The radio frequency spectrum has become very crowded with a combination of commercial and personal communications devices. At the same time, the world-wide spectrum committees require extreme measures to insure frequency avoidance; such that communications are maintained, especially for emergency and flight safety. The radar community needs to adopt the techniques developed for cognitive communications to continue to provide the needed surveillance for both military and earth resource monitoring. These techniques include monitoring the environment to detect clear frequencies, spectral notching on transmit, and adaptive radio frequency interference mitigation on receive.