This whitepaper will serve as a primer or tutorial for designing and implementing in-building Emergency Responder Radio Communications Systems (ERRCS), or public safety Distributed Antenna Systems (DAS). ERRCS provide high-quality radio coverage for fire, police, and emergency medical services personnel where people are and are not located within a building. Commercial cellular DAS provides service in populated areas of buildings where people gather. To deliver these emergency communications, an ERRCS uses an outdoor donor antenna and transmission line passing wide area public safety radio traffic to a bi-directional amplifier (BDA) located in an equipment room, along with a back-up battery unit and annunciator alarm panel. The output of the BDA connects to DAS riser and coverage coaxial cabling across a floor terminating at the DAS coverage antenna. Passive tappers or directional couplers are inserted in the cable path tapping a portion of the total RF energy floor-over-floor and equalizing RF coverage throughout the building. Due to its mission-critical nature, monitoring the integrity of public safety DAS is a growing requirement of Authorities Having Jurisdiction (AHJ) nationwide. In this whitepaper, learn the fundamental design, testing benchmarks, and critical need for monitoring the performance of these communications networks, with particular focus on the SMART (System, Monitor, Alarm, Report Technology) Passives System from Microlab.