Place one or more (more demonstrative) pop-up target(s) via editor.
In init field of each of them add:
this setVariable ["nopop",true,true];
At this time you can have raised or lowered target with:
this animate ["terc",0] (raised); or this animate ["terc",1]; (lowered).
Choose to raise or lower target(s) (raised by default).
preview the mission
Situation of target(s) is stable (no more anim). They are lowered or raised as you chose.
Now, fired at a raised target. This will lower then raise it. Target is animated in its cycle even if nopop is true.
You can't randomize pops-up delay, like at a firing range. The situation is weird with several pop-up targets.