Detection of Nuclear Explosions Using Infrasound Techniques

The performance of typical IMS infrasound monitoring stations has been examined in detail in order to evaluate the detection capability of the global network for regional and distant nuclear explosions. Three significant problems have been identified: a) problems with the loss of higher frequency signal components in the primary monitoring passband, b) detection problems associated with a low degree of signal coherence between array elements and c) problems with high levels of wind-generated background noise. Loss of higher frequency signal components normally occurs when signal propagation is restricted to a thermospheric waveguide. This problem can often be resolved by ensuring that routine processing algorithms include a long-period passband. Coherence studies show that detection capability for regional and distant explosions may be limited by the small degree of signal correlation between array elements. This problem can be resolved by modifications to the array configuration. Wind-generated background noise is a potentially serious problem at most infrasound monitoring stations. We have developed a new wind-noise-reducing system that effectively eliminates wind-generated noise in the monitoring passband. This system is based on the use of a closed screened enclosure that mechanically degrades turbulent eddies in the atmospheric boundary layer. This system can be used as an effective, stand-alone wind-noise-reducing system that does not require the use of a pipe array.
The original document contains color images.