Configure AIS Reception

YAAC does not handle AIS data directly. However, the DireWolf software TNC is also capable of demodulating AIS packets (assuming a suitable receiver and sound card are used) and converting them to experimental data APRS packets encapsulating NEMA-0183-formatted AIS frames. Connecting YAAC to such a DireWolf instance using AGWPE or KISS-over-TCP port types allows the AIS decoder plugin to parse the AIS frames and render the resulting ship information on the YAAC displays.

Per the DireWolf documentation, the direwolf executable (of release 1.6 or later) should be launched with the following command-line options:

    -B AIS -r 48000

The normal configuration file options should be used to specify the sound card, which must support at least a 44100 Hz sample rate (preferably 48000 Hz); note the -r option above specifies the sample rate, which is required if the - final command-line parameter is used to indicate audio is being piped into direwolf (such as from SDR programs like rtl_fm) such that DireWolf doesn't know what the sample rate is. Also, the receiver must have adequate audio passband; direct discriminator output (such as the 9600 audio output on a standard data port) or a sufficiently wide-band Software-Defined Radio (SDR) should be used to ensure the signal is not distorted beyond decodeability.

When using the AIS decoder plugin for YAAC, it is recommended not to use the -A option to DireWolf, as YAAC can do the conversions for itself, so using this option will cause duplicate displays for ships using the different AIS-to-APRS translation algorithms in YAAC versus DireWolf.