development of the marine radar wave observation system have already been made to obtain such 2- dimensional real-time information of prevailing waves from the radar sea echo. These researches have provided satisfactory information about sea surfaceconditions 6)-9)
In this paper, the on-board experiment of the marine radar wave observation system is described based on about 50-run observations operated in the waters near around Izu-Oshima Island and Goto Islands for 8 days in total in 1994. For the wave analysis, the 2- dimensional spectral method was applied to acquire 2- dimensional information of prevailing waves, the wavelength and the propagating direction (direction propagating from).
2. OUTLINE OF MARINE RADAR WAVE OBSERVATION SYSTEM
Table 1 shows the outline of the ship and the marine radar used for this experiment. The ship is a super high speed vessel, the Techno Super Liner, and her maximum navigation speed is about 50 knots. This radar is a usual marine radar. The frequency of the transmitted microwave is 9.4GHz and the power of the transmitted radar beam is 25kw. The radar antenna was set up on her foremast at 14m height above the sea level on cushion at high speed sailing and 12 m off cushion at low speed sailing.
The main specification of the system is listed in Table 2. This system consists of the radar system (radar antenna, radar indicator), the data acquisition system (sampling data device, internal data memory device), the sampling control system (personal computer), the external memory system (external data memory device), and software for the wave observation and analysis.
Radar echo signals are sampled and stored to the internal data memory device through the 8bit A/D converter. The maximum sampling frequency is 120MHz. That is, the data are sampled every 1.25m.
The setting conditions of this system, a radar range, a sampling frequency, a sampling area and so on, are also listed in Table 3. The sampling area on the PPI radar image is mostly circular. The number of the data on this mostly circular sampling area is about 4.7 million. This marine radar wave observation system is detailed in previous papers4)5)6).
Table 1 Outline of the super high speed vessel and the marine radar.
Table 2 Main specification of the marine radar wave observation system.
