New sensitive seismic cable with imbedded geophones

Abstract

Seismic detection systems for homeland security applications are an important additional layer to perimeter and border protection and other security systems. General Sensing Systems has been developing low mass, low cost, highly sensitive geophones. These geophones are being incorporated within a seismic cable. This article reports on the concept of a seismic sensitive cable and seismic sensitive ribbon design. Unlike existing seismic cables with sensitivity distributed along their lengths, the GSS new cable and ribbon possesses high sensitivity distributed in several points along the cable/ribbon with spacing of about 8-12 to 100 meters between geophones. This cable/ribbon is highly suitable for design and installation in extended perimeter protection systems. It allows the use of a mechanical cable layer for high speed installation. We show that any installation mistakes in using the GSS seismic sensitive cable/ribbon have low impact on output seismic signal value and detection range of security systems.

Low-frequency signals detection and identification as a key point of software for surveillance and security applications

“…We have the same ambiguous footstep signal envelope in case of using a seismic string instead of single geophone. Figure 4 presents the signal envelope when distance between an eight-geophone seismic string and a walking person is about 8 meters [1]. The distance between GS-20DX geophones in the string is 15 meters.…”

“…Raw seismic signal record and corresponding signal envelope for almost ideal environment conditions with low background noise level are shown in Figures 1 and 2 below. The distance between a standard GS-20DX geophone and a walking person for the shown signal is nine meters [1]. Envelope of seismic signals is typically used for footstep detection because it represents the main and most informative characteristics of a person's footstep.…”