NMEA Simulator

A versatile marine data simulator supporting both NMEA 0183 and NMEA 2000 protocols simultaneously.

Features

NMEA 0183

• TCP Server (default port 10110)
• WebSocket Server with web interface (default port 8080)
• Configurable Baud Rates: 4800, 9600, 19200, 38400
• Supported Sentences
  • Position: GGA (GPS Fix), GLL (Geographic Position)
  • Navigation: RMC (Recommended Minimum), HDT (True Heading), VTG (Track & Speed), XTE (Cross-Track Error)
  • Environment: DBT (Depth Below Transducer), MTW (Water Temperature), MWV (Wind), VHW (Water Speed & Heading), DPT (Depth)

NMEA 2000

• TCP Server (default port 10200)
• WebSocket Server with web interface (default port 8081)
• Supported PGNs
  • 127250 (Vessel Heading)
  • 128259 (Speed)
  • 128267 (Water Depth)
  • 129025 (Position Rapid Update)
  • 129026 (COG & SOG Rapid Update)
  • 130306 (Wind Data)

Installation

go install github.com/captv89/nmea-simulator/cmd/nmeasim@latest

Or clone and build:

git clone https://github.com/captv89/nmea-simulator.git
cd nmea-simulator
make build

Usage

By default, the simulator runs both NMEA 0183 and NMEA 2000 protocols simultaneously:

nmeasim

Run Specific Protocol

Run only NMEA 0183:

nmeasim --protocol nmea0183

Run only NMEA 2000:

nmeasim --protocol nmea2000

Command Line Options

Protocol Selection:

• --protocol: Protocol to use ("both", "nmea0183", or "nmea2000", default: "both")

NMEA 0183 Options:

• --nmea0183-ws-port: WebSocket server port (default: 8080)
• --nmea0183-tcp-port: TCP server port (default: 10110)
• --baud: Baud rate for TCP output (default: 4800)

NMEA 2000 Options:

• --nmea2000-ws-port: WebSocket server port (default: 8081)
• --nmea2000-tcp-port: TCP port (default: 10200)

Common Options:

• --host: Host to bind servers to (default: "0.0.0.0")
• --interval: Data update interval (default: 1s)

Web Interface

The web interface now supports viewing both NMEA 0183 and NMEA 2000 data simultaneously. Access it at:

• NMEA 0183: http://localhost:8080
• NMEA 2000: http://localhost:8081

Viewing TCP Data

You can use common terminal commands to view the NMEA data streams directly:

Using netcat (nc)

For NMEA 0183:

nc localhost 10110

For NMEA 2000:

nc localhost 10200

Using telnet

For NMEA 0183:

telnet localhost 10110

For NMEA 2000:

telnet localhost 10200

Using socat with hex dump

To view data with timestamps and hex dump:

For NMEA 0183:

socat TCP:localhost:10110 STDOUT | hexdump -C

For NMEA 2000:

socat TCP:localhost:10200 STDOUT | hexdump -C

Note: You may need to install these tools first:

• macOS: brew install netcat socat
• Ubuntu/Debian: sudo apt install netcat-openbsd socat
• Windows: Use PowerShell's Test-NetConnection or install WSL

Development

Prerequisites

• Go 1.24 or higher
• Make (optional, for using Makefile commands)

Available Make Commands

• make build: Build the binary
• make test: Run tests
• make coverage: Generate test coverage report
• make clean: Clean build files
• make release: Create a new release
• make release-dry-run: Test release process without publishing

Running Tests

make test

Generate coverage report:

make coverage

License

This project is licensed under the LICENSE file in the repository.

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request