Output format¶

By default, datalink emits newline-delimited JSON on stdout.
Every decoded row uses a common DecodedEvent envelope.

JSONL format¶

datalink normalizes all supported input paths into a common event shape.

The output includes:

bearer: vhf, vdl2, hfdl, decoded, or unknown;
source: file, SDR, websocket, or standalone decode metadata;
receiver: channel information for I/Q receivers;
aircraft: best-effort ICAO24, aircraft id, or registration;
kinematics: best-effort position, speed, altitude, or meteorological values;
raw_frame_hex: raw frame bytes when available;
message: the protocol-specific decoded body.

An ADS-C event captured from the airframes.io websocket feed looks like this:

{
  "event": "message",
  "timestamp": 1781378212.80346,
  "bearer": "unknown",
  "source": {
    "id": "airframes",
    "name": "airframes.io",
    "class": "events",
    "format": "airframes.io"
  },
  "aircraft": {
    "icao24": "3c4582",
    "aircraft_id": 2727,
    "registration": "D-AALB"
  },
  "kinematics": {
    "position": {
      "latitude": 45.166098,
      "longitude": 24.740809
    },
    "altitude_ft": 37000,
    "track": 116.67,
    "derived_from": "airframes_flight"
  },
  "message": {
    "kind": "airframes",
    "data": {
      "payload": {
        "label": "A6",
        "text": "/PIKCPYA.ADS.D-AALB08060A1812B113227921E314E5DD",
        "from_hex": "90",
        "to_hex": "3C4582",
        "latitude": 0.0,
        "longitude": 0.0,
        "altitude": 0.0,
        "track": null,
        "source_type": "unknown",
        "timestamp": 1781378212.80346,
        "created_at": 1781378212.802201,
        "frequency": 0.0,
        "id": "6885605082",
        "airframe_id": 2727,
        "flight_id": 5544633336,
        "tail": "D-AALB",
        "link_direction": "uplink",
        "airframe": {
          "icao": "3C4582",
          "tail": "D-AALB"
        },
        "flight": {
          "latitude": 45.166098,
          "longitude": 24.740809,
          "altitude": 37000.0,
          "track": 116.67
        }
      },
      "dst": {
        "icao24": "3c4582",
        "addr_type": "aircraft"
      },
      "app": {
        "Arinc622": {
          "atsu_address": "PIKCPYA",
          "imi": "ADS",
          "registration": "D-AALB",
          "payload": {
            "kind": "Adsc",
            "data": {
              "atsu_address": "PIKCPYA",
              "registration": "D-AALB",
              "tags": [
                {
                  "EventContractRequest": {
                    "contract_number": 6,
                    "groups": [
                      {
                        "kind": "lateral_deviation_change",
                        "value": {
                          "threshold_nm": 3.0
                        }
                      },
                      {
                        "kind": "vertical_speed_change",
                        "value": {
                          "threshold_ft_per_min": -5056
                        }
                      },
                      {
                        "kind": "altitude_range",
                        "value": {
                          "ceiling_ft": 220425,
                          "floor_ft": 216675
                        }
                      },
                      {
                        "kind": "report_waypoint_changes"
                      }
                    ]
                  }
                }
              ]
            }
          }
        }
      }
    }
  }
}

For an ACARS frame decoded directly by the VHF path, the top-level envelope is the same, but message.kind is "acars" and message.data contains the ACARS fields such as label, text, and app.

The exact nested body depends on the decoded protocol, but the top-level envelope is designed to make mixed sources easier to consume.

Sinks¶

By default, decoded events are written to stdout as JSONL.

[output]
jsonl = "-"

Write to a file and optionally publish to Redis:

[output]
jsonl = "datalink.jsonl"
redis_url = "redis://localhost:6379"

Redis topics are selected from decoded application type where possible, including:

datalink-acars
datalink-adsc
datalink-cpdlc
datalink-hfdl
datalink-sq
datalink-vdl2
datalink-x25
datalink-xid
datalink-unknown