Multiple targets produce multiple signals. Mixed targets provide mixed signals. Simply put, the detector is processing the information of each target separately when they are adjacent. When one target is "covering" another, the detector is only capable of identifying the target(s) that the eddy currents are being created from. For example, if you laid a very small nail on top of a quarter, with the quarter "sticking out" on all sides of the small nail, you will get a mixed target response that represents the eddy currents created by the nail and by the portion of the quarter that is "sticking out" beyond the nail. However, if you put a smashed aluminum can completely over a quarter, you will only get the signal response of the can because the quarter does not receive the transmit signal, in order to generate eddy currents of it's own. If you had four or five coins all touching each other in the same hole, you will get a target response based on the composite value of that target. For example, more silver coins would make it a higher response and more nickels would make it a lower response. If they are in the same hole but not all touching, the signal received will be mixed, based on the values of each grouping of targets. In the example you provided, the boot buckle was above the coins, telling the detector that there was a low conductive target under the coil. But apparently enough of the coin surfaces were within reach of the transmit signal from the coil that informed the detector that there were other eddy currents being generated. JMHO HH Randy
