Propagation and Detection of Radio Signals Before, During, and After the Implosion of a Large Convention Center
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Catherine A. Remley, Susan A. Schima, M. McKinley, Robert T. Johnk
In this report, we investigate radio communications problems faced by emergency responders (firefighters and police) in disaster situations such as collapsed buildings. A fundamental challenge to communications into and out of large buildings is the strong attenuation of radio signals caused by losses and scattering in the building materials and structure. We designed experiments that take advantage of building demolitions in an effort to quantify radio-signal attenuation through standing and collapsed structures. We also investigated various schemes for detecting signals from firefighters and civilians with portable radios or cell phones who are trapped in voids in these collapsed buildings. We placed RF transmitters, similar to those used by first responders, in various locations in these buildings and performed measurements before, during, and after the building was imploded. The transmitters were tuned to frequencies near public safety and cell phone bands. Once the building was down, we measured the signals from the buried transmitters in the building to investigate weak-signal detection schemes that involved searching with directional antennas and connecting instruments to some of the metal debris located on the perimeter of the collapsed building. This report summarizes the third in a series of such experiments, performed in a large convention center (the Washington DC Convention Center) in Washington, DC. In this report, we describe the experiments, detail the measurement system, show primary results of the data we collected, and discuss some of the interesting propagation effects we observed.