It might surprise you to learn that it is completely legal to listen to official police scanner radio transmissions in the United States. There is even a hobbyist community dedicated to exactly that, which is full of people who find it interesting to hear what the police are up to as they go about responding to crimes and other dispatches. Some states do have a couple of limitations, such as listening while driving or while committing a crime. But as long as you’re just listening at home, it’s legal in every state. If you want to do that yourself, YouTuber Kevin Darrah has a guide on how to use a Raspberry Pi to build an inexpensive police scanner.
You can go purchase a police scanner right now if you’d like — in fact, most hobby radios can pick up the frequencies used by the police and other public personnel. But with a Raspberry Pi and a few other inexpensive components, you can make yourself a desktop police scanner to listen to radio transmissions anywhere in the country — not just those that are within range of your current location. That’s because other hobbyists around the country run online live feeds from their police scanners, which you can access through the Broadcastify service.
As Darrah explains, this project is as simple as pulling one of those feeds and streaming it through the Raspberry Pi to a speaker. Darrah is using a Raspberry Pi 3 Model B+, but any Raspberry Pi model should do the job. The audio output from the Raspberry Pi is piped out to a small speaker through an inexpensive Class D amplifier. The current channel is shown on an Adafruit 3.5” LCD touchscreen, and pushing a button will cycle through the available stations.
Those stations are pulled from a pre-compiled list of Broadcastify stations that you can choose. For instance, you can add the stations for your hometown, New York City, Los Angeles, and Chicago — or whatever cities or counties you’re interested in. The software to do this is straightforward, and anyone with a little bit of experience working with Raspbian, or Linux in general, should be able to set it up easily. Once you’re done, you’ll have a handy way to listen to police radio from all around the country. You can even add music stations if you want to mix things up.