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Duplicate Repeater IDs

Packets identify each repeater they pass through by a short hop ID: the first 1, 2 or 3 bytes of its Public ID. As a region grows, two repeaters can end up with the same hop ID. This is a collision, and MeshMapper can't always tell which of the two a packet went through.

This page explains how MeshMapper decides, what you'll see, and how to fix it.

The best fix is multi-byte

With 1-byte IDs there are only 254 to go around, so collisions are common. With 2 or 3 bytes they become rare. See Multi-Byte Repeaters to upgrade.

The Rules

MeshMapper follows two rules, on the server and on the map.

Rule A: When a Repeater Is Ambiguous

A repeater is marked Ambiguous if it can't be told apart from another repeater at its own width:

  • A 1-byte repeater is judged on its first byte.
  • A multi-byte repeater is judged at the width it advertises (at least 2 bytes).

This is judged separately for each repeater, so a collision doesn't always flag both:

Repeaters Result
AB (1-byte) and AB (1-byte) Both Ambiguous. They can't be told apart.
AB (1-byte) and AB12 (2-byte) Only AB is Ambiguous. A 1-byte AB hop could be either, but AB12 is unique at its own width.
AB12 (2-byte) and AB9F (2-byte) Neither. They're different at 2 bytes.

Rule B: When a Ping's Hop Is Credited

A hop in a ping's path is credited to a repeater only if exactly one repeater's ID starts with that hop, at the hop's own width.

  • One match: credited to that repeater.
  • More than one: ambiguous. The ping still counts for coverage, but isn't linked to any repeater.
  • No match: unknown. The ping still counts, unlinked.

Other Rules

  • Discovery (DISC) pings carry the repeater's full Public ID, so they're always credited to the right repeater, even during a collision. TRACE pings only carry the short hop ID, so Rule B applies to them.
  • Corrupted adverts: a garbled advert that makes a near-copy of a repeater's ID is recognised as the same repeater and doesn't make it Ambiguous.
  • Far-away matches: if the only match is unusually far from the ping, it's held for a region admin to review instead of being linked.
  • Groups: in a multiregion group, collisions are checked across every region in the group.
  • Outside the boundary: repeaters outside a region's boundary are still counted (tagged Out of Region), because RF doesn't stop at the border.

What You'll See

  • On the map: the repeater's chip has a red edge (Ambiguous in the Legend).
  • In its details: an Ambiguous status and a red AMBIGUOUS ID DETECTED box listing its Collision Group.
  • On a ping: when you select a single ping with an ambiguous hop, red dashed Duplicate lines go to each possible repeater with their distance, so you can judge which was likely involved.
  • On leaderboards: Ambiguous repeaters stay listed, marked with a red * ("Ambiguous ID"). Pings where their hop was ambiguous don't count towards them.
  • For admins: an Ambiguous Public IDs Detected box in the admin panel, plus an optional Discord DM and region webhook (both called Ambiguous Repeater ID).

What Happens to the Data

A ping whose hop was ambiguous is stored as unlinked, and stays unlinked, even after the collision is resolved. MeshMapper won't guess later.

When a new repeater creates a collision, MeshMapper also checks recent pings that were linked to the old repeater before the collision existed. Any that could now belong to either repeater are unlinked.

Avoiding Collisions

Upgrade to Multi-Byte

The most effective fix. Once repeaters advertise 2 or 3 bytes, most collisions clear up on their own. See Multi-Byte Repeaters.

Wardrive in Hybrid Mode

Hybrid mode sends Discovery (DISC) requests: "who's out there?" Any repeater in range (firmware 1.10+) replies with its full Public ID, so the ping is credited correctly even when its short ID collides.

Enforce Hybrid

Region admins can require Hybrid mode for a radio preset with the Hybrid column under Settings → Wardriving → Radio Channels in the admin panel. Wardrivers on that preset can't use Active mode.

Resolving a Collision

Automatic Cleanup

Often a collision is an old, offline repeater still on record when a new one comes online. That fixes itself:

  • Every day, a repeater that hasn't been heard for the region's Repeater Inactive After (Days) (default 30, under Settings → Repeaters, Neighbours & Scopes) is marked Inactive and drops off the map.
  • Inactive repeaters don't count in collisions, so the remaining repeater returns to normal on the next advert in that ID range.
  • If the silent repeater comes back on air, it's reactivated, and if the ID still collides, it's Ambiguous again.

Inactive repeaters aren't deleted unless the region has set a retention period for removing them.

Bypass Auto Delete

For a repeater that goes offline for long periods (seasonal, remote), admins can tick Bypass Auto Delete in its edit window. Automatic cleanup then skips it. It also keeps its partner Ambiguous while it's away.

Manual Resolution

If both repeaters are live and genuine:

  • The best fix is to ask one owner to generate a new ID for their repeater, or to upgrade both to multi-byte.
  • If one repeater is gone for good, a region admin can set its Status to Inactive or Disabled in the admin panel. The other returns to normal on the next advert.
  • Setting an Ambiguous repeater back to Active doesn't stick. It's re-checked on the next advert.

Deleting doesn't help

A deleted repeater adds itself back on its next advert. Change its status instead.

Turning Detection Off

A region can turn this off with Disable Duplicate ID Detection Logic, and show every possible repeater instead. See Override Duplicate IDs.

Repeater States

For every repeater state and colour (Active, New, Stale, Ambiguous, Backbone), see Repeater States.