wideband RF anomaly detection · homelab security
An RTL-SDR dongle that continuously sweeps 24 MHz–1.7 GHz, learns what's normal nearby, and flags what isn't — from a dispatch radio nobody expected to a strong signal sitting where nothing should be transmitting at all.
Cell towers, two-way dispatch radios, garage door remotes, weather sensors, aircraft transponders, FM stations, the occasional pager still in service — the air around any property is genuinely busy, all the time, and almost nobody has any visibility into it. A real spectrum analyzer that could actually watch for changes over weeks costs $2,000–$20,000–plus, and even then you're looking at one snapshot, not a trend.
The alternative most people actually have is: none. If something new starts transmitting near your property tomorrow, there is currently no way you'd ever know.
A $30 RTL-SDR dongle sweeps the entire 24 MHz–1.7 GHz range every three minutes and learns what a normal signal level looks like at each frequency, hour by hour — a Tuesday-afternoon baseline isn't the same as a 3am one. When something deviates enough, it captures a few seconds of raw radio and tries to decode it directly. If that fails, a mostly-free lookup cascade takes over — a real decoder match first, then a check against 11 million+ FCC license records, then a static band-allocation table, then matching against signals it's already identified before — and only asks Claude for a tentative guess when literally nothing else resolves it.
Everything here is receive-only. Nothing is ever transmitted, decrypted, or interfered with — it's a passive listener, not a jammer or an intercept tool.
The 98.3% figure is real, current, and improving as the fingerprint/decoder layers grow — but it's a snapshot from one antenna, one location, about three weeks in. It'll drift as new signal types show up.
A plain status ledger, not a sales sheet — this is what's verified, what's degraded, and what's still open.
The hardware is already sweeping the full 24MHz–1.7GHz range continuously — the ceiling isn't the antenna, it's what gets built on top of it. A second, narrower-band instance watching just an amateur radio or business band for a HAM operator, automatic correlation against FCC enforcement bulletins for known interference sources, or a portable version for a one-off site survey are all realistic next steps on the same underlying pipeline.
"I wanted to know what was actually happening in the air around my own property, not just guess at it. Turns out the answer is: a lot — and most of it's mundane once you can actually see it." — Ray, designer & builder of RF Hunter