TrueRandom is not truly random

A while ago I had to get microcontrollers to generate truly random addresses for themselves, truly random 32-bit addresses to minimize collisions.  I looked around for inspiration and found the TrueRandom library for Arduino.   After testing it, I realized it’s not actually random and shouldn’t be used for anything important. Here’s a scatterplot of 4800 […]

Audio analysis in Python

Some signal-analysis-related Python scripts: Several different methods of estimating the frequency of a waveform Peak detection for spectra Measure total harmonic distortion plus noise of a sine wave (THD+N) Apply an A-weighting filter to audio files I’m sort of intending to combine them all into one eventually.

Android audio applications

Signal generator 1.0.2 Outputs sine, pink noise, and white noise Volume and frequency sliders Controls are hard to grab at the edges Volume control is independent from the phone’s volume control Doesn’t go below 100 Hz Sine waves are distorted and badly aliased at high frequencies.  THD+N measurements: 100 Hz 0.149% 1 kHz: 0.08% 10 […]

A simple FastICA example

Wikipedia describes independent component analysis as “a computational method for separating a multivariate signal into additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals”. (Clearly, this was written as part of their campaign to make technical articles accessible.) In normal people words, ICA is a form of blind source separation — a […]

Two improvements to Google Earth

In wide views, it should show whole-Earth (or whole-Mars, etc) images like the Blue Marble instead of a patchwork of smaller images. There should be a “fovea” at the poles to avoid the problem of hundreds of converging strips when zoomed into the poles.  This happens for both the planets and sky views, making Polaris […]

Is Ubuntu getting any better?

Here’s the same Ubuntu Forums experience polls charts as in Ubuntu release quality, but I’ll keep this one up-to-date with each release: These charts lump together upgrades and clean installs, since the ratios are similar for both, and it shows more clearly the overall trend. Feisty (1,387) 47% 23% 30% Gutsy (5,479) 22% 44% 34% […]

Jaunty fresh install notes

Similar to the Intrepid fresh install notes, I kept notes while installing Jaunty from the CD on my Dell Inspiron 8600, trying to see it the way a complete newcomer would. Again, the language selection screen is ugly. Again, you have to reboot after checking the CD for errors. Currently it says “Press F4 to […]

Ubuntu newcomer experience

I recently got a new hard drive, and installed Ubuntu on it from scratch.  I decided to put myself in the mindset of a newcomer and see how the experience compares now that I’ve been using it for two years. My unorganized notes: Language selection screen after booting from CD is jarring, not totally intuitive, […]