The concepts relate to radio channel utilization and more specifically to determining whether individual radio channels are available for use. One example can obtain a signal on a radio channel. The example can identify that the signal is an occurrence of a licensed use when a power level exceeds a threshold. The example can also determine that the signal is not the occurrence of the licensed use when the power level of the signal and a phase of the signal do not match an expected power level and an expected phase of the occurrence of the licensed use.