Abstract: A high resolution data acquisition (DAQ) system is initially calibrated with a reference source having a resolution higher than the DAQ system. Measurements over the operating range of the DAQ system are taken, and characteristic calibration coefficients are determined from the measurements. Software corrections based upon the calibration coefficients are made to DAQ system measurements. A digital to analog converter (DAC) on-board the DAQ system having a lower resolution than the DAQ system is calibrated by generating a look-up table of input digital codewords and output electrical signals measured by the calibrated DAQ system. This look-up table is used to field calibrate the DAQ system using only the DAC, rather than the high resolution reference source.

Abstract: A data acquisition system for vibration analysis signals includes a logarithmic amplifier for compressing wide dynamic range signals. The logarithmic amplifier replaces attenuators, gain amplifiers, and gain switches used in a conventional system. Further, only a low bit-count analog to digital converter is needed in combination with the logarithmic amplifier. Consequently, the footprint of the system and system cost are reduced.