| 摘要 |
PROBLEM TO BE SOLVED: To measure an ocean current with high accuracy, or easily analyze a sea route of one's own ship by changing an irradiating signal frequency to an irradiating area when moving speed is measured by a frequency analysis of a received signal. SOLUTION: An ultrasonic pulse signal having frequencies f1 and f2 and a time interval T is respectively sent in order from echo transducers 1 and 2. From an echo transducer characteristic, it is respectively irradiated in the specific directionsθ1 andθ2 decided by a frequency, and become ultrasonic beams 16 and 17. This signal is reflected by a floating microorganism such as plankton, and is received by the echo transducers 1 and 2. This received signal receives a Dappler effect by speed (v) of an ocean current, and a reflected signal received by the echo transducers 1 and 2 shows a frequency movement corresponding to ocean current speed. Therefore, a Dappler shift frequency [fd1=f1(2v1/c)] is realized. Here, [v1=vcos(θ+θ1)] is realized, and (v) is an absolute value of ocean current speed, andθis the direction of the ocean current speed, and therefore, v1 is found. Similarly, fd2 is measured, and v2 is found, and vector speed (v) of an ocean current is found from v1 and v2 by a simple calculation. |
