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The FreeDV project offers a suite of digital voice modes for HF radio, with its flagship mode being the Radio Autoencoder (RADE). This free GUI application for Windows, Linux, and macOS allows any SSB radio to be used for high-quality digital voice communications. The technology, including the Codec 2 speech codec, is 100% open source under the GNU Lesser Public License v2.1 and two-clause BSD license, fostering experimentation and innovation in amateur radio digital voice. Development is managed by a six-person Project Leadership Team and funded by an ARDC grant, with Software Freedom Conservancy as the financial sponsor. Controlled testing indicates that RADE technology performs comparably to SSB on both high and low SNR channels. The resource lists various FreeDV nets and activities, including a worldwide activity day, and specific nets in Argentina (7.045 MHz LSB), Australia (7.197 MHz LSB), the UK (3.640 MHz LSB, 5.3685 MHz USB), and the USA (7.181.5 MHz LSB, 7.177 MHz LSB). Support resources include a mailing list, Discord channels, and a Zoom channel. Documentation such as the FreeDV GUI User Manual and the SM1000 Manual are provided, alongside access to source code for RADE, FreeDV GUI, and Codec 2.

Codec2, an open-source speech codec, targets low bit rate voice communication, specifically designed for digital radio applications operating within constrained bandwidths. The project focuses on achieving intelligible speech quality at data rates around 2400 bits per second, a critical parameter for efficient spectrum utilization in amateur radio. Its development addresses the need for robust voice transmission over channels where higher bit rate codecs would be impractical or inefficient. The resource details the technical specifications and implementation aspects of Codec2, including its underlying algorithms and performance characteristics. It provides insights into how the codec processes speech to achieve its low bit rate, outlining the various coding schemes and their impact on voice fidelity and error resilience. The information presented allows radio amateurs and developers to understand the codec's operational principles and its suitability for integration into custom digital communication systems. Applications for Codec2 extend to digital voice modes on HF and VHF bands, enabling more users to share limited spectrum resources. The project's open-source nature facilitates community contributions and widespread adoption, fostering innovation in digital amateur radio. It represents a significant effort to provide a freely available, high-performance speech coding solution for the amateur radio community.

Codec2 is an open source low bit rate speech codec designed for communications quality speech at around 2400 bit/s. Applications include low bandwidth HF/VHF digital radio.

Codec2 is an open source low bit rate speech codec designed for communications quality speech at 2400 bit/s and below. Applications include low bandwidth HF/VHF digital radio and VOIP trunking.