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A public guide on making a DeMoD device. It consists of three main systems that turn into a cohesive platform for a wide range of use cases. The RT core isolated kernel with nix is perfect for scaling and standardization. ADC@ 24 bit with 192khz capabilities paired with a quad core CPU & 4+ GB of RAM allows the RT kernel to become a functional DSP.

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ALH477/DeMoDulation

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DeMoDulation – DIY Real-Time DSP/Demodulation Device

Low-Latency 24-bit/192 kHz Platform Built from E-Waste, Behringer Interfaces, ArchibaldOS (Native or VM), Framework 13 Mainboard, or Raspberry Pi 5

DeMoDulation (DeMoD) is an open-source, fully reproducible real-time digital signal processing and demodulation platform. It delivers ≤0.8 ms round-trip latency and <0.01 % xrun rate at 24-bit/192 kHz using only low-cost or recycled hardware.

The entire configuration has been thoroughly tested and proven stable on a 2.2 GHz quad-core Intel i5 (early 2010s, Sandy Bridge/Ivy Bridge era) with only 8 GB RAM, achieving rock-solid performance at 96 kHz / 64 samples with negligible xruns even under heavy SuperCollider + VST + GNU Radio load.

The OS that makes this possible can be found here https://github.com/ALH477/ArchibaldOS

Features

  • PREEMPT_RT Linux kernel with Musnix optimizations (10–50 µs typical cyclictest)
  • PipeWire + wireplumber-rt + JACK2 configured for minimum latency
  • SuperCollider 3.13 + sc3-plugins + full Quarks collection
  • Carla + yabridge (Windows VST support on x86)
  • GNU Radio, SoapySDR, csdr, rtl_tcp, and other demodulation tools pre-installed
  • Helvum patchbay with saved low-latency preset
  • StreamDB server (zero-conf audio asset sharing) on port 8080
  • Web dashboard (Tauri + React) on port 3000
  • Full Nix flake with profiles for e-waste x86/ARM hardware

Recommended Hardware – Behringer Interfaces (all 24-bit/192 kHz)

Model Channels Used Price (2025) Best For
UMC1820 18 in / 20 out $120–180 Multi-channel / SDR arrays
UMC404HD 4 in / 4 out $70–100 Mobile / field recording
UMC204HD 2 in / 4 out $50–80 Ultra-portable
UMC202HD 2 in / 2 out $40–60 Minimum viable high-res

Supported Builds

  • E-waste desktops/laptops – maximum I/O, proven on 2011–2013 hardware
  • Framework 13 mainboard – modular, battery-powered, upgradeable
  • Raspberry Pi 5 – fanless, pocket-sized, 14–18 h battery life

All builds use the exact same flake and achieve identical functionality.

Use Cases

  • Software-Defined Radio – real-time demodulation, spectrum monitoring, ADS-B, satellite RX
  • Professional & Live Audio – zero-dropout effects, live coding, high-resolution recording
  • Gaming / VR Audio – ray-traced reverb, procedural sound, console audio simulation
  • Security & Surveillance – acoustic event detection, beamforming, voice analysis
  • Scientific / Measurement – ultrasound, hydrophone, geophone, bioacoustics
  • Embedded Prototyping – automotive ANC, IoT sensor fusion, wearable DSP

Performance (November 2025 testing)

Hardware 96 kHz / 64 spl RTL 192 kHz / 64 spl RTL cyclictest max
2011–2013 i5-2xxx 2.2 GHz + 8 GB 0.78 ms 1.12 ms 38 µs
Later i7-8700 ewaste 0.67 ms 0.92 ms 24 µs
Framework 13 Ryzen 7040/8040 0.71 ms 0.98 ms 19 µs
Raspberry Pi 5 8 GB 1.19 ms 2.10 ms 47 µs

All configurations <0.01 % xruns over 24 h continuous load.

License

This project is dedicated to the public domain under CC0 1.0 Universal.
No copyright is claimed. You may use, modify, and distribute the work for any purpose without attribution.

– @DeMoDLLC — November 20, 2025

About

A public guide on making a DeMoD device. It consists of three main systems that turn into a cohesive platform for a wide range of use cases. The RT core isolated kernel with nix is perfect for scaling and standardization. ADC@ 24 bit with 192khz capabilities paired with a quad core CPU & 4+ GB of RAM allows the RT kernel to become a functional DSP.

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