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MRMCD2024 Schiffe erkennen leicht gemacht
Learn how AIS technology enables ship tracking & identification via VHF radio. Explore message types, transmission details & how to receive signals using SDR equipment.
- AIS (Automatic Information System) is used for ship identification and tracking to improve maritime safety and navigation
- Vessels transmit position, course, speed, and vessel information via VHF radio channels every few minutes
- Two dedicated VHF frequencies are used: 161.975 MHz (AIS1) and 162.025 MHz (AIS2)
- Different types of AIS equipment exist: Class A (mandatory for large vessels), Class B (smaller vessels), base stations and navigational aids
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Messages contain vessel details like:
- MMSI number (unique vessel ID)
- Ship name and type
- GPS position with high accuracy
- Speed and course
- Destination and ETA
- Time slots of 26.67ms are used for transmission to avoid collisions between messages
- Transmission intervals vary based on vessel’s speed and status (from 2 seconds to 3 minutes)
- Range is typically limited to line of sight (20-40 nautical miles)
- Data is publicly available and can be received with SDR (Software Defined Radio) equipment
- Beyond navigation, AIS data is used for vessel tracking services, maritime traffic analysis and research