SYSTEM FOR LOCATING THE SOURCES OF WIDE-BAND DE DT FROM LIGHTNING/

A system has been developed to measure wideband electric field derivat ives (dE/dt) at five ground stations in a 15 km x 15 km network at Ken nedy Space Center. Individual station responses are normalized using d igital filters. Pulse-timing resolution is improved to much less than the 50-ns sample interval by interpolation using packing in the freque ncy domain. A time tag for each pulse is defined as the mean of the ti mes of the rising-edge half peak, peak, and falling-edge half peak. Th e standard deviation in these times defines the timing error and is sh own to be a function of noise and bandwidth rather than digitization r ate. Each of the four unknowns for a pulse source location (x,y,z) and time of occurrence (t) is found from the five time-tag measurements u sing different weightings for all five combinations of the four-statio n hyperbolic equations. Weighting factors and errors in x,y,z and t ar e estimated using error propagation techniques.