When using a drill rig, the blade can also be advanced by the so called Sciacca method. In this configuration the cable exits from the rods above ground, via a slotted adaptor.
When the slotted adaptor is near the ground surface, another push rod is inserted, to continue the sounding.
The rod pushed by the drill rig is typically Ø76 mm. It is not going below ground. The remaining rods are typically Ø36mm or Ø50 mm penetrometric push rods.