| If the peak to peak distance Δ t is less or equal to 0.04 s, then the pulses in between are evaluated as one flash. If this distance Δ t is longer only the flash with the highest effective intensity is valid. Moreover, the period is limited depending on the ratio between the effective intensities of the flashes within a group (IH= max. effective intensity of the highest peak, IL = max. effective intensity of the lowest peak) as follows: | a0c0 |