In the development of a public safety radio system design, Concepts To Operations follows standards set forth in 2009 International Building Code Section 915 for emergency responders’ radio coverage and believes that all coverage (on-street and in-building) should be in accordance with the International Fire Code Section 510, which sets forth the following standards:
510.4.1 Radio signal strength. The building shall be considered to have acceptable emergency responder radio coverage when signal strength measurements in 95% of all areas of the building and 99% in elevators (measured at the primary recall floor), stair shafts and Fire Command Centers meet the signal strength requirements in Sections 510.4.1.1 and 510.4.1.2.
510.4.1.1 Minimum signal strength into the building. Minimum signal strength of -95 dBm shall be receivable within the building.
510.4.1.2 Minimum signal strength out of the building. Minimum signal strength of -95 dBm shall be received by the agency’s radio system when transmitted from within the building.
510.4.2 System Design. The emergency responder radio coverage system shall be designed in accordance with Sections 510.4.2.1 through 510.4.2.5.
Based upon IFC Section 510 standards, Concepts To Operations determined the design should include the following signal strengths:
On-street -95 dBm
Low-density (residential wood buildings) -83 dBm
Medium-density (commercial cinderblock buildings) -77 dBm
High-density (hospitals and contemporary buildings) -65 dBm
In layman’s terms, to compensate for the loss of voice quality due to building materials, the strength and location of antennas (i.e. additional tower and the power generated by the antennas) needs to be increased. The denser the building material the higher the signal loss and the closer a tower or more power to an antenna is needed for the penetration. In designing a new system, CTO looks to compensate for the signal loss as noted above, as well as compensate for a loss of 6 dB for a fully-geared firefighter in the building. Our designs also seek a 3.4 DAQ for 97% of the coverage area, with 97% reliability.