machine-readable source that clients or third-party firmware could sync from. Adding off-grid
    presets there, with their modem settings, would fix both problems above at once and let everyone track changes
    automatically.

Happy to test any change against T-Deck and T-Watch hardware.

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions