Abstract: Apparatus for the measurement of quasi-static gravity gradients comprising: a flexible ribbon held under tension at both ends; sensing means arranged to detect the transverse displacement of the ribbon from an undisturbed position due to the gravitational field acting on said ribbon and to generate a signal representing the displacement; and output means coupled to said sensing means and responsive to said displacement signal to generate an output signal which is a function of the gravitational gradient tensor of the gravitational field; wherein the ribbon has a non-uniform rigidity profile and/or mass profile along its length such that, in use, the displacement response of the ribbon due to the gravitational gradient of the gravitational field is enhanced and/or the displacement response of the ribbon due to the absolute gravitational acceleration of the gravitational field is suppressed.

Abstract: Apparatus for the measurement of quasi-static gravity gradients comprising: a flexible ribbon held under tension at both ends; sensing means arranged to detect the transverse displacement of the ribbon from an undisturbed position due to the gravitational field acting on said ribbon and to generate a signal representing the displacement; and output means coupled to said sensing means and responsive to said displacement signal to generate an output signal which is a function of the gravitational gradient tensor of the gravitational field; wherein the ribbon has a non-uniform rigidity profile and/or mass profile along its length such that, in use, the displacement response of the ribbon due to the gravitational gradient of the gravitational field is enhanced and/or the displacement response of the ribbon due to the absolute gravitational acceleration of the gravitational field is suppressed.

Abstract: A rotational vibration isolator for a sensor is disclosed. The isolator comprises a first enclosure surrounding the sensor and a second enclosure surrounding the first enclosure, with a spherical gap between the enclosures. A fluid is supplied into this gap, the density of the fluid being sufficient to support the first enclosure in a condition of neutral buoyancy. The first and second enclosures are connected by springs of low spring constant.

Abstract: A data acquisition system for gathering geophysical data, a corresponding method, and a data acquisition unit for use with the system and method are disclosed. The system (10) comprises a plurality of data acquisition units (14) for gathering geophysical data, each data acquisition unit (14) being connectable to at least one sensor (15) and being arranged, during use, to gather geophysical data from the at least one sensor (15). Each data acquisition unit (14) comprises time referencing means (48) arranged to generate time reference data usable to control the time at which samples of geophysical data are taken. The system (10) further comprises means for calculating spatial derivatives between samples associated with adjacent sensors (15) connected during use to the data acquisition units (14).

Abstract: A data acquisition system for gathering geophysical data, a corresponding method, and a data acquisition unit for use with the system and method are disclosed. The system (10) comprises a plurality of data acquisition units (14) for gathering geophysical data, each data acquisition unit (14) being connectable to at least one sensor (15) and being arranged, during use, to gather geophysical data from the at least one sensor (15). Each data acquisition unit (14) comprises time referencing means (48) arranged to generate time reference data usable to control the time at which samples of geophysical data are taken. The system (10) further comprises means for calculating spatial derivatives between samples associated with adjacent sensors (15) connected during use to the data acquisition units (14).