Question 43F3

The current and most recent implementations of NMEA 0183 utilize **RS422** for data communications. NMEA 0183 is a serial data standard widely used in marine electronics and amateur radio for GPS, AIS, and other device data. RS422 is a differential signaling standard, meaning data is transmitted as the voltage difference between two wires for each signal. This provides superior noise immunity and allows for longer cable runs compared to single-ended standards like RS232. RS422 is designed for one talker (transmitter) and multiple listeners (receivers), which perfectly suits the typical NMEA 0183 setup where a single device broadcasts data to several others. RS232, while used in early NMEA 0183 implementations, is a single-ended standard with limited distance and noise rejection, making it less suitable for robust marine or mobile environments. RS485 is also differential but supports multiple talkers and listeners on a shared bus, which is not the primary mode for NMEA 0183. ISO 11783 is actually the standard for NMEA 2000, a completely different, CAN-bus-based network protocol, not NMEA 0183.