GNS 5851 is a high performance single channel receiver for the marine Automatic Identification System (AIS). It receives the Marine Band channels 87B (Ch. A) and 88B (Ch. B) at 161.975 MHz and 162.025 MHz respectively and can be configured to statically receive either channel or to automatically hop between channels. Two GNS 5851 can be chained to form a continuous two-channel AIS receiver if necessary.
Only an appropriate power supply of 3.3V and a suitable antenna must be connected for operation, no external clocks are required.
The GNS 5851 outputs all received AIS data as standard NMEA messages via its UART at 115200 baud using 3.3V levels.
Main UART Interface details
GNS 5851 must be connected to the host system via a UART Interface.
Transmission protocol is industry standard NMEA 0183 using VDM sentences for received vessel data, see https://www.nmea.org for reference.
I/O levels are 3.3V (see electrical data), baud rate is either 115200 bps or 38400 bps using 8 data bits, one stop bit and no parity (‘8-N-1’). The baud rate for the hopping receiver can be selected via the Mode Selection bits (see §5.4), the
master/slave combination is fixed at 38400 bps..
The idle state of the UART lines is positive voltage. To interface a standard RS232 UART (e.g. a PC serial interface), please add an inverting level shifter. To interface processors that have a different interfacing voltage level, level shifters are required.