sends out a sync signal when the slope (steepness, delta) of the analyzed wave is larger or smaller than a defined value.

signal input: input to look at
sync output: output for impulse
mode: what to trigger the impulse: positive = when positive slope is above threshold (below), negative = same, but negative, zero = when the slope is zero, horizontal/silent, cycle = when it has changed sign two times, from positive, then negative, for counting waveform cycles.
threshold: the threshold to cross, depending on mode
decay: