There is discloses a new method for identifying an electromagnetic signal having a known waveform. The method includes using a lightning matched filter receiver having a bank of filters matched to nominal but arbitrary lightning waveforms for detecting lightning. The use of a lightning matched filter receiver facilitates detection of lightning discharges below the noise level. Positioning three or more monitoring stations at different spaced apart geographic locations where each monitoring station has a lightning matched filter receiver where the filters are matched to nominal but arbitrary lightning waveforms can be used to detect and determine the location of a lightning discharge.