@windytan

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181 Posts
Curious experiments with sound, waveforms, and computers. Slow account.
Project blog: Absorptionshttps://www.windytan.com
YouTube: Windytan's waveshttps://www.youtube.com/@windytan
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Show threadwindytanFeb 21
You can sort of see the 5 repeats in the audio spectrogram (left) but especially the cepstrum (right - which shows echoes and repeating structure) has a sharp peak at 1878 ms, just a couple of bins wide
windytanFeb 21

Viral shortform video is often augmented with subtle glued-on sound effects, but here's an interesting one - the background noise was "looped" for around 9 extra seconds to drive home the wow effect :)

https://www.youtube.com/shorts/7UZetfRezzI

This How Dangerous 😳 Cave #shorts #ytviral #facts #factshorts #like #trending

YouTube
Show threadwindytanFeb 1
@abraxas3d Ooo. There's never too much RGB. :)
windytanJan 31
Have you ever had a déjà vu where you also catch yourself predicting what happens next? Of course the prediction will be wrong, but there is some sense of what *should* happen for the déjà vu sensation to continue.
windytanDec 28
Fellow myopics, do you ever stare into a faraway LED just to appreciate the details in your eyes' point spread functions?
windytanAug 24, 2025
@mkouhia That one was just a niche application working at a much lower frequency:)
Show threadwindytanAug 23, 2025

Update: One of the places that had this ultrasonic beep from their PA system has now stopped using it!

There's now a much quieter tone at a much higher frequency, outside anyone's hearing range for sure, which only shortly appears every now and then. Maybe they upgraded their sound system?

windytanJul 20, 2025

It's amazing how noise resistant LoRa is. It took me a while to realize that there can be plenty of perfectly decodable LoRa traffic even though the recording spectrograms look empty.

Here's a complete Meshtastic GPS position message (~50 chirp symbols each 250 kHz wide) buried in noise and some kind of smart meter traffic. I got a correct CRC after just 1 parity flip!

Show threadwindytanJul 8, 2025
@dg3hda @ipg lol!
windytanJun 5, 2025
Show threadDaniel EstévezJun 5, 2025
@windytan when you feed only part of a CW into the FFT you get the Fourier transform of a rectangle, which is a sinc of frequency proportional to the rectangle width. The symmetry that happens in time is best explained by thinking that feeding a CW that fills more than 1/2 of the FFT is equivalent to feeding a CW for the whole FFT duration plus a negative rectangle that occupies the beginning less than 1/2 of the FFT duration.