TISA 3D december 2019 update

The new TISA 3D Borehole Radar has improved a lot compared to the 3D BHR introduced in 2001:

  • The diameter has been reduced from 160 to 135 mm. The probe can now be applied in 145 mm boreholes, for instance borings with a 160 mm OD plastic casing.
  • Reduction of the length (4,2 to 3,1 m) and weight (250 to 50 kg) of the, making it easier to operate. The probe can now be lowered into a borehole with a tripod instead of a crane.
  • Improved quality of the radar signal due to the use of synthetic materials instead of metal and a modified positioning of several parts in de probe. This has led to an increased number of possible applications.
  • More robust depth recording. The depth recording of the probe is now carried out by an encoder in the top of the tripod, instead of by measuring the water pressure in the borehole.
  • A substantial reduction of the dissipated electrical power from 50 W to 12 W. The probe can now be fed by batteries inside the probe instead of wall power that is transported through the borehole.
  • Data communication in the borehole now takes place by glass fibre cabling instead of metal coaxial cabling. In addition to the absence of a power cable in the borehole, this means that there are no metal cables left in the borehole, enhancing the radar data quality.
  • Radar electronics have been modified: the transmission of radar signals has shifted from incidental high power pulses to continuous low power sines of varying frequency. This has improved the signal to noise ratio and increased the dynamic range from 40 to 65 dB, enabling the detection of objects at larger distances.
  • Measurement speed has been increased and the duration of a measurement was reduced by a factor 10. Measurement of one borehole can now be done with a speed of 1 m/minute. The achieved resolution is 3 cm in borehole direction and 0,5 degrees azimuthally.   

The first measurements with the new system have been carried out successfully. We will report further on this at the beginning of 2020.