Abstract: A method, apparatus, and computer usable program code for identifying change indices for a structure. In one advantageous embodiment a method receives a response signal in response to a transmission of an interrogation signal into the structure. The response signal is decomposed into a first plurality of modes. The first plurality of modes is compared to a second plurality of modes for a comparison signal to form a comparison. A change index is assigned to the response signal using the comparison.

Abstract: A method, apparatus, and computer program product for monitoring structures using virtual time reversal signal processing. In one embodiment, a signal having a frequency range is sent into a structure in a vehicle from a fixed transmitter to form an original transmitted signal. A response to the original transmitted signal is received at a fixed sensor associated with the structure to form a received response. The received response is reversed. The reversed response is processed using a transfer function to simulate propagation of the reversed response from the fixed sensor to the fixed transmitter to form a simulated time reversed response. The simulated time reversed response is a simulation of a response of the fixed transmitter to receiving the reversed response from the fixed sensor. The simulated time reversed response is analyzed to monitor for anomalies associated with the structure.

Abstract: A method, apparatus, and computer usable program code for identifying change indices for a structure. In one advantageous embodiment a method receives a response signal in response to a transmission of an interrogation signal into the structure. The response signal is decomposed into a first plurality of modes. The first plurality of modes is compared to a second plurality of modes for a comparison signal to form a comparison. A change index is assigned to the response signal using the comparison.

Abstract: A method, apparatus, and computer program product for monitoring structures using virtual time reversal signal processing. In one embodiment, a signal having a frequency range is sent into a structure in a vehicle from a fixed transmitter to form an original transmitted signal. A response to the original transmitted signal is received at a fixed sensor associated with the structure to form a received response. The received response is reversed. The reversed response is processed using a transfer function to simulate propagation of the reversed response from the fixed sensor to the fixed transmitter to form a simulated time reversed response. The simulated time reversed response is a simulation of a response of the fixed transmitter to receiving the reversed response from the fixed sensor. The simulated time reversed response is analyzed to monitor for anomalies associated with the structure.