Part of our Getting On The Air guide.
Before I owned a dedicated scanner, I was doing most of my public safety and airband monitoring off a $30 RTL-SDR dongle. It’s not always the better tool, but it’s the cheapest way to find out whether you even want a scanner.
Airband Is the Easy Win
Civil aviation uses AM voice from 118 to 137 MHz, squarely inside RTL-SDR’s native range, and it just works. Point SDR++ or SDR# at a local tower or approach frequency and you’ll hear traffic within minutes. Pair it with an ADS-B feed (dump1090) on a second dongle and you can watch the aircraft on a map while you listen to it talk.
Trunked Public Safety Is Harder
A lot of modern public safety traffic runs on trunked P25 systems, which hop across a pool of frequencies according to a control channel. Software like SDRTrunk or OP25 can decode this, but it takes more setup than airband, and you may need two SDR dongles running simultaneously (one on the control channel, one following voice) for a busy system. Check Radio Reference for your county’s system type before you invest time.
Know the Legal Line
Listening is legal almost everywhere in the US. Acting on what you hear, rebroadcasting it, or using it to interfere with law enforcement operations is not. Some public safety agencies encrypt their traffic specifically because of scanner listeners, and there’s nothing you can do about that legally, encryption on those systems is their call to make, not yours to defeat.