Abstract: The disclosed full-duplex communication system includes a pair of full-duplex modems, one at each end of a two wire circuit. Each of the modems includes a transmitter for transmitting over the two wire circuit a stream of synchronous data at a first carrier frequency, and a receiver for receiving over the two wire circuit a stream of synchronous data at a second carrier frequency. The receiver includes means for coherently demodulating the stream of synchronous data. In a preferred embodiment, an asynchronous-to-synchronous converter converts asynchronous input data into a stream of synchronous data for transmission by the transmitter. Also, the preferred embodiment transmits the data and receives the data as double side band suppressed carrier quadrature amplitude modulation. The system includes a remote test capability for automatically looping back test data for comparison with the transmitted test data.

Abstract: In a building construction method a plurality of building segments are coupled together and raised in unison from a central control point via a crane. The crane has a plurality of lifting cables selectively driven from a plurality of winches under the control of the operator. The building segments are pivotably coupled together for lifting into position and for locking together to form a rigid self supporting building structure. Successive layers of the building are hoisted into position via detachable pulleys affixed to the previously raised building segments.

Abstract: A decompression analog computer and indicator includes an ambient pressure sensing chamber exposed to hydrostatic pressure as experienced by the diver. The pressure in sensing chamber produces a flow of fluid between the sensing chamber and a pair of parallel connected second chambers via the intermediary of first and second diffusion membranes introducing a delay to simulate different tissues of the body. Each of the second chambers has a movable wall portion operatively connected to a spring biased pressure responsive indicating piston. The indicating pistons move to and fro in a track overlying at indicating scale visible to the diver. The indicators indicate uptake and release of nitrogen by different tissues within the body and indicate to the diver when decompression is necessary.