Architecture

MeshSky is built as three cooperating tiers bound together by a single gossip protocol. Every tier is independently operable, and every node is verifiable from cryptographically signed inputs.

The three tiers

1. Feeders

Feeders are the edge of the mesh. A feeder is any device that:

• Listens to one or more aviation radio bands (ADS-B 1090, UAT 978, Mode-S, ACARS, …).
• Time-stamps each reception with a sub-microsecond clock (typically GPS-disciplined).
• Signs the resulting observation record with its long-lived feeder key.
• Streams those records to one or more AirBridge relays.

A feeder can be a $35 Raspberry Pi with an RTL-SDR, an OpenWrt router, or a rack-mounted multi-channel SDR. The protocol is identical.

2. AirBridge

AirBridge is the gossip layer. AirBridge nodes:

• Accept signed observations from many feeders.
• De-duplicate, batch, and fan-out observations to peer relays.
• Maintain a Voronoi-style geographic shard map so most traffic stays regional.
• Speak QUIC to peers and TLS+TCP to feeders that can’t speak QUIC.

A healthy mesh has many AirBridges per region. They peer with each other in a small-world topology so any observation reaches every interested ControlTower in well under 200 ms.

3. ControlTower

ControlTower is the apex. ControlTower nodes:

• Ingest the gossiped observation stream.
• Fuse ADS-B, Mode-S, and MLAT solutions into authoritative tracks.
• Compute MLAT solutions for non-cooperative aircraft.
• Maintain feeder reputation rollups.
• Expose a REST + streaming public API.

Crucially, anyone can run a ControlTower. Outputs are reproducible from the signed observation log, so consumers can verify the network end-to-end.

How it fits together

     ┌─────────────┐    ┌─────────────┐    ┌─────────────┐
     │ ControlTower│ ←→ │ ControlTower│ ←→ │ ControlTower│
     └──────┬──────┘    └──────┬──────┘    └──────┬──────┘
            │                  │                  │
            ▼                  ▼                  ▼
     ┌──────────────────────────────────────────────────┐
     │                 AirBridge mesh                   │
     │   (regional gossip relays, QUIC peering)         │
     └─────────────────────┬────────────────────────────┘
                           │
              ┌────────────┼────────────┐
              ▼            ▼            ▼
         ┌────────┐   ┌────────┐   ┌────────┐
         │ Feeder │   │ Feeder │   │ Feeder │
         └────────┘   └────────┘   └────────┘

Design principles

1. Verifiable, not trusted. Every output is reducible to signed inputs.
2. No single point of failure. Lose any tier of any region; the mesh routes around the loss.
3. Bandwidth-aware. The protocol negotiates compression and sample rates per peer.
4. Open by default. Implementations, the spec, and the data are all public.
5. Privacy-respecting. Operators choose what to share, with first-class fuzzing & opt-in identity.

Where to go next

• The Protocol doc covers wire format and signing.
• The Feeders doc shows how to run one.
• The Security doc explains the threat model.