Plug in an RTL-SDR dongle, pick a band, and Sweep finds every frequency with a live carrier on it — then names each one against the scanner directory. No channel list needed; it discovers what's actually transmitting.
What you need: an RTL-SDR USB dongle and Chrome (or Edge) on Android, Windows, Mac, Linux, or ChromeOS. iPhone/iPad can't do this — Apple blocks USB access in the browser, and every iOS browser is affected. On Android, use a USB-OTG adapter.
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MHz
8 dB over noise
Not connected.
waterfall (top) + live spectrum (bottom) · brighter = stronger signal
How it reads. Sweep tunes across the band in ~2 MHz steps, runs an FFT on each chunk, measures the noise floor, and flags any bin sitting above it — that's a live carrier. It rounds each hit to the nearest channel and checks it against the directory, so 463.5875 shows up as its real label when we know it. Listening is experimental and uses narrowband-FM; race comms are NFM, so most will be clear, but quiet or weak signals may need a better antenna. Always follow track and FCC rules — receive only.