2024-09-22 18:49 UTC
The voice signals in this challenge included narrowband FM, AM, and SSB. The SSB signal was almost hiding below the noise floor to make things even harder. In the post I explain how to solve the challenge, including a trick to avoid having to do phase alignment when dechirping.
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@destevez@mastodon.social 2024-09-22 18:49
I also go into quite some detail about why frequency glitches are almost inevitable after dechirping, regardless of the procedure. The typical quadrature demodulator is quite sensitive to these frequency glitches, so the narrowband FM signals sound quite bad. Read more: https://destevez.net/2024/09/not-lora-grcon24-ctf-challenge/