New lightning flash counter and calibration circuit with improved discrimination of cloud and ground discharges

A low-power lightning flash counter (LFC) utilising active elements (Micropower ICs) is presented. Better discrimination is achieved by using a narrow frequency band, centred around the 10 kHz according to the CIGRE specification. A simple circuit for producing double exponential pulses of variable rise times, accompanied by a modified in situ testing circuit which gives a more definite state of the batteries and calibration stability of the system, is used to calibrate various types of counters including the improved LFC. Experimental and theoretical determinations of the response characteristics of the active and CIGRE counter networks show a better discrimination for pulse signals than for sine signals, and an improved discrimination of the cloud and ground discharges by the active network over the passive conventional networks