Abstract: In order to detect buried compliant objects such as land mines and pipes, an acoustic signal is directed into the ground to excite vibration of a buried compliant object. A probing signal is also directed into the ground toward the vibrating object, and the probing signal is modulated and reflected by the vibrating object. The modulated, reflected probing signal is processed to determine therefrom the presence of the buried compliant object.

Abstract: The invention relates to a method and apparatus for nondestructive testing and evaluation of materials and mechanical structures to determine their integrity reducing contact-type flaws such as cracks, fractures, delamination, unbondings, etc. and also presence of ice on a structure. The invention employs an ultrasonic probing signal and a low frequency vibration applied to a structure tested. In a structure without flaws or ice, these signals propagate independently without any interaction. If the structure contains a defect or ice thereon, the vibration varies the contact area of the defect or ice/structure interface, modulating the phase and amplitude of the higher frequency ultrasonic probing signal passing through the structure. In the frequency domain the result of this modulation manifests itself as sideband spectral components with respect to frequency of the probe wave.

Abstract: A device which employs an acoustic signal having one or more frequencies for penetrating into ground, water, or sediments and vibrating a compliant buried object is provided. When these acoustic signals encounter an acoustically compliant object such as a mine, the acoustic signals vibrate the compliant object, leading to a vibration of the compliant object against the boundaries of the surrounding medium such as ground sediment, creating a nonlinear distortion of the probing signal including the generation of harmonics and acoustic waves with combination frequencies (nonlinear signals). These nonlinear vibrating signals are received from the surface by a sensor. The amplitude of the measured nonlinear signals indicates the presence of an acoustically compliant object such as a mine.

Abstract: A device which employs an acoustic signal having one or more frequencies for penetrating into ground, water, or sediments and vibrating a compliant buried object is provided. When these acoustic signals encounter an acoustically compliant object such as a mine, the acoustic signals vibrate the compliant object, leading to a vibration of the compliant object against the boundaries of the surrounding medium such as ground sediment, creating a nonlinear distortion of the probing signal including the generation of harmonics and acoustic waves with combination frequencies (nonlinear signals). These nonlinear vibrating signals are received from the surface by a sensor. The amplitude of the measured nonlinear signals indicates the presence of an acoustically compliant object such as a mine.