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 b y a powerful coherent hydroacoustic source operating at 227 Hz in a psuedor andom sequence (PRS) mode are presented. This operating mode makes it possi ble 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 ro ute by steps, using one set of receivers with coherent summation and accumu lation of signals. The experimental results include the data on the geologi cal 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 inhomo geneities can be seen in the profilograms. Sounding of the earth's structur e down to the aforementioned depths at the frequencies above 200 Hz is a re cent achievement. Recommendations concerning further improvement of the par ameters of the measuring system are given.