US Patent 10464569 Vibration sensor

One example discloses a vibration sensor, comprising: an RF receiver circuit configured to receive an RF input signal; an RF signal characterization circuit configured to measure an attribute of the RF input signal over a set time-period; wherein the attribute of the RF input signal varies based on a physical motion between the vibration sensor and an RF source transmitting the RF input signal; and a vibration profiling circuit configured to map the attribute of the RF input signal to a vibration level.