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Magnetic Resonance Sounding

The group is currently developing a lightweight wireless surface NMR system, called APSU. The wireless APSU receive system is currently working and is compatible with all commercial MRS transmitters. A novel surface NMR transmitter is also under development within the group.

The group has a NUMIS Poly MRS instrument from Iris Instruments for surface MRS. The NUMIS Poly is a four channel MRS-instrument. Typically we record the MRS signal in a coincident loop configuration, while the three other channels are used to simultaneous acquisition of the EM-noise characteristics in the surroundings (remote reference technique). Sophisticated filtering techniques using the remote references have been developed within HGG improving the signal to noise/ratio significantly.

A magnetometer is needed to determine the Larmor frequency and for recording of fluctuations in the earth's magnetic field during recording of a full MR-sounding, which can take 5-10 hours. Furthermore the MRS-sounding is followed up by a WalkTEM-sounding, to obtain the resistivity model. The resistivity structure is important to include in the modeling of the MRS signal.

Mobilization of the MRS-instrument is relatively time-consuming and we therefore often use our EM-noise collector instrument to scout the survey area for suitable MRS-locations before deploying the full MRS system.

Key Specifications

MRS-system, APSU

  • 2 three-channel receiver units, wireless
  • Current-probe 
  • GPS synchronized detection

MRS-system, NUMIS Poly

  • 2 x DC/DC converter units: Power supply unit for AC generator.
  • Transmitter unit: Generates the oscillating transmitter pulses.
  • Max. output:  600 A., 4000 V
  • 2 x Tuning capacitor units
  • 4 x receiver units
  • Coincident loop: Square 100 x 100 m2, eight figure shape
  • 3 x Remote reference loops(20x20m2)
  • Supplementary instruments: magnetometer, GPS, WalkTEM, EM-noise collector