Codec 2 wins the ARRL Technical Innovation Award

I’ve won the ARRL Technical Innovation Award for 2012 for my Codec 2 work.

When I first became interested in Ham Radio as a 12 year old in the late 70′s my grandfather bought me the 1979 ARRL handbook. Quite an honor to one day be contributing back to this fine hobby that was my start in a communications and electronics career.

That version of the handbook even had a chapter on “Narrow Band Voice Modulation” – an esoteric analog technique to compress speech by removing chunks of audio bandwidth. Who would have thought that 30 years later I ‘d be contributing in the same area…….

The Codec 2 project is moving along nicely. Recently I have been working on integration of the FDMDV modem with Codec 2, and have written a GUI program called fl_fdmdv to help me debug the combined system. Here is a screen shot (click for large version):

This looks really cool as the graphics update in real time, a static image doesn’t really do it justice. Displaying parameters in real time has helped me spot a few bugs, which I missed with the static plots I get from the Octave simulations. I have used fl_fdmdv to send the Codec2/FDMDV signal over an audio cable between two laptops. It’s really exciting to see the bits being modulated onto the waveform on the GUI while listening to audio flowing over the system! Next step is to replace the audio cable with SSB radios and do some over the air testing.

I am also working on a high quality version of Codec 2 at about 4000 bit/s. The target is speech quality similar to CELP type algorithms such as g.729/Speex/Opus that run at 8000 bits/s. The main application is VOIP, but it might also be useful for a “FM quality” mode for VHF digital radio. The key to high quality is quantising and transmitting the phase of the sine waves used by Codec 2 to model speech. The challenges are working with phase (modulo 2-pi hurts my head) and the time varying number of sine waves and hence phases that must be transmitted. The technique I am currently working on is “sparse vector quantisation of phases”. Tough work but I am slowly making progress. This work is being generously supported by a company who wishes to remain anonymous – but I wanted to thank them anyway!

10 comments to Codec 2 wins the ARRL Technical Innovation Award

  • Nice to hear that someone is supporting you to create Open Source code.

  • Robert Boerner

    Although I can’t profess to completely understand the science at work here, it never ceases to amaze me how well you can communicate your thought process. Excellent work and thanks for your efforts!

  • dan

    congrats brother!!
    As a kid, i use to love pouring over the ARRL handbook…


  • happy to hear that – i already played with codec2 using fm-”like 8-)” music, e.g. which is promising.

  • Jeff N1KDO

    Congratulations, David, on a well-deserved award.

    I am very much looking forward to using your work over the air.



  • Henrique Gravina

    Congratulations! For you David for this work and for the anonymous company that is supporting codec2.

  • Mel Whitten

    Again, congratualations! The DV HF community continues to be very excited about your good work. Together with Dave Witten’s FDMDV2 GUI, we look forward to using it the HF bands.

  • David Bern

    Congratulations and thank you for all your good work.

    I am constantly amazed how a book can change a life. When I was in the fifth grade, I discovered Using Electronics : A Book of Things to Make, by Harry Zarchy (1958), and it described how to make a crystal radio using an empty toilet paper roll. It worked and I’ve been hooked ever since!

  • David,
    i’m kit happy with your nice work
    congratulation for that

  • Karl Wagner

    Excelent work!
    C2 for voice, OPUS for music ;)