Public Safety DAS Equipment Overview
A public safety Distributed Antenna System (DAS), otherwise known as In-Building Coverage or an Emergency Responder Radio Coverage System (ERRCS), refers to a system that is installed in a property to enhance emergency responders (e.g., fire fighters, law enforcement) radio communications. DAS enhance radio service by taking the broadcast radio signal from outside, amplifying it, and rebroadcasting it inside the property. A Bi-Directional Amplifier (BDA) is the core electrical device connected to the DAS. The BDA amplifies radio signal, from the broadcast tower outside into the emergency responder radios within the property and from those radios out to the broadcast tower. There are non-public safety DAS that may support cellphone coverage within properties.
Example of DAS operating in a property with a BDA amplifying radio signal on each floor.
General Requirements for Public Safety DAS
Public safety DAS generally need to satisfy the following:
• Approval from the frequency licensee (PSERN, within King County) to rebroadcast their signals
• Approval from the fire code authority (generally the local Fire Marshal)
• Communications coverage over 90% or 95% of each floor of the building
• 2 independent sources of power (usually normal AC power and battery backup over 12 or 24 hours)
• Waterproof enclosures for the electronics
• Monitoring of the DAS integrated with the fire alarm system
• Annual testing and maintenance