SDR Opens a $30 Window Into Unencrypted Sub-GHz Signals

Software-defined radio (SDR) lets anyone sniff sub-gigahertz signals from smart meters, traffic sensors, and other IoT devices using a $30 USB dongle. Many of these devices transmit unencrypted data because engineers assumed RF attacks were too expensive. The RTL-SDR Blog V4 and open-source tools like GNU Radio make it trivial to capture and decode these signals from a laptop.