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What's New?

Edge

ITU-R M.1371-6 alignment

The JSON output has been aligned with the 2026 ITU-R M.1371-6 spec.

  • Message type 28 (single-slot AtoN report, M.1371-6 §A7-3.26) is now expanded into structured JSON fields. See the type 28 reference.
  • Messages 25 and 26: the addressed/broadcast envelope is now exposed in JSON; when the payload carries a recognised (dac, fid) pair the same ASM fields are emitted as for messages 6 and 8.
  • Spec field renames in messages 1/2/3, 4/11, 9, 18, 19, 21: bits previously labelled regional/reserved are now exposed under their M.1371-6 names (power, transmission_control, alt_sensor, aton_status, …). See the JSON reference for the per-message field list.
  • Type 23: ship_type is renamed to shiptype and now includes a shiptype_text description, matching the convention used elsewhere.

Version 0.68

Web Viewer

  • Fixed vessel track polylines drifting ahead of the ship marker due to an incremental merge bug
  • Incremental plane updates now support ?since= with timeout-based cleanup of stale aircraft
  • RainViewer refresh interval increased from 2 minutes to 10 minutes
  • RainViewer updates pause while the browser tab is hidden
  • Removed the clouds overlay layer
  • Fixed sticky hover suppression after map moves

Data and API Fixes

  • Fixed MMSI key corruption in path JSON
  • Added support for @filename response files

Service and Packaging

  • systemd unit no longer uses a bash -c subshell

Version 0.67

New Features

HydraSDR Support

HydraSDR is now a supported input device. See the HydraSDR input page for details.

Duplicate Removal

When combining multiple input streams, overlapping reception can result in duplicate messages. To remove duplicates from output channels, use the unique option. For example, the following removes duplicates from both console and a UDP stream:

AIS-catcher -o 1 unique on -u 127.0.0.1 5012 unique on

In JSON, set the unique key to true (remove duplicates) or false (default). Note that this could come at a performance cost that increases with the number of MMSIs so keep an eye on that.

Downsampling Options

Two additional options, position_interval and own_interval, downsample position messages and VDO messages by limiting each MMSI to at most one update per specified interval (in seconds). Both default to 0 or, equivalent, false (disabled).

Example: 

AIS-catcher -u 127.0.0.1 5012 position_interval 30

Alternatively, these options are available in the Visual Web Control interface:

image

Thanks to user Manny for suggesting these options.

Note: These options are intended for users aggregating across multiple receivers to reduce bandwidth, and have not been optimized for large vessel counts.

Serial Device Improvements

  • init_seq now accepts multiple comma-separated commands
  • Fixed init_seq issues on macOS (and Windows buffer flushing during init)
  • Serial devices supporting AIS-catcher format can now relay warning, info, and error messages through the program
  • New flowcontrol option (hardware/software/none) and disable_xonoff switch
  • Serial port opened in non-blocking mode to avoid DTR hang on some adapters
  • New dump_file option to save raw serial bytes for debugging
  • DC16H frame format support

Zones

Support for tailoring routing of messages from receivers to output channels via zones in JSON configuration and Visual Web Control.

Channel Designation (AB/CD)

Channel designation is now configurable via JSON config and is shown in model startup output of the Visual Web Control.

Microsecond Timestamps

rxuxtime field added to JSON_FULL output, providing microsecond-resolution receive timestamps. NMEA 4.0 tag-block timestamps now use microseconds where available.

Reboot Watchdog

A systemd OnFailure watchdog can automatically reboot the host if AIS-catcher stops repeatedly. Configurable burst/interval parameters with a 5-minute grace period after toggling, controlled via the install script.

