Patent ID: 8359920

Claim:
A gravity gradiometer instrument having a gyro-stabilized platform for maintaining a selected orientation with regard to a local gravity field and of a type that outputs a lower-order gravity-gradient signal having respective first and second higher-order gravity-related signal components associated therewith and having further instrumentation associated therewith for determining said respective higher-order gravity-related signal components, comprising: a gyro-stabilized platform for maintaining said selected orientation with regard to the local gravity field; a rotatably mounted accelerometer arrangement including six accelerometers arranged at an equal spacing from a spin axis and at an equi-angular spacing about the spin axis, a sensing axis of each accelerometer aligned substantially tangentially to a circle subscribed by the accelerometers as they rotate about the spin axis; means for isolating and extracting said respective higher-order gravity-related signal components in accordance with ( A 1 + A 5 ) - 1 2 ⁢ ( A 2 + A 3 + A 4 + A 6 ) = 3 ⁢ R ⁡ ( 1 2 ⁢ ( W x ⁢ ⁢ x - W y ⁢ ⁢ y ) ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ ⁢ Ω ⁢ ⁢ t - W x ⁢ ⁢ y ⁢ ⁢ cos ⁢ ⁢ 2 ⁢ ⁢ Ω ⁢ ⁢ t ) , wherein A 1 , A 2 , A 3 , A 4 , A 5 , A 6 : six accelerometers, R: radius of the circle, W xx , W yy , W xy : second-order tensor components, Ω: spin rate of the accelerometers, and; means for combining said respective higher-order gravity related signal components with corresponding first and second lower-order gravity related signal components to substantially attenuate the respective higher-order gravity related signal components in said first and second lower-order gravity-related signal components.