Pulse compression subsurface radar

The application of subsurface radar using electromagnetic waves in the VHF band is wide and includes surveying voids under the ground and archaeologic al prospecting. To achieve a wider application range, the survey depth must be deeper. In this paper, a method of pulse compression using a chirp sign al as one of the methods to fulfill this requirement is described, and its advantages and problems are discussed. First, a delay correlation method is proposed as a processing method of pulse compression. It converts RF band chirp signal directly into a pulse. Moreover, the method improves the S/N r atio by over 40 dB compared with conventional pulse radar. Therefore, it ha s the same detection ability as conventional pulse radar even though it use s less transmitting power. Next, the influences of RF amplifier saturation and underground propagation characteristics on the chirp signal are discuss ed; both are shown to have little influence on the detection ability of the method.