I use an AT PRO have had it about a month and have these questions...when I'm swing my coil sometimes various numbers come on the screen but make no noise...then sometimes it makes all kinds of noise with various numbers...Garrett sent me another coil but it still does this...I turned the sensitivity down 3 bars which helped on the chirping ..but the varying numbers confuse me...am I just a newbie or is it something in the box?...also when I find something it will give me a certain depth...but if I pinpoint it with the AT PRO it gives me a different depth...any input is greatly appreciated