Trr No. 1293 Pavement Design, Management, And Performance, pp. 24-30
Geophones were selected for the calibration of the FW I) sensors after an evaluation of the accuracy and precision oti five candidate sensors. An aluminum loading plate was constructed to allow mounting of the load cells in line with and below the FWll load cell. The calibration curves of all load cells were traceable to the National Bureau of Standards. The effects on the calibration factors of load cells of using the aluminum plate were small. The signal-conditioning unit was developed to condition the signals before acquisition. The system was used to calibrate an FWD device. The system was effective. A calibration process is proposed on the basis of an analysis of the data collected. The calibration system is cost-effective, accurate, and rugged, and it can be used b_v highway agencies to calibrate their FWD devices.