A lightning location sensor determines angle of incidence and precise arrival time (accuracy better than 100 nanoseconds) of the electromagnetic field pulse emitted by the discharge.

 
LS 7000 Sensor

In the direction finder (DF) two crossed magnetic loop antennas are used to measure the north-south and east-west component of the magnetic field and an electric flat plate antenna is used to determine the field polarity. The signal waveform of the magnetic loop antenna is also used to distinguish between cloud to ground (CG) discharges and other signals like intra- and intercloud lightning. The angle of incidence of the field of the lightning return stroke is calculated from the ratio of the signals from the magnetic loop antennas as shown in Fig. 1.

 
Fig. 1: Principle of flash localization

To discriminate CG and CC signals from any other signals, the so called "Waveform Discrimination" is used. Waveform discrimination is a check of several criteria a field waveform has to satisfy. With this method, field signals from CG return strokes can be selected with high confidence from all the signals received by the sensor.