Document	Description
Signal Flow	Complete data path from SDR hardware to audio output, including queue topology and buffer management
Threading Model	Thread inventory, lifecycle management, synchronization mechanisms, and producer-consumer patterns
Modem System	Modem plugin architecture, factory registration, data processing pipeline, and available modem types

Quick Reference

Source Directory Layout

src/
  sdr/           SDR hardware interaction (SoapySDR wrapper)
  demod/         Demodulator lifecycle and processing
  audio/         Audio output (RtAudio) and recording
  visual/        OpenGL canvas rendering
  modules/modem/ Modem plugins (analog and digital)
  process/       FFT and visual data processing
  util/          Core utilities (queues, timers, data trees)
  rig/           Hamlib CAT control (optional)
  forms/         UI forms (device selection, bookmarks, dialogs)
  panel/         Display panels (scope, spectrum, waterfall, meter)

Key Classes

Class	File	Role
`CubicSDR`	`src/CubicSDR.h`	Application singleton, owns all global threads
`AppFrame`	`src/AppFrame.h`	Main wxWidgets window, UI event loop
`AppConfig`	`src/AppConfig.h`	Application configuration persistence
`SDRThread`	`src/sdr/SoapySDRThread.h`	Reads IQ samples from hardware
`SDRPostThread`	`src/sdr/SDRPostThread.h`	Channelizes and distributes IQ data
`SDREnumerator`	`src/sdr/SDREnumerator.h`	Background device discovery
`DemodulatorInstance`	`src/demod/DemodulatorInstance.h`	Orchestrates one demodulator's thread chain
`DemodulatorMgr`	`src/demod/DemodulatorMgr.h`	Manages all demodulator instances
`DemodulatorWorkerThread`	`src/demod/DemodulatorWorkerThread.h`	Offloaded modem/filter creation
`Modem`	`src/modules/modem/Modem.h`	Abstract modem base class with factory pattern
`AudioThread`	`src/audio/AudioThread.h`	Manages RtAudio output device
`AudioSinkThread`	`src/audio/AudioSinkThread.h`	Per-demod audio sink (base class)
`AudioSinkFileThread`	`src/audio/AudioSinkFileThread.h`	WAV file recording
`IOThread`	`src/IOThread.h`	Base class for all worker threads
`ThreadBlockingQueue`	`src/util/ThreadBlockingQueue.h`	Primary inter-thread communication mechanism

CMakeLists.txt Source/Header Mismatches

The CMakeLists.txt source file lists have several entries in the wrong category:

File	Listed As	Should Be
`src/sdr/SoapySDRThread.h`	Source	Header
`src/panel/MeterPanel.h`	Source	Header
`src/sdr/SoapySDRThread.cpp`	Header	Source
`src/ui/UITestCanvas.cpp`	Header	Source
`src/ui/UITestContext.cpp`	Header	Source

These mismatches don't affect the build (CMake treats both lists as source files for compilation), but they misrepresent the project structure and should be corrected.