The new Fisher Impulse AQ is doing something new with pulse induction discrimination. I think I have a pretty good idea of what the engineers are up to and so want to pass on my thoughts in case it will help people have a better idea of what to expect. I have posted numerous articles in the past about coin detecting with ground balancing PI detectors. GBPI detectors split targets into two classes depending on the ground balance setting. The two target classes exhibit by different tones. All