SignalShow

Overview

SignalShow is an educational signal processing application, originally built in Java Swing. This proposal explores modernizing it for web and desktop platforms.

Vision: "SignalShow is to DSP what Desmos is to algebra"

Status: Early prototype phase

Versions

1. Web Version - Browser-based prototype in React/Plotly.js
2. Desktop Version - Proposed Tauri app with optional Julia backend
3. Java Version - Original Swing GUI with 80+ functions (legacy)

---

Web Prototype

Repository: /nuthatch-desktop

Features

• 4 signal types: Sine, Cosine, Chirp, Gaussian
• Interactive waveform visualization (Plotly.js)
• FFT analysis
• Window functions: Hanning, Hamming, Blackman
• 5 educational demos
• JSON export
• Responsive 3-column layout

Components

• SignalDisplay - Interactive waveform plots
• FunctionGenerator - Signal parameter controls
• OperationsPanel - FFT and windowing operations
• DemoGallery - Educational examples

Development

cd /Users/julietfiss/src/nuthatch-desktop
npm install
npm run dev
# Open http://localhost:5173

Planned (Phase 2)

• Rust/WebAssembly backend for performance
• Additional signal types and operations
• Advanced filtering
• 3D visualizations

---

Java Desktop Version (Original)

The original implementation with 80+ functions and 40+ operations.

Key Features

• Analytic function generators (Gaussian, Chirp, Delta, Bessel, windows, noise models, etc.)
• 1‑D / 2‑D interactive plotting (zoom, pan, overlays)
• Frequency-domain and convolution operations
• Educational demos (sampling, filtering, holography, more)
• Modular operation architecture

Project Structure

SignalShow/
  SignalShow.java          # Main entry point
  jai_core.jar             # JAI core classes (bundled)
  jai_codec.jar            # JAI codec classes (bundled)
  signals/                 # Application packages
  run-signalshow.sh        # Launcher script

Prerequisites

• Java Development Kit (JDK) 11+
• Bundled JAI jars: jai_core.jar, jai_codec.jar

Quick Start

./run-signalshow.sh

This script verifies JAI jars, sets the classpath, and launches the main class.

Building from Source

find SignalShow -name "*.java" > /tmp/sigshow-srcs.txt
javac -d . @/tmp/sigshow-srcs.txt
java -cp "SignalShow:SignalShow/jai_core.jar:SignalShow/jai_codec.jar" SignalShow

Or one-liner:

find SignalShow -name "*.java" -print0 | xargs -0 javac -d . && \
java -cp "SignalShow:SignalShow/jai_core.jar:SignalShow/jai_codec.jar" SignalShow

---

Troubleshooting

Symptom	Likely Cause	Resolution
NoClassDefFoundError: javax/media/jai/PlanarImage	JAI jars not on classpath	Ensure classpath includes JAI jars. Remove any extracted SignalShow/javax directory.
SecurityException: sealing violation	Duplicate package definition	Delete stray javax/ directory.
UnsatisfiedLinkError for JAI native libs	Platform mismatch (x86 vs arm64)	Run under Rosetta with x86 JDK, or obtain arm64 native builds.

Diagnostics

List native libraries:

find . -type f \( -name "*.so" -o -name "*.dylib" -o -name "*.jnilib" -o -name "*.dll" \) -print

Check jar contents:

jar tf SignalShow/jai_core.jar | grep javax/media/jai/PlanarImage.class

Remove accidentally extracted classes:

rm -rf SignalShow/javax

---

Extending the Application

New analytic functions or operations can be added by creating classes under signals/... subpackages and wiring them into existing registries or menus.

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/your-feature)
3. Commit changes with clear messages
4. Open a pull request

License

Refer to LICENSE file or header comments in source. JAI libraries are bundled in binary form; their original licensing terms apply.