Abstract: A system and method are provided for multiplexing/demultiplexing asynchros high-speed digital data and asynchronous low-speed digital data. A first digital signal processor (DSP) receives complete low-speed data messages and is programmed to assemble each complete message into data blocks in accordance with a block format. Each data block is identical in size and includes provisions for a header that identifies the data assembled therein. A second DSP has a plurality of I/O ports, each of which has a direct memory access (DMA) associated therewith. One of the I/O ports is coupled to the first DSP to receive each complete message assembled into data blocks. The other I/O ports are coupled to a second plurality of channels transmitting asynchronous high-speed digital data. The DMAs associated with the other I/O ports are configured to assemble the high-speed data into data blocks in accordance with the same block format used for the low-speed messages.

Abstract: A telephone system for use by divers employing demand breathing apparatus. ounds picked up by each diver's microphone are processed by selective filtering, amplification, rectification and comparison to a reference voltage level to provide logic signals representative of presence or absence of inhalation noise that could mask voice transmissions of other divers or of a tender. The microphone output to listening stations is switched through an attenuation path by the logic signal representing inhalation noise and through a by-pass or full strength path by the other logic signal.

Abstract: Relative phase and sensitivity characteristics of individual transducer eents in a long acoustic array are determined by sequentially positioning a transmitting element in predetermined spaced relation to each array element by means of an array holding member and a trough-like spacing member that contains a known transmission medium, driving the transmitting element with a test frequency input signal that is pulsed at a predetermined repetition rate, gating the output signal from the array element under test to an oscilliscope for phase comparison with an adjustably phase shifted version of the input signal, and measuring amplitudes of both input and output signals.