Abstract: A lightning strike detection and mapping system which determines the range and bearing of each valid lightning strike by (1) computing the Fourier Transform, and more preferably the discrete Fourier Transform (DFT) of the X and Y waveforms, classifying the lighting strike based on the DFTs, and estimating the range of the lightning strike based on a type-dependent weighted sum of the DFT coefficients; (2) detecting whether the X or Y waveform is a doublet waveform and classifying the lightning strike based on the detection of a doublet; (3) performing range correction based on type classification and tail activity; and (4) reconstructing clipped waveforms in order to extend the dynamic range of the system.

Abstract: A system for classifying detected lightning strikes detects signals representative of a lightning strike and processes such signals to generate a frequency signature thereof which is used to classify the lightning strike represented by the detected signals into a type. In a preferred embodiment, the type is selected from a plurality of predetermined types based on the frequency signature. In an alternate embodiment, a pulse width of the lightning strike is determined from the detected signals and used in combination with the frequency signature to classify the lightning strike into its type.

Abstract: A sampled data lightning strike detection and mapping system receives a signal waveform representative of a lightning strike and digitizes samples of the waveform to generate a train of digital data samples. The digital data samples are monitored to identify a trigger sample which exceeds a predetermined threshold. The trigger sample governs the commencement of processing of digital samples of the train for detection and mapping of the lightning strike. Upon determination of an invalid lightning strike from the digital data samples, the processing is aborted and the monitoring operation resumed until a next trigger sample is identified.

Abstract: A sampled data lightning strike detection and mapping system receives first and second signal waveforms representative of a magnetic field, and a third signal waveform representative of an electrical field, the first, second and third signal waveforms each including a pulse shaped portion and a trailing shaped portion. Samples of the first, second and third signal waveforms are digitized to generate first, second and third trains of digital data signals representative of their respective signal waveforms. A sample which exceeds a predetermined threshold level from the first and second trains is identified as a trigger sample and the train including the trigger sample is designated as the trigger train.

Abstract: An apparatus for providing a map-like display of weather phenomena such as lightning discharges, in which the distance from an observation location to the source of the discharge is determined from the ratio of the integrated intensity of two different components of lightning produced signals, the intensity of the first component varying as the inverse of the distance and the intensity of the second component varying as the inverse of the square of the distance.

Abstract: An apparatus for providing a map-like display of weather phenomena such as lightning discharges, in which the distance from an observation location to the source of the discharge is determined from the ratio of the integrated intensity of two different components of lightning produced signals, the intensity of the first component varying as the inverse of the distance and the intensity of the second component varying as the inverse of the square of the distance.

Abstract: A storm mapping system detects electrical activity caused by weather phenomona such as lightning strokes, and the like and displays information related to the electrical activity indicative of storm location in a frame of reference in which the observation location is taken as the origin. In order to give the observer good spatial understanding, signals detected from a relatively close disturbance (which produces relatively large signals) are displayed relatively close to the observation location as compared to display of signals generated from a relatively further disturbance which produces relatively smaller signals which are displayed relatively far from the observation location. The limited resolution display is effectively driven by signals read from digital storage wherein mapping between the different display segments and digital storage is maintained.

Abstract: The present invention provides an improvement in a "solvent stretch" process which renders it possible to transverse stretch a microporous film prepared from a precursor film which has been previously uniaxially stretched in a direction perpendicular to the intended transverse stretching direction to thereby improve the permeability of the microporous film while also improving the balance of mechanical properties thereof in both directions of stretch.The improvement lies in uniaxially stretching the precursor film to form a microporous film having a specifically defined permeability as measured by the Gurley test. The requisite permeability of the uniaxially stretched microporous film is obtained by selecting the polymer employed to prepare the precursor film based on certain specifically defined property requirements and by employing specifically defined process conditions during uniaxial stretching.

Abstract: A speed sensing tachometer is built into the end bracket or end bell of a variable speed dynamoelectric machine such as a DC motor. The tachometer is completely recessed and close to the bearing supporting the shaft to occupy a minimum of longitudinal space in the machine. Multiple poles are provided on the rim of the tachometer rotor fastened to the machine shaft and these poles cooperate with first and second Hall effect switches. An electrical circuit is also provided in the same recess in the end bracket and connected to the Hall switches so that the output from the stator of the tachometer includes both a digital and an analog signal output with rotational direction sensing. Such built-in tachometer permits the DC motor to be a double shaft extension motor so that a load, fan or brake may be mounted at each end.

Abstract: A phase-control type of closed-loop control system for motors. A reference signal generator generates a digital reference signal having a binary value which varies between first and second values n times during each a-c input voltage cycle. An error signal generator generates a digital error signal having a binary value which varies in accordance with the difference between the desired and actual values of a motor variable such as armature current. The most significant bits of the digital error signal are utilized to select the angular range within which firing signals will be applied to a phase-controlled rectifier network that is arranged to drive the motor. The least significant bits of the digital error signal are compared with the digital reference signal to determine the time, within the selected angular range, when firing signals will be applied to the controlled rectifier network.