SOTDMA

SOTDMA - Self-Organising TDMA. (Time-Division Multiple Access).

SOTDMA is the most complex TDMA access scheme defined for AIS. It allows the unit to 'negotiate' with other AIS units to find a regular transmission timeslot, increasing reliability in heavy traffic zones. This increases your update speeds and gives more accurate locations. In other words, prior to transmitting, the device communicates its intent and organises its own time slot, meaning you never miss a tranmission

TDMA is used by AIS across two dedicated VHF frequencies – AIS 1 (161.975 MHz) and AIS 2 (162.025 MHz).

Although Class A and Class B both use TDMA, Class A units use a Self-Organised TDMA (SOTDMA; Self-Organizing amongst Class A's).