See those hand held have to be activated all the time by pushing a button on the electronic callers are riflemen predator calling tools..
You need one of the type that once you turn it on it keeps playing and you walk down wind with your shotgun. the predator comes from the down wind gets in direct line with the loudest part of the speaker and comes to the call. Your waiting down wind but set up cross wind with your red light to act as a shield and when the predator passes your position en route to the caller you shoot it...
When I use mouth calls.. Most times that is when I use the rifle and shoot them farther down wind as they make their arc..
Also as the wind picks up more velocity the scent will not reach the predators.. So just say past 15 MPH scent is not a problem.
Now you have to compensate and use louder sounds too carry in the wind..The Jack Rabbit and Canine sounds..Gray Fox Pup, red Fox Pup, Coyote Pup, Gray Fox with rabbit, Red Fox with Rabbit, Coon with bird, Not field mice, quail, voles, etc etc...
you need to read Dennis Kirk book "Everything You Want To Know About Fox Hunting!"
www.huntsmart.com It gives good set up info for the new caller...
If you just can remember what I said: They come into the wind.. They will always get in line with the loudest part of the sound, and they will use paths of least resistance.. So set up when your using your mouth calls that when they come into view they will start to make an arc and head for the down wind sound and then come into the wind and get in direct line with the loudest part of the sound...Now the rifle person then shoots them before they get int line with you the caller.