Abstract: An underwater viewing system suitable for providing images of an area around an underwater lure is described. The system includes a video camera coupled, via a cable, to a display. The cable has a plurality of electrical leads twisted about, and electrically isolated from, each other. Surrounding the electrical leads is an outer shield comprised of a plurality of stainless steel strands. The shield, and thus the cable, has an outer diameter less than 0.070 inches.

Abstract: An A/D converter includes a limiting circuit for limiting the amplitude of bipolar input signals. A comparator compares the amplitude limited signals with reference voltages and provides pulse output signals corresponding to the duration of each half-cycle of the bipolar signals. The pulse output signals are applied to a counter circuit which counts clock pulses for each of the half-cycle intervals to provide a digital word for each half-cycle of bipolar signal information which accurately indicates the duration of each half-cycle of the input signal. The A/D circuit is employed, in one embodiment of the present invention, with a microprocessor programmed to analyze the engine speed signals from a tachometer according to a prescribed relationship to provide output information useful for predicting when engine maintenance is required.