This paper explores how to detect if a radio channel is being used, even if the signal turns on and off unexpectedly. They tested two ways to do this with energy detectors. The first one averages out the energy in the signal to see if the channel is in use. The second one compares the energy levels to a specific threshold to guess if the channel is occupied. They came up with mathematical models for both detectors, tested them out in simulations, and figured out the best threshold to make the right decision based on the primary signal's characteristics.