Abstract: A doppler sonar speed measuring system incorporating a digital adaptive filter responsive to the difference in newly received raw speed data and previously received speed data to determine the amount and sign of change of the previously received data. The allowable amount of change increases to a maximum allowed value if the sign of the change remains the same on successive received data as under acceleration conditions and reduces to a minimum value when the sign changes on successive received data.

Abstract: A ship-borne sonar heave compensation system measures the heave at time of transmit and at the expected time of receive of a bottom-echo which is approximated by the previous depth determination corrected for heave. Using these values of heave, the depth of the detected bottom-echo is corrected to provide the true depth corrected for heave. A chart recorder reads out from memory the sonar return signals, including the bottom-echo, corrected for these heave values to present a true picture of the bottom contour.

Abstract: An electrolytic measurement system incorporating a probe for the measurement of the conductivity of fluids such as sewage and other industrial effluents. The probe has a smooth surface to passage of the fluid with flush-mounted electrodes arranged serially along the passage. The passage is formed within material that is an electrical insulator and is surrounded by a metallic shield symmetrically positioned with respect to the ends of the serially arranged electrodes. An electric potential is impressed between the outer electrodes and the shield, the latter being grounded, while an inner electrode is used for the measurement of electric current flowing through the fluid from the outer electrodes to the inner electrode.