Abstract: A synthesizer for complex acoustic signatures includes a generator for an ectrical analog of a complex acoustic waveform corresponding the the "shaft rub" noise produced by the interaction of a marine propeller shaft and a stern tube or other through-the-hull marine fitting. This circuitry employs digital random generators to produce a nonrecurring characteristic signal synthesizing this acoustic noise. An arrangement to process this signal with other simulation circuitry is also disclosed.

Abstract: An underwater acoustic communication system provides an operator with adjable frequency diversity so that data rates may be tailored to specific multipath environments. Transmitted messages are sent with precursor transmission/reception synchronization data and transmission parameter data so that the receiving communication end will recognize when message data starts, tone length as-well-as the frequency diversity of the transmitted message. Timing is extracted from the data to compensate for Doppler shift.

Abstract: An adaptive slant range compensator, suitable for use with an optical mapg system for remote viewing, comprises a logarithmic amplifier which compresses an analog input signal having a wide range of values to a tractable range. An analog-to-digital (A/D) converter converts the compressed signal to a 10-bit binary number. The digitized compressed data is then used to address antilog programmable read-only memories (PROMs) which contain the antilog of the address data in scientific notation. Control and data processing circuits are used to accumulate sample scans from the antilog PROMs in a summing memory, calculate an average scan from the accumulated sample scans, and transfer this average to a working memory. The data stored in the working memory is used to drive an attenuation/amplification network that divides succeeding scans by the stored average scan. In this way, the inverse transfer function is applied to the analog input signal, which forms another input to the attenuation/amplification network.

Abstract: A submarine power package converts direct current electrical energy to alnating current energy and is adapted to function while exposed to the high pressures of the deep ocean. A diode protection circuit and special semiconductor mounting arrangement makes this performance possible without the use of a pressure housing.

Abstract: In a diver's navigation system employing a receiver having three equal, alarly disposed hydrophone locations, a digital signal processing circuit is employed which receives frequency shift keyed digital data from remote beacons. Circuitry is provided to process this data to derive a bearing indication to the beacon.