Leah Rowe 273bd992dd spkmodem-decode: edge detection *and* amplitude
for pulses, we currently use amplitude detection.

edge detection is better, because weak / low gain
signals will be more reliable. if audio is coming
in on/from a system that does automatic gain
adjustment, this once again is more robust too.

microphones and speakers (which people often use
with spkmodem if nothing else available) often
clamp amplitude, to an extent that this software
may not detect those pulses reliably that way.

so we detect slope edges instead. this causes
very little performance penalty (use of abs(),
that's about it)

however, edge detection is inherently vulnerable
to noise, so we will also detect amplitude. this
acts as an effective noise filter, while still
improving pulse detection.

Signed-off-by: Leah Rowe <leah@libreboot.org>
2026-03-26 06:59:41 +00:00
2026-02-26 00:58:06 +00:00
2021-05-18 13:56:12 +01:00
2025-11-14 18:22:51 +00:00

Libreboot

Documentation: libreboot.org
Support: #libreboot on Libera IRC

Libreboot provides libre boot firmware on supported motherboards. It replaces proprietary vendor BIOS/UEFI implementations, by

  • Using coreboot to initialize the hardware (e.g. memory controller, CPU, etc.) while minimizing unwanted functionality (e.g. backdoors such as the Intel Management Engine)
  • ... which runs a payload such as SeaBIOS, GRUB, or U-Boot
  • ... which loads your operating system's boot loader (BSD and Linux-based systems are supported).

Why use Libreboot, and what is coreboot?

A lot of users who use libre operating systems still use proprietary boot firmware, which often contain backdoors and bugs, hampering user freedom and right to repair.

coreboot provides libre boot firmware by initializing the hardware then running a payload. However, coreboot is notoriously difficult to configure and install for most non-technical users, requiring detailed technical knowledge of hardware.

Libreboot solves this by being a coreboot distribution (in the same way that Alpine Linux is a Linux distribution). It provides a fully automated build system that downloads and compiles pre-configured ROM images for supported motherboards, so end-users could easily fetch images to flash onto their devices.

Libreboot also produces documentation aimed at non-technical users and excellent user support via IRC.

Contribute

You can check bugs listed on the bug tracker.

You may use Codeberg pull requests to send patches with bug fixes or other improvements. This repository hosts the code for the main build system. The website lives in a separate repository.

Development is also done on the IRC channel.

License for this README

It's just a README file. It is released under Creative Commons Zero, version 1.0.

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