Specter

Specter is a high-performance Android application designed for real-time acoustic signal spectral analysis and precision signal generation ✨ Key Features 📊 Real-Time Visualizations Specter provides three synchronized, hardware-accelerated views for deep signal inspection: Waveform (Amplitude vs. Time): A high-speed oscilloscope plot displaying the raw variations of the incoming audio signal over the selected integration window. Periodogram (Power Spectrum): A logarithmic frequency plot (dB vs. Hz) revealing the intensity of discrete frequency components. Supports customizable dynamic ranges from 1 Hz up to 20 kHz. Spectrogram (Waterfall Plot): A 2D heat map visualizing how the frequency spectrum evolves over time. Retains up to 20 seconds of acoustic history. 📡 Precision Signal Generator Bypass external equipment and synthesize high-fidelity signals directly through the device's audio hardware: CW (Continuous Wave): Standard sine wave generation at a fixed frequency. LFM (Linear Frequency Modulation): A "chirp" signal that sweeps linearly between a defined start and end frequency. HFM (Hyperbolic Frequency Modulation): A constant-Q sweep where the frequency changes exponentially, ideal for specific acoustic and sonar testing. Pulse Train: Periodic transmission of CW pulses with precise control over pulse length and PRI (Pulse Repetition Interval). 🔍 Interactive Data Analysis Precision Tooltips: Long-press anywhere on the rendering canvas to extract exact numeric data points: Waveform: Exact Time (s) and Amplitude. Periodogram: Exact Frequency (Hz) and Intensity (dB). Spectrogram: Time, Frequency, and Intensity at the specific touch coordinate. Logarithmic Scaling: Frequency axes utilize logarithmic mapping for an accurate representation of acoustic octaves. ⚙️ Professional Configuration Variable Integration: Adjust the FFT window from 0.1s to 5s to perfectly balance time resolution against frequency resolution. Dynamic Range Control: Clamp the Upper and Lower dB limits (e.g., -80 dB to 20 dB) to eliminate background noise floors or visual saturation. Windowing Functions: Toggle between a standard rectangular window or a Hamming window to suppress spectral leakage. A-Weighting (Human Ear Mode): Optional filter to map raw decibels to human hearing sensitivity. 🛠️ Technical Details Component Specification Sample Rate 44,100 Hz (Hardware Native) DSP Engine Custom real-time FFT (Fast Fourier Transform) with overlap processing UI Framework Jetpack Compose (Native Canvas Drawing) Data Persistence SharedPreferences for lightweight configuration state Min SDK API 24 (Android 7.0 Nougat)