Downhole seismic-sonic receiver

A downhole drilling system for gathering formation data from inside a borehole, the downhole drilling system comprising:

• downhole drill string;
• source coupled to the downhole drill string, the source adapted to generate at least one of seismic and sonic waves;
• and
• receiver coupled to the drill string and adapted to receive at least one of the seismic and sonic waves, the receiver comprising a tubular housing adapted for axial connection to a drill string and a plurality of sensors coupled to the tubular housing and arranged at the corners of a rectangular prismatic shape, the plurality of sensors comprising:
• a first pair of sensors aligned along a first axis, the first pair adapted to measure a spatial derivative along the first axis;
• a second pair of sensors aligned along a second axis orthogonal to the first axis, the second pair adapted to measure a spatial derivative along the second axis;
• and
• a third pair of sensors aligned along a third axis orthogonal to the first and second axes, the third pair adapted to measure a spatial derivative along the third axis;
• and
• diaphragms to flexibly couple the sensors to the tubular housing while rigidly coupling the sensors to a borehole wall.