KAHU radar hub 0.1.182

Developer: Egil Moeller

Summary

Contribute AIS and ARPA targets from your vessel to crowdsourcing for marine safety!

This plugin lets you upload AIS and radar ARPA targets (or any NMEA) to an internet server. Upload can be continuous, over intermittent internet, or scheduled, and tracks can be downsampled to fit your bandwidth. The communication protocol is based on Apache Avro and batches track points so that the overhead for each point above timestamp and lat/lon is low, meaning it is designed to be as bandwidth conservative as possible.

Server

An example server written in Python is provided in the the server subdirectory of the plugin sources. This server implements the full protocol, but just dumps all received tracks to disk in geojson format. It can be used as a simple shore based VDR, but mostly serves as an example base for anyone wanting to build a more elaborate server side setup.

Integration with other plugins

This plugin is designed to be used in conjunction with the radar_pi radar plugin. Make sure to enable ARPA targets, as that is what this plugin uses. Alternatively, it can use $RATTM and $RATTL NMEA messages originating from an external radar system.

Settings

Options > Plugins > KAHU radar hub > Preferences

The settings window is also the only user interface provided by the plugin. During normal operations, the plugin is only working in the background, sending tracks.

Server account

To use the plugin, you need an API key for an account on a server / crowdsourcing platform, as well as servername and port. Start by making an account with the KAHU radar hub. Once signed in, create an API key for your boat and fill it in in the plugin preferences. Hit save.

Once you open the plugin preferences again, the connection status (shown under the last connection time) should say "logged in".

Internet connectivity

The plugin will connect to the server over TCP, and will reconnect of the connection is terminated. It will use exponential back-off to not saturate a bad connection with reconnection attempts. The shortest and longest reconnection times for this back-off algorithm can be specified in the Minimum reconnect delay and Maximum reconnect delay fields respectively.

Connection status

The preferences dialog shows when the plugin managed to connect to the server last (time and date), and right under that, the connection status - connected, logged in, or an error.

The dialog also shows how many received tracks (that is, individual ARPA targets from your radar) are waiting to be sent, as well as the total number of unsent trackpoints.

Track cache

Tracks are stored in ~/.opencpn/routecache.sqlite3 (and the corresponding path on windows). If this file is deleted, all sent and unsent tracks are deleted. The file will be created as soon as the plugin runs.

Note: The size of the data in this file is larger than what is transferred over the network - both due to metadata needed for bookkeeeping, due to downsampling of tracks, not sending all details of messages and due to a less compressed format.