Abstract: My invention relates to ship'logs and speedometers, comprising magnetometers and associated circuitry located inside the hull of the vessel, for accurately sensing, indicating, and recording the revolutions of an external rotator equipped with a small permanent magnet assembly. The rotator with a low-friction bearing arrangement is suitably located outside and below the hull of the vessel so that its rotation accurately registers the movement of the vessel through the water. The elimination of any mechanical or electrical connection between the rotator and the inside sensing components of the magnetometer assembly facilitates removal of the rotator for maintenance and substantially reduces the risk of leaks through the hull of the vessel.

Abstract: A digital data processing arrangement for providing automatic substitution of a spare memory module for a malfunctioning portion of the system memory is disclosed. The substitution takes place in a manner transparent to the software programs being run in the processing system. The system memory is organized as a plurality of memory modules, each having an identical number of individually addressable words. A particular module is enabled on receipt of an appropriate signal via a dedicated lead from the system processor unit, while a particular word within that module is specified by an address received via an address bus running to address decoder units at all modules. When the error detection and identification routines of the system processor determine that a particular module is malfunctioning, a hardware register and accompanying comparison logic are arranged such that a spare module is accessed whenever the particular malfunctioning module is subsequently addressed.

Abstract: A water-proof air-pressure equalizing valve for an enclosure capable of being pressurized to match a wide range of ambient air pressures including that corresponding to the pressure of several feet of water when totally submerged, such as the instrument housing of a military-type field telephone set, comprises a sandwich structure having a thin air-permeable hydrophobic membrane clamped between two rigid perforated sheets providing mechanical support against deformation due to water or air pressure.

Abstract: An arrangement for preventing false reseizures of loop-signaling, repeat coil-coupled interoffice trunk circuits for telephone switching systems is disclosed. In the prior art, false reseizures of an incoming trunk circuit can be caused by discharge of the midpoint capacitor at the facility side of the repeat coil bridge of an associated outgoing trunk circuit at the opposite terminus of the interoffice trunk facility. During the talk state, this midpoint capacitor is charged approximately to the signaling battery supply level with polarity such that, upon termination of the talk state and accompanying tip-ring reversal, the capacitive discharge is sufficient to re-operate the supervisory relay in the distant office incoming trunk circuit, thereby generating a false reseizure attempt.

Abstract: An electronic hybrid circuit for coupling a two-wire communication path with a four-wire communication path is disclosed wherein the use of transformer coupling is eliminated. The hybrid features a novel arrangement whereby the unbalanced four-wire path incoming voice signal is amplified, then converted to a pair of balanced signal components by complementary signal injection devices coupled to opposite sides of the two-wire path. Each resultant balanced component is injected in series with a DC battery feed potential via current amplifiers in each signal injection means. Balanced two-wire path output signals are converted for transmission to the outgoing portion of the four-wire path by coupling the two-wire path to the series combination of a differential amplifier and an output buffer amplifier.

Abstract: A regulated voltage converter utilizing an improved method of pulse width modulation is disclosed wherein acceptable current balance and limiting in the converter switching elements are speedily achieved within one half cycle of converter operation. Converter output current is monitored, shaped according to a non-linear transfer function, and integrated to form a voltage signal for comparison with a predetermined reference level. When the integrated signal exceeds the reference level, a control signal is generated to terminate the current pulse in the inverter section of the converter. The inherent balancing and limiting characteristics of this arrangement are easily extended to applications wherein multiple converter stages are paralleled to supply higher power to a common load.

Abstract: A transformer-coupled power switching device control arrangement utilizes an active feedback energy source connected to the primary of the coupling transformer to enhance the turn-off drive to the power switching device. The active feedback energy source produces an output directly dependent upon the magnitude of the power switching device output current and independent of the duration of said output current. When the output current drops to zero, the active feedback source is disabled, and a bias network is connected to the transformer primary. The bias network maintains a reverse voltage at the control electrode of the power switching device and establishes a bias current through the primary suitable for resetting the transformer core flux.

Abstract: A transformer-coupled transistor base drive circuit is disclosed wherein the transformer primary control circuit includes a switching transistor, a bias supply, and a RC biasing network arrangement. The biasing arrangement is designed to ensure that the transformer core will never enter the positive saturation region of its hysteresis characteristic; regardless of variations in the power transistor duty cycle. The base drive circuit also features provision of high sweep-out current in the power transistor base during turn-off, reverse base-emitter voltage during the power transistor off state, and regenerative current drive to minimize storage time and to control the bias power drain.

Abstract: A virtual encoding scheme for use in random access memories is disclosed. Data errors, incorrect memory word access errors, and errors resulting from multiple memory word access are all detectable through use of the encoding scheme. The novel approach includes the generation of two distinct check code fields which are stored along with the data. A first check code field is generated as a function of the data and is capable of reflecting all unidirectional data failures. A second check code field is generated as a function of the address of the memory word containing the data and is capable of reflecting incorrect memory word access. The two check fields can be stored either in the same physical memory location as the data or in a supplementary memory at an address numerically identical to that at which the data is kept. During readout, the two check fields are regenerated and compared to those previously stored.