How c_scan work?

I want a camera to be set if player enter the yellow circle, but by the F1 guide I haven't undersand nothing, someone can create an example?
I've this code now, and only one camera work (and not good).
Code:

---

action detect_player
{
	my.invisible = on; // hide the model
	my.passable = on;
	while (player == null) {wait (1);} // wait until the player is loaded
	if (my.cam_number == 0) {beep; beep; beep; exit;}
	if (my.cam_range == 0) {beep; beep; beep; exit;}
	while (1)
	{
		temp.x = 360; // horizontal scanning angle 
		temp.y = 180; // vertical scanning angle
		temp.z = my.cam_range; // scanning range
		c_scan(my.x,my.pan,vector(120,180,my.cam_range),SCAN_ENTs);

		if (result > 0) // got something?
		{
			set_camera(my.cam_number); // then set the proper camera position and angles
		}
		wait (1);
	}		
}

---

More from one AUM

try it with my example i use for my game

ACTION Metal_Opties
{
my.invisible = on; // so it is hidden
my.ENABLE_SONAR = on; //activate sonar
my.event = pickup_event; //event call
}

function pickup_event()
{


if (event_type == EVENT_SONAR) // if you get in the sonar
{

beep;
beep;
beep;

}
}


Try this maybe it is what you want.