An AM radio is a receiver built to decode amplitude-modulated broadcast signals. In this format, the information is carried by changes in signal strength rather than frequency. AM receivers are simple, low-power, and often compatible with very old hardware, which is why they still show up in repair projects and embedded retrofits.
In cyber security, AM radio matters because broadcast systems are resilient, one-way channels. Defenders may rely on them for public alerts or backup information paths when IP networks are unavailable, while attackers can use radio as a covert or hard-to-block medium for sending signals. In the context of aging hardware, an AM radio also illustrates a common security and operations problem: devices can become obsolete not because they fail mechanically, but because the surrounding communications ecosystem changes. Reuse and retrofit can extend useful life and reduce e-waste.