The natural accidents connected to deformation of a terrestrial surface have negative economic and social consequences. Now the attention of geophysicists involves an active method vibroseismic sounding. Result vibroseismic researches of the grounds is "photo" of an earth's crust as seismogram. She shows a transit time of seismic waves. Quality seismogram depends on the correlation characteristic of a probing signal that is defined by size of deviation of frequency of a source of a probing signal. The closer the form of the correlation characteristic of a probing signal to the form delta of a pulse, the above resolution seismogram. This circumstance gives persevering preconditions to search of broadband sources of probing signals with the narrow correlation characteristic. However there are theoretical preconditions for improvement of the correlation characteristic of a probing signal after registration of this signal in a point of reception and reception qualitative seismogram at a narrowband probing signal.

In the report the way of improvement of the correlation characteristic of probing signals is considered at processing narrowband signals after registration of the seismic data. A basic element of an offered way is the functional converter of the data. In the report the characteristic of the converter received by a method of a return filtration is submitted.

The basic result of the given way of improvement of the correlation characteristic of probing signals is the opportunity of "virtual" expansion of a frequency range of a source of a signal. It allows raising resolution seismogram.