I have a lifestyle that is different to many people, and I have been encouraged to write about it. According to my friends, I am “living the dream”. I get up in the morning and can choose to do anything I want. I don’t work for money any more. I’ve been able . . . → Read More: A Miserable Debt Free Life
For the last few weeks I’ve been working on improving the quality of the 700 bit/s Codec 2 mode. It’s been back to “research and disappointment” however I’m making progress, even uncovering some mysteries that have eluded me for some time.
I’ve just checked in a “FreeDV 700B” mode, and ported it to the FreeDV API . . . → Read More: FreeDV Robustness Part 7 – FreeDV 700B
Justin, VK7TW, has published a video of my recent presentation at Gippstech, which was held in July 2015. Good summary of FreeDV, the SM1000, and the exciting possibilities for VHF Digital Voice. Thanks Justin! Here are the Open Office slides of the presentation.
Oh, yes and in the cut out image below my head doesn’t really . . . → Read More: Advanced VHF Digital Radio using Codec 2
My good friends at the Amateur Radio Experimenters Group (AREG), an Adelaide based Ham radio club, have organised a special FreeDV QSO Party Weekend on Sat/Sun September 12/13th. This is a great chance to try out FreeDV, work VK5 using open source HF digital voice, and even talk to me!
All the details including paths, frequencies, . . . → Read More: FreeDV QSO Party Weekend – September 12/13th
I’ve been working on the Linear Predictive Coding (LPC) modeling used in the Codec 2 700 bit/s mode to see if I can improve the speech quality. Given this mode was developed in just a few days I felt it was time to revisit it for some tuning.
LPC fits a filter to the speech spectrum. . . . → Read More: Low Order LPC and Bandpass Filtering
This week I have been looking at the effect different speech samples have on the performance of Codec 2. One factor is microphone placement. In radio (from broadcast to two way HF/VHF) we tend to use microphones closely placed to our lips. In telephony, hands free, or more distance microphone placement has become . . . → Read More: Microphone Placement and Speech Codecs
I’m a believer in self driving car technology, and predict it will have enormous effects, for example:
Our cars currently spend most of the time doing nothing. They could be out making money for us as taxis while we are at work.
How much infrastructure and frustration (home garage, driveways, car parks, finding a park) do we . . . → Read More: Self Driving Cars
Anyone who writes software should be sentenced to use it. So for the last few days I’ve been radiating FreeDV 700 signals from my home in Adelaide to this websdr in Melbourne, about 800km away. This has been very useful, as I can sample signals without having to bother other Hams. Thanks John! . . . → Read More: FreeDV Robustness Part 6 – Early Low SNR Results
I recently went on a nice road trip to Gippstech, an interstate Ham radio conference, with Andrew, VK5XFG. On the way, we were chatting about Electric Cars, and how much of infernal combustion technology is really just a nasty hack. Andrew made the point that if petrol cars had been developed now, we would . . . → Read More: 8 Mega Watts in your bare hands
OK, so FreeDV 700 was released a few weeks ago and I’m working on some ideas to improve it. Especially those annoying R2D2 noises due to bit errors at low SNRs.
I’m trying some ideas to improve the speech quality without the use of Forward Error Correction (FEC).
Speech coding is the art of “what can I . . . → Read More: Trellis Decoding for Codec 2