[LW] [LW11] AIS Target time out quest

[Louise - Raymarine - Moderator]

Dear Garry71118,

Thank you for your query.

The Vesper XB8000 is a little vague but simply based around 2W of power the report rate (refresh rate) is every 30 sec > 2 knots or 3 min < 2 knots.

The AIS unit is most likely using CSTDMA (Carrier Sense Time Division Multiple Access) protocol which is used primarily for pleasure boating (Class B). The CSTDMA method uses carrier-sensing to defer transmissions until no other stations are transmitting. If a free slot is found, the transmission starts. Than the transmission is stopped for a 30 second time interval before the next one starts. Newer AIS units use SOTDMA (Self Organised Time Division Multiple Access) and will take precedence over CSTDMA.

This simply sounds like a timing issue.

Best Regards
Louise