A Pretty Waterfall Spectral Analyzer, for RTL-SDR (and more to come), Inspired by GQRX, with Cyberpunk Vibes, written in Odin and Raylib.

1. I wanted to learn Odin and build something useful with it.
2. I work in RF/telecom and wanted a simple, focused waterfall display that just works, nothing too fancy.
3. I like Raylib becayse it makes things easy.
4. I like pretty, graphical things.
5. The SDR community could use another general-purpose waterfall open-source spectrum analuzer with some style.

• Requirements:
  • Odin compiler brew install odin
  • librtlsdr brew install librtlsdr on macOS or apt install librtlsdr-dev on Linux

Clone the repo and initialize submodules:

git clone https://github.com/grplyler/spectro.git
cd spectro
git submodule update --init --recursive
./b # or odin build spectro -o:speed -out:build/spectro

Build Script:

odin build spectro -o:speed -out:build/spectro

./r or ./build/spectro to run the application.

• RTL-SDR Integration: Continuous sample acquisition from RTL-SDR device
• GPU Accelerated: Efficient scrolling effect using fragment shader and ring buffers
• Click to Tune: Click on the waterfall to retune the SDR to the clicked frequency
• Peak Visualization: With variable hold time
• FFT Processing: In-house real-time FFT computation (probably chatgpt fueled garbage I don't really understand, but hey, its still 6x faster than KissFFT)
• Sick Frequency Control: Frequency control with digits (also inspired by GQRX)
• Pretty Waterfall: Scrolling spectrogram display using Raylib
• Spectrum Line Plot: Basic Stuff
• Color Mapping: Viridis colormap for dB-to-color conversion
• Cyberpunk UI: Yes

• handle FFT size changes
• handle samplerate changes
• handle gain changes (AGC switching)
• handle device changes
• binary builds for macOS, Linux, Windows
• save/load settings
• WBFM demodulation
• IQ Sample Recording
• Frequency Bookmarks

• Theme Changer
• Colormap Changer
• SoapySDR support (for lots more SDR Support)
• Better IQ sample playback (Sorry by GQRXs is so unintuitive and finicky)
• Multiple SDRs working in sync to capture wide spectrum
• Frequency Bookmarks
• Audio recording
• Audio live output
• Zoom feature for waterfall

• FFT Size: 2048 samples
• Sample Rate: 2.048 MSPS
• History: 1024 waterfall rows
• Default Frequency: 101.1 MHz

• The codes kind of a mess, but it just wanted something quick, will clean up in the meantime.
• Feel free to contribute!

• KissFFT for being an implementation Benchmark for speed and testing before I wrote my own FFT code.
• Raylib for making graphics easy and fun.
• Odin for being a fun (and faster) language to learn and use.
• The SDR community for inspiring this project and providing the RTL-SDR hardware.
• GQRX
• The (poor) LLMs that I probably abused in the process of writing this, getting angry, then having to figure it out myself anyway.

• MIT License