The NIST work, which supports public safety programs of the U.S. departments of Homeland Security and Justice, is intended to help improve the communications capabilities of first responders. First responders who rely on radio communications often lose signals in shielded or complex environments such as the basements or elevator shafts of buildings. It also is very difficult to detect radio signals through the dense rubble of a building that has collapsed as a result of a natural disaster or terrorist attack.

To simulate disaster environments, NIST is using real-world “laboratories”—buildings that are scheduled to be imploded as part of construction and recycling projects. The NIST team placed a set of about 25 battery-operated transmitters at various locations in the old Washington Convention Center prior to demolition. The transmitters emitted signals near the frequency bands used by emergency personnel and mobile telephones. Scientists monitored and mapped the strength of signals sent by the transmitters to receivers outside the building before, during and after the implosion.

To detect the weak signals, the researchers used a variety of techniques, including connecting radio receivers to metal debris in the rubble as improvised antennas and converting radio signals to visual images like Morse code (see image below). NIST researchers hope to develop reliable, cost-effective tools that can be retrofitted to existing radio systems to assist emergency personnel in locating and perhaps communicating with rescuers and other survivors trapped inside a collapsed building.

For more information, see http://www.nist.gov/public_affairs/releases/demolition_dcconv.htm.

Note: If no author is given, the source is cited instead.

• Telecommunications
• Electronics
• Construction
• Medical Technology
• Engineering and Construction
• Civil Engineering

• Radio
• Electrical phenomena
• Radiant energy
• Mobile phone radiation and health
• Microwave
• Collapse of the World Trade Center