MICROWAVE V/H SENSOR EXPERIMENTATION

An experimental program was conducted to determine the feasibility of utilizing a passive microwave sensor of velocity/altitude ratio (V/H) as the basis for a navigation device in Army aircraft. This sensor, combined with a radar altimeter, yields the velocity information needed for navigation. The technical objectives of the program were to: (1) characterize the microwave thermal radiation from various types of terrain; (2) demonstrate the principle of V/H sensing, (3) determine the feasibility of using this principle in a navigational device. Airborne measurements were made with a government-furnished two-beam X-band radiometer, which was modified and installed in a C-47 test aircraft. Radiometer signals and related information were recorded on magnetic tape. Ground-based data processing provided a comparison of radiometer-derived V/H measurements with those derived from independent sensors. Good results (fluctuating error comparable to experimental uncertainties) were obtained over green farmland, urban areas, rice paddies, and centain desert areas; marginal results were obtained over other deserts and winter farmland. It was concluded that use of a microwave V/H sensor as a basis for a navigation system is feasible at low altitude over favorable terrains. (Author)