Abstract: In Aug. 1984, we observed lightning discharge radiation in Hefei, Anhai Province by using the lightning digital receiver developed by ourselves. The signals were processed by digital filter. Fourier translation and so on with microcomputer. One group of the signals has obvious return strokes, and the other not. 21 typical signals were selected as examples. Some characteristics of signals and their amplitude frequency spectrum were drawn, and were compared with theoretical and other analogue observational results