Patent ID: 7505852

Claim:
A method for determining a current status of an apparatus, said method comprising the steps of: monitoring stress waves generated by the apparatus during a normal operation of the apparatus for at least one time period to generate first stress wave data; analyzing at least a portion of said first stress wave data to generate first analyzed data that captures one or more features of said first stress wave data; processing at least a portion of said first analyzed data to generate baseline data, wherein said baseline data has substantially reduced influence from normal operating variations compared to said first analyzed data; further monitoring stress waves generated by the apparatus during a current operation of the apparatus for a current time period to generate second stress wave data; analyzing at least a portion of said second stress wave data to generate second analyzed data that captures one or more features of said second stress wave data; processing at least a portion of said second analyzed data to generate current status data, wherein said current status data also has substantially reduced influence from normal operating variations compared to said second analyzed data; and comparing said current status data to said baseline data to determine the current status of the apparatus.