#firmware.
Posts on the Alpisto engineering blog filed under #firmware.
- 01#flybeeper #fanet-vario #sun-vario
When does a vario beep? How a FlyBeeper vario decides, and what you can change
Between a climb tone and a sink alarm there is a band where a vario has to make up its mind, and pilots disagree about what it should do there. Some want silence the moment a thermal fades, some want to keep hearing a weak core, some want a tone almost all the time. This is how a FlyBeeper vario makes that decision, step by step: the averaging, the tone curve, two thresholds on each side, a memory of which tone is playing and an early exit on a weakening climb. Every example plays in the page, and opens in the configurator with one click.
16 min read - 02#flybeeper #fanet-vario #sun-vario
The note that never sounds: what a piezo vario actually plays
Small varios beep in a way nobody would call pleasant, and it is not because nobody cared. A piezo disc is a bell with one note of its own, and a vario plays a tune on it by feeding it square waves and letting the bell pick what it likes. I put one in a desk drawer with a microphone: at 1000 Hz the note that was asked for comes out 33 dB below its own third harmonic, loudness swings 16 dB across the tone table, and the obvious way to soften a beep turns out to make it sharper.
17 min read - 03#flybeeper #sun-vario #variometer
Fourteen metres that were never there: a soldered barometer's thermal drift
Everyone who builds these devices knows you must not solder near the barometer, and that the third rework kills it. Nobody says by how much. This one came off the bench at 470 Pa/K against a rated 0.5, inventing 14.5 metres of climb while sitting still. Thirty lines of firmware removed 95 % of that and every bench test agreed — until somebody picked the device up and the vario went the wrong way. The number behind the folklore, and why the fix helps an altimeter and provably cannot help a variometer.
24 min read