APRS

APRS Bridge

Crow can bridge APRS text messages through a configurable APRS backend, allowing AREDN nodes to send and receive messages with APRS stations. The default backend is APRS-IS, but Crow also supports Dire Wolf KISS-over-TCP and Xastir/YAAC-style TCP text streams.

⚠️ Important: APRS is public amateur-radio traffic. Keep transmit (tx_enabled) disabled until the station callsign, APRS-IS login/passcode or local TNC path, and operator control requirements are fully understood.

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Configuration

Add an aprs block to your crow.conf and include an APRS channel in the channels array:

{
  "callsign": "N0CALL-10",
  "aprs": {
    "enabled": true,
    "callsign": "N0CALL-10",
    "channel": "APRS og==",
    "default_group": "APRSgroup1",
    "inline_max_members": 10,
    "backend": {
      "type": "aprsis",
      "host": "rotate.aprs2.net",
      "port": 14580,
      "tx_enabled": false
    },
    "groups": [
      {
        "name": "APRSgroup1",
        "members": ["N0CALL-4", "N0CALL-7"],
        "repeat_member_messages": false,
        "rate_limit_seconds": 20,
        "max_members": 10
      }
    ]
  },
  "channels": [
    { "namekey": "AREDN og==", "telemetry": false },
    { "namekey": "APRS og==", "telemetry": false }
  ]
}

Field	Description
callsign	Your station callsign with SSID
channel	The Crow channel name that carries APRS traffic
default_group	The group used when no group is specified
inline_max_members	Maximum stations allowed in an inline address list
backend	Connection details for the APRS backend (see below)
groups	Pre-configured station groups for group messaging

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Backends

Crow supports three APRS backend types. Choose the one that matches your station setup.

APRS-IS

Connect to the internet APRS gateway. This is the only backend that requires a passcode — see APRS-IS Passcode below.

For receive only, no passcode is needed (Crow defaults to -1, which gives read-only access). To transmit, set a valid APRS-IS passcode and enable tx_enabled.

"backend": {
  "type": "aprsis",
  "host": "rotate.aprs2.net",
  "port": 14580,
  "passcode": "REPLACE_WITH_APRS_IS_PASSCODE",
  "filter": "b/N0CALL-4/N0CALL-7",
  "tx_enabled": true
}

Field	Default	Description
host	rotate.aprs2.net	APRS-IS server hostname
port	14580	APRS-IS server port
passcode	-1 (read-only)	APRS-IS passcode for your callsign (required for TX)
filter	(none)	Optional server-side filter (e.g. b/N0CALL-4/N0CALL-7)
tx_enabled	false	Enable transmitting messages to APRS-IS

Dire Wolf KISS TCP

Connect to a local Dire Wolf TNC via KISS-over-TCP. No passcode is needed — authentication is handled by the TNC/radio path.

"backend": {
  "type": "kiss_tcp",
  "host": "127.0.0.1",
  "port": 8001,
  "kiss_port": 0,
  "path": [],
  "tx_enabled": true
}

Field	Default	Description
host	127.0.0.1	Dire Wolf host
port	8001	KISS TCP port
kiss_port	0	KISS port number (0–15)
path	[]	Digipeater path (e.g. ["WIDE1-1", "WIDE2-1"])
tx_enabled	false	Enable transmitting

TCP Text Stream (Xastir / YAAC)

Connect to an APRS application that exposes a TNC2-style TCP text interface. No passcode is needed — the connected application handles its own authentication to APRS-IS or RF.

"backend": {
  "type": "tcp_text",
  "host": "127.0.0.1",
  "port": 14580,
  "tx_enabled": true
}

Field	Default	Description
host	127.0.0.1	Application host
port	14580	TCP text port
tx_enabled	false	Enable transmitting

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APRS-IS Passcode

The APRS-IS passcode is a numeric hash derived from your callsign (without SSID). It is used only by the APRS-IS backend to authenticate for transmit access. The other backends (KISS TCP, TCP Text) do not use or need a passcode.

How it works

When Crow connects to an APRS-IS server, it sends a login line:

user N0CALL-10 pass 12345 vers Raven 0.1

• If the passcode is omitted or set to -1, the server grants read-only access — you can receive APRS messages but cannot transmit.
• If a valid passcode is provided and tx_enabled is true, the server grants read-write access.

Generating your passcode

The APRS-IS passcode is a simple hash of your base callsign (without SSID). Many tools can generate it:

• Online: Search for "APRS-IS passcode generator" (e.g. aprs-passcode)
• Command line: Various scripts exist — the algorithm is a public, well-known hash

Note: The passcode is not a security secret — it is a simple validation that you are using your own callsign. Anyone can compute the passcode for any callsign. APRS-IS transmissions are public amateur radio traffic and all standard FCC Part 97 rules apply.

When do you need a passcode?

Backend	Passcode needed?	Why
aprsis — receive only	❌ No	Default passcode -1 gives read-only access
aprsis — transmit enabled	✅ Yes	APRS-IS server requires valid passcode for write access
kiss_tcp (Dire Wolf)	❌ No	Direct TNC connection, no APRS-IS login
tcp_text (Xastir/YAAC)	❌ No	The application handles its own APRS-IS auth

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Sending Messages

All APRS messaging happens on the configured APRS channel (e.g. APRS og==).

Direct message to a station

@N0CALL-4 message text

Send to a configured group

#APRSgroup1 message text

Send to an inline list (without changing the group)

#APRSgroup1 N0CALL-4, N0CALL-7 message text

Create or update a group and send

join #APRSgroup1 N0CALL-4, N0CALL-7 message text

The join command creates the group if it does not exist, replaces its member list with the listed stations, and sends the message to all of them.

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Group Message Repeating

Each group can optionally repeat a received APRS message from one member back out to the other members of the group. Enable this with repeat_member_messages:

{
  "name": "APRSgroup1",
  "members": ["N0CALL-4", "N0CALL-7"],
  "repeat_member_messages": true,
  "rate_limit_seconds": 20,
  "max_members": 10
}

When enabled, a message received from one group member is forwarded to the other members — not echoed back to the sender. Crow applies duplicate suppression and rate limiting to prevent loops.