FreeDV: OPEN SOURCE AMATEUR DIGITAL VOICE

Here is what you will need:

OR:

  • An SM1000 Digital Voice Adaptor
  • Cables to connect the SM1000 to your SSB radio

Connecting Your Radio

If you don’t have a built-in sound card for digital modes you can use the normal audio inputs and outputs of your radio. The same cables and hardware that you use for other digital modes that are based on PC programs will work with FreeDV, but you will need a second sound interface for the microphone and speaker connections to the FreeDV program. A USB headset of the sort used by gamers is all you need for the second sound interface.

Configuring Your Radio

Turn off as much processing as possible. In general, noise blankers, DSP band limit filtering and narrow bandpass filters are more likely to hurt than help, while compression, DSP noise or carrier elimination, and voice processing are definitely wrong for digital modes. FreeDV’s HF modem does its own DSP, and in general, this is true for other digital programs as well.

You can see the received effect of different settings in the S/N (signal-to-noise ratio) display of FreeDV. A higher S/N is better.

Drive your transmitter to an average power of about 20% of its PEP power. There is an 8-12 dB peak-to-average power ratio in our HF modem. Over-driving will reduce the received S/N. More is not better for DV!

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FreeDV is a high-quality digital voice mode for clear communication over HF radio frequencies. It’s easy to use and accessible to all, eliminating the need for complex equipment or specialized training. FreeDV delivers clear voice with minimal delays under weak signal conditions, perfect for emergency responders, humanitarian aid efforts, and remote workers. It’s also compatible with different radios and interfaces, making it adaptable for any situation.

Credits and Contact Information

FreeDV is being maintained and extended by Mooneer Salem K6AQ and David Rowe, VK5DGR. Richard Shaw KF5OIM maintains the Cmake build system and Fedora packaging. Walter, K5WH is leading Windows testing in the USA. Debian packaging thanks to A. Maitland Bottoms (AA4HS) and the Debian Hamradio Maintainers.

As development continues, many people are helping whom we have not credited on this website, but we appreciate all of their work.

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