The first airborne scalar gravimetry system based on SINS/DGPS in China

China has developed an airborne gravimetry system based on SINS/DGPS named SGA-WZ, the first system in which a strapdown inertial navigation system (SINS) has been used for airborne gravimetry in China. This gravity measurement system consists of a strap-down inertial navigation system and a differential global positioning system (DGPS). In April 2010, a flight test was carried out in Shandong Province of China to test the accuracy of this system. The test was designed to assess the repeatability and accuracy of the system. Two repeated flights and six grid flights were made. The flying altitude was about 400 m. The average flying speed was about 60 m/s, which corresponds to a spatial resolution of 4.8 km when using 160-s cutoff low-pass filter. This paper describes the data processing of the system. The evaluation of the internal precision is based on repeated flights and differences in crossover points. Gravity results in this test from the repeated flight lines show that the repeatability of the repeat lines is 1.6 mGal with a spatial resolution of 4.8 km, and the internal precision of grid flight data is 3.2 mGal with a spatial resolution of 4.8 km. There are some systematic errors in the gravity results, which can be modeled using trigonometric function. After the systematic errors are compensated, the precision of grid flight data can be better than 1 mGal.