The figure below shows
the main window of the GEORADAR-EXPERT software system, where the red frames
indicate the location of the histogram of the **Probability** attribute and the graph of the **Permittivity – Probability** corrective function.

The **Probability** attribute provides an estimate of the probability that
a combination of GPR profile signals identified by the BSEF analysis as a
reflection from a subsurface object is indeed a reflection from a real-life
subsurface object. The measure of probability is the ratio of the number of
in-phase signals on the line passing through the maxima of the diffracted
reflection to the length of this line. If all diffracted reflection maxima
consist of signals of the same phase, the probability value is 100%.

Based on the information
provided by the **Probability** attribute histogram, the user can exclude field analysis points with low
probability values from the section calculation, thereby increasing the truth
of that section. Note: a field analysis point is a point on a GPR profile with
X[m] and Y[ns] coordinates, which indicate the position of the top of the
diffracted reflection, the measured kinematic and dynamic characteristics of
which are attributes of this point. As attributes, also, are the values
calculated on the basis of the measured characteristics.

The figure below shows
an example of a histogram of the **Probability** attribute. The **Probability** range is
set using the input boxes located under the axes of the histogram.

Using the **Permittivity - Probability** corrective
function, the user can minimize possible errors of automated BSEF analysis, and
using the **Permittivity - Probability** corrective function plot, one can evaluate the reliability of certain
dielectric constant values. For example, from the corrective function plot
shown below, it can be inferred that high values of permittivity have low
Probability attribute values.

The following is a
comparison of the final results of a GPR survey obtained without using the **Probability** attribute range constraint
and with such a constraint. GPR survey was carried out in order to study the
landslide situation in the area of the road. Below is a photograph of a site
of the road with a landslide displacement of soil on the side of the road, and
a GPR profile obtained during the study of this section using a 150 MHz GPR. In
the photograph, the manifestation of the landslide process is marked with a
rounded frame, the black arrow shows the movement of the the GPR unit.

Below is the result of
processing the above GPR profile using automated BSEF analysis as a section of
the **Central Frequency** attribute
(central frequency of reflected signals). Two variants of the section are
presented: without limiting the range of the **Probability** attribute and with the application of a limiting. As a
result of the limitation of the **Probability** attribute range, only those field analysis points whose **Probability** attribute value was equal to 100% were used to create the section.

It can be seen that in
the section created with the **Probability** attribute limiting, the boundary between the fill and bedrock is traced much
better than in the section where the **Probability** attribute limiting was not applied.

The following shows the
results of creating a section of the **Re(permittivity)** attribute (the real part of the complex relative permittivity) without limiting
the range of the **Probability** attribute and with the limiting applied. As a result of the limitation of the **Probability** attribute range, only those
field analysis points were used to calculate the section, the **Probability** attribute values of which
lay within the specified probability range of 85 - 100%.

On both sections, the
cross section of the landslide body is colored red, however, on the section on
the left, the landslide body is displayed fragmentarily. Further, to obtain
more complete information about the subsurface, the sections of the **Central Frequency** and **Re(permittivity)** attributes were summed
in the **Summation** module of the
GEORADAR-EXPERT software system. The results of this summation are shown below.
On the left - the result of the summation of the sections calculated without
applying the **Probability** attribute
range limiting, on the right - the result of the summation of the sections
calculated using such a limiting.

The summation result
obtained with the **Probability** attribute range limiting fully shows the cross section of the landslide body,
which is not the case with the summation result of sections calculated without
the probability range limiting. It is noticeable that on the summation result
shown on the left, there is no fragment of the landslide body located in the
zone of manifestation of external signs of the landslide process, and on the
summation result shown on the right, one can observe the exit of the landslide
body to the surface in this place:

Undoubtedly, the ability
to create a section using only those field analysis points whose **Probability** attribute values are high
enough increases the truth of this section, but such a restriction does not
always lead to such a result. Real reflections from subsurface objects can also
have a low value of the **Probability** attribute. This happens when a local object that generates a diffracted
reflection is at such a depth that the reflected signals from this object are
comparable in amplitude to random interference and noise. In this case, the
application of the range limitation of the **Probability** attribute will lead to the removal of field analysis points from the section
calculation that do not contain BSEF analysis errors, which will lead to a
deterioration in the quality of the final result.

The decision to apply
the limitation of the attribute range should be made on the basis of the
principle of the best correspondence of the created section to the a priori
information about the object under study and / or the greatest consistency in
the shape and location of the section elements for a given type of the
subsurface. To do this, a section is created without limiting the range of the **Probability** attribute and several
sections with different values of the boundaries of the range of the **Probability** attribute. As the final
result, the section that best meets the above criteria is selected. As
experience shows, the lower limit of the range of the Probability attribute can
be in the range of 70 - 100%, and the upper limit of the range is 100%.

Previously, in the list
of corrective function (CF) creation modes, which were selected using the
drop-down list located in the lower right corner of the CF panel, there were
only two items - **Auto** and **Manual** (automatic and manual CF
creation modes). Now several options for calculating the corrective function in
automatic mode have been added - see the figure below.

The drop-down list items
with the name **Auto** or consisting of
the abbreviation **CF** and a serial
number represent different ways of automatically creating a corrective function
that take into account various features of the subsurface structure. The choice
of the method for automatic creation of CF is carried out according to the
principle of the best correspondence of the created section to a priori
information about the object under study and / or the greatest consistency in
the shape and location of the section elements for a given type of the
subsurface. Index **R** in the name of
the list item means reversal of the corrective function. For example, the
corrective function created when selecting the list item **CF 1R** is calculated in the same way as the corrective function from
the list item **CF 1**, and then
reversed.

As practice has shown,
after it became possible to apply various options for creating a corrective
function in automatic mode, the **Manual** CF creation mode using the mouse became used quite rarely.