Signal processing technique for ultrasonic inspection

A correlation receiver for processing an electrical signal derived from an acoustic signal in a test object, comprising:

• a signal generator for producing a first reference waveform and a second reference waveform in quadrature with said first reference waveform;
• a first multiplier for combining said electrical signal and said first reference waveform;
• a second multiplier for combining said electrical signal and said second reference waveform;
• a first integrator for integrating said first combined signal;
• a second integrator for integrating said second combined signal;
• and
• means for combining said integrated first and second combined signals to produce an output indicating the structural integrity of the test object.

An apparatus for evaluating the structural integrity of an object, comprising:

• a signal generator for producing an input signal and a reference waveform;
• an input transducer for receiving said input signal and generating an acoustic signal in the object;
• an output transducer for detecting said acoustic signal and generating an electrical output signal responsive thereto;
• a multiplier for combining said electrical output signal and said reference waveform;
• and
• an integrator for integrating the combined signal.

An apparatus for evaluating the structural integrity of an object, comprising:

• a signal generator for producing an input signal, a first reference waveform, and a second reference waveform;
• an input transducer for receiving said input signal and generating an acoustic signal in the object;
• an output transducer for detecting said acoustic signal and generating an electrical output signal responsive thereto;
• a first multiplier for combining said electrical output signal and said first reference waveform;
• a second multiplier for combining said electrical output signal and said second reference waveform;
• a first integrator for integrating said first combined signal;
• a second integrator for integrating said second combined signal;
• and
• means for combining said integrated signals to produce an output indicating the structural integrity of the test object.

A method of time domain correlating an electrical signal derived from an acoustic signal in a test object, comprising the steps of:

• (a) generating a first reference waveform;
• (b) combining the electrical signal and the reference waveform by multiplication;
• and
• (c) integrating the product of the multiplication.