A NEW METHOD FOR ABSOLUTE CALIBRATION OF HIGH-SENSITIVITY ACCELEROMETERS AND OTHER GRAVIINERTIAL DEVICES

To investigate the dynamic characteristics of high-sensitivity graviin ertial devices (accelerometers, seismometers, and others) it seems adv antageous to use for the input signal the gravitational acceleration p roduced by bodies with a known mass distribution. This eliminates the need for moving the transducer under investigation. Such motion is nee ded in the inertial acceleration reproduction as well as for inclining a measuring instrument in the Earth's gravity field. Error in measuri ng the parameters of the transducer motion is determined by the uncert ainties of the length- and angle-measuring instruments being used. Par ticularly, it concerns the angle measurement errors when the gravity f ield effects have been taken into account. The existing methods for re producing gravitational acceleration are based on the use of nonunifor m fields of simple shape bodies (sphere, cylinder, and the like). Thes e methods require calculation of the corresponding acceleration, takin g into account the spatial mass distribution of the instrument sensing element. The commonly employed approximation results in a procedural error of the order of 10% and over. It is proposed to calibrate a meas uring instrument using a uniform, flat gravity field of varying direct ion. The set-up designed to realize this method reproduces varying acc elerations over the frequency range 0.01 to 0.3 Hz with amplitude less than 1.3 x 10(-7) m/sec2. This enables calibration of seismometers of various types with a higher accuracy.