From original forum post 5/27/2008 updated 2/14/2010, 1/13/2013 and 1/3/2014 The White’s PulseScan TDI is a ground balancing pulse induction (GBPI) metal detector and as a rule these detectors are considered “dig-it-all” type detectors. The TDI, however, has a number of manual controls that can be adjusted to allow for a degree of discrimination not normally found in PI units. Most normal pulse induction (PI) detectors have a monotone audio response on targets. In other words, the soft