Patent ID: 7414918

Claim:
A method for normalizing transducer signals produced by an acoustic receiver in a cement bond logging tool suspended from the surface and positioned down hole, comprising the steps of: providing in the logging tool an anti-resonant mode receiving transducer formed of a plurality of acoustically isolated transducer rings stacked longitudinally, being operated below its resonant frequency, and configured to output signals from a plurality m of channels representing uniform azimuthal positions disposed around the transducer rings; operating elements of the receiving transducer corresponding to each of the m channels in the anti-resonant mode during a calibration process to obtain and store in memory in the tool a set of digitized gain factors for each of the plurality m of transducer channels; and operating the logging tool in the anti-resonant mode down hole while executing a normalization process under standard excitation conditions to generate and store in the memory in the tool digitized transducer output signals containing cement bond logging data from each channel m normalized to account for transducer variations according to the stored gain factors determined during the calibration process.