Strapdown airborne gravimetry error estimation based on undulated flight

Abstract

Strapdown airborne gravimeter is an effective way to obtain the gravity disturbance. The performance of strapdown gravimeter depends largely on the time-varying error factors in the instrument. To improve the accuracy, besides calibration in the lab, error factors should be also estimated during the survey test. Theory shows that time delay and scale factor error are two main error sources in strapdown airborne scalar gravimetry. The error in strapdown gravimeter was stimulated by the experimental undulated flights. Inspired by the bandpass filter, sliding window correlation analysis supports the correction of error theory and testifies the feasibility of estimation by error theory in undulated flights. However, the estimation should be established under the premise that the error is larger than the gravity signal, which can just be satisfied in the undulated flight. Using the weighted least square method, in which the weight was from sliding window correlation analysis, the estimation results show good consistence in undulated flights. The improvements of accuracy are from 2.04mGal (1mGal=10−6m/s2) to 1.72mGal under 1.8km resolution, 1.27mGal to 1.15mGal under 2.4km resolution and 0.96mGal to 0.90mGal under 3.0km resolution after using estimated parameters to correct gravimetry result, in which the percentage of promotions are 15.6%, 9.4% and 6.3%. Error estimation and correction method shown in the paper is an effective way to improve the quality of strapdown airborne gravimetry.