def nmea_checksum(sentence_without_start): # Input: string after $ up to * (exclude *) xor_sum = 0 for ch in sentence_without_start: xor_sum ^= ord(ch) return f"xor_sum:02X"
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47 | ID | Device Type | |----|--------------| | GP | GPS | | GL | GLONASS | | GA | Galileo | | GN | Combined GNSS | | BD | BeiDou | | II | Integrated Instrumentation | | RA | Radar | | SD | Sounder (Depth) | | HC | Heading/Compass (Magnetic) | | HE | Heading (Gyro) | | AI | AIS (Automatic Identification System) | | VW | Wind speed/angle | | MT | Meteorological | 5. Comprehensive List of Standard Sentence Formatters Below is a detailed table of the most widely used NMEA 0183 sentences: nmea 0183 sentences
Report ID: NMEA-RPT-2024-001 Subject: Comprehensive analysis of NMEA 0183 protocol sentences Date: April 14, 2026 Author: Marine Data Systems Engineering Team 1. Abstract NMEA 0183 is a combined electrical and data specification for communication between marine electronic devices such as echo sounders, sonars, anemometers, gyrocompasses, autopilots, GPS receivers, and many other types of instruments. It has been the de facto standard for marine data interchange since its introduction in the early 1980s. This report details the structure, transmission rules, and common sentence types within the protocol, including real-world examples for system integration. 2. Introduction and Background The National Marine Electronics Association (NMEA) developed the 0183 standard to allow multiple devices to share data over a simple serial interface. Unlike its successor NMEA 2000 (a CAN-based system), NMEA 0183 is asynchronous serial (RS-232, RS-422, or TTL levels) with a talker-listener architecture: only one device (talker) can transmit on a line at a time, but multiple listeners can receive the same data stream. It has been the de facto standard for
$TTSSS,data1,data2,...,dataN*HH<CR><LF> | Field | Description | |-------|-------------| | $ or ! | Start delimiter ( ! used for proprietary sentences) | | TT | Talker ID (2 chars) – e.g., GP for GPS, II for integrated instrument, RA for radar, AI for AIS | | SSS | Sentence formatter (3 chars) – e.g., GGA , RMC , HDT | | , | Field delimiter | | data1...dataN | Variable data fields; null fields are allowed (consecutive commas) | | * | Checksum delimiter | | HH | Hexadecimal checksum (XOR of all characters between $ and * , excluding delimiters) | | <CR><LF> | Carriage Return + Line Feed (ASCII 13 and 10) | GP for GPS