A single microbarometer recording infrasound — pressure waves below human hearing (0.05–20 Hz). This station watches for a steady, narrowband tone that a nearby datacenter would add to the background, tracked over months against a quiet pre-dawn baseline.
Primary detection · night-only
Persistent-tone hunt No steady tone
Each night's spectrum with its broadband level removed, so only narrowband prominence remains. A datacenter tone would appear as a steady bright horizontal line climbing toward 100% of nights at a fixed frequency. Quiet window 07:00–12:00 UTC · ~00:00–05:00 local.
Frequencies more persistent at night than day are the datacenter-like signature. Currently the strongest are weak and consistent with local equipment, not a steady source — the baseline reads tone-free.
| Freq | Night | Day | Δ pts |
|---|---|---|---|
| 1.77 Hz | 19% | 2% | +17 |
| 7.16 Hz | 26% | 9% | +17 |
| 7.16 Hz | 20% | 4% | +16 |
| 7.21 Hz | 22% | 3% | +19 |
| 7.21 Hz | 16% | 1% | +15 |
| 7.50 Hz | 23% | 5% | +18 |
Overview
Spectral waterfall — full record
Time × frequency, loudness in color. Vertical banding is the day/night cycle; blank columns are data gaps. Open interactive waterfall →
Noise characterization
Long-term spectrum (PDF-PSD)
PDF-PSD — the probability density function of the power spectral density. A noise fingerprint of the whole record: for each frequency, color shows how often (%) each loudness level occurred — bright = the typical level, dark = rare. The three curves are the quiet (10th pct), typical (median), and loud (90th pct) hourly levels.
How to read this
Each vertical slice is a histogram of the ~2,000 hourly spectra at that frequency. It's a "red" spectrum — loudest at low frequency (wind, weather, microbaroms) and quieter toward 20 Hz. The wide spread at low frequency is the day/night swing; the tight band up high is the sensor's steady noise floor. A datacenter tone would appear as a bright pip at one fixed frequency and lift the quiet (10th-pct) line there — because even the calmest hours would then carry the tone.
| Band | Median dB | RMS Pa | dB SPL |
|---|---|---|---|
| 0.05–0.5 Hz | -35.2 | 0.0110 | 54.8 |
| 0.5–5 Hz | -36.3 | 0.0305 | 63.7 |
| 5–20 Hz | -53.9 | 0.0152 | 57.6 |
| 0.05–20 Hz | -50.1 | 0.0358 | 65.1 |
Station health
Data availability
Hourly coverage over the record — green is data, red is a gap.
