Two different methods are often used to calibrate the crustal deformation instrument One of them is indirect calibration.We have calculated the scale value of the instrument by measuring some parameters.Since there are a lot of conversion links,they easily lead to sys- tem error.Another is direct calibration.The scale value is calibrated through comparison of the known physical calibration with the output signal of the instrument.This method is higher accuracy and repetition. Most of the crustal deformation...