What is minimodem?
minimodem is a command-line program that decodes (or generates) audio modem tones at any specified baud rate, using various framing protocols. It acts as a general-purpose software FSK (Frequency-Shift Keying) modem, enabling data transmission over audio.Quick Start
Get up and running with minimodem in minutes
Installation
Install minimodem on Linux, macOS, or Windows
CLI Reference
Complete command-line interface documentation
Protocols
Learn about supported protocols and standards
Key Features
Universal FSK Modem
Transmit and receive at any baud rate with configurable framing
Standard Protocols
Built-in support for Bell 103/202, RTTY, TTY/TDD, NOAA SAME, and Caller-ID
Real-Time Processing
Process audio in real-time via your system audio device
File Mode
Work with audio files for batch processing and testing
Multiple Backends
Support for ALSA, PulseAudio, sndio, and sndfile
Auto-Detection
Automatic carrier frequency detection and tuning
How It Works
minimodem uses FSK (Frequency-Shift Keying) modulation to encode digital data as audio tones. Different frequencies represent binary 0s and 1s, allowing data transmission over any audio channel.Transmit Mode
minimodem reads data from stdin and generates corresponding audio tones based on the specified baud rate and protocol.
Receive Mode
minimodem captures audio from your microphone or file, decodes the FSK tones, and outputs the data to stdout.
Use Cases
Air-Gapped Data Transfer
Air-Gapped Data Transfer
Transfer data between computers with no network connection using only sound waves. Perfect for secure environments where physical network connections are restricted.
Ham Radio Communications
Ham Radio Communications
Integrate with amateur radio equipment for digital data transmission over HF, VHF, or UHF bands using standard protocols like RTTY.
Legacy System Integration
Legacy System Integration
Connect to legacy modems, teletype systems, or vintage computing equipment using authentic modem protocols.
Weather Alert Monitoring
Weather Alert Monitoring
Decode NOAA SAME (Specific Area Message Encoding) weather alert broadcasts from NOAA Weather Radio.
Caller-ID Decoding
Caller-ID Decoding
Decode caller identification information from telephone line audio using Bell 202 FSK protocol.
Educational Projects
Educational Projects
Learn about digital communications, signal processing, and modem technology through hands-on experimentation.
Getting Started
Ready to start using minimodem? Follow our quickstart guide to transmit your first message:Quickstart Guide
Send and receive your first audio modem transmission
Community and Support
minimodem is open source software licensed under GPLv3+. Contributions and feedback are welcome!GitHub Repository
View source code, report issues, and contribute
FAQ
Find answers to common questions