Abstract: A wave measuring buoy for measuring ocean surface wave amplitude and frequency is disclosed. The buoy includes a single-axis accelerometer suspended as a pendulum inside a water-proof housing. The waterproof housing is connected to and beneath the flotation hull of the buoy and is located at the center of rotation of the buoy assembly so that the accelerometer is substantially insensitive to roll and pitch motions of the buoy. The output of the accelerometer is an analog signal proportional to the vertical (heave) acceleration of the buoy. A frequency transfer calibration can be applied to the accelerometer output to compensate for the mass, size and resonant heave behavior of the buoy.

Abstract: The thickness of a layer of oil on water is obtained in digital form, which in one embodiment is recorded on a visually identifiable analog type display chart. An underwater ultrasonic transducer arrangement produces and receives pulses, which are digitalized and processed in a digital computer for thickness calculation and organization for the display. To handle a wide range of signal conditions that need be detected at various interfaces, such as water to oil and the oil to air, a dynamic threshold is computed that permits the detection and processing of signals appearing at two diverse interfaces in conventional signal processing circuits that therefore can handle a large range of different signal conditions, thus permitting measurement of the thickness of a liquid layer of oil on the surface of water. The thickness of other fluids interposed between fluids having dissimilar acoustical properties can also be obtained.

Abstract: A net blocking a stream or canal to prevent fish from traveling up the stream but permitting the normal flow of water and having a normally closed opening therein adapted to be opened by trash and debris carried by said water to permit said trash and debris to pass therethrough.