Abstract: A lightning detection system utilizes a gated magnetic direction finder for determining the range and direction of lightning discharges to ground. The magnetic direction finder is controlled by an electric field detector that includes logic circuitry for analyzing the waveforms of the detected electric field to determine whether the discharge is a ground stroke or other type of discharge, or background noise. The magnetic direction finder is gated by the electric field control logic circuitry so that a direction measurement may be made for a few microseconds after it has been determined from the electric field waveform analysis that a ground stroke has occurred. Different criteria are used for determining whether or not a stroke is a ground stroke depending on whether the stroke being analyzed is the first stroke in a flash or a subsequent stroke.