**Software PROBA** is meant for preprocessing of measuring results of TDEM, its quality rating, run-through and analysis of field material as transforms, preparation of data to be interpreted in the PODBOR system.

Our experience tells us that the quality rating of measuring results and their geophysical content can be most effective in visual-graphical data analysis. This analysis should be better carried out at Rotau or Stau transform level. In this system we use Rotau curves with respect to the late asymptotic form in the half-space; Stau curves are calculated by a complete S-plane transient formula (after Sidorov); in this case a receiving loop is thought to have small dimensions, Htau = 0.75 m.

In the version Proba_10 we added curves of resistivity as function of depth Ro(Heff) for measuring configuration “loop-in-loop”. This curves is the result of fast approximate 1-D inversion based on Christensen’s algorithm. Approximate 1-D inversion models can be good start models for other phases of the inverse problem solution.

The system provides a means for the following operations:

- Editing of measuring results – pruning of points at the beginning and the end of a sounding curve;
- Smoothing of measuring results (if advisable);
- “Sewing modes together”, i.e. the results obtained under different conditions of measuring (different points, coils and so on);
- Combining of duplicates by averaging over the robust estimate algorithm;
- Input of definite changes into source data: time shift, absolute or relative “addition” to a signal and data interpolation to a different time scale;
- Calculating of Rotau(t) and Stau(Htau) transforms;
- Approximate 1-D inversion with output of results in Ro(Heff)
- Type-out or filing of digital and graphic material.
- Besides, the package is used for presenting results of
**equipment testing and control observations**.

A case history of the program for processing and integrating of initial data obtained with low- and high-ampere current of excitation is given below:

3. Comparison of Rotau curves with different current on “cleaning” (scissoring of noise areas)

4. Final single Rotau curve, “stitched” from low-and high-ampere current data

*Thanks to two modes (low- and high-ampere current) of signal recording and PROBA program probabilities, we easily obtain a single sounding curve extended in the domain of both short times (shallow depths of investigation) and long times (great depths of investigation).*