Output and Configuration

  • Receiver index is now included in output; -v applies to all receivers, -v+ to the last one only
  • webcontrol_http option for the webviewer
  • ssl_verify setting on HTTP outputs to disable TLS certificate verification when needed
  • NMEA 4.0 tag blocks now include the group ID only for multi-line sentences
  • Default repeat for message type 27 is now 3
  • Aliases: rssi/fo for signalpower/ppm; DESC for description
  • Internal settings unified to a key-based API with structured error reporting (SetKey); legacy aliases kept for backward compatibility
  • Community feed restricted to local SDR hardware only

Web Viewer

Vessel Tracks — Major Overhaul

  • Incremental (delta) loading: only new path points are fetched on each update
  • Tracks capped at 250 points per vessel, consistent between "Show Track" and "Show All Tracks"

Multi-Receiver View

A new view in the webviewer lets users see and switch between multiple receivers from a single interface.

Realtime and UI Improvements

  • Realtime NMEA tab now displays the shipname instead of just MMSI
  • Station name passed via plugins.js for immediate tab title display
  • Community feed gained a binary compact endpoint, sprite-sheet icons, and click-to-livemap
  • Dark info panel, darker hover background, fixed truncated SVG flags
  • Fixed RainViewer overlay (CORS and API path), MBTiles import, distance charts, "Show all tracks", strict-mode violations, missing planes sprite, ship-shape highlight stuck on hover
  • Shrunk favicon.ico from 97 KB to 15 KB
  • marked library now bundled (no CDN runtime dependency)

Bug Fixes

  • Signal level charts: fixed extreme values for UDP/TCP sources
  • Static data refreshed correctly when a ship comes back into scope
  • HTTP stats fixed under TLS

Performance

This release contains a substantial performance overhaul of the I/O hot path. Highlights:

  • NMEA parser: zero-alloc split, SWAR scanning, bulk 6-bit decode, line-aware start detection — ~64% fewer instructions
  • JSON parser: zero-copy tokenizer, hand-rolled number parsing, flat open-addressing hash table for key lookup, allocation-free steady-state parsing
  • JSON Writer: replaces legacy JSONBuilder and ad-hoc serializers with a std::string-backed writer; ~5–10% faster on -o 0/3/5/7
  • AIS::Message: SWAR getText/getUint, batched 6-bit payload decode (~7–10% faster on -o 5 / nmea_refresh)
  • Lock-free output: thread-local screen buffers, atomic ByteCounter, DB mutex released before downstream Send cascade (dual -N benchmark: 9.05s → 6.03s)
  • POSIX read() for stdin, single newline flush per message (replacing per-message fflush)

Stability and Networking

  • TCP: try all addrinfo entries, connect timeout for blocking mode, guard repeated stop requests
  • WebSocket/MQTT: handshake fixes, Windows socket check, max frame drop, PUBREL handling, buffer-growth fix
  • Logger: fixed circular buffer and mutex issues
  • GPS: fixed use-after-free and JSON memory issue, warn-once on bad data, scan limits
  • Postgres/N2K: traffic monitoring extended, empty AIS messages handled, filter shadow fixed (settings now apply to the active filter)
  • File input, hybrid config, NMEA RMC parsing, NMEA checksum in -o 6, timer handling for non-frontend models (NMEA, N2K, ADSB, Export)
  • Backup writer wrapped in try/catch with additional diagnostics
  • Compiler-warning cleanup across the tree; spellcheck CI added (typos)

Packaging

  • Debian packages now store HydraSDR and RTL-SDR libraries as DLLs in /usr/lib/AIS-catcher instead of statically linking
  • Switched to debhelper — dh_shlibdeps auto-resolves correct dependencies per distro/arch
  • Fixed several .deb packaging issues (libssl3/t64, ETXTBSY, empty Depends field)
  • Added CI install test covering the full platform matrix
  • New Ubuntu ARM64 and ARMhf packages; RPM packages added; Fedora dropped
  • Frontend libraries bundled via npm/Vite — no CDN dependencies at runtime. Webassets repo is archived
  • Modular CMake dependency management — individual scripts per library
  • Install script: parallelized builds, non-root install option, hardened reboot handling, removed Docker support for i386/armel
  • Copyright extended to 2026

Version 0.66

  • Improve documentation for configuration via JSON
  • Fix chart colors when running web viewer in iframe on Firefox
  • Technical details of equipment added to shipcard (press information icon in sender field)
  • CS unit for class B is displayed in shipcard of the web viewer if available
  • Serial devices can be initialized with an init sequence
  • Remodelling of realtime NMEA tab with options to filter on MMSI and share NMEA lines with decoder tab for message parsing
  • Option to track NMEA in webviewer for a specific ship or station
  • Shortcut to measure distance between two objects or points is now SHIFT-CLICK to select the first point. This should improve behaviour for devices that cannot distinguish between a left and right mouse click.

Version 0.64 - 0.65

Various updates to improve stability, security and minor bug fixes.

Version 0.63

Enhanced Features

  • NMEA 4.0 Tag Blocks: support for NMEA tag blocks (msgformat nmea_tag for networking or -o 7 for screen). Note that when reading the timestamps are overwritten by default which can be switched off with -go stamp off

Version 0.63

Enhanced Features

  • Data throughput: significant reduction in data throughput to community hub
  • Online NMEA decoder: Built-in NMEA decoder in the local webviewer
  • Kiosk Mode: Full-screen display mode for dedicated monitoring setups
  • MSGFORMAT Configuration: Flexible output format definitions for customized data presentation. Introduction of msgformat binary_nmea to save on bandwidth
  • Extended Binary Messages: Additional binary message types now decoded and displayed
  • Verbose JSON Output (-o 6): Enhanced JSON format with detailed field descriptions (WIP)
  • Debian Trixie Support: Compatibility with Debian 13 (Trixie)
  • Filesystem-based Map Tiles: 
      # Serve map tiles from filesystem
  AIS-catcher -N 8100 FSTILES /path/to/tiles
  # Filesystem overlay maps
  AIS-catcher -N 8100 FSOVERLAY /path/to/overlay

For complete edge changes, see the commit history.

Version 0.62

ADSB Integration

Connect to ADSB feeds to visualize aircraft alongside vessels: 

# Beast format
AIS-catcher -t beast localhost 30003 -N 8100

# BaseStation format
AIS-catcher -t basestation localhost 30002 -N 8100

Binary Message Decoding

The WebViewer now decodes and displays regional binary AIS messages (availability varies by location).

Offline Mapping

# MBTiles format support
AIS-catcher -N 8100 MBTILES map.mbtiles
# Or as overlay
AIS-catcher -N 8100 MBOVERLAY map.mbtiles

RTL-SDR V4 Support

Debian packages now include statically-linked RTL-SDR library with V4 dongle support.

AIS-catcher for Android

  • Auto-start decoding when USB device connects
  • Built-in webviewer on configurable port

Version 0.61

MQTT Integration

# Publish messages
AIS-catcher -Q mqtt://127.0.0.1:1883
AIS-catcher -Q wsmqtt://127.0.0.1:1883
AIS-catcher -Q mqtt://127.0.0.1:1883 admin MSGFORMAT JSON_FULL TOPIC data/ais
AIS-catcher -Q mqtt://username:password@127.0.0.1:1883 admin CLIENT aiscatcher

# Subscribe to messages
AIS-catcher -t mqtt://username:password@127.0.0.1:1883

Protocol Expansion

  • WebSocket text transmission (ws://)
  • SDR data streaming (sdr://)
  • Text over TCP (txt://)
  • GPSD integration (gpsd://)
  • RTL_TCP support (rtltcp://)
  • Raw IQ data (tcp://)

Web Viewer Improvements

  • Map-first default view
  • Enhanced color palette
  • Draggable ship information cards
  • Context-aware card positioning
  • Configurable vessel track display (on hover/selection)

Configuration

  • NMEA2000 settings in JSON configuration
  • System daemon auto-restart (10s interval)