Method of displaying AIS information & SOTDMA
SOTDMA to share VHF frequency
SOTDMA – self organized time division multiple access.
All AIS station can synchronize their time slots from highly accurate time reference.
This highly accurate time reference is called SOTDMA.
Per minute there are 2,250 Slots available for the transmission of AIS data.
Position, course, speed, and other data are transmitted on the two VHF channels 161.9 MHz and 162.0 MHz.
SOTDMA allow the system to be overloaded by 400-500%
Incase, system overloaded, far away target will be drop out and nearby target will be visible.
Method of displaying AIS information
Minimum 3 data: range, bearing, ship name. Scrolling will give more data.
Sleeping target: within range but don’t show any information.
Activated target: users activate sleeping target. will show – vector, heading, ROT
Selected target: show details of a target. CPA, TCPA, navigation stutus, range, bearing, ship name
Lost target: target outside range. (Give Alarm)
Dangerous target: target within preset CPA TCPA range value. (Give Alarm)