Determining drill bit failure by use of a neural network

A drill string 102 is equipped with a downhole sub assembly 104 which contains sensors 106 to detect equipment condition during drilling. The sub assembly 104 has no electrical communication with the drill bit 108 itself and the sensors 106 detect the drill bit's 108 condition from vibrations or strain. Sensors in the drill bit 108 are not needed. The method utilizes a neural network in which data analysis can be spectral power ratio analysis, adaptive filter analysis, or mean strain ratio analysis.