Communication system for an autonomous passenger ferry
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NTNU is currently in the development process of an autonomous passenger ferry which will carry pedestrians and bicyclists across the channel between Ravnkloa and Vestre Kanalhavn in Trondheim harbour. To reduce the risk of potential collisions between the ferry and other vessels trafficking the channel, a wireless communication system should be developed. This master s thesis is about the development of such a wireless communication system. The system is going to broadcast navigational information gathered from the ferry such as position, course, and speed, at rapid intervals of one second with the use of two VHF radios, more specifically two microcontroller units of the type EFR32 Flex Gecko 169 MHz from Silicon Labs. The system gathers navigational information from an on-board computer on the ferry by a USB data interface. This was resolved by using the built-in serial communication protocol UART in the microcontroller unit. When the navigational information is correctly acquired from the computer and made accessible on the VHF transmitter, the information is packed into a suitable message format with a similar structure to messages found in the NMEA 0183 communication protocol. The information is transmitted according to frequency regulation 8.7 found in the regulation of general permissions for use of frequencies (The free use regulation), on 169.4 MHz VHF band. The transmitted signal is GFSK modulated with a 14 kHz deviation and a 36.8 kbps bitrate. When the transmitted message is received at the VHF receiver, it is processed and reformatted on to an appropriate NMEA 0183 message format. Received information is then transmitted over a new data interface which also uses the built-in serial communication protocol UART, to a chartplotter.