Maths on WII5 — Waves In Ice Buoys

Maths Control

Mon, 01 Jan 0001 00:00:00 +0000

The Linux Maths Control package runs on Raspberry Pi, BeagleBone Black, Intel Edison, and other embedded Linux options. It’s a distribution image plus a set of services, scripts, and a Node web app. It’s commonly called the Maths CPU because the maths code hasn’t been optimised for smaller CPUs — it needs more memory and CPU power than the AVR can offer.

Any of these embedded Linux hosts is fairly power-hungry, so the Maths CPU is only powered up for two reasons:

Waves

Mon, 01 Jan 0001 00:00:00 +0000

The wave-statistics calculation reduces raw accelerometer samples to a compact summary: significant wave height (Hs), peak period (Tp), and total wave energy across the spectrum.

Status: placeholder.

Calculations

Mon, 01 Jan 0001 00:00:00 +0000

What the buoy turns its raw sensor stream into before transmission.

Waves — significant wave height, peak period, energy.
Direction — directional spectrum analysis.

Direction

Mon, 01 Jan 0001 00:00:00 +0000

Directional analysis combines accelerometer data with GPS heading to estimate where the wave energy is coming from.

Status: placeholder.

Onboard Data Processing

Mon, 01 Jan 0001 00:00:00 +0000

The on-board processing pipeline takes raw accelerometer and GPS samples captured by the buoy and reduces them — on the buoy itself — into a compact summary that fits inside an Iridium short-burst-data message: significant wave height, peak period, directional spectrum, energy bands.

Doing the maths on the buoy (rather than transmitting raw samples) is what makes long-duration polar deployments practical — satellite bandwidth is expensive, power-hungry, and unreliable.

The maths code is written in C and compiles for any Linux. On the buoy it runs on the Maths Control host (a low-power Linux board woken briefly to do the calculation), described below.

Other WII Software

Mon, 01 Jan 0001 00:00:00 +0000

Beyond the pieces already featured under Firmware, Server, Analysis, Viewers, and Onboard Data Processing, the WII project carries a large family of related repositories — earlier buoy generations, dashboards, server tooling, maths libraries, test rigs, and data archives.

None of these have been individually assessed yet, so it’s genuinely unclear which ones can or can’t be released — that’s why they aren’t already public. Some are clean and would be straightforward; others may have licensing, customer-specific identifiers, or third-party dependencies that need looking at first.

Onboard Data Processing

Mon, 01 Jan 0001 00:00:00 +0000

The on-buoy maths — Alison Kohout’s wave-motion algorithms running on the Maths CPU to reduce raw acceleration into a wave-statistics payload — is documented under Software → Onboard Data Processing.

This entry exists here so the Buoys sidebar has a pointer to it, because the processing runs on the buoy even though the code lives in the Software section.

Go to Software → Onboard Data Processing