The Promis is a modern implementation of the Slingram technique which uses a coil to produce a primary magnetic field, this is linked by a cable to a receiver sensor at distances between 20 and 200m. The receiver coil measures 3 in-phase components and one out of phase component of the secondary magnetic field induced by ground conductors. Traditional Slingram type techniques only measure the vertical component of the magnetic field, but by measurement of the two additional horizontal components the Promis is able to give information on the strike of any conductive structure that has been intercepted. Penetration depths are determined both by Tx-Rx coil separation and frequency recorded but a rule of thumb is penetration is approximately 1/2 of the inter-coil separation.
The system includes 2 inclinometers in the transmitter for horizontal positioning and will record 3 frequencies (at 100m spacing) within 20s, If all 10 frequencies are required then the full measurement process takes 50s.
Through analysing all 3 components of the magnetic field it is possible to derive additional information about conductive dykes and water baring fracture zones, making the system a fast simple tool for shallow mineral exploration and hydrology studies.
Data processing is undertaken using EMSYS software which is provided with the instrument. The package includes editing and processing tools for removing sources of noise and rouge measurements. Data can be exported to a number of third party formats for inversion and interpretation.