Codec2 - Next-Generation Digital Voice for Amateur Radio

Codec2 offers very significant advantages over any voice system available for Amateur, Commercial and Emergency Services communications.

• Telephone-quality voice, comparable to industry-standard codecs used on landline, cell phones, and VoIP while using 1/8 of the bandwidth or less.
• Using the FDMDV-derived softmodem:
  • 1.1 KHz bandwidth, half the bandwidth of an SSB channel!
  • Works well on existing SSB radios, using the same set-up as other digital modes.
  • Can be carried on FM audio of existing VHF/UHF radios.
• Using a GMSK modem for VHF/UHF
  • Potential for 2 KHz channels, given sufficient frequency precision in mobiles and handhelds.
  • 2.5-3 KHz channels are easily possible with today's designs.
  • Less than half the bandwidth of D-STAR, less than 1/4 the bandwidth of Yaesu DMR/TRBO systems.
  • At least double the power efficiency (and thus the range) of wider-bandwidth modes.
  • Can use non-linear amplification, for best battery life.
• Fully legal for international communications because it is not an unspecified digital code under FCC rule 97.309(b) or laws of other nations.
• The codec is separate from modem, modulation and error-correction, choose the best modulation and error-correction for your channel.
• Open Source code available for download, for both the codec and the soft-modem.
• Avoids intellectual-property issues common to codecs:
  • No royalties, liberal grant of copyright rights to everyone.
  • Engineered to avoid existing patents in the field.
  • Exportable to all nations: "public domain" information under U.S. ITAR 120-125, found unrestricted in a letter of determination from the Australian government.
• Any Amateur Radio manufacturer can use Codec2, no charge, no agreements to sign.
• Hams like you are again leading development in telecommunications, not following commercial developments. Please join us.

Please join Our Announcement List so that we can notify you of new Codec2 software and events.

You can listen to the received signal, over a real 925 mile HF path. This is an alternating 1/0 bit pattern to test the modem, we'll put up a signal containing encoded audio ASAP. The image is a spectrogram (waterfall plot) of the same signal. Time is along the x axis, frequency along the y axis. The “hotter” the colour, the stronger the signal. Our FDM signal is the parallel red lines between 600 and 1700Hz. Above the modem signal is some analog SSB. You can hear this as the high frequency “Donald Duck” sound in the received signal. Now around 2.5 and 3.3 seconds there are strong bursts of SSB right on top of our signal, in the 0 to 1100 Hz range.

David Rowe VK5DGR is the codec and modem software developer. These pages on his site provide information on Codec2 and the FDMDV modem:

• Video: David Rowe explains Codec2 at Linux.conf.AU 2012
• Codec2
• Codec2 at 1400 bits-per-second.
• FDMDV
• README for FDMDV source code.
• Testing an FDMDV Modem
• Source Code.
• Public Mailing Lists at lists.codec2.org .
• Developers mailing list at Sourceforge.
• People who will give a speech about Codec2 at your hamfest or club.