Blue Pebble

Blue Pebble is a research-oriented simulation framework for underwater acoustic sensing, currently focused on passive sonar signal processing, acoustic propagation modelling, beamforming, detection, and multi-target tracking.

Designed as a plugin for Stone Soup, Blue Pebble supports research in:

  • Underwater acoustics

  • Passive sonar signal processing

  • Towed array modelling

  • Acoustic propagation modelling

  • Beamforming and detection theory

  • Target tracking and data association

Naming conventions: The project is referred to as Blue Pebble throughout documentation. The repository and PyPI package use the hyphenated form blue-pebble (e.g., pip install blue-pebble). Within Python code, the package is imported as bluepebble (e.g., import bluepebble).

Research Applications

Blue Pebble is intended for controlled, simulation-based studies, including:

  • Evaluation of tracking and data association algorithms

  • End-to-end sonar performance analysis

  • Synthetic dataset generation for validation

  • Sensitivity analysis of propagation effects on detection and estimation

Although current functionality centres on passive sonar, the architecture supports extension to additional modalities (e.g., active or multistatic configurations).

Architecture

Blue Pebble follows a modular design that separates physical modelling from signal processing and tracking logic. Core components include:

  • Platform dynamics - Kinematic modelling of ownship, targets, and arrays

  • Acoustic propagation - Pluggable propagation backends (analytical or external solvers)

  • Signal generation - Source modelling and noise synthesis

  • Beamforming - Array processing algorithms

  • Detection - Measurement formation and statistical thresholding

  • Tracking - Integration with Stone Soup estimators and data association

This separation enables systematic experimentation across modelling assumptions and algorithmic choices without tightly coupling components.

Features

Implemented capabilities include:

  • Multi-body kinematic modelling for flexible towed arrays

  • Analytical spreading models and external ray-tracing integration (e.g., rtrs)

  • Configurable source signature synthesis

  • Ambient, biological, and ownship noise modelling

  • Multiple beamforming algorithms

  • Detection algorithms with performance metrics

  • Passive sonar simulation pipelines

  • Native integration with Stone Soup tracking workflows

  • Plotting utilities for bearings and Cartesian tracks

  • Gallery-based tutorials and worked examples

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