John,
S.A.T.: Self Adjusting Threshold. This is a circuit that maintains the threshold settings as you sweep the coil over ground. Changes in ground makeup alter the threshold as you sweep. With S.A.T. it does the circuit re-setting for you. The Deepstar, Aquastar, and the Goldquest SS, have a control the user can adjust, to change the rate of when the circuit re-sets automatically.
Most detectors today employ S.A.T., VLF, and PI.. It is the motion needed, in the motion mode. Without motion, the S.A.T. tunes out the target, trying to maintain the threshold. In no motion pin point, as in some VLF detectors, that turns off the S.A.T. so you can pin point easier.
With the adjustable S.A.T. control, one can set up the threshold re-set speed for the different hunting conditions encountered while detecting. With slower S.A.T. speeds, one can detect targets deeper than they can in the same instance with a fast S.A.T., because your giving the circuit more time to analyze the signal. The trade off is that the ground will also have a affect. Tougher ground generally requires a faster S.A.T..
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