Recent findings from tests of wireless emergency safety equipment in New York City conducted by the(NIST) have provided researchers with ways emergency communications might be improved. NIST researchers visited New York City in 2012 to evaluate emergency radio transmissions in challenging settings such as high-rise buildings and underground tunnels. Researchers measured path loss, or reduced signal strength, which can occur when signals must travel through thick walls and dense material.
The study is part of an ongoing NIST project, launched in 2008, supporting the development of performance metrics and laboratory tests for electronic safety equipment with two-way radio-frequency (RF) transmission capabilities. The New York tests focused on RF-based personal alert safety systems used by firefighters as distress beacons. They used four commercial RF-PASS systems operating in three frequency bands: 450 MHz, 902 to 928 MHz and 2.4 GHz.
Researchers measured whether a firefighter-down signal was received by a base station outside the subway or building and whether a portable RF-PASS unit inside the structure received an evacuation signal from the base station, within 30 seconds, given a certain amount of path loss. They found that wireless emergency beacons could be unreliable beyond the street-level stairwell entrance to a four-level subway station, and that signal strength depended on the frequency used in the 100-story Empire State Building.
The NIST tests, conducted with the help of the Fire Department of New York, were funded by the U.S..