Figure 1 shows a block diagram of the AS3935. The external antenna is directly connected to the Analog Front-end (AFE), which amplifies and
demodulates the received signal. The watchdog continuously monitors the output of the AFE and alerts the integrated lightning algorithm block in
the event of an incoming signal. The lightning algorithm block validates the signal by checking the incoming signal pattern, calculates the energy
and then the AS3935 provides the MCU with an estimate of the distance to the head of the storm. The lightning algorithm block, processing the
demodulated signal, can distinguish between lightning signal and man-made disturbers. If the received signal is classified as a man-made
disturber, then the event is rejected and the system automatically goes back into listening mode to minimize current consumption. If the incoming
signal identifies a lightning event, then the statistical distance estimation block performs an estimation of the distance to the head of the storm.
The LC oscillator together with the calibration block can calibrate both the TRCO and the SRCO clock generator to compensate process
variations.