The use of gravimeters on mobile platforms is a technological challenge. To reach the required accuracy of 1 mGal, the kinematic acceleration must be measured very precisely. The interfering signal due to the movement of the platform is up to 10,000 times stronger than the gravity signal.
Gravimeters are used on board of ships for marine gravimetry. During marine surveys, the system can deliver data with an accuracy of 0.3 mGal in crossing points.
The use of gravimeters in airborne environments is more demanding due to air turbulences during flight.
GRAVIONIC has considerably improved the hardware (i.e. the sensor) and uses precise GNSS/INS processing and special Kalman filter algorithms to calculate accurate gravity signals. As a spin-off from the Institute of Flight Guidance (Braunschweig / Germany), GRAVIONIC also has special skills in precise positioning and navigation.
In airborne application the Chekan-AM gravity system features the noise characteristics shown in the figure below. The flight speed during the measurements was 70 m/s at an altitude of 300 m above ground level in the vicinity of Magdeburg, Germany. The repeated line has a RMS of 1.34 mGal. The gravity signal is recovered with a direct form II transposed filter with a time constant of 37.22 s. The resulting signal is then twice filtered with a zero phase (forward and backward) combined filter based on direct form transposed filters with time constants t1 = 16s, t2 = 24s and t1 = 32s, t2 = 48s, respectively.
The performance of the Chekan-AM is comparable with well known gravity systems as LaCoste & Romberg and Bodenseewerke KSS gravity systems. The Chekan-AM shows a RMS = 0.3 mGal in crossing points regularly.
The new developed gravity system iCAGS (innovative enhanced Chekan-AM Gravity System) significantly outperforms other marine and airborne gravity systems.
High performance GPS based 3D true heading, attitude sensing and positioning system: