The Robertson Geo PS Logger® is a compact, self-contained borehole probe that measures P-wave (compression) and S-wave (shear) velocities without external energy sources. Widely used in civil engineering and offshore investigations, it provides fast, accurate subsurface data for calculating elastic moduli like Young’s, Shear, and Bulk. Using indirect excitation and advanced waveform software, the PS Logger® delivers reliable, high-resolution seismic measurements, making it a trusted tool for geotechnical and geophysical applications worldwide.