Design and Initial Testing of a Three-Axis Current Meter

A prototype of an attended 3-axis acoustic current meter/CTD has been built and has undergone extensive laboratory testing. In addition to a conventional CTD sensor head, the instrument includes transducers for measuring current velocity along three paths, three components of earth magnetic field and three components of acceleration. Reported here are results of testing the velocity sensors in a tow tank. A noteworthy feature of the instrument design is that the acoustic paths, along which the current velocity is measured, are arranged so that disturbance of the measured flow by supporting struts or by the sensors themselves is greatly reduced. Estimated errors in the velocity measurements are found to be characteristically on the order of a few tenths of a percent at a speed of 40 cm/sec.