Overview In this guide I will explain how to build an inexpensive SDR (software defined radio) that can be used to receive police, fire, taxi, and other digital radio transmissions. I will do my best to explain the steps in detail, and provide further resources to help along the way. I have to give a lot of credit to the creator of the following guide: http://public-xrp.s3.amazonaws.com/docs/sdrsharptrunk.htm This how to is based largely from that, and other sites listed in the Resources section. For questions or comments please see the instructables page: http://www.instructables.com/id/How-to-Make-a-19-Police-Radio-Scanner/ Please use the information in this guide responsibly. Demo Video Hardware The only hardware required besides a computer is going to be a SDR receiver. The bulk of these radios are just USB TV tuners, rebranded and sold as SDR receivers. Many are available on Amazon and eBay. A quick google search should turn up some more as well. I rec