Method and system for non-destructive evaluation of conducting structures

Abstract

Method and system for non-destructive evaluation for a conducting structure by measuring the electrical impulse response thereof including applying a PRBS test input signal to the conducting structure, detecting an output signal from the conducting structure and processing the data to assess the condition of the conducting structure via changes in the electrical impulse response and to locate any defects along the conducting structure.

1 . A system for non-destructive evaluation of a conducting structure comprising 
 generator means supplying a series of high frequency input signals to the conducting structure;    means providing a time delayed replica of each of said input signals;    an analog multiplier receiving an output signal from the conducting structure in response to each of said input signals, receiving said time delayed replica of each of said input signals and producing a multiplication output thereof;    a sample and hold circuit receiving said multiplication output and supplying unsynchronized samples forming an impulse response function output;    an analog-to-digital converter receiving said sample and hold circuit output; and    a data processor receiving an input from said analog-to-digital converter to produce an average signal from a fixed number of samples, to initiate successive series of input signals and time delayed replicas of each input signal with increasing time delays and to produce an average signal from each successive time delay of said time delayed replicas of said input signals creating, in aggregate, the impulse function of the conducting structure.    
     
     
         2 . The system for non-destructive evaluation of a conducting structure recited in  claim 1  wherein said data processor means includes means for performing principle component analysis of said impulse response.  
     
     
         3 . The system for non-destructive evaluation of a conducting structure recited in  claim 2  wherein said input signals are PRBS signals.  
     
     
         4 . The system for non-destructive evaluation of a conducting structure recited in  claim 3  wherein said PRBS signals have a frequency greater than 20 MHz.  
     
     
         5 . The system for non-destructive evaluation of a conducting structure recited in  claim 1  and further comprising an input inductive device for coupling said input signals to said conducting structure.  
     
     
         6 . The system for non-destructive evaluation of a conducting structure recited in  claim 5  and further comprising an output device disposed adjacent said input inductive device for detecting said output signal from said conducting structure.  
     
     
         7 . The system for non-destructive evaluation of a conducting structure recited in  claim 1  wherein said generator means includes shift register means supplying said input signals and said time delayed replicas of said input signals.  
     
     
         8 . A method for non-destructive evaluation of a conducting structure comprising the steps of 
 supplying a series of high frequency input signals to the conducting structure;    deriving a series of output signals from the conducting structure, each output signal corresponding to one of the input signals;    generating a time delayed replica of each of the series of high frequency input signals;    multiplying the time delayed replica input signals and the output signals to produce a multiplication signal;    sampling the multiplication signal at unsynchronized discrete points in time to produce an impulse response function;    converting the impulse response function to a digital signal; and    processing the digital signal to produce average signals from at least first and second time delayed series of generated signals.    
     
     
         9 . The method for non-destructive evaluation of a conducting structure recited in  claim 8  wherein said processing step includes principle component analysis, a clustering algorithm and a final diagnosis algorithm.  
     
     
         10 . The method for non-destructive evaluation of a conducting structure recited in  claim 8  wherein said supplying step includes supplying PRBS input signals.  
     
     
         11 . The method for non-destructive evaluation of a conducting structure recited in  claim 10  wherein said supplying step includes supplying PRBS signals having a frequency greater than 20 MHz.  
     
     
         12 . The method for non-destructive evaluation of a conducting structure recited in  claim 10  wherein said supplying step includes supplying PRBS signals having a frequency range between a few to hundreds of MHz.