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Digital P-S Suspension

The Digital P-S suspension probe is a low-frequency acoustic sonde designed to measure compressional and
shear-wave velocities (slowness) in soils and soft-rock formations. It operates using indirect excitation rather than mode conversion as in a conventional sonic. It is capable of acquiring high-resolution P and S wave data in borehole depths of up to 600m in water.

Principle of Measurement:

The P-S suspension probe contains a unique-design of powerful hammer source and two receivers, separated by acoustic damping tubes. To acquire data, the probe is stopped at the required depth and the source is fired under surface command. Firing causes a solenoid-operated shuttle aligned across the borehole axis to strike plates on opposite sides of the probe in turn, setting up a pressure doublet in the surrounding fluid. The resultant fluid motion produces a tube wave at the borehole wall with velocity close to the shear velocity of the formation together with a compressional wave. As the waves propagate parallel to the borehole axis, they set up corresponding fluid movements that are detected by the two neutral-buoyancy 3D hydrophone receivers, allowing the wave velocity to be directly measured. The facility to stack multiple shots and filter the data as in normal seismic data acquisition is included in the operating software.


  • High-energy shear-wave source has typically 20x power of conventional sonic probes
  • Low-frequency measurement, more representative of engineering situations
  • Stacking of multiple shots
  • Probe separates for shipping
  • Real-time wavelet (wiggle) display
  • Compatible with RG Micrologger2


  • Formation
    compressional-wave velocity (slowness)
  • Formation shear-wave
    velocity (slowness)


  • Engineering


Diameter 54mm
Length 8.25m (assembled)
Shipping case length 1.45m (4.75ft)
Weight 38kg
Max. temperature 70ºC
Max. pressure 6.5MPa
Transducer type solenoid and hammer
Receiver type 3D hydrophones
Receiver spacing 1000mm (3.28ft)
Waveform acquisition
5.12mS to 409.6mS
Sampling 2.5µs minimum
Down-hole gain 0db to 42db (surface control)

Operating Conditions

Borehole type: Open-hole, water-filled

Sales Information


26 070 000 Digital P-S suspension log probe
in carrying case.

Download Digital P-S Suspension sheet


...Practical Innovation with Global Service & Support...

Robertson Geologging Ltd., 2017

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