Accession Number : AD0602293

Title :   OCEAN WAVE PROFILING RADAR SYSTEM,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Morrow,C. W.

Report Date : 21 APR 1964

Pagination or Media Count : 30

Abstract : An airborne oceanographic sensor, using a precise radarranging technique, is used for high-speed profile mapping of the ocean wave structure. The instantaneous distance to a spot on the ocean surface contour directly beneath a lowaltitude level-flying aircraft is continuously recorded on a roll chart. This record portrays a laterally compressed cross section of the ocean surface along the flight track. Frequency modulation of a cw microwave source is used to obtain a measure of transmission delay by phase comparison of the demodulated return with the modulating reference signal. The use of microwaves is necessary to develop a narrow vertical beam, from a convenient size aircraft antenna, in order to short-range spot-illuminate and resolve the fine structure in each ocean wave as the profile is followed. Wave heights may be resolved to less than 6 inches, over a dynamic range up to 50 feet, by making the radarilluminated spot sufficiently small and the transmission bandwidth sufficiently large. Multi-path interference between reflecting wave facets within the beam may seriously distort the phase coherence of the side frequencies in an unsmoothed FM ranging system unless this distortion is minimized by the transmission of a diverse spectral bandwidth. The equipment thus uses a sinusoidal FM output over a 4-percent spectral bandwidth centered at 9400 Mc to overcome this effect and to obtain the resolution necessary to prove the principle. Flight tests over various sea states experimentally verified the feasibility of the system and helped to establish design parameters for future equipment. (Author)

Descriptors :   (*OCEAN WAVES, MEASUREMENT), (*RADAR EQUIPMENT, RANGE FINDING), (*RADAR SCANNING, OCEAN WAVES), AIRBORNE, OCEANS, SURFACE PROPERTIES, MAPPING, FEASIBILITY STUDIES

Distribution Statement : APPROVED FOR PUBLIC RELEASE