What signal strength is required for ERRCS coverage under IFC Section 510?

Coverage is deemed adequate when the received signal strength indicator (RSSI) meets or exceeds −95 dBm on both uplink and downlink in 95% of all areas on each floor, and 99% of all Critical Areas as defined by the AHJ. This threshold must be verified by walk-test measurement after installation with all building systems, including HVAC and elevators, in normal operation.

What is the difference between a Class A and Class B BDA?

A Class A BDA (FCC Part 90.219) is frequency-selective, narrowband amplification on specific licensed frequencies with a channel bandwidth typically of 25 kHz or 12.5 kHz, amplifying only designated public safety channels with minimal noise amplification. A Class B BDA amplifies a broad band including all channels, which is simpler and cheaper but can cause uplink desensitisation at site base stations — most AHJs and carriers now require Class A BDAs for ERRCS, and some jurisdictions prohibit Class B entirely.

How much isolation is required between a BDA's donor and server antennas?

The donor antenna must be isolated from the interior server antennas by at least 15 dB more than the BDA gain to prevent oscillation. For a 70 dB gain BDA, isolation must therefore exceed 85 dB. The required donor-to-server isolation is specified in FCC KDB 935264 and must be verified during commissioning with a gain-reduction/oscillation test.

Do BDAs need to be registered with the FCC?

Yes — per FCC Part 90.219, all signal boosters (BDAs) operating on licensed Part 90 frequencies must be registered with the FCC in the ULS (Universal Licensing System) under the relevant public safety licensee's call sign, including frequency band, location, and BDA manufacturer/model, within 30 days of installation. The carrier must also consent to the booster installation, and unregistered boosters can draw FCC fines up to $19,246 per violation per day.

How long must ERRCS battery backup last during a power outage?

IFC 510.4.2.3 requires battery backup to power the ERRCS for a minimum of 12 hours without commercial power. This backup capability is verified as part of the annual operational testing mandated under IFC 510.5.3, alongside confirmation that signal levels still meet the −95 dBm threshold in all required areas.

Engineering·13 min read·June 17, 2026

📡 BDA and ERRCS: In-Building Public Safety Radio Coverage Systems

A code-compliant engineering guide to BDA and ERRCS design: IFC Section 510 and NFPA 1225 requirements, signal thresholds, Class A vs Class B amplifiers, FCC Part 90 registration, and AHJ acceptance testing.

📖Radio Communications — Illustrated Guide (Full Access)

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Regulatory Driver: When ERRCS Is Required

Emergency Responder Radio Coverage Systems (ERRCS) are mandated by the International Fire Code (IFC) Section 510 (2018 and later editions) and NFPA 1225 (Standard for Emergency Services Communications Systems). The IFC requires that all new buildings (and buildings undergoing substantial alteration) provide adequate radio coverage for emergency responders on the local jurisdiction's public safety frequencies. Coverage is deemed adequate when the received signal strength indicator (RSSI) meets or exceeds −95 dBm on both uplink and downlink in 95% of all areas on each floor, and 99% of all Critical Areas.

Topics covered

BDAERRCSin-building public safety radioIFC Section 510NFPA 1225FirstNetbi-directional amplifierFCC Part 90public safety DAS700 MHz800 MHzAHJ testingRSSI -95 dBm