Application of complex phase-shift keyed signals in seismic sounding of ground with a hydroacoustic source

The results of experimental studies of the seismoacoustic field generated by a powerful coherent hydroacoustic source operating at 227 Hz in a psuedorandom sequence (PRS) mode are presented. This operating mode makes it possible to perform high-energy sounding of the medium at large depths with high spatial resolution. The coherency of the source allows one to cover the route by steps, using one set of receivers with coherent summation and accumulation of signals. The experimental results include the data on the geological section to two-kilometer depths: from the low-velocity zone (to 20 m), through the upper part of the section (300-500 m), and down to the crustal structures (2 km). Besides the reflections from the layers, isolated inhomogeneities can be seen in the profilograms. Sounding of the earth's structure down to the aforementioned depths at the frequencies above 200 Hz is a recent achievement. Recommendations concerning further improvement of the parameters of the measuring system are given.