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youtube-at-vach edited this page Jul 23, 2026 · 1 revision

Glossary

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This page provides definitions for codebase-specific terminology, Digital Signal Processing (DSP) jargon, and domain concepts utilized within the MeasureLab ecosystem.

Core System Terms

Term Definition Code Reference
MODULE_REGISTRY A dictionary mapping unique module keys to their dynamic import paths and class names. Used for lazy-loading GUI components. src/gui/main_window.py:74-116
AudioEngine The singleton responsible for managing hardware I/O, sample rate conversion, and the master callback loop. src/core/audio_engine.py:1-20
ConfigManager Manages persistent application state, hardware settings, and user preferences with debounced disk writes. src/core/config_manager.py:1-20
CalibrationManager Handles V/FS (Volts per Full Scale) sensitivity, SPL offsets, and frequency response correction curves. src/core/calibration.py:1-20
FFTManager A centralized utility for performing Fast Fourier Transforms, utilizing pyfftw wisdom for performance optimization. src/core/fft_manager.py:1-20

System Entity Mapping

The following diagram illustrates how natural language concepts map to specific classes and files within the MeasureLab architecture.

Diagram: Natural Language to Code Entity Mapping

graph TD
    subgraph "Natural Language Space"
        A["'The Audio Driver'"]
        B["'App Settings'"]
        C["'Calibration Data'"]
        D["'Language Files'"]
    end

    subgraph "Code Entity Space"
        A --> E["AudioEngine (src/core/audio_engine.py)"]
        B --> F["ConfigManager (src/core/config_manager.py)"]
        C --> G["CalibrationManager (src/core/calibration.py)"]
        D --> H["LocalizationManager (src/core/localization.py)"]
    end

    E -.-> I["PortAudio / ASIO / PipeWire"]
    F -.-> J["settings.json"]
    G -.-> K["calibration.json"]
    H -.-> L["src/assets/lang/*.json"]
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Sources: src/gui/main_window.py:23-25, src/core/config_manager.py:1-10, src/core/calibration.py:1-10

DSP & Measurement Jargon

SSS (Synchronized Swept Sine)

A measurement technique using an exponential chirp to characterize nonlinear systems. In MeasureLab, this is used to extract kernels for the Parallel Hammerstein Model (PHM).

  • Implementation: Found in NonlinearAnalyzer and RealtimeSSSEngine.
  • Kernels: $h_1$ (linear response) through $h_5$ (5th order nonlinearity).
  • Sources: src/core/nonlinear_analyzer_core.py:1-50, src/gui/main_window.py:111-114

Lock-in Detection (PSD)

Phase Sensitive Detection extracts a signal with a known carrier frequency from an extremely noisy environment.

  • Implementation: LockInAmplifier uses dual-phase (I/Q) demodulation.
  • Hardware Loopback: Required to maintain phase coherence between the software generator and the physical ADC input.
  • Sources: src/gui/widgets/lock_in_amplifier.py:1-30, src/gui/main_window.py:85

Weighting Filters

Frequency-dependent curves applied to audio measurements to simulate human hearing or standard compliance.

  • A-Weighting: IEC 61672:2003 standard, used in the SoundLevelMeter.
  • Implementation: Calculated via _calculate_ra_raw(f) and cached for performance.
  • Sources: src/core/analysis.py:15-26, src/core/analysis.py:45-54

Allan Deviation

A measure of frequency stability in clocks and oscillators, used to quantify jitter and drift over time.

  • Implementation: Calculated in FrequencyCounter to evaluate sample clock stability.
  • Sources: src/assets/lang/en.json:150, src/gui/widgets/frequency_counter.py:1-20

Codebase Implementation Concepts

Module Lifecycle

The MainWindow manages modules using a QStackedWidget. Modules are not instantiated until selected in the sidebar to reduce startup time.

Diagram: Module Lifecycle and Data Flow

sequenceDiagram
    participant MW as MainWindow
    participant REG as MODULE_REGISTRY
    participant AE as AudioEngine
    participant MOD as MeasurementModule

    MW->>REG: _load_module_class(module_key)
    REG-->>MW: Returns Class (e.g., SpectrumAnalyzer)
    MW->>MOD: Instantiate & Add to QStackedWidget
    MW->>AE: register_client(callback)
    AE->>MOD: stream_data(numpy_array)
    MOD->>MOD: process_dsp()
    MOD->>MW: update_ui()
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Sources: src/gui/main_window.py:119-134, src/gui/main_window.py:151-170

Key Abbreviations

Abbreviation Full Term Context
dBFS Decibels relative to Full Scale Digital signal level. src/assets/lang/en.json:14
THD+N Total Harmonic Distortion + Noise Quality metric in DistortionAnalyzer. src/gui/widgets/distortion_analyzer.py:1-10
IMD Intermodulation Distortion Two-tone test (SMPTE/CCIF). src/core/analysis.py:1-10
LUFS Loudness Units relative to Full Scale EBU R128 / ITU BS.1770 standard. src/gui/widgets/lufs_meter.py:1-5
1PPS One Pulse Per Second High-precision clock sync monitoring. src/gui/widgets/one_pps_monitor.py:1-10
OSL Open-Short-Load Calibration technique for Impedance Analyzers. src/gui/widgets/impedance_analyzer.py:1-10

Specialized Components

Sonifier

A utility that converts measurement data (like spectrum peaks) into audible tones, allowing "eyes-free" monitoring of signal changes.

  • Sources: src/core/sonifier.py:1-20, tests/logic_verification/core/test_sonifier.py:1-10

Boxcar Averager

A module for synchronous averaging of repetitive signals to improve Signal-to-Noise Ratio (SNR).

  • Sources: src/gui/widgets/boxcar_averager.py:1-20, src/gui/main_window.py:92

DetachableWidgetWrapper

A GUI utility that allows any measurement module to be "popped out" of the main window into its own top-level window.

  • Sources: src/gui/widgets/detachable_wrapper.py:1-10, src/gui/main_window.py:71

Sources: src/core/analysis.py:1-100, src/gui/main_window.py:74-116, src/core/module_constants.py:1-70, src/assets/lang/en.json:1-200

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