Anything cheaper than that was likely to be a kit, and often operated within a narrower range of frequencies. Today, we would argue that an RTL-SDR receiver is a must-have tool. For the cost of a ...
He didn’t have any equipment to test the sensor, but he did have an RTL-SDR dongle and some know-how to figure out how to listen in on the sensors. The key was to use some software called RTL ...