# uranashel instrument lab

> Browser demos of the sensor and DSP instruments behind the uranashel apps. Every instrument runs locally in the page — sensor access is opt-in, and nothing is uploaded.

Live page: https://uranashel.com/lab.html (needs JavaScript, and a phone for the motion instruments).

## Instruments on the page

- **Benchmarks** — times a 256-point FFT, one synthesis buffer and an IMU integration step in your browser, so you can see the per-frame budget the apps work inside.
- **Spectrogram waterfall** (Sonarish) — a scrolling 2D FFT of the microphone: frequency against time, the same view the noise meter uses.
- **Parking garage barometer** (Wheria) — scroll to descend and watch pressure rise about 1.2 hPa per floor. This is the hydrostatic estimate Wheria uses to guess B2 from B3.
- **GPS dies · IMU drifts · Fusion fixes** (Wheria) — drag a path and compare raw GPS, raw IMU dead reckoning and the fused estimate, with the error between them reported live.
- **Attitude indicator** (Phyzix) — a wireframe globe driven by device orientation, or by dragging on desktop.
- **AR pin** (Wheria) — a camera preview with a parking pin, via WebXR where the device supports it.
- **Instrument terminal** — a small command line: `help`, `calibrate`, `bench`.

## The physics underneath

- Spectra come from a windowed FFT; A-weighting and LAeq turn them into numbers comparable with real noise limits.
- Altitude comes from the barometric relation between pressure and height, which is why a garage floor is guessable when GPS is not.
- Position underground comes from step detection plus heading rather than double integration, because double integration drifts within seconds.
- Longer explanations of each: https://uranashel.com/blog/

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