Overview of DAS/In-Building Coverage

DAS/In-Building Coverage/ERRCS

The PSERN Project affects DAS/In-Building Coverage. A Distributed Antenna System (DAS), or Emergency Responder Radio Coverage System (ERRCS), all refer to a system installed in buildings to enhance radio communications. When there are significant amounts of concrete and metal, or portions of the building are underground, the radio service used by emergency personnel, such as fire fighters or police officers, may be affected. DAS, ERRCS, or In-Building Coverage, commonly referred to as DAS, address this radio service problem by taking the broadcast radio signal from outside, amplifying it, and rebroadcasting it inside. Click here to view an example diagram of DAS/In-Building Coverage.


A Bi-Directional Amplifier (BDA) is the core electronic device connected to the DAS. A BDA amplifies radio signal, both from the broadcast tower outside, in the building, and from emergency personnel inside the building, out to the broadcast tower. DAS can also include supplemental devices and functionality. Other equipment can include Uninterruptible Power Supplies (UPS), fire alarm monitoring, and Dedicated Annunciator Panels (DAP).

Legal Requirements for DAS

The State of Washington will adopt the International Fire Code, 2018 Edition, in February 2021, per RCW 19.27.031 and WAC 51-54A-003. The principle fire code applicable to emergency responder radio coverage is the International Fire Code, Section 510. There are various additional applicable sections as well as reference standards. Each local jurisdiction may modify the code so long as it is at least as stringent as the adopted State Code (per RCW 19.27.040). Broadly, this code describes when and how emergency radio systems are required. Each jurisdiction has their own application of this code. The PSERN Project recommends consulting with a qualified DAS vendor or a professional engineer specializing in these systems, and the Authority Having Jurisdiction (AHJ) to interpret the code. In nearly all cases, in King County, the local Fire Marshal is the AHJ.

Click here for information on Property Owner/Building DAS requirements.