An Electronic Wave-Height Measuring Apparatus

摘要

This report describes briefly the salient features of new instrumentation for measuring and recording the wave amplitudes and wave forms of water waves. Because of the increased accuracy and flexibility afforded by the instrumentation described, it has replaced other techniques which were formerly used. The gaging element of this system consists of extremely small insulated wire, suspended rigidly upright in the water. The conductor acts as one plate of a capacitor and the water in which the gaging element is partially submerged acts as the other; the insulation material on the wire forms the dielectric of the capacitor. The capacity of this 'condenser' (measured between the conductor and water) is directly proportional to the linear length of the submerged portion of the wire. This capacitor is connected in one arm of a resonant-bridge circuit, which may be balanced for the quiescent level of the water. Variations in water height which occur as waves pass the gaging element produce capacitive unbalance of the a-c bridge in each sense, and the direction of unbalance is recovered by a more or less conventional phase sensitive demodulator circuit incorporated in the circuit of the wave-height recorder. This report includes schematic wiring diagrams of the instrument, its power supply, and a direct-coupled amplifier suitable for driving the recording galvanometer in a Sanborn direct-wiring recorder. (Author)