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: 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.