Democratising HF Radio Part 1

I recently submitted a Shuttleworth Fellowship grant application. I had planned to use the funding to employ people and accelerate the roll out of the project described below. I just heard that my application was unsuccessful (they wanted something more experimental). Never mind, the ideas lives on!

I’m exploring some novel ideas for messaging over . . . → Read More: Democratising HF Radio Part 1

Reducing FDMDV Modem Memory

For the SM1000 (SmartMic) project I need to run the FDMDV HF modem on the STM32F4 micro-controller. However The STM32F4 only has 192k of internal RAM, and the modem in it’s original form uses over 400k. I wrote a unit test to break down the memory usage:

david@bear:~/tmp/codec2-dev/build_dir$ ./unittest/fdmdv_mem
struct FDMDV.......…: 409192
prev_tx_symbols....…: 168
tx_filter_memory......: 1008
phase_tx..........….: 168
freq..................: . . . → Read More: Reducing FDMDV Modem Memory

Energy Equivalents of a Krispy Kreme Factory

My 15 year old son is rather excited at the prospect of Adelaide’s first Krispy Kreme factory. This factory will be pumping out 5,000 donuts an hour.

Now a donut contains about 1000 kJ of energy. This is chemical energy, in the form as fat and sugars and carbohydrates. Our bodies are . . . → Read More: Energy Equivalents of a Krispy Kreme Factory

HF Modem Frequency Offset Estimation

One of my goals for 2014 is to make FreeDV work as well as SSB on HF radio channels. Recently I have been working on improvements to the frame sync algorithms used in the FDMDV modem. I would like to move from a “hard” sync decision to a “soft” one, such that the demod . . . → Read More: HF Modem Frequency Offset Estimation

Email to an Anti-Vaxer

I recently had an email conversation with an anti-vaxer. I enjoy critical thinking exercises like this, and thought my response might be useful to publish.

The anti-vaxers key points (I’ve paraphrased here as it was a private email) were:

“An Australian TV program A Current Affair (ACA) screened a segment around a family who was awarded a . . . → Read More: Email to an Anti-Vaxer

Fixed Point Goertzal Tone Detector

This post is a tutorial on fixed point DSP, where I provide a detailed worked example of porting a Goertzal algorithm based tone decoder from float to fixed point.

My post on Fixed Point Scaling is consistently popular. I think that’s because there just isn’t much information out there on fixed point DSP. In particular, . . . → Read More: Fixed Point Goertzal Tone Detector

SmartMic Prototype PCB Ready for Manufacture

Over the past few weeks Rick Barnich KA8BMA has been doing some fine work on the schematic and PCB design for SmartMic. Yesterday Rick and I had a PCB and schematic review meeting over Skype, and Rick is now working on a few small changes. The PCB board layout will go in for manufacture . . . → Read More: SmartMic Prototype PCB Ready for Manufacture

Fluksometer Update

Hello, I am David’s 18 year old daughter, Amy. Some of you may remember me as the girl who’s father busted her teenage party using an energy monitor, from 800km away. Since my social life was destroyed in one night due to this product, I have had a lot of time on my hands. My father . . . → Read More: Fluksometer Update

wxWidgets Checkbox Tooltips

I need to post this so that no one else experiences the same pain with wxWidgets (2.9.4). Tooltips weren’t working for me when I hovered over checkboxes. This has bothered me for about 2 years and Google doesn’t seem to throw up a solution.

We are using wxWidgets for FreeDV, as we needed cross platform . . . → Read More: wxWidgets Checkbox Tooltips

Fixing Broken Plastic Fridge Shelves

I have a small Samsung fridge that developed several cracks in the shelves on the door. After a while the cracks spread and one of the shelves became unusable. We couldn’t seem to buy a spare. This was really annoying. I felt like Samsung was telling me to buy a new fridge! . . . → Read More: Fixing Broken Plastic Fridge Shelves