Morse Transceiver - Ultrasonic Audio Steganography

Version: 2.0.0

Overview

Morse Transceiver is a cross-modal information embedding framework that leverages ultrasonic frequency carriers (17.5–19.5 kHz) to embed hidden data into audio/video files. The embedded signals are:

• Inaudible to humans: Above the adult hearing threshold (~16 kHz for ages 30+)
• Recordable by computers: Below the Nyquist frequency (22.05 kHz at 44.1 kHz sampling)
• Compression-resilient: Survives AAC/MP3 encoding at ≥64 kbps bitrates

This enables persistent metadata embedding, copyright watermarking, and secure cross-modal communication.

Key Features

Ultrasonic Steganography

• Dual-Tone FSK Modulation: Encodes Morse dots and dashes at distinct ultrasonic frequencies
• Adaptive Frequency Selection: Optimizes carriers based on sample rate, target bitrate, and age demographic
• Protocol Framing: KA/AR preamble/postamble with MD5 checksum verification
• Redundancy: Configurable repetition (3–5×) for compression resilience

Cross-Modal Embedding

• Audio Files: WAV, FLAC, OGG, MP3
• Video Files: MP4, MOV, AVI, MKV (with audio track)
• High-Bitrate Preservation: Uses 320 kbps AAC to maintain ultrasonic fidelity

CLI Interface

# Embed message into video
morse-embed sample.mp4 -m "SECRET MESSAGE" -o output.mp4

# Extract message from video
morse-extract output.mp4 -f 17500

# Verify frequency inaudibility
morse-verify --age 40

The Science

The Perceptual-Technical Boundary

Human hearing follows an age-dependent decline (presbycusis):

• Young (<25): ~19–20 kHz upper limit
• Adult (30–40): ~16–18 kHz upper limit
• Adult (40–50): ~14–16 kHz upper limit
• Senior (50+): ~12–14 kHz upper limit

Standard audio sampling (44.1 kHz) supports frequencies up to 22.05 kHz (Nyquist limit).

This creates an optimal embedding window of 17.5–19.5 kHz—inaudible to most adults yet fully representable digitally.

Frequency Modes

Mode	Dot (Hz)	Dash (Hz)	Use Case
Conservative	17,000	18,000	Maximum compatibility
Standard	17,500	18,500	Default (recommended)
Aggressive	18,000	19,000	Enhanced stealth
Maximum	18,500	19,500	Maximum inaudibility

Installation

From PyPI (Recommended)

pip install morse-transceiver

From Source

git clone https://github.com/cycleuser/Morse-Transceiver.git
cd Morse-Transceiver
pip install -r requirements.txt

Optional GUI Dependencies

pip install morse-transceiver[gui]

Quick Start

Embed Message

from stego_engine import UltrasonicStegoEngine

# Embed into video
UltrasonicStegoEngine.embed_signal(
    "sample.mp4", "output.mp4",
    text="SECRET MESSAGE",
    wpm=15, freq=17500, volume=0.1,
    redundancy=5, use_dual_tone=True
)

Extract Message

morse, status = UltrasonicStegoEngine.extract_signal(
    "output.mp4", freq=17500, wpm=15, use_dual_tone=True
)

from morse_transceiver.morse_logic import MorseLogic
decoded = MorseLogic.morse_to_text(morse)
payload, proto_status = MorseLogic.parse_packet(decoded)
print(f"Extracted: {payload}")

CLI Usage

# Embed
morse-embed sample.mp4 -m "HELLO WORLD" -o output.mp4 --wpm 15 --redundancy 5

# Extract
morse-extract output.mp4 --freq 17500 --wpm 15

# Verify inaudibility for age group
morse-verify --age 40 --mode standard

Testing

Run the full test suite:

python test_ultrasonic.py

Or with pytest:

pip install pytest
pytest tests/ -v

Transcoding Resilience

Profile	Bitrate	Result
High Quality	320 kbps	✓ 100% Recovery
Standard	192 kbps	✓ 100% Recovery
Social Media	128 kbps	⚠ Partial Recovery
Low Bandwidth	64 kbps	✓ With Lower Frequencies
Ultra Low	32 kbps	✗ Failure

Project Structure

Morse-Transceiver/
├── morse_transceiver/          # Python package
│   ├── __init__.py             # Package metadata
│   ├── morse_logic.py          # Morse encoding/decoding
│   └── cli.py                  # Command-line interface
├── stego_engine.py             # Ultrasonic steganography engine
├── test_ultrasonic.py          # Full test suite
├── tests/                      # pytest tests
│   ├── __init__.py
│   └── test_stego.py
├── Article.md                  # English paper
├── Article_CN.md               # Chinese paper
├── pyproject.toml              # Package configuration
├── requirements.txt            # Dependencies
├── publish.py                  # PyPI publishing script
├── upload_pypi.sh              # Bash upload script
├── upload_pypi.bat             # Windows upload script
├── build.sh                    # Bash build script
└── build.bat                   # Windows build script

Development

Build Package

# Linux/macOS
chmod +x build.sh
./build.sh

# Windows
build.bat

# Or using publish.py
python publish.py build

Publish to PyPI

# Linux/macOS
chmod +x upload_pypi.sh
./upload_pypi.sh

# Windows
upload_pypi.bat

# Or using publish.py
python publish.py test     # TestPyPI
python publish.py release  # PyPI

License

GNU General Public License v3.0 (GPLv3)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Citation

If you use this work in your research, please cite:

@misc{morse-transceiver-2026,
  title={Cross-Modal Information Embedding via Ultrasonic Audio Steganography},
  author={Morse Transceiver Contributors},
  year={2026},
  url={https://github.com/cycleuser/Morse-Transceiver}
}

References

See Article.md and Article_CN.md for full academic paper with 20 references.