Post #1107108
2026-04-12 12:10 UTC
I'm trying to fix one thing that really bugs me about my video decoder. In short, that fix involves converting my simple arrays of samples into I/Q, the kind that SDRs use. And that involves FFT. And that means I can't get this meme out of my mind
Replies (1)
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@grishka@mastodon.social 2026-04-12 12:16
The problem is that my "genius" FM demodulation algorithm isn't so genius after all, at least with the sample rate involved, where I get 7-ish samples per period of the carrier. The algorithm measures the distances between zero crossings using inverse linear interpolation, to (try to) directly get the inverse value of the frequency. And it turns out that linear interpolation doesn't approximate a sine wave well enough with this few samples. This manifests as some rather nasty noise: