# Underwater Acoustic Channel Library > An open-access library of underwater acoustic channel impulse responses and noise models recorded during at-sea experiments, with a replay interface for simulating communication signals. The library is described in the paper [Underwater Acoustic Channel Library](https://arxiv.org/abs/2609.03207) (arXiv:2609.03207). The channel and noise `.mat` files are on Zenodo, [doi:10.5281/zenodo.21287414](https://doi.org/10.5281/zenodo.21287414). The toolboxes that read them are available for MATLAB and Python, and Julia support is provided by UnderwaterAcoustics.jl. Every page below is linked to its Markdown version. ## Site index - [Home page](https://uwa-channels.github.io/index.md) - [Channels](https://uwa-channels.github.io/channels/index.md): Eight color-labeled underwater acoustic channels recorded across sites worldwide, spanning shallow and deep water, short and long range, and fixed and mobile platforms. - [Noise](https://uwa-channels.github.io/noises/index.md): Site-specific ambient noise models accompanying every channel except Brown, covering colored Gaussian noise and, for the Red channel, impulsive alpha-stable noise. - [User's Guide](https://uwa-channels.github.io/docs/index.md): Instructions for downloading the channel library, replaying a signal through a channel, adding site-specific noise, and visualizing a decompressed channel. ## Channels - [Blue](https://uwa-channels.github.io/channels/blue/index.md): A 13 kHz mobile channel from the North Atlantic (MACE'10), recorded over a 3-7 km range with a moving transmitter and a 12-element vertical array. - [Red](https://uwa-channels.github.io/channels/red/index.md): A 25 kHz drifting-boat channel recorded near Singapore in November 2024, over a 100-400 m range with a 3-element vertical array and impulsive ambient noise. - [Yellow](https://uwa-channels.github.io/channels/yellow/index.md): A 13 kHz channel from the KAM'11 experiment off Kauai, Hawaii, recorded over 3 and 7 km ranges using four vertical receiving arrays. - [Purple](https://uwa-channels.github.io/channels/purple/index.md): A 12.5 kHz shallow-water channel from the SPACE'08 experiment off Martha's Vineyard, with cross and vertical receiving arrays at ranges from 60 m to 1 km. - [Green](https://uwa-channels.github.io/channels/green/index.md): A 6 kHz single-hydrophone channel from a Norwegian fjord (Norway'24), providing time-diversity data from repeated transmissions over a 270 m range. - [Black](https://uwa-channels.github.io/channels/black/index.md): A vertical, 18 kHz channel recorded over the Mariana Trench in October 2024, linking a near-surface planar array to a transmitter 8718 m below. - [Pink](https://uwa-channels.github.io/channels/pink/index.md): A 6 kHz, 14 km channel recorded off Kochi Prefecture, Japan in 2022, covering flat, up-slope, and down-slope bathymetry with a 24-element vertical array. - [Brown](https://uwa-channels.github.io/channels/brown/index.md): A 75 Hz trans-Pacific channel from the 1994 ATOC project, spanning 3250 km between a deep-water source off San Diego and a 20-element vertical receiving array east of Hawaii. ## User's Guide - [Channel file format specifications](https://uwa-channels.github.io/docs/file_specifications/index.md): Specification of the required and optional fields in the channel and noise .mat files, including the impulse response, phase/delay tracking, and metadata formats. - [Code Contribution Guide](https://uwa-channels.github.io/docs/code_contrib/index.md): A guide for contributing to the MATLAB and Python implementations of the channel replay library, covering setup, coding standards, and pull requests. ## Paper and data - [Underwater Acoustic Channel Library](https://arxiv.org/abs/2609.03207): The paper describing the library, arXiv:2609.03207. Cite it if you use the channels, the noise models, or the code. - [Underwater Acoustic Channel Repository](https://doi.org/10.5281/zenodo.21287414): The channel impulse responses and noise statistics on Zenodo, version 1.0, CC BY 4.0. [doi:10.5281/zenodo.21287413](https://doi.org/10.5281/zenodo.21287413) always resolves to the newest version. ## Code - [MATLAB toolbox](https://github.com/uwa-channels/matlab): `replay`, `noisegen`, and `unpack`; files load with the built-in `load`. Install the add-on with `matlab.addons.install(websave([tempname '.mltbx'], 'https://github.com/uwa-channels/matlab/releases/latest/download/uwa-channels.mltbx'))`. MIT license. - [Python package](https://github.com/uwa-channels/python): the same functions, plus `load_channel` and `load_noise`, which read `-v7.3` and MAT v5 files. Install with `pip install uwa-channels`. MIT license. - [UnderwaterAcoustics.jl](https://github.com/org-arl/UnderwaterAcoustics.jl): Julia support, maintained by the Acoustic Research Laboratory. `BasebandReplayChannel` loads a channel (a path, or `uacr://` to download from Zenodo) and `transmit` replays a signal through it; `ReplayNoise` and `PinkGaussianNoise` add the noise models ([pull request #95](https://github.com/org-arl/UnderwaterAcoustics.jl/pull/95), not yet merged). - [Channel estimation](https://github.com/uwa-channels/estimate): MATLAB/Octave scripts that estimate a channel from a recording, in the file format above, and plot it. - [Calibration](https://github.com/uwa-channels/calibrations): runs the MATLAB and Python toolboxes side by side on the released files and reports where they agree. ## Optional - [llms-full.txt](https://uwa-channels.github.io/llms-full.txt): All of the pages above in one file.