FreeDV

This compressed digital stream is then modulated into an audio signal (typically using 16QPSK or similar modulation) and sent through a standard SSB transceiver. On the receiving end, another FreeDV setup demodulates the signal and reconstructs the original voice—often with surprisingly intelligible results even under weak signal conditions.

🛠️ How It Works

• Software: FreeDV runs as a cross-platform GUI application for Windows, Linux, and macOS. It interfaces with your radio via a sound card and optionally a CAT interface.

• Modem + Codec: It uses a digital modem to encode/decode the signal and Codec2 to compress/decompress the voice.

• Bandwidth: Most FreeDV modes occupy about 1.25 kHz, making them comparable to narrow SSB signals.

• Performance: Voice remains intelligible down to 2 dB SNR, and successful QSOs have been logged using as little as 1–2 watts of power.

🌍 Why Use FreeDV?

• Open Source: No proprietary hardware or licensing—FreeDV is developed by an international team of hams and engineers and is freely available under open-source licenses.

• Efficient: It enables voice communication where analog SSB might fail, especially in noisy or low-power conditions.

• Community-Driven: It’s a collaborative project, with ongoing development including machine learning enhancements like the new RADE (Radio Autoencoder) mode.

🚀 Getting Started

To try FreeDV, all you need is:

• An SSB-capable HF transceiver

• A computer (Windows, Linux, or macOS)

• An audio interface (like a USB sound card or audio interface box)

• The FreeDV software from freedv.org

Once installed, you can tune to known FreeDV calling frequencies and start experimenting with digital voice on HF.