Abstract: A method for controlling the magnetic field value within a specific volume subject to an external ambient magnetic field wherein detection means detecting the value of the ambient magnetic field in the volume is included, together with compensation means for nulling the ambient field in the volume within a predetermined compensation range. The method and apparatus includes use of a deperming means for inserting a magnetizing field independent of the compensation means into the volume whenever the value of the ambient magnetic field detected becomes greater than the predetermined compensation range.

Abstract: A method and apparatus for controlling the magnetic field value within a specified volume, subject to an external ambient magnetic field, wherein the method and apparatus employ a plurality of magnetic field sensors and an associated plurality of coils, together with an electrical drive circuit connecting each of the sensors to the associated coil and including a feedback coupling the output of each of said coils to all of said sensors.

Abstract: A method and apparatus for controlling the magnetic field value within a specified volume subject to an external ambient magnetic field wherein the apparatus includes a number of magnetic field generators each associated with one of a number of magnetic sensors. The disposition of the magnetic field generators with respect to one another and to the associated sensors is such that the total effect of current selectively applied to the generators is to produce within the volume a magnetic field in opposition to the ambient external magnetic field.

Abstract: An improvement to sustain drive circuitry for an AC plasma display panel wherein the sustainer signal applied to panel electrodes is simplified to comprise a sequential series of square waves. The actions of writing, selectively erasing and bulk erasing of light emissions in cells of the plasma panel are also performed by combinations of square wave signals generated in sustainer and driver circuits of the device. A combination of integrated circuits comprise both the X and Y axis drivers with the Y axis drivers also including an internally generated Y axis sustain signal onto which Y axis write or erase signals are impressed. The prior art requirement of floating supply voltages is removed and the number of supply voltages is decreased such that all driver and sustainer circuits utilize a common power source, with a maximum of three source voltage levels for operation of all sustainers, drivers, address inputs and logic and timing control of the circuitry.

Abstract: Complex waveforms used to control a plasma panel are formed as sequences of common elemental waveform modules. These modules are combined in various orders into strings capable of performing various functions on the plasma panel. Large scale parallel addressing is accomplished by forming a string of several sustain modules, followed by a write or erase module.

Abstract: An electronic control system allows control over the safe operation of an aerial work platform machine. The control system uses a firmware programmed digital processor to execute a sequence of steps to monitor and control the safe operation of the work platform machine so that tipping and damage are prevented. The control system has sensors to measure the condition of the work platform machine and has outputs allowing control over the work platform machine.

Abstract: A constant data rate brightness control for an AC plasma panel is disclosed in which a waveform ROM is used to store two groups of control signals. The first group performs sustain, write, erase, and bulk-erase functions in a normal manner emitting two pulses of light per cycle. The second group performs the same functions with emission of substantially no light. By mixing functions from the two groups and varying the ratio of the two groups, a broad range of variable brightness in the operation of the plasma panel is achieved.

Abstract: A signal pattern recognition system includes a reference pattern memory storing plural reference data patterns against which input patterns are compared for recognition. The reference data patterns are formed by merging training patterns together. Each training pattern, to be accepted for merging, must match the previously merged patterns by a threshold amount. The threshold is automatically varied as the number of previously merged training patterns increases. If a predetermined number of successive training patterns is below the threshold, the training process is repeated, from the beginning, for the reference pattern which generates the errors. The system automatically trains each reference pattern with the same number of training patterns to assure uniformity when input data patterns are compared for recognition.

Abstract: A signal encoder and classifier particularly adapted to speech recognition includes a circularly addressed buffer which is independently addressed by a new data writing address system and a buffered data reading system so that writing and reading of data may be accomplished on a time shared basis. This time shared operation permits serial writing and reading of the pattern data without interrupting income signal storage. The writing data address system addresses the data into the buffer in a circular fashion while the reading data address system utilizes stored addresses identifying the beginning and end of the signal patterns for addressing sequential patterns from the buffer.

Abstract: A remote sensor for the measurement of the amount of gas present in the drilling fluid or "mud" in an offshore well-drilling operation, for the purpose of giving prompt warning of geologic conditions conducive to the occurrence of a blow-out. An acoustic projector projects an acoustic wave of fixed wavelength through the mud returning upwardly from the borehole. The wave is received by a first array of acoustic receivers locked in a known phase relationship with the projector. Changes in the speed of sound due to changing relative amounts of mud and gas produce a shift in frequency of the acoustic wave which is proportional to the speed of sound in the mud/gas mixture. The change in frequency is electronically detected and scaled to yield the value of the speed of sound, from which the mud to gas mass ratio is calculated by means of a computer.

Abstract: Sustainer drive circuitry for an AC plasma display panel wherein a multiple level sustainer signal is applied to panel electrodes along one axis only. The sustainer circuit includes a pair of series connected NPN pull-high and pull-down output driver transistors which (a) are respectively driven by low voltage drive circuits isolated from the NPN output driver transistors by capacitors; (b) respectively charge up the panel to a relatively high voltage and discharge the panel to ground; and (c) include a feedback network for limiting the rise time of the high voltage across the panel for reducing noise and electromagnetic interference. Diode circuitry insures that these output driver transistors are turned on and off without ringing and are never driven on simultaneously. A common voltage supply provides both (a) the write pulse level and (b) the write pedestal level of the sustainer waveform.