Weatherdock Academy AIS Transmission procedure SOTDMA vs CSTDMA

Weatherdock Academy AIS Transmission procedure SOTDMA vs. CSTDMA

SOTDMA vs. CSTDMA In order to ensure that the VHF transmissions of different AIS transponders do not occur at the same time, there are two different procedures implemented for Class A and Class B service. AIS Chanel-Management Class A Transmission process: Class B Transmission process: SOTDMA oder CSTDMA SOTDMA = „Self-Organized Time Division Multiple Access“ CSTDMA = „Carrier Sense Time Division Multiple Access“ Weatherdock AG Distributor Academy 07. 03. 2021 – Page 2 CONFIDENTIAL – all rights reserved ©Weatherdock AG - AIS Transmission procedure

AIS Transmission procedure Weatherdock AG Distributor Academy SOTDMA CSTDMA 5 watt 2 watt Up to every 15 sec. Fix all 30 sec. Reservation of future slots X Sending/receiving of text messages X Priority to Class A devices 2 nd Priority 3 rd Priority SOTDM Transmission power A Transmission interval 07. 03. 2021 – Page 3 CONFIDENTIAL – all rights reserved ©Weatherdock AG - SOTDMA vs. CSTDMA The Differences between SOTDMA and CSTDMA at a glance

SOTDMA vs. CSTDMA SOTDMA „Self-Organized Time Division Multiple Access“ Weatherdock AG Distributor Academy This means: "Self-organizing time slot procedure" • • This procedure separates the participants in reserved time slots. Participants can occupy up to 4 time slots in a row. The information is transmitted redundantly on two VHF channels. The update rate of the individual vehicle information depends on the condition of the vehicle. 07. 03. 2021 – Page 4 CONFIDENTIAL – all rights reserved ©Weatherdock AG - How does SOTDMA work?

SOTDMA vs. CSTDMA SOTDMA Weatherdock AG Distributor Academy 07. 03. 2021 – Page 5 CONFIDENTIAL – all rights reserved ©Weatherdock AG - How does SOTDMA work?

SOTDMA vs. CSTDMA Channel allocation using the time slot procedure Weatherdock AG Distributor Academy approximately 2000 telegrams per channel per minute possible 07. 03. 2021 – Page 6 CONFIDENTIAL – all rights reserved ©Weatherdock AG - How does SOTDMA work?

SOTDMA vs. CSTDMA „Carrier Sense Time Division Multiple Access“ Weatherdock AG Distributor Academy This means: „Listen before talk“ • It is “listened” whether another transmission is in progress, before initiating a transmission on the next free timeslot. 07. 03. 2021 – Page 7 CONFIDENTIAL – all rights reserved ©Weatherdock AG - How does CSTDMA work?