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Signal Clusters 24MHz–1.7GHz · rtl_power sweep
A Raspberry Pi 3 + RTL-SDR dongle continuously sweeps 24 MHz–1.7 GHz in 50 kHz bins, comparing
each pass against a rolling per-hour statistical baseline. Anything that deviates enough gets a raw IQ capture
and a decode attempt against known protocols — rtl_433 (ISM-band devices), multimon-ng
(POCSAG/FLEX pagers, etc), and rtl_adsb (aircraft transponders near 1090 MHz). Anything that
doesn't match a known decoder ships here, where it's grouped by frequency into clusters — so the same repeat
transmitter (a cell carrier, a garage door remote, a fixed telemetry device) isn't reported over and over.
Genuinely new clusters trigger a short automated write-up reasoning about likely band allocation and anything
statistically unusual, sent straight to the operator. Nothing here is decoded content — just RF metadata
(frequency, bandwidth, signal-to-noise, rough symbol rate) from a passive receiver.
New clusters also get a small waterfall image rendered from the actual capture before the raw IQ is discarded
(click a thumbnail to view it full-size) — Claude looks at that image, not just the numbers, when deciding
whether a signal looks structured/bursty enough to flag worth a manual look.
Formerly this hardware ran a TPMS/weather-station sniffer, and before that a from-scratch Random Forest
RF classifier — both retired in favor of this general-purpose anomaly hunter.