The RIU-4010/4110 Radio Interface Unit is a member of the Pro Line 21 CNS family of products that feature state-of-the-art digital signal processing technology, digital audio, a consolidated tuning/data/audio bus, comprehensive maintenance software, software data loading and data link communication management. The RIU-4010 combines the data/audio concentration features of the RIU-4110 with the data link communications management function of the CMU-4000.