A digital phase coded ground probing rada

Ground probing short pulse radars are used for relatively shallow (less than 20 meters) subsurface mapping of geologic strata, ice sheets, depths of fresh water bodies and for locating underground utilities. One problem in particular, the ability to map the depth of rivers, is not currently possible because of the limited range capability of short pulse radars. Airborne depth measurement would be of great use in monitoring sedimentation and in planning dredging operations in waterways. Dredging operations in rivers are very expensive and improvements in river depth mapping could result in great cost savings for these programs.;This thesis describes the evolution, design and testing of a new kind of ground probing radar. It uses the pulse compression technique of digital phase coding to achieve both better resolution and range than current commercial ground probing radar systems. The transmitted signal consists of a complementary digital code which is phase modulated onto a sine wave carrier. The received signal is coherently detected to recover the code and digitized with a high speed analog to digital converter. The resulting sequence is then cross-correlated with the transmitted code yielding a close approximation to the desired reflectivity sequence of the ground.;Initial performance of the radar was tested in the laboratory with coaxial cable delays and attenuators to measure time performance and sensitivity. Theoretical calculations and field tests showed a range capability of up to 10 meters (depending on water resistivity) in typical river water, which is sufficient to map most areas where dredging is important.