St.Petersburg Collector

Profile is taken in full-wave mode (colored frame), with coding of the amplitude of the signal reflected by color in the logarithmic gradation. Reasonable user question arises, why dark-blue spot higher at depth 1m (see colored frame) as collector image is not selected. On the frame with threshold +32 (it is possible to select any threshold in the program) it is evident that the first spot disappeared. Therefore, reflected singnal is weak and, most probably, it was caused by the heterogeneities of the collector trench. Other objects are visible on the image. Additional data are required for their identification.