The energy-detector module provides signal-strength indication in various scenarios. Because it is based on an IIR filter, this robust energy detector has excellent reaction time and reliability. The filter output is compared to predefined thresholds to decide the presence or absence of an incoming signal. The energy detector also implements hysteresis to avoid jittering in signal-detect indication. Additionally, it has fully-programmable thresholds and listening-time periods, enabling shortening of the reaction time if required.