Abstract: A device for detecting the presence of items made of recyclable materials randomly located and arranged within randomly arranged solid waste having random characteristics. A transmitter produces acoustic energy of at least one predetermined wavelength in a desired direction. The acoustic energy causes the items made of recyclable material present within the randomly arranged solid waste to resonate and thereby produce resonated acoustic energy. A receiver receives the resonated acoustic energy. The receiver generates a signal based upon the resonated acoustic energy. A processor connected at least to the receiver receives the signal from the receiver for analyzing the resonated acoustic energy, for calculating the signal based upon the resonated acoustic energy, and comparing the calculated signature to known signatures of items made of recyclable materials.

Abstract: An array of acoustic receiving transducers is placed next to the body to be imaged. Acoustic energy is initially projected through the body, picked up by these receiving transducers, and processed to determine any time domain deviations which exist in the paths actually followed by that energy from those paths which would have been followed if the body were substantially homogeneous and the transducer array substantially fixed. Further acoustic energy is also picked-up by the transducers, after reflection within the body to be imaged. The image of any given point within the body is then formed by selecting from each transducer output signal that portion which corresponds to the image forming energy emanating from that point, as corrected in accordance with the previously determined deviations.