trig_fall :
A trigger generator for an xreal-typed signal’s falling events.

The trig_fall primitive generates an xbit-typed trigger out when an xreal-typed signal in has the (N+k*P)-th event falling above a given threshold after a specified delay, where k is 0, 1, 2, and so on. The threshold, triggering count N, period P, and delay are defined by the parameters threshold, times, period, and delay, respectively. When the parameter times is less than or equal to 0, the primitive triggers out whenever in falls below the threshold after the delay. This primitive is equivalent to the trig_cross primitive with the direction parameter set to -1.

The xbit-typed trigger out can be used as an input to the measurement primitives to measure the time instants, delays, periods, etc. of the triggering events. The trigger signal is initialized to X and changes to 1 when the first event occurs. The trigger output out then toggles to a different value (0 or 1) whenever a subsequent event occurs.

Input/Output Terminals

Name	I/O	Type	Description
out	output	xbit	output trigger
in	input	xreal	input signal

Parameters

Name	Type	Default	Unit	Description
threshold	real	0.0	None	threshold level
delay	real	0.0	seconds	triggering delay
times	integer	0	None	triggering count
period	integer	0	None	triggering